Association of the triglyceride-glucose index with early-onset atherosclerotic cardiovascular disease events and all-cause mortality: a prospective cohort study

BACKGROUND

The association between the triglyceride glucose (TyG) index and the risk of early-onset atherosclerotic cardiovascular disease (ASCVD) events or all-cause mortality in young and middle-aged people is not fully elucidated.

METHODS

The present study included 64,489 young and middle-aged people who participated in the 2006 Kailuan Study physical examination. Multivariate Cox proportional hazards models and restricted cubic spline curves were used to assess the association of TyG index with early-onset ASCVD events and all-cause mortality.

RESULTS

During a median of 11-year follow-up, 1984 (3.08%) participants experienced at least one ASCVD event and 1,392 (2.16%) participants experienced all-cause death. A higher TyG index was significantly associated with a higher risk of early-onset ASCVD events (HR: 1.61, 95% CI 1.38-1.89) and all-cause mortality (HR: 1.39, 95% CI 1.17-1.65), respectively. For each unit increase in TyG index, the risk of early-onset ASCVD events increased by 20%. In addition, there was a non-linear association between the TyG index and early-onset ASCVD events (P for non-linear < 0.01), and a linear association between TyG index and all-cause mortality (P for non-linear = 0.476).

CONCLUSIONS

A higher TyG index is significantly associated with an increased incidence of early-onset ASCVD events and all-cause mortality in a young and middle-aged population from North China.

Aerosol-radiation interaction and its variation in North China within 2015-2019 period under continuous PM2.5 improvements

A study was conducted on aerosol-radiation interactions over six cities in this region within the 2015-2019 period. WRF-Chem simulations on 2017 showed that based on the six-city average, the aerosol load (PM2.5 concentrations) of 121.9, 49.6, 43.3, and 66.3 µg/m3 in January, April, July, and October, mainly lowered the level of downward shortwave radiation by 38.9, 24.0, 59.1, and 24.4 W/m2 and reduced the boundary layer height by 79.9, 40.8, 87.4, and 31.0 m, via scattering and absorbing solar radiation. The sensitivity of meteorological changes to identical aerosol loads varied in the order July > January > October and April. Then, the cooling and stabilizing effects of aerosols further led to increases in PM2.5, by 23.0, 3.4, 4.6, and 7.3 µg/m3 respectively in the four months. The sensitivity of the effect of aerosols on PM2.5 was greatest in January rather than in July, contrary to the effect on meteorology. Moreover, a negative linear relation was observed between daily BLH reductions and aerosol loads in fall and winter, and between PM2.5 increases and aerosol loads in all seasons. With the PM2.5 pollution improvements in this region, the aerosol radiative forcing was effectively reduced. This should result in daily BLH increases of 10-24 m in fall and winter, and the estimates in Beijing agreed well with the corresponding results based on AMDAR data. Additionally, the reduction in aerosol radiation effects brought about daily PM2.5 decreases of 1.6-2.8 µg/m3, accounting for 7.0%-17.7% in PM2.5 improvements.

Isotopic comparison of ammonium between two summertime field campaigns in 2013 and 2021 at a background site of North China

Ammonia (NH3) is the primary atmospheric alkaline gas, playing a crucial role in the atmospheric chemistry. Recently, non-agricultural emissions have been identified as the dominant sources of NH3 in urban areas. However, few studies have quantified the contributions of different sources to regional NH3. This study conducted two summertime field observations in 2013 and 2021 at a background site of North China to comprehensively explore the regional variations in concentration, nitrogen isotope composition (δ15N), and sources of ammonium (NH4+). The results indicate that NHx (NHx = NH3 + NH4+) concentration has increased in 2021, but the fNH4+ (NH4+/ NHx) has decreased significantly. The δ15N-NH4+ values show a significant increase, ranging from -4.7 ± 8.1 ‰ to +12.0 ± 2.4 ‰. The increase can be attributed to two primary factors: changes in fNH4+ resulting from the reduction of atmospheric acid gases and alterations in the sources of NH3. Bayesian simulation analysis reveals substantial variations in NH3 sources between 2013 and 2021 observations. Non-agricultural sources have significantly increased their contribution to NHx concentration, with vehicle exhaust and NH3 slip experiencing growth rates of 187 % and 104 %, respectively. Our results confirm the dominate contribution of non-agricultural sources to regional NH3 at the present stage and propose relevant mitigation strategies, which would provide essential insights for reducing NH3 emissions in North China.

Multiple Sulfur Isotopic Evidence for Sulfate Formation in Haze Pollution

The mechanism of sulfate formation during winter haze events in North China remains largely elusive. In this study, the multiple sulfur isotopic composition of sulfate in different grain-size aerosol fractions collected seasonally from sampling sites in rural, suburban, urban, industrial, and coastal areas of North China are used to constrain the mechanism of SO2 oxidation at different levels of air pollution. The Δ33S values of sulfate in aerosols show an obvious seasonal variation, except for those samples collected in the rural area. The positive Δ33S signatures (0‰ < Δ33S < 0.439‰) observed on clean days are mainly influenced by tropospheric SO2 oxidation and stratospheric SO2 photolysis. The negative Δ33S signatures (-0.236‰ < Δ33S < ∼0‰) observed during winter haze events (PM2.5 > 200 μg/m3) are mainly attributed to SO2 oxidation by H2O2 and transition metal ion catalysis (TMI) in the troposphere. These results reveal that both the H2O2 and TMI pathways play critical roles in sulfate formation during haze events in North China. Additionally, these new data provide evidence that the tropospheric oxidation of SO2 can produce significant negative Δ33S values in sulfate aerosols.

A regional cooperative reduction game model for air pollution control in North China

Due to variations in economic scale, economic structure, and technological advancement across different Chinese provinces and cities, the cost of air pollution reduction differs significantly. Therefore, the total reduction cost can be decreased by capitalizing on these regional discrepancies in reduction cost to carry out cooperative emission reduction. In this paper, taking NOx reduction in North China as an example, a regional cooperative reduction game (CRG) model was constructed to minimize the total cost of emission reduction while achieving future emission reduction targets. The fair allocation of benefits from cooperation plays a crucial role in motivating regions to participate into the cooperation. A comprehensive mechanism of benefits allocation was proposed to achieve fair transferred compensation. The mechanism combines the consumption responsibility principle based on input-output theory and the Shapley value method based on game theory. Compared to the cost before the optimized collaboration, the CRG model will save 20.36% and 13.71% of the total reduction cost in North China, respectively, under the target of 17.68% NOx reduction by 2025 and 66.44% NOx reduction by 2035 relative to 2020. This method can be employed in other regions to achieve targets for air pollution reduction at minimum cost, and to motivate inter-regional cooperation with this practical and fair way of transferred compensation.

[Changes in Health Risks and Pollution Sources of Atmospheric PM2.5-bound Metals in a Background Site in North China]

To explore the change features of PM2.5-bound metals in a background site of North China in the past ten years, 71 and 160 samples were collected from December 2011 to January 2013 (period Ⅰ) and from September 2019 to November 2021 (period Ⅱ) in Tuoji Island National Atmospheric Monitoring Station, respectively.The concentration of metals sampled was determined using ICP-MS, and the concentrations, sources, and health risks of heavy metals were compared. The results revealed that the average concentration of PM2.5 was (54.06±39.71) μg·m-3during period Ⅱ, which was 3.53 ng·m-3 lower than that during period Ⅰ. The concentrations of Zn, Mn, As, Pb, and V in stage Ⅱ decreased by 54.53, 172.63, 0.8, 79.06, and 3.81 ng·m-3, respectively, whereas the concentrations of Cr, Cu, Cd, and Ni increased by 2.01, 5.42, 3.03, and 3.55 ng·m-3, respectively. The PMF model results indicated that the biggest contributor to PM2.5-bound metal was industrial emissions (32.32%), followed by coal combustion (27.47%), vehicle emissions (23.70%), ship emissions (9.69%), and dust sources (6.83%) during period Ⅱ. The contribution ratio of dust sources and ship emissions decreased by 20.73% and 8.83%, respectively, whereas for coal combustion and industrial emissions it increased by 2.50% and 13.52%, respectively, when compared with that during period Ⅰ. The total carcinogenic risk induced by PM2.5-bound heavy metals of period Ⅱ increased, with the highest contributions by Cr and Cd. The total non-carcinogenic risk decreased, with Mn contributing the most. Therefore, in the process of air pollution control, the control of pollution sources of heavy metals such as Cr and Mn should be reinforced.

First record of cyst nematode (Heterodera filipjevi) on winter wheat from Shanxi Province in North China

Heterodera avenae, H. filipjevi, and H. laptipons are considered to be the major cyst nematode pathogens affecting most cereals and causing severe crop losses (Smiley and Yan 2015). In China, H. filipjevi was first recorded in Xuchang, Henan Province (Peng et al. 2010). Recently, H. filipjevi has been found in Anhui, Hebei, Shandong and Xinjiang provinces of China (Cui et al. 2021). To further understand the latest occurrence and distribution of H. filipjevi in China, a survey of cyst nematodes was conducted in the wheat planting area of Shanxi Province of North China from June 2018 to November 2020. White female cysts (5.8 ± 2.99 cysts per plant) were found on wheat roots in the sandy soil, and wheat was displaying symptoms of dwarfing, yellowing, and had few tillers in Licheng of Changzhi (N36°32´010´´, E113°27´039´´; N36°29´050´´, E113°23´023´´; N36°29´035´´, E113°22´020´´) and Zezhou of Jincheng (N35°33´057´´, E112°56´020´´) in Shanxi Province, and second-stage juveniles (J2s) were obtained from 13 soil samples using the sieving-decanting method. Four of the 13 samples were identified as H. filipjevi on the basis of morphological and molecular studies of female cysts and J2s. Morphologically, the cysts were lemon shaped and featured a pronounced vulval cone. The color ranged from light to dark brown. The white female shell was covered with a white crystalline layer. The vulval cone was bifenestrate with horseshoe-shaped bullae numerous and distinct, and a strongly developed underbridge. The main measurements (mean ± SD, range) of cysts (n = 13) were as follows: body length including neck 780.5 ± 53.9 μm (692 to 843 μm); body width 527.3 ± 55.5 μm (435 to 620 μm); length/width ratio 1.50 ± 0.21 (1.20 to 1.93); fenestra length 55.5 ± 4.1 μm (49 to 61 μm); fenestra width 24.8 ± 2.2 μm (21.1 to 28.8 μm); vulval slit length 9.0 ± 0.7 μm (7.8 to 9.6 μm); and underbridge length 66.8 ± 5.0 μm (61 to 77 μm). The measurements of J2s (n = 13) were as follows: body length 554.4 ± 23.4 μm (520to 587 μm); stylet length 22.7 ± 0.7 μm (21.5 to 23.8 μm); tail length 61.0 ± 5.5 μm (51.2 to 68.9 μm); and hyaline tail terminus length 37.3 ± 2.7 μm (33.4 to 42.3 μm). These morphological measurements are within the range characteristic of H. filipjevi (Peng et al. 2010). Genomic DNA was extracted from individual cyst (n = 6) and the rDNA internal transcribed spacer (ITS) sequence was amplified using the universal primers TW81 and AB28 (Joyce et al. 1994). The PCR test for each sample was repeated five times. The obtained ITS sequences (GenBank accession No. OQ421499 to OQ421502, 1054 bp) showed more than 99.5% similarity to those of H. filipjevi from the United States (GU079654 and KP878490), Turkey (KR704304 and KR704292), and China (MW789611, KY448473 and KT314234). The results were confirmed again by the species-specific primers HfF1 and HfR1of H. filipjevi and the target PCR fragments of 646 bp were obtained (Peng et al. 2013). The pathogenicity of H. filipjevi was verified by infesting winter wheat (Triticum aestivum 'Wenmai 19') and studying nematode developmentand reproduction with growth chamber (Cui et al. 2015). Eggs were hatched at 14-16°C, and freshly hatched J2s were used to inoculate wheat plants when the roots were approximately 1-centimeter long. Fifteen wheat plants were inoculated with 200 J2s, and three wheat plants without J2s were set as controls (Cui et al. 2021). Parasitic J2s and third- and fourth-stage juveniles were found in roots stained with acid fuchsin at 5, 15, and 25 days after inoculation (DAI), adult females were detected at 50 DAI, and a mean of 23.7 cysts per pot were extracted at 70 DAI (Cui et al. 2015). The morphological and molecular characteristics of the new cysts were identical to those of the H. filipjevi cysts from the original field samples, and no cysts formed in the control groups. Wheat is the main food and economic crop in Shanxi, and H. filipjevi, a potential threat to cereal crop production in Shanxi, should arouse sufficient attention. H. filipjevi is major cyst nematode pathogens of wheat and shows high prevalence in China. The loss of wheat production due to H. filipjevi is as high as 32.3% when the initial density ≥ 64 eggs/mL in soil (Li 2018). To the best of our knowledge, this is the first report of H. filipjevi in Shanxi Province of North China.

Two-century sediment records of atmospheric mercury variations in North China and their relations with regional and global emissions

Sedimentary mercury (Hg) records from remote areas are significant for revealing historical variations of regional Hg and understanding the influence of regional and global Hg emissions. In this study, sediment cores were retrieved from two subalpine lakes in Shanxi Province in North China and employed to reconstruct atmospheric Hg variations over the last two centuries. The two records show similar anthropogenic Hg fluxes and evolution trends, corresponding with that they were affected mainly by regional atmospheric Hg deposition. Before ~1950, the records show negligible Hg pollution signals. Atmospheric Hg in the region had increased rapidly since the 1950s, lagged more than a half-century compared to the global Hg. This indicates that they were seldom affected by Hg emissions dominated by Europe and North America after the industrial revolution. The Hg increases since the 1950s in the two records corresponded well with rapid industrial developments in and around Shanxi Province after the founding of the China, implying the dominant contribution of domestic Hg emissions. By comparing other Hg records, we find that widespread increases in atmospheric Hg in China likely occurred post ~1950. This study rouses to re-examine historical variations in atmospheric Hg at various settings, which is significant to understanding global Hg cycling in the industrial era.

Sediment records of black carbon variations over the last two centuries in North China

Reconstructing historical black carbon (BC) variations based on sedimentary records are significant for understanding long-term BC emissions, tracing sources, and establishing effective strategies for pollution control. By comparing BC profiles between four lake sediment cores, historical BC variations were reconstructed on the southeast Mongolian Plateau in North China. Except one, the other three records show close fluxes and similar temporal trends of soot, indicating their repetitiveness on revealing historical variations at a regional scale. Unlike soot, char and BC in these records, derived mainly from local sources, reflected the occurrence of natural fires and human activities near the lakes. Before the ~1940s, these records showed no well-established anthropogenic BC signals except some occasional natural-related increases. This was different from the global BC increased since the Industrial Revolution, indicating a negligible influence of transboundary BC on the region. Anthropogenic BC in the region had increased since the 1940s-1950s ascribed to emissions from this/nearby provinces. The increases were moderate in the 1950s-1970s, corresponded with the initial development of industry after the founding of the P.R. China. The most pronounced BC increases occurred in 1980s-2016, commensurate with rapid socio-economic development after the Reform and Opening-up in 1978. Different from model estimations on Chinese BC emissions, our records show unexpected BC increases in recent two decades caused by pollutant emission rises in this undeveloped region. This study highlights that BC emissions in relatively small cities and rural areas in China were likely underestimated and their role on national BC cycling needs to be reassessed.

Reversal of soil moisture constraint on vegetation growth in North China

The response of vegetation growth to soil moisture varies greatly from space and time under climate change and anthropogenic activities. As an important grain producer in China, the vegetation growth and grain production of North China are constrained by the region's water resources. With the significant increase in vegetation greenness in North China over the last 40 years, it is essential to explore the changes in soil moisture constraints on vegetation growth to water management. However, to what degree vegetation growth responds to soil moisture and how the response varies spatiotemporally in North China remain unclear. In this study, the response patterns of vegetation growth to soil moisture at different depths and the spatiotemporal trend patterns of their relationships were explored thoroughly based on long time series remote sensing data in North China over the past 40 years. The results showed that compared to forests, the growth of grasslands and crops with one maturity per year and two maturity per year in North China was more constrained by soil moisture. Due to the combined effects of climatic conditions and human activities, vegetation growth in North China has been significantly less constrained by soil moisture over the last 40 years. This was especially seen in one maturity per year crop and natural vegetation in Shanxi and central Shandong. However, with the significant increase in temperature, potential evapotranspiration and water demand of the crop, the moisture constraints on vegetation growth in North China have begun to show an increasing trend since the early 2000s, especially for irrigated crop in central and southern North China. These findings highlight a comprehensive understanding of the vegetation response to soil moisture from the time-varying perspective and provide a theoretical basis for water management and appropriate planning of agricultural water use in North China.

Characteristics of groundwater microbial communities' structure under the impact of elevated nitrate concentrations in north China plain

In groundwater environments, the interaction between microbial communities and the hydrogeochemical parameters have been investigated extensively in the past years. However, little is known whether the maximum contamination level (MCL) is a threshold value that dictates the microbial composition. In this study, we analyzed 10 groundwater samples for their nitrate, nitrite, COD and sulfate concentrations, and characterized their microbial compositions using 16 S rRNA based high-throughput sequencing methods. All the 10 samples had oxygen demands higher than the corresponding MCL of China (10 mg L^-1); moreover, 4 out of 10 samples also had nitrate concentrations higher than the corresponding MCL, which indicated that the groundwater quality was negatively impacted by anthropogenic activities. Comparing the microbial composition of groundwater that had higher-than-MCL nitrate concentrations to those that had lower-than-MCL nitrate concentrations, no significant differences were detected in communities' richness and diversity. However, the non-metric multi-dimensional analysis suggested that the 4 groundwater samples whose nitrate concentration exceed MCL are distinctly different from those of the rest 6 samples, indicating that MCL does have a significant impact on microbial structures. Pearson's correlation analysis suggested that none of the four analyzed hydrochemical parameters had significant impact on microbial communities' richness and diversity; however, at the genus level, the correlation results suggested that JG30-KM-CM45, Sphingomonas and Rhodococcus are closely correlated with nitrate concentration. The findings of this study deepened our understanding with respect to the relationships between the environmental quality indices and the microbial compositions of groundwater.

Clinical Impact and Risk Factors of Intensive Care Unit-Acquired Nosocomial Infection: A Propensity Score-Matching Study from 2018 to 2020 in a Teaching Hospital in China

Purpose

Nosocomial infection (NI) is associated with poor prognosis. The present study assessed the clinical and microbiological characteristics of NI patients in the intensive care unit (ICU) and investigated the clinical impact and risk factors for NI in ICU patients.

Patients and Methods

An observational study was conducted in an adult general ICU. The electronic medical records of all patients admitted to the ICU for >2 days from 2018-2020 were analyzed retrospectively. Multivariate regression models were used to analyze the risk factors for NI in ICU patients. Propensity score-matching (PSM) was used to control the confounding factors between the case and control groups, thus analyzing the clinical impact of NIs.

Results

The present study included 2425 patient admissions, of which 231 (9.53%) had NI. Acinetobacter baumannii (33.0%) was the most common bacteria. Long-term immunosuppressive therapy, disturbance of consciousness, blood transfusion, multiple organ dysfunction syndromes (MODS), treatment with three or more antibiotics, mechanical ventilation (MV), tracheotomy, the urinary catheter (UC), nasogastric catheter, and central venous catheter (CVC) were risk factors for NI in the ICU patients. After PSM, patients with NI had a prolonged length of stay (LOS) in the ICU and hospital, significant hospitalization expenses (all p<0.001), increased mortality (p=0.027), and predicted mortality (p=0.007). The differences in the ICU and hospital LOSs among three pathogens were statistically significant (p<0.001); the results of the Escherichia coli infection group were lower than the other two pathogenic groups.

Conclusion

NI was associated with poor outcomes. The risk factors for NI identified in this study provided further insight into preventing NI.

Modeling of the potential geographical distribution of naked oat under climate change

INTRODUCTION

Naked oat (Avena sativa L.), is an important miscellaneous grain crop in China, which is rich in protein, amino acids, fat and soluble dietary fiber. The demand for functional foods is gradually increasing as living standards rise, and the output of minor cereals in China is increasing annually. The planting layout of naked oat is scattered and lacks planning, which seriously restricts the development of the naked oat industry. The increase in miscellaneous grain production will not only be impacted by cultivation methods and management techniques, but the potential impact of global climate change needs to be considered. North China is the main area for naked oat production, worldwide.

METHODS

In this study, the potential distribution range of naked oat in North China was forecast based on historical distribution data and the Maxent model under climate change conditions. The performance of the model was relatively high.

RESULTS

The results indicated that the most suitable area for the potential geographic distribution of naked oat in North China was 27.89×104 km², including central and northeastern Shanxi, and northeastern and western Hebei and Beijing, gradually moving northward. The core suitable area increased, and the distribution of naked oat had an obvious regional response to climate warming; the main environmental factors affecting the potential geographic distribution were precipitation factor variables (precipitation seasonality (variation coefficient)), terrain factor variables (elevation) and temperature factor variables (temperature seasonality (Standard Deviation*100)).

DISCUSSION

In this study, the Maxent model was used to analyze and predict suitable areas for naked oat in North China, and the distribution of suitable areas was accurately divided, and the main climatic factors affecting the distribution of naked oat were identified. This research provides data support and theoretical support for the optimal planting zone of naked oat in North China.

Sediment records of global and regional Hg emissions to the atmosphere in North China over the last three centuries

Reconstructing the long-term Hg history in major emission countries is important for understanding the global Hg cycle and controlling Hg pollution. In this study, the atmospheric Hg history was reconstructed over the last three centuries based on three lacustrine sediment records from southeastern Inner Mongolia in North China, and its relationship with global and regional Hg emissions was revealed. These records show little Hg pollution in the 18th and 19th centuries. This implies a limited influence of Hg emitted from Europe and North America in this region, which is confirmed by their different Hg trends during the two World Wars and the post-1970s. Atmospheric Hg in the region had increased gradually since the 1900s, primarily contributed by emissions from the former Soviet Union in Lake Dalihu (DLH) and Lake Zhagesitai (ZGST) and from the Beijing-Tianjin-Hebei region in Lake Kulunnao (KLN). In the last century, two decreases in Hg fluxes occurred in the KLN core due to the economic recession in the 1960s-1970s and reduced energy consumption and industrial production in the 1990s. In the DLH and ZGST cores, only one decrease occurred, corresponded with the dissolution of the Soviet Union in the 1990s. Although atmospheric Hg emissions in China had stabilized or even decreased in the last decade, atmospheric Hg continued to increase, particularly in KLN, because of emissions from small cities in the region. This study can help understand Hg sources and control Hg pollution in North China and supplement the understanding of the global Hg cycling.

Chemical characterization, source apportionment, and health risk assessment of PM2.5 in a typical industrial region in North China

To clarify the chemical characteristics, source contributions, and health risks of pollution events associated with high PM_2.5 in typical industrial areas of North China, manual sampling and analysis of PM_2.5 were conducted in the spring, summer, autumn, and winter of 2019 in Pingyin County, Jinan City, Shandong Province. The results showed that the total concentration of 29 components in PM_2.5 was 53.4 ± 43.9 μg·m^-3, including OC/EC, water-soluble ions, inorganic elements, and metal elements. The largest contribution was from the NO₃^- ion, at 14.6 ± 14.2 μg·m^-3, followed by organic carbon (OC), SO₄^2-, and NH₄⁺, with concentrations of 9.3 ± 5.5, 9.1 ± 6.4, and 8.1 ± 6.8 μg·m^-3, respectively. The concentrations of OC, NO₃^-, and SO₄^2- were highest in winter and lowest in summer, whereas the NH₄⁺ concentration was highest in winter and lowest in spring. Typical heavy metals had higher concentrations in autumn and winter, and lower concentrations in spring and summer. The annual average sulfur oxidation rate (SOR) and nitrogen oxidation rate (NOR) were 0.30 ± 0.14 and 0.21 ± 0.12, respectively, with the highest SO₂ emission and conversion rates in winter, resulting in the SO₄^2- concentration being highest in winter. The average concentration of secondary organic carbon in 2019 was 2.8 ± 1.9 μg·m^-3, and it comprised approximately 30% of total OC. The concentrations of 18 elements including Na, Mg, and Al were between 2.3 ± 1.6 and 888.1 ± 415.2 ng·m^-3, with Ni having the lowest concentration and K the highest. The health risk assessment for typical heavy metals showed that Pb poses a potential carcinogenic risk for adults, whereas As may pose a carcinogenic risk for adults, children, and adolescents. The non-carcinogenic risk coefficients for all heavy metals were lower than 1.0, indicating that the non-carcinogenic risk was negligible. Positive matrix factorization analysis indicated that coal-burning emissions contributed the largest fraction of PM_2.5, accounting for 35.9% of the total. The contribution of automotive emissions is similar to that of coal, at 32.1%. The third-largest contributor was industrial sources, which accounted for 17.2%. The contributions of dust and other emissions sources to PM_2.5 were 8.4% and 6.4%, respectively. This study provides reference data for policymakers to improve the air quality in the NCP.

Historical trends in atmospheric metal(loid) contamination in North China over the past half-millennium reconstructed from subalpine lake sediment

Trace metal (loid) contamination in the atmosphere is widely monitored, but there is a gap in understanding its long-term patterns, especially in North China, which is currently a global contamination hotspot mainly caused by heavy industry emissions and coal combustion. Herein, historical trends of atmospheric As, Cd, Cr, Cu, Hg, Ni, Pb and Zn contamination in North China over the past ∼500 years are comparatively studied with sediment cores from two subalpine lakes (Gonghai and Muhai). Arsenic, Pb, Cd and Hg were main pollutants according to Pb isotopes and enrichment factors. Mercury contamination has increased continuously since the late 1800s and increasing As, Pb and Cd contamination started in the 1950s in Gonghai. In contrast, the contamination in Muhai lagged two decades for As, Cd and Pb and a half-century for Hg behind that in Gonghai, although the trends were similar. This contamination lag was attributed to the low sensitivity of Muhai sediment to early weak atmospheric metal contamination under 2.1-fold higher detrital sedimentation. As, Pb and Cd contamination has intensified since the 1980s, and the metals showed similar sedimentary fluxes in the cores. However, sedimentary fluxes of Hg contamination were 3.4-fold higher in Gonghai than in Muhai due to combination with organic matter. No obvious Cr, Cu and Ni contamination in the cores was mainly because of the low atmospheric deposition from anthropogenic sources relative to detrital input, although some of their atmospheric emissions were higher than those of As, Cd and Hg. Atmospheric As, Pb and Cd contamination was mainly from domestic sources of coal combustion and nonferrous smelting. Mercury contamination was mainly from global and Asian sources in the first half of the 20th century, and domestic emissions gradually dominated Hg contamination after the mid-1900s.

Spatiotemporal dynamics of grassland aboveground biomass and its driving factors in North China over the past 20 years

Although remote sensing has enabled rapid monitoring of grassland aboveground biomass (AGB) at a regional scale, it is still a difficult challenge to construct an accurate estimation model of grassland AGB in a vast region to support the AGB dynamics analysis over a long time series. In this study, extensive grassland AGB measurements (collected in North China during the grassland growing season of 2000-2019), MODIS data, and environmental factors (climate, topography and soil) were employed to construct the grassland AGB models using four machine learning algorithms (random forest, support vector machine, artificial neural network and extreme learning machine) combined with four variable selections. The spatial distributions of annual grassland AGB from 2000 to 2019 were simulated based on the optimal AGB model. The temporal change and future trend of AGB series from 2000 to 2019 were comprehensively analyzed by the slope model and Hurst exponent. The influences of natural and anthropogenic factors on grassland AGB dynamics were explored quantitatively using the Geodetector model. The results showed that (1) the random forest model constructed from the variables selected by the successive projections algorithm is the optimal grassland AGB model. (2) The 20-year average grassland AGB in North China showed an overall spatial distribution of being low in the central and western parts and high in the southeastern part. (3) The annual maximum grassland AGB in most regions (82.71%) showed an increasing trend during 2000-2019; and most of the grasslands with a decreasing trend of AGB were located in regions with low AGB values and arid climates. (4) The future trend of grassland AGB after the study period may be optimistic, as reflected by more grassland AGB was predicted to increase rather than decrease (70.38% vs. 29.62%). (5) The main driving factors of spatiotemporal dynamics of grassland AGB were precipitation, soil type, and livestock density; the interactive influence of two drivers on AGB showed mutual enhancement.

Investigating the climatology of North China's urban inland lake based on six years of observations

There are unclear characteristics of the effect of lake breeze in small urban inland lakes due to little research on lake breezes. In this work, six-year observations were performed to study the comprehensive climatologic characteristics of lake breezes on North China's urban inland lake, Lake Hengshui (75 km²). By removing background winds calculated by ERA5 data and successfully recording the lake-land breeze cycle, we devised a succinct and effective approach for distinguishing lake-land breezes. Lake-land breeze had a high annual occurrence frequency of 13.4%-24.7% and a yearly mean lake-breeze speed of 1.6 m/s and yearly mean lake-breeze duration of 4.8 h; spring has the highest frequency and summer has the lowest frequency because of the greater thermal differences between lake and land in spring. The lake breeze mostly started at 06:00-07:00 and 10:00-13:00 (LST), showing a double-peak pattern, and ended at 17:00-19:00 (LST). On the other hand, the land breezes mainly started at 00:00-01:00 (LST) and ended at 05:00-06:00. The distance between each station and the lake has a negative correlation to the frequency and duration of the lake-land breeze, showing the higher frequency and duration at the near stations and the lower frequency and duration at the stations far from the lake. The land breeze has similar spatial characteristics. Winter has relatively lower seasonal average wind speeds of the lake breeze at most stations; spring and winter have high average wind speeds of the land breeze at each station, while summer and autumn have low. The study of the city lake's lake-land breeze will shed new insights into addressing the urban layout.

Air pollutant spatiotemporal evolution characteristics and effects on human health in North China

North China, the political, economic, and cultural center of China, has been greatly harmed by frequent air pollution incidents. Therefore, it is vital to study air pollution characteristics and clarify their impact on human health. In this study, we first analyzed the spatiotemporal variations of air pollutants (PM_2.5, PM₁₀, CO, SO₂, NO₂, and O₃) in North China from 2016 to 2019. Then, the air quality index (AQI), aggregate air quality index (AAQI), and health risk based air quality index (HAQI) were used to assess health risks. Based on these, the AirQ_2.2.3 model was used to quantify health effects. The results showed that the major pollutant in the cities surrounding Beijing was PM_2.5, while PM₁₀ dominated in distant cities. Annual concentrations decreased (except for O₃), which is related to governmental emission reduction policies. However, O₃ concentrations increased owing to the complex precursor emissions. The AQI underestimated air pollution, while the AAQI and HAQI were accurate; the latter indicated that 55% of the study region population was exposed to polluted air. The AirQ_2.2.3 model quantified the total mortality proportions attributable to PM_2.5, PM₁₀, SO₂, CO, NO₂, and O₃, which were 1.87%, 3.12%, 1.11%, 1.40%, 4.19%, and 2.52%, respectively. In high concentrations, PM₁₀ and PM_2.5 pose significant health risks. The health effects of SO₂, NO₂, CO, and O₃ at lower concentrations were more obvious, indicating that the expected mortality rate due to low concentrations of some pollutants was much higher than that due to high concentrations of other pollutants.

Carbon dioxide emissions, urbanization level, and industrial structure: empirical evidence from North China

This paper aims to examine the nexus among carbon dioxide (CO₂) emissions, urbanization level and industrial structure in North China over the period 2004-2019, according to an expanded Cobb-Douglas production function. The panel econometric techniques are employed to complete the empirical analysis, including cross-sectional correlation test, panel unit root test, panel co-integration test, and panel Granger causality test. The empirical results support the long-term equilibrium relationship among CO₂ emissions, urbanization level and industrial structure in North China, and the urbanization level contributes most to CO₂ emissions, followed by fossil energy consumption. Furthermore, the bidirectional causality between CO₂ emissions and urbanization level and unidirectional causality from industrial structure to CO₂ emissions are found in North China, indicating that urbanization level and industrial structure have significant impacts on CO₂ emissions. Finally, according to the empirical findings, several policy suggestions are proposed for the purpose of reducing CO₂ emissions in North China.

Characterization of peroxyacetyl nitrate (PAN) under different PM2.5 concentration in wintertime at a North China rural site

As a secondary pollutant of photochemical pollution, peroxyacetyl nitrate (PAN) has attracted a close attention. A four-month campaign was conducted at a rural site in North China Plain (NCP) including the measurement of PAN, O₃, NO_x, PM_2.5, oxygenated volatile organic compounds (OVOCs), photolysis rate constants of NO₂ and O₃ and meteorological parameters to investigate the wintertime characterization of photochemistry from November 2018 to February 2019. The results showed that the maximum and mean values of PAN were 4.38 and 0.93 ± 0.67 ppbv during the campaign, respectively. The PAN under different PM_2.5 concentrations from below 75 μg/m³ up to 250 μg/m³, showed different diurnal variation and formation rate. In the PM_2.5 concentration range of above 250 μg/m³, PAN had the largest daily mean value of 0.64 ppbv and the fastest production rate of 0.33 ppbv/hr. From the perspective of PAN's production mechanism, the light intensity and precursors concentrations under different PM_2.5 pollution levels indicated that there were sufficient light intensity and high volatile organic compounds (VOCs) and NO_x precursors concentration even under severe pollution level to generate a large amount of PAN. Moreover, the bimodal staggering phenomenon of PAN and PM_2.5 provided a basis that PAN might aggravate haze through secondary organic aerosols (SOA) formation.

Attenuated sensitivity of ozone to precursors in Beijing-Tianjin-Hebei region with the continuous NOx reduction within 2014-2018

Facing the elevated surface summer O₃ over North China in recent years with the continuous NO_x reduction, we conducted the ozone-precursor sensitivity study in summer (July) in Beijing-Tianjin-Hebei region (BTH) under the 2018 and 2014 emissions, based on WRF-Chem model. On 2018 emission condition, 30% precursor reduction simulations presented the positive contribution of VOCs and the negative contribution of NO_x to daytime O₃. The occurrence probabilities of VOCs-sensitive, NO_x-titration, mixed sensitive, NO_x-sensitive, and non-sensitive regimes respectively reached 3-49%, 2-82%, 0-7%, 0-6% and 14-82% in the urban grids, and 2-32%,1-19%, 1-6%, 0-5% and 54-86% in the rural grids. For several widely used photochemical indicators, their values in VOCs-sensitive regime were well separated from those in NO_x-sensitive regime, but the NO_x-sensitive values were very similar to the non-sensitive values, which implied the inefficiency of these indicators in indicating NO_x-sensitive regime. Finally, VOCs-sensitive regime was discerned based on the indicator HCHO/NO₂, occupying about a third of areas in morning and dusk but shrinking to about a tenth of areas in 11:00-16:00 in BTH. And these areas apparently decreased from 2014 emission to 2018 emission. However, the rest areas of this region were under non-sensitive regime but not NO_x-sensitive regime, for the noticeable O₃ drop never happened in NO_x reduction scenario. Meanwhile, the modeled O₃/PAN in the areas under non-sensitive regime exceeded 60, which also implied the minor impact of local photochemistry on O₃ there. Additionally, the responses of daytime O₃ to precursor emissions in the urban grids were calculated, declining by 20.8% for NO_x and 6.9% for VOCs from 2014 to 2018. Therefore, to solve the ozone pollution problem of BTH, the cross-region strategy coupled with the VOCs and NO_x co-control will be essential.

Multi-scale assessment of water security under climate change in North China in the past two decades

Climate change is projected to affect the hydrological cycles in China, while the effects are expected to vary spatiotemporally. Understanding the variations in water security conditions and their sensitivity to climatic variables is crucial for assessing regional ecosystem responses to climate change. In the present study, we estimated the water yield capacity, an important indicator of water security in North China (NC), at a spatial resolution of 1 km during the last two decades based on the Budyko framework and quantified the sensitivity of water yield change to climate change among different vegetation types. The results showed that the performances of the Budyko framework were reliable both at the pixel scale and across large watersheds. The annual water yield in North China was estimated to be 7.61 ± 2.67 ∗ 10¹⁰ m³/yr, with an average mean water yield (MWY) of 49.51 ± 17.49 mm/yr. The spatial pattern of mean water yield change (MWYC) exhibited high heterogeneity; 46% of the study region was dominated by an increasing trend, while 9.84% was statistically significant (P < 0.05). Compared with temperature, the water yield capacity was more sensitive to precipitation variation. A consistent trend of variation was found in cropland between water yield and precipitation, while negative sensitivity coefficients were found in natural vegetation types. The variation in sensitivity coefficients (Swyp) in natural vegetation showed that in regions with a decrease in precipitation, the variation in water yield capacity also decreased, while in regions with an increase in precipitation from 0 to 8 mm/yr, the water yield capacity first decreased and then increased with precipitation. Our findings suggest that grass and shrubs would be more beneficial to regional water security in North China's revegetation, while afforestation would provide protection for the regional environment from extreme rainfall events.

An unexpected large continental source of reactive bromine and chlorine with significant impact on wintertime air quality

Halogen atoms affect the budget of ozone and the fate of pollutants such as hydrocarbons and mercury. Yet their sources and significances in polluted continental regions are poorly understood. Here we report the observation of unprecedented levels (averaging at 60 parts per trillion) of bromine chloride (BrCl) at a mid-latitude site in North China during winter. Widespread coal burning in rural households and a photo-assisted process were the primary source of BrCl and other bromine gases. BrCl contributed about 55% of both bromine and chlorine atoms. The halogen atoms increased the abundance of 'conventional' tropospheric oxidants (OH, HO₂ and RO₂) by 26%-73%, and enhanced oxidation of hydrocarbon by nearly a factor of two and the net ozone production by 55%. Our study reveals the significant role of reactive halogen in winter atmospheric chemistry and the deterioration of air quality in continental regions where uncontrolled coal combustion is prevalent.

[Concentration and Reactivity of Carbonyl Compounds in the Atmosphere of North China]

To reveal the characteristics of photochemical pollution in North China, adsorbing columns with 2, 4-dinitrophenylhydrazine(DNPH) were used to sample carbonyl compounds in Shijiazhuang and Xinglong between May 2018 and April 2019. The samples were analyzed by high-performance liquid chromatography to understand the composition, volume fraction, source, ·OH loss rate, and ozone formation potential of the carbonyl compounds. A total of 13 carbonyl compounds containing carbonyl groups were determined, of which acetone, formaldehyde, and acetaldehyde were highest at(6.46±5.25)×10^-9, (3.76±2.29×10^-9), and(2.65±1.74)×10^-9 in Shijiazhuang compared to(1.85±1.27)×10^-9, (1.29±1.02)×10^-9, and(0.72±0.48)×10^-9 in Xinglong, respectively. The estimated maximum ozone formation potential(OFP) of formaldehyde was much higher than that of acetaldehyde; the C1/C2 and C2/C3 ozone formation potential(OFP) of formaldehyde was much higher than that of acetaldehyde; and the C1/C2 and C2/C3 values showed that vehicle exhaust and fossil fuel combustion were the main sources in Shijiazhuang in association with the higher level of industrialization. In Xinglong, the carbonyl compounds mainly originated from natural sources. Acetaldehyde(1.77 s^-1), formaldehyde(1.57 s^-1), and butyraldehyde(0.42 s^-1) contributed most to L_·OH in Shijiazhuang, and formaldehyde(0.53 s^-1), acetaldehyde(0.47 s^-1), and butyraldehyde(0.12 s^-1) were the three main contributors to L_·OH in Xinglong. The carbonyl compounds contributing most to O₃ production were formaldehyde and acetaldehyde at(34.61×10^-9 O₃) and (16.73×10^-9 O₃) in Shijiazhuang, compared to (11.77×10^-9 O₃) and (4.47×10^-9 O₃) in Xinglong, respectively.

Association between Dietary Patterns and Low HDL-C among Community-Dwelling Elders in North China

We aimed to investigate the association between dietary patterns and low HDL-C among the elderly population living in North China. The data were from a national cross-sectional survey conducted in 2015. General information in terms of living habits, health status, and food intake using 24 h dietary recall for three consecutive days was procured, and the weight of edible oil and condiments recorded. Anthropometric index, blood pressure, and fasting serum lipids were measured using standard methods. Dietary patterns were derived from food categories by exploratory factor analysis, and multivariate logistic regression was used to estimate the odds ratios of low HDL-C across quartiles of dietary patterns. Among 3387 elderly participants, 21.9% had low HDL-C levels. After adjusting for potential confounding factors, participants with highest score versus lowest score in the balanced dietary pattern had a decreased risk of low HDL-C (OR = 0.38, 95% CI: 0.16-0.88, p for trend = 0.013) in the group with a BMI of 27.1 kg/m² and above. Compared to the lowest quartile, there was a statistically significant negative association between the highest scores of the Western dietary pattern and low HDL-C (OR = 0.37, 95% CI: 0.17-0.82, p for trend = 0.018) in the group with a BMI of 21.6-24.8 kg/m². However, greater adherence to a thrifty dietary pattern (highest quartiles vs. lowest quartiles) was associated with increased risk of low HDL-C (OR = 3.31, 95% CI: 1.05-10.40, p for trend = 0.044), especially in the subgroup with a BMI of 21.6 kg/m² and below. The study revealed that it is urgent to develop district-specific dietary improvement plans for dyslipidemia based on the nutritional status of the elderly population in North China.

Epidemiology of patients with central nervous system infections, mainly neurosurgical patients: a retrospective study from 2012 to 2019 in a teaching hospital in China

BACKGROUND

Central nervous system (CNS) infections are relatively rare but are associated with high mortality worldwide. Empirical antimicrobial therapy is crucial for the survival of patients with CNS infections, and should be based on the knowledge of the pathogen distribution and antibiotic sensitivities. The aim of this study was to investigate the features of pathogens in patients with CNS infections in North China and evaluate the risk factors for mortality and multi-drug-resistant (MDR) bacterial infections.

METHODS

A retrospective study was conducted with patients with positive cerebrospinal fluid (CSF) cultures in a teaching hospital from January 2012 to December 2019. The following data were collected: demographic characteristics, laboratory data, causative organisms and antimicrobial sensitivity results. Data were analyzed with SPSS 16.0. Univariate analysis and binary logistic regression analyses were performed to identify the risk factors for mortality and MDR bacterial infections.

RESULTS

A total of 72 patients were diagnosed with CNS infections, and 86 isolates were identified. The proportions of Gram-positive bacteria, Gram-negative bacteria and fungi were 59.3, 30.2 and 10.5%, respectively. The predominant Gram-positive bacteria was Coagulase-negative Staphylococci. Acinetobacter baumannii, Escherichia coli and Klebsiella spp. were the predominant Gram-negative bacteria. Compared to 2012-2015 years, the proportion of Gram-negative bacteria increased markedly during 2016-2019 years. Coagulase-negative Staphylococci, Streptococcus pneumoniae and Enterococcus faecium had 100% sensitivity to vancomycin, teicoplanin and linezolid. Acinetobacter baumannii and Klebsiella pneumoniae were 100% sensitive to tigecycline. Escherichia coli had 100% sensitivity to amikacin, meropenem and imipenem. The overall mortality rate in the 72 patients was 30.6%. In multivariate analysis, age > 50 years, pulmonary infections and CSF glucose level < the normal value were associated with poor outcomes. CSF adenosine deaminase level > the normal value and the presence of external ventricular drainage/lumbar cistern drainage were associated with MDR bacterial infections.

CONCLUSIONS

The mortality rate due to CNS infections reached 30.6% in our study. The proportion of Gram-negative bacteria has increased markedly in recent years. We should give particular attention to patients with risk factors for mortality and MDR bacterial infections mentioned above.

Serum perfluoroalkyl substances in relation to lipid metabolism in Chinese pregnant women

Laboratory and epidemiologic studies suggested that exposure to perfluoroalkyl substances (PFASs) could affect lipid metabolisms, but data remain limited for pregnant women. A total of 436 pregnant women were selected in Tangshan City, North China. Serum levels of 11 PFASs were determined in the early term of pregnancy. Four lipids (total cholesterol (TC), triglyceride (TG), high-density lipoprotein (HDL), and low-density lipoprotein (LDL)) were measured in the late term of pregnancy. Of 11 PFASs, seven had a detection rate of greater than 70%. After adjusting for potential confounders, natural log-transformed perfluororohexanesulfonic acid (ln PFHxS) was positively associated with TC (β: 0.184, 95% CI: 0.045-0.321), HDL (β: 0.040, 95% CI: 0.001-0.083), and LDL (β: 0.091, 95% CI: 0.001-0.185). Ln perfluoroundecanoic acid (PFUdA) was positively associated with HDL (β: 0.021, 95% CI: 0.001-0.044), while Ln perfluorodecanoic acid (PFDA) was negatively associated with LDL (β: -0.053, 95% CI: -0.098∼-0.009) and ln perfluorootanoic acid (PFOA) was negatively associated with LDL/HDL (β: -0.042, 95% CI: -0.075∼-0.009). In principal component analysis, the component with a large loading of 31.3% for PFOA, perfluorononanoic acid (PFNA), PFDA and PFUdA showed a negative association with LDL/HDL. After serum concentrations of PFASs were categorized into quartiles, a higher level of TC was seen in the second quartile of PFOA or PFNA than the first quartile, but a lower LDL/HDL ratio was seen in the fourth quartile of PFOA, PFUdA or PFDA. These results suggested that exposure to PFASs has a potential to influence lipid metabolisms in pregnant women.

A July-August relative humidity record in North China since 1765 AD reconstructed from tree-ring cellulose δ18O

Since the late 1970s, East Asian summer monsoon (EASM) has shown a significant weakening trend, and sustained drought has occurred across North China. Placing recent climate changes in the paleoclimatic context can better understand the EASM variations. Four δ¹⁸O sequences based on tree-ring cellulose of Chinese pine were developed from Mt. Beiwudang, North China, covering a period from 1700 to 2013. Based on a climatic response analysis, a transfer function was designed to reconstruct the relative humidity from July to August (RH_JA hereafter). The RH_JA spans from 1765 to 2013 and explains 49% (R²_adj = 48%) of the instrumental variance during the calibration period (1961-2013, r = - 0.70, p < 0.0001). The RH_JA is mainly influenced by precipitation in the summer rainy season and reflect EASM variations. Spatial representation analysis indicates that RH_JA represents the dry/wet variations across North China. At the interannual scale, RH_JA records many extreme dry/wet events, among which the events in 1876-1878, 1900, and the 1920s are extensive droughts. Those events correspond well to ENSO events, plus further correlation and periodicity analysis indicate that RH_JA contains ENSO signals. At the interdecadal scale, RH_JA shows a decreasing trend and unprecedented low values from 1981 to 2013, suggesting that the weakening of EASM since the late 1970s is unprecedented in the past 249 years. Similarly, the significantly correlating region in the spatial correlation analysis, covering the Meiyu/Baiu/Changma rainfall belt and India, have also undergone a climatic shift since the late 1970s according to previous papers.

Sensitivity of PM2.5 to NOx emissions and meteorology in North China based on observations

This study examines the sensitivity of daily PM_2.5 to NO_x emissions and meteorology using in situ observations from main cities of North China (NC). NC cities are divided into low-, medium-, and high-emission groups by the ranking of their 4-year mean NO₂. For each emission group, daily NO₂ levels are used to divide the days into good-, medium-, and bad-meteorological conditions. Regardless of their emission levels, all cities reveal significant decreases (96%-172%) in daily PM_2.5 levels from bad to good meteorological conditions. The largest difference in PM_2.5 concentrations between the emissions groups is found under bad meteorological conditions, with 56% higher PM_2.5 in high-emission cities than low-emission cities, indicating PM_2.5 under bad meteorological conditions has the largest sensitivity to emissions. The high-emission, bad-meteorology group saw a 24% decrease in mean daily PM_2.5 levels from 2017, a high-emission year, to 2019, a low-emission year. However, under good meteorological conditions, the high-emissions group shows an increase of 8.8 μg/m³ in mean daily PM_2.5 from 2017 to 2019 with a 2.6% increase in the possibility of high PM_2.5. These results suggest the current emission reduction measures are more effective in controlling PM_2.5 in high-emission cities under bad meteorological conditions than under other meteorological conditions.

Serum Bisphenol A, glucose homeostasis, and gestational diabetes mellitus in Chinese pregnant women: a prospective study

Lab studies have suggested that exposure to Bisphenol A (BPA) could disturb glucose homeostasis, but epidemiologic studies are limited and show inconsistent results for pregnant women. For this, 535 pregnant women were selected from a pregnant women cohort established in Tangshan City in North China between 2013 and 2014. Serum concentrations of BPA were measured in the early term of pregnancy, and fasting glucose and insulin levels were repeatedly measured in each of three terms of pregnancy (early, middle, and late). Gestational diabetes mellitus (GDM) were examined by Oral Glucose Tolerance Test (OGTT) in the middle and late terms of pregnancy. BPA was detected in 97.5% of pregnant women with a median of 6.50 ng/ml. Natural log-transformed BPA (Ln BPA) was positively associated with fasting glucose level (β (95% CI): 0.038 (0.015~0.061)), fasting insulin level (0.195 (0.069~0.321)), and homeostasis model insulin resistance index (HOMA-IR) (0.226 (0.087~0.364)) in the middle term of pregnancy by multiple linear regression model after adjusting for potential confounders. After serum BPA levels were divided into three groups (low, middle, and high), BPA showed a positive dose-response relationship with blood glucose, insulin, and HOMA-IR in the middle term of pregnancy. Increased BPA concentration tended to increase the RR of GDM although not statistically significant (risk ratio: 2.51 (95% CI: 0.68~9.30) for high vs low tertile of BPA concentrations). These findings suggested that exposure to BPA might affect glucose homeostasis and the middle term of pregnancy was a potentially sensitive period.

Advanced Cambrian hydroid fossils (Cnidaria: Hydrozoa) extend the medusozoan evolutionary history

Primitive cnidarians are crucial for elucidating the early evolution of metazoan body plans and life histories in the late Neoproterozoic and Palaeozoic. The highest complexity of both evolutionary aspects within cnidarians is found in extant hydrozoans. Many colonial hydrozoans coated with chitinous exoskeletons have the potential to form fossils; however, only a few fossils possibly representing hydroids have been reported, which still require scrutiny. Here, we present an exceptionally well-preserved hydroid found in the Upper Cambrian Fengshan Formation in northern China. It was originally interpreted as a problematic graptolite with an uncertain systematic position. Based on three characteristic morphological traits shared with extant hydroids (with paired hydrothecae, regular hydrocaulus internodes and special intrathecal origin pattern of hydrocladium), we propose this fossil hydroid as a new genus, Palaeodiphasia gen. nov., affiliated with the advanced monophyletic hydrozoan clade Macrocolonia typically showing loss of the medusa stage. More Macrocolonia fossils reviewed here indicate that this life strategy of medusa loss has been achieved already as early as the Middle Devonian. The early stratigraphical appearance of such advanced hydroid contrasts with previous molecular hypotheses regarding the timing of medusozoan evolution, and may be indicative for understanding the Ediacaran cnidarian radiation.

First report of Heterodera filipjevi on winter wheat from Hebei Province in North China

Three of the cereal cyst nematodes, Heterodera avenae, H. filipjevi and H. latipons are considered to be the most economically important cyst nematodes that affect cultivated cereals around the world. H. filipjevi was first detected in China from Xuchang, Henan Province in 2010 (Peng et al. 2010) and now has been recorded in the Central China of Henan, Shandong and Anhui provinces and the Northwest China of Xinjiang Uygur Autonomous Region (Cui et al. 2020). In June 2019, 42 samples consisting of roots and soil were collected from winter wheat fields in Hebei Province of North China. Cysts were detected in 37 soil samples with a mean of 6.4 ± 1.67 cysts per 100 ml of soil. Cysts and second-stage juveniles (J2s) were extracted from root and soil following Cobb's sieving gravity method. Morphological and molecular studies of J2s and cysts confirmed its identity with H. filipjevi in 5 samples from Handan (N36°10'052" and E114°35'056"; N36°37'054" and E114°22'052"), Xingtai (N36°53'060" and E114°30'011") and Shijiazhuang (N 37°26'048" and E 116°05'039") in Hebei Province, China. Morphologically, the cysts are lemon-shaped, light or dark brown in color. The vulval cone is bifenestrate with horseshoe-shaped semifenestrae, strongly globular bullae, and well-developed underbridge. Measurements (mean +_ sd (range)) of cysts (n=10), body length not including neck is 743.0 ± 36.1 μm (665 - 780 μm), body width is 559.0 ± 50.0 μm (455 - 639 μm), length / width ratio is 1.33 ± 0.07 (1.20 - 1.46); neck length is 99.3 ± 8.8 μm (85 - 122 μm); fenestrae length is 56.8 ± 5.0 μm (49 - 65 μm) and width is 25.5 ± 1.8 μm (21.1 - 27.8 μm); underbridge length is 84.0 ± 8.1 μm (62 - 93 μm); and vulval slit length is 8.6 ± 0.5 μm (7.2 - 9.1 μm). Measurements of J2s (n = 12), body length is 541 ± 11.4 μm (490 - 578 μm); stylet length is 22.3 ± 0.5 μm (22.0 - 25.0 μm) with anchor-shaped basal knobs; tail length is 57.7 ± 3.7 μm (52.7 - 65.2 μm), and hyaline tail terminal length is 36.5 ± 2.8 μm (32 - 39.8 μm). The tail had a sharp terminus. Morphology of the cysts and J2s were consistent with the record of H. filipjevi (Peng et al. 2010; Subbotin et al. 2010). The amplifications of rDNA-internal transcribed spacer (ITS) fragments were generated with a PCR fragment of 1054 bp from single cysts of each population, using primers TW81 and AB28 (Joyce et al. 1994). The PCR tests for each sample were repeated five times. The PCR product was purified and sequenced. All nucleotide sequences of ITS-rDNA were submitted to GenBank under accession numbers MW282843-6. Sequences from the ITS region were more than 99.5% identical to those of H. filipjevi from Egypt (KF225725), Turkey (KR704308, KR704293 and MN848333) and China (KT314234, MT254744 and KY448473). These results from ITS supported its identity as H. filipjevi. The results were also confirmed by species specific sequence characterized amplified region primers of H. filipjevi (Peng et al. 2013). Pathogenicity of the H. filipjevi was confirmed by infection of winter wheat (Triticum aestivum L cv. 'Aikang58') and examination of the nematode development and reproduction. Wheat seeds were germinated in petri dishes and then transplanted into five polyvinyl chloride tubs (3 cm in diameter, 25 cm in length) that contained 150 cm3 of a sterile soil mixture (loamy soil: sand = 1:1), each with 5 cysts (mean of 252.0 eggs/cyst). Plants were grown in an artificial climate box for one week at 14/18°C, two weeks at 16/20°C, five weeks at 18/25°C and two weeks at 22/30°C, under 8 h of darkness/16 h light and normal culturing practices (Cui et al. 2015). The parasitic J2s, third and fourth-stage juveniles, and adult females were observed in roots stained with acid fuchsin at 10, 20, 30, and 50 days after inoculation (DAI), and an average of 32.0 cysts per tubes were extracted 70 DAI. The new cyst' morphological and molecular characteristics were identical to the H. filipjevi cysts from the original soil samples. Three other tubes without cysts were set as control and there were no newly formed cysts. Heterodera avenae and H. filipjevi had been detected in a total of 16 wheat-producing provinces in China, which resulted in losses of 1.9 billion CNY year-1 (Cui et al. 2015). To our knowledge, this is the first report of H. filipjevi in Hebei Province of North China. Cereal cyst nematodes are easily transferred to non-infested areas by many avenues, resulting in increased species and pathotype complexity (Cui et al. 2020). Once H. filipjevi continues to spread in main wheat producing area of China, it could become be a new threat to cereals production. It is time to take effective control methods to prevent H. filipjevi further dispersal, especially through the farming machinery transmission. Hebei Province is one of the most important major grain-producing areas, our findings will be very beneficial for H. filipjevi management and further research on winter wheat in Hebei Province, North China.

Seasonal variations in the mass characteristics and optical properties of carbonaceous constituents of PM2.5 in six cities of North China

Carbonaceous constituents have various adverse impacts on human health, visibility, and climate change. Although comprehensive studies on the characteristics of carbonaceous constituents have been conducted recently, systematic studies covering both the mass characteristics and light-absorption properties of carbonaceous constituents on a regional scale in China are quite limited. In this study, current seasonal measurements of organic carbon (OC) and elemental carbon (EC) in PM_2.5 were investigated during autumn and winter (1-30 October 2017 and December 18, 2017 to January 17, 2018) in six selected cities located at the eastern foot of the Taihang Mountains: Beijing, Baoding, Shijiazhuang, Handan, Xinxiang, and Zhengzhou. Seasonal variations were similar when Beijing was excluded. The lowest concentrations of OC (18.33 ± 9.39 μg/m³) and EC (7.66 ± 5.64 μg/m³) were observed in Xinxiang (autumn) and Beijing (winter), respectively, while the highest concentrations of OC (38.43 ± 62.10 μg/m³) and EC (12.24 ± 24.67 μg/m³) occurred in Baoding during winter mainly due to elevated fuel combustion for space heating. The results of the potential source contribution function (PSCF) analysis suggested that border zones between several provinces in North China should be highlighted in order to strengthen pollution control. Moreover, by separating the optical properties of brown carbon from those of black carbon, we were able to estimate the contributions of brown carbon to the PM_2.5 total light-absorption coefficient. The results show that the brown carbon absorption coefficient (at 405 nm) in winter at six sites accounted for 21.2%, 33.3%, 34.7%, 39.1%, 48.6%, and 23.3% of the PM_2.5 light absorption, which are values that are comparable to the contribution of black carbon in Xinxiang. These results provide a more comprehensive understanding of carbonaceous constituents on a regional scale.

Association of serum 25-Hydroxyvitamin D with Vitamin D intervention and outdoor activity among children in North China: an observational study

Background

Living at high latitudes is one of the risk factors for vitamin D deficiency in children. However, evidence on vitamin D improvement for this pediatric population to date is limited. This study aims at evaluating the association of different vitamin D intervention methods and outdoor activity on the vitamin D status of children in North China.

Methods

In this observational study, a total of 55,925 children aged 1 month to 18 years old were recruited from pediatric outpatient departments from July 2016 to June 2017. Data on demographics, anthropometric measurements, vitamin D intervention (either prescribed by physicians or given by parents) and outdoor activity were recorded. The serum levels of 25-hydroxycholecalciferol (25(OH)D) were determined by high performance liquid chromatography tandem–mass spectrometry. Logistic regression analysis was performed to assess the association of vitamin D intervention or outdoor activity with blood vitamin D status, adjusted for age, gender, BMI for age, and seasons.

Results

The overall rate of hypovitaminosis D was 65.60%. Of the children’s outdoor activity, 35.63, 31.95, and 32.42% were below 30 min/d, 30–60 min/d and over 60 min/d, respectively. Furthermore, the proportion of therapeutic intervention, supplementation intervention and no vitamin D intervention among the children was 16.48, 32.87, and 50.65%, respectively. After adjusted for confounding factors, vitamin D intervention was associated with a lower risk of hypovitaminosis D, with OR (95% CI) of 0.191 (0.180, 0.202) in children with therapeutic doses and 0.423 (0.404, 0.443) in those with supplementation doses, compared with children without vitamin D intervention. In addition, longer outdoor time was associated with a lower risk of hypovitaminosis D [0.479 (0.456, 0.504) for 60 min/d, 0.737 (0.701, 0.776) for 30–60 min/d], independent of vitamin D intervention.

Conclusions

High prevalence of vitamin D deficiency was found in children living at high latitudes. Vitamin D intervention and outdoor activity are all negatively associated with children’s vitamin D deficiency. Routine vitamin D intervention combined with increased outdoor time might be an effective approach to prevent hypovitaminosis D among children, especially those at school, living at high latitudes.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12887-020-02435-9.

On-road vehicle emission inventory and its spatio-temporal variations in North China Plain

Vehicle emissions are a major contributor to air pollution in China. In this study, a high-resolution inventory of eight on-road vehicle-emitted pollutants in 53 cities within the North China Plain (NCP) was established for 152 sub-sources. Monthly emission factors were then simulated using the COPERT v5 model and their spatial distribution at 4 km × 4 km resolution was allocated based on the transportation network. In 2017, emissions of BC, CO, NH₃, NMVOCs, NO_x, PM₁₀, PM_2.5, and SO₂ were 38.3, 2900, 21.8, 578, 2460, 113, 85.9, and 4.7 kt, respectively. These emissions and their sources differed between cities, mainly due to different vehicle populations, fleet compositions, emission share rates of different vehicle types, and emission standards in each city. Small-medium petrol passenger cars and both 20-26 t and 40-50 t heavy-duty diesel trucks of China 3 and 4 emissions standards were the main contributors for all pollutants. Higher cold-start emission factors caused higher emissions of CO, NMVOCs, NO_x, and PM_2.5 in winter. The cities of Beijing, Zhengzhou, Tianjin, Tangshan, Xuzhou, Qingdao, Jinan, Jining, and Zibo had the highest emission intensities. Overall, emissions decreased from the city centers toward surrounding areas. The higher contributions of heavy-duty trucks meant that higher emissions appeared along highways in a vein-like distribution. These results provide a theoretical basis for the effective prevention and control of air pollution in the NCP.

Persistent ozone pollution episodes in North China exacerbated by regional transport

Summertime ozone (O₃) concentrations over China continue to increase although the governmental Clear Air Actions have been carried out since 2013. The worst O₃ pollution is confronted over North China Plain. Ozone polluted days (with observed regionally-averaged maximum daily 8-h average (MDA8) O₃ concentrations exceeding 80 ppbv) in May-July in North China increased from 35 days in year 2014 to 56 days in year 2018, and persistent O₃ pollution episodes that lasted for 5 days or longer (OPEs5) contributed 14.3% and 66.1% to those O₃ polluted days in 2014 and 2018, respectively. Model simulations suggest that O₃ transport from central eastern China (including Shandong, Henan, Jiangsu and Anhui Provinces) contributes 36% of the enhanced O₃ concentrations in North China during OPEs5 relative to the seasonal mean. We find that emission control of volatile organic compounds in central eastern China is most effective to alleviate intensity of OPEs5 in North China.

Spatio-temporal distribution of ammonia (NH3) emissions in agricultural fields across North China

Ammonia (NH₃) is one of the main polluted gases in the atmosphere, and its emission has markedly increased in recent years. In China, NH₃ is mainly emitted from agricultural fields. Using city-wide data on NH₃ emissions in agricultural fields, the spatio-temporal emission of NH₃ was estimated for North China. This included emissions from nitrogen fertilizers, field straws, background soil, nitrogen-fixing plants, human feces, and livestock/poultry manure. Based on the results, the range of NH₃ emission in agricultural lands was 1623.0-1801.5 Gg/year. The rate of increase in NH₃ emission in the period 2003-2015 was 0.74% per year, which was relatively stable. The leading sources of NH₃ emission included the excessive use of chemical fertilizers in agriculture and the continuous expansion of livestock and poultry industries scale, accounting respectively for 44.9% and 43.9% NH₃ emission in the study area, respectively. Hebei and Shandong provinces contributed the highest NH₃ emission in North China. The contribution rate of NH₃ emission in each province varied with sources, agricultural development, and population density. Based on the 1 km × 1 km grid resolution map for NH₃ emission, the range and average of emission were 9.72-10.13 kg/ha and 9.95 kg/ha, respectively. High emissions were in the southeast of Hebei province and most of Shandong province. For these regions, there is a need for changes in policies relating to the use of chemical fertilizers in agriculture and the management methods of livestock production in the region.

Responses of Litter Decomposition and Nutrient Dynamics to Nitrogen Addition in Temperate Shrublands of North China

Plant litter decomposition is a crucial ecosystem process that regulates nutrient cycling, soil fertility, and plant productivity and is strongly influenced by increased nitrogen (N) deposition. However, the effects of exogenous N input on litter decomposition are still poorly understood, especially in temperate shrublands, which hinders predictions of soil C and nutrient dynamics under the context of global change. Temperate shrub ecosystems are usually N-limited and particularly sensitive to changes in exogenous N input. To investigate the responses of Vitex negundo and Spiraea trilobata litter decomposition to N addition, we conducted a field experiment in Vitex- and Spiraea-dominated shrublands located on Mt. Dongling in Beijing, North China. Four N treatment levels were applied: control (N₀; no N addition), low N (N₁; 20 kg⋅N⋅ha^-1⋅year^-1), moderate N (N₂; 50 kg⋅N⋅ha^-1⋅year^-1), and high N (N₃; 100 kg⋅N⋅ha^-1⋅year^-1). The litter decomposition in V. negundo was faster than that in S. trilobata, which may be due to the differences in their nutrient content and C/N ratio. N addition increased the amount of remaining N in the two litter types but had no effect on the remaining mass, C, or P. Nitrogen treatment did not affect the litter decomposition rates (k) of either litter type; i.e., N addition had no effect on litter decomposition in temperate shrublands. The neutral effect of N addition on litter decomposition may be primarily explained by the low temperatures and P limitation at the site as well as the opposing effects of the exogenous inorganic N, whereby exogenous N inhibits lignin degradation but promotes the decomposition of readily decomposed litter components. These results suggest that short-term N deposition may have a significant impact on N cycling but not C or P cycling in such shrub ecosystems.

Exploring the regional pollution characteristics and meteorological formation mechanism of PM2.5 in North China during 2013-2017

In the last decade, North China (NC) has been one of the most populated and polluted regions in the world. The regional air pollution has had a serious impact on people's health; thus, all levels of government have implemented various pollution prevention measures since 2013. Based on multi-city in situ environmental and meteorological data, as well as the meteorological reanalysis dataset from 2013 to 2017, regional pollution characteristics and meteorological formation mechanisms were analyzed to provide a more comprehensive understanding of the evolution of PM_2.5 in NC. The domain-averaged PM_2.5 was 79 ± 17 µg m^-3 from 2013 to 2017, with a decreasing rate of 10 μg m^-3 yr^-1. Two automatic computer algorithms were established to identify 6 daily regional pollution types (DRPTs) and 48 persistent regional pollution events (PRPEs) over NC during 2014-2017. The average PM_2.5 concentration for the Large-Region-Pollution type (including the Large-Moderate-Region-Pollution and Large-Severe-Region-Pollution types) was 113 ± 40 µg m^-3, and more than half of Large-Region-Pollution days and PRPEs occurred in winter. The PRPEs in NC mainly developed from the area south of Hebei. The number of Large-Region-Pollution days decreased notably from 2014 to 2017, the annual number of days varying between 194 and 97 days, whereas a slight decline was observed in winter. In addition, the averaged PM_2.5 concentrations and the numbers and durations of the PRPEs decreased. Lamb-Jenkinson weather typing was used to reveal the impact of synoptic circulations on PM_2.5 across NC. Generally, the contributions of the variations in circulation to the reduction in PM_2.5 levels over NC between 2013 and 2017 were 64% and 45% in summer and winter, respectively. The three most highly polluted weather types were types C, S and E, with an average PM_2.5 concentration of 137 ± 40 µg m^-3 in winter. Furthermore, three typical circulation dynamics were categorized in the peak stage of the PRPEs, namely, the southerly airflow pattern, the northerly airflow pattern and anticyclone pattern; the averaged relative humidity, recirculation index, wind speed and boundary layer height were 63%, 0.33, 2.0 m s^-1 and 493 m, respectively. Our results imply that additional emission reduction measures should be implemented under unfavorable meteorological situations to attain ambient air quality standards in the future.

Understanding the Spatial-Temporal Patterns and Influential Factors on Air Quality Index: The Case of North China

North China has become one of the worst air quality regions in China and the world. Based on the daily air quality index (AQI) monitoring data in 96 cities from 2014–2016, the spatiotemporal patterns of AQI in North China were investigated, then the influence of meteorological and socio-economic factors on AQI was discussed by statistical analysis and ESDA-GWR (exploratory spatial data analysis-geographically weighted regression) model. The principal results are as follows: (1) The average annual AQI from 2014–2016 exceeded or were close to the Grade II standard of Chinese Ambient Air Quality (CAAQ), although the area experiencing heavy pollution decreased. Meanwhile, the positive spatial autocorrelation of AQI was enhanced in the sample period. (2) The occurrence of a distinct seasonal cycle in air pollution which exhibit a sinusoidal pattern of fluctuations and can be described as “heavy winter and light summer.” Although the AQI generally decreased in other seasons, the air pollution intensity increased in winter with the rapid expansion of higher AQI value in the southern of Hebei and Shanxi. (3) The correlation analysis of daily meteorological factors and AQI shows that air quality can be significantly improved when daily precipitation exceeds 10 mm. In addition, except for O₃, wind speed has a negative correlation with AQI and major pollutants, which was most significant in winter. Meanwhile, pollutants are transmitted dynamically under the influence of the prevailing wind direction, which can result in the relocation of AQI. (4) According to ESDA-GWR analysis, on an annual scale, car ownership and industrial production are positively correlated with air pollution; whereas increase of wind speed, per capita gross domestic product (GDP), and forest coverage are conducive to reducing pollution. Local coefficients show spatial differences in the effects of different factors on the AQI. Empirical results of this study are helpful for the government departments to formulate regionally differentiated governance policies regarding air pollution.

The complete chloroplast genome of Lonicera oblata, a critically endangered species endemic to North China

Lonicera oblata, a critically endangered species endemic to North China with about 30 wild individuals, has long been ignored for conservation since its publication because of little attention on its living situation. In this study, we characterized the complete chloroplast (cp) genome of L. oblata. The cp genome was 155,481 bp in length, included a large single-copy (LSC) region of 89,139 bp, a small single-copy (SSC) region of 18,676 bp, and two inverted repeat (IR) regions of 23,833 bp each. The genome contains 130 genes, including 85 protein-coding genes, 37 tRNA genes, and 8 rRNA genes. Phylogenetic position of L. oblata was also investigated based on cp genome phylogeny of Lonicera representatives. This study is valuable for molecular phylogenetic study and conservation of Lonicera and related taxa.

One-century sediment records of heavy metal pollution on the southeast Mongolian Plateau: Implications for air pollution trend in China

Historical records of heavy metals from remote areas are important for assessing temporal pollution trends of the regional atmosphere. Based on comparison analyses of heavy metals, Pb isotopes, and total carbon in sediment cores from two relatively remote lakes on the southeast Mongolian Plateau, atmospheric heavy metal pollution trends during ∼1900-2016 were reconstructed. The current anthropogenic fluxes of Zn, Cd and Pb in the region are 11.7, 0.104 and 2.44 mg m^-2 yr^-1, respectively, close to those in Lake Sayram in West China, but lower than most other records in China. Anthropogenic metal fluxes and ²⁰⁶Pb/²⁰⁷Pb ratios suggest that (1) before ∼1950 atmospheric metal pollution was negligible in the region; (2) since ∼1950, the pollution became detectable but was relatively slight until ∼1980, corresponded with the beginning of socio-economic development after the foundation of China in 1949 and the rapid development after the Reform and Opening-up in 1978; and (3) since ∼2000, atmospheric Pb stopped increasing because of the phasing out of leaded gasoline. Based on comparison and fitting analyses with other sediment records, a similar four-stage evolution picture of atmospheric heavy metals in China over the last century was uncovered. This study indicates rapid increase trends of atmospheric heavy metals in China since ∼1980 associated with economic development.

RNA Sequencing Characterizes Transcriptomes Differences in Cold Response Between Northern and Southern Alternanthera philoxeroides and Highlight Adaptations Associated With Northward Expansion

Alternanthera philoxeroides recently expanded its range northwards in China. It is unknown if the range expansion has a genetic and/or epigenetic basis, or merely an environmental basis due to a warming climate. To test these possibilities, we used an RNAseq approach with a common greenhouse design to examine gene expression in individuals from the northern edge and central portion of alligator weed range from China to determine if there were differences in their responses to cold temperatures. We hypothesized that if the recent range expansion was primarily environmental, we would observe few differences or only differences unrelated to low-temperature adaptations. We assembled over 75,000 genes of which over 65,000 had long open reading frames with similarity to sequences from arabidopsis. Differences in expression between northern and southern populations that were both exposed to low temperatures showed similar expression among genes in the C-REPEAT/DRE BINDING FACTOR (CBF) regulon. However, gene set and sub-network enrichment analysis indicated differences in the response of photosynthetic processes and oxidative stress responses were different between the two populations and we relate these differences to cold adaptation. The transcriptome differences in response to cold between the individuals from the two populations is consistent with adaptations potentiating or resulting from selection after expansion into colder environments and may indicate that genetic changes have accompanied the recent northward expansion of A. philoxeroides in China. However, we cannot rule out the possibility of epigenetic changes may have a role in this expansion.

Land-Water-Food Nexus and indications of crop adjustment for water shortage solution

While agriculture places the greatest demand on water resources, increasing agricultural production is worsening a global water shortage. Reducing the cultivation of water-consuming crops may be the most effective way to reduce agricultural water use. However, when also taking food demand into consideration, sustaining the balance between regional water and food securities is a growing challenge. This paper addresses this task for regions where water is unsustainable for food production (Beijing-Tianjin-Hebei Region for example) by: (i) assessing the different effects of wheat and maize on water use; (ii) analyzing virtual water and virtual land flows associated with food imports and exports between Beijing-Tianjin-Hebei and elsewhere in China; (iii) identifying sub-regions where grain is produced using scarce water resources but exported to other regions; and (iv) analyzing the potentiality for mitigating water shortage via Land-Water-Food Nexus. In the Beijing-Tianjin-Hebei Region, the study reveals that 29.76 bn m³ of virtual water (10.81 bn m³ of blue virtual water) are used by wheat and maize production and 8.77 bn m³ of virtual water used in nearly 2 million ha of cropland to overproduce 12 million ton of maize for external food consumption. As an importing-based sub-region with high population density, Beijing & Tianjin imported mostly grain (wheat and maize) from Shandong Province. Then, Hebei Province, as an exporting-based sub-region with severe water shortage, overproduced too much grain for other regions, which aggravated the water crisis. To achieve an integrated and sustainable development of the Beijing-Tianjin-Hebei Region, Hebei Province should stop undertaking the breadbasket role for Beijing & Tianjin and pay more attention to groundwater depletion. The analysis of the Land-Water-Food Nexus indicates how shifts in cultivated crops can potentially solve the overuse of water resources without adverse effects on food supply. It also provides meaningful information to support policy decisions about regional cropping strategies.

The Study on the Correlation Between Six Kinds of Mineral Elements and Diabetes

The study aimed to explore the relationship of six kinds of mineral elements and diabetes among adults in northeast China. A cross-sectional survey was conducted in Jilin Province, northeast China. A total of 366 males and 204 females aged 18 ~ 77 years from Jingyu town, Dongliao town, and Changling town were included using a multistage stratified random cluster sampling design. Data was obtained from face to face interview, physical examination, and laboratory measurement. We defined the normal people (3.9 ~ 6.0 mmol/L), impaired fasting glucose (IFG) individuals (6.1 ~ 6.9 mmol/L), and diabetes mellitus (DM) (> 7.0 mmol/L) according to the WHO diagnostic criteria. Kruskal-Wallis test, Spearman rank correlation, as well as binary logistic regression were used to analyze influencing factors. lg(Cu/Zn)was correlated with DM (OR 8.390; 95% CI of OR 1.272-55.347). The specific mineral elements such as Zn, Ca, as well as Cu/Zn ratio may be the potential risk factors for diabetes. So, the supplement or reduction of these elements is supposed to be told to IFG to prevent or delay the occurrence of diabetes or DM to avoid its complication.

Risk assessment models to evaluate the necessity of prostate biopsies in North Chinese patients with 4-50 ng/mL PSA

Background

Prostate-specific antigen (PSA) is widely used for prostate cancer screening, but low specificity results in high false positive rates of prostate biopsies.

Objective

To develop new risk assessment models to overcome the diagnostic limitation of PSA and reduce unnecessary prostate biopsies in North Chinese patients with 4–50 ng/mL PSA.

Methods

A total of 702 patients in seven hospitals with 4–10 and 10–50 ng/mL PSA, respectively, who had undergone transrectal ultrasound-guided prostate biopsies, were assessed. Analysis-modeling stage for several clinical indexes related to prostate cancer and renal function was carried out. Multiple logistic regression analyses were used to develop new risk assessment models of prostate cancer for both PSA level ranges 4-10 and 10-50 ng/mL. External validation stage of the new models was performed to assess the necessity of biopsy.

Results

The new models for both PSA ranges performed significantly better than PSA for detecting prostate cancers. Both models showed higher areas under the curves (0.937 and 0.873, respectively) compared with PSA alone (0.624 and 0.595), at pre-determined cut-off values of 0.1067 and 0.6183, respectively. Patients above the cut-off values were recommended for immediate biopsy, while the others were actively observed. External validation of the models showed significantly increased detection rates for prostate cancer (4-10 ng/mL group, 39.29% vs 17.79%, p=0.006; 10-50 ng/mL group, 71.83% vs 50.0%, p=0.015).

Conclusions

We developed risk assessment models for North Chinese patients with 4–50 ng/mL PSA to reduce unnecessary prostate biopsies and increase the detection rate of prostate cancer.

The distribution of three candidate cold-resistant SNPs in six minorities in North China

BACKGROUND

Heilongjiang Province located in northeast China is a multi-ethnic region with people who have lived in cold conditions for several generations. Fatty acids are important to people with cold resistance. CPT1A encodes a protein that imports long-chain fatty acids into the mitochondria for fatty-acid oxidation. FADS is an essential enzyme for the synthesis of long-chain polyunsaturated fatty acids.

RESULTS

In the present study, we investigated the distributions of three cold resistance-related SNPs (rs80356779 G > A in CPT1A, rs7115739 T > G in FADS3 and rs174570 C > T in FADS2) from six populations that included 1093 individuals who have lived in Heilongjiang Province for at least three generations. The frequencies of rs174570 and rs7115739 were different in our six north minorities compared to the Chinese Dai in Xishuangbanna (CDX) in southern China. All the SNPs in Hezhen were significantly different from other five studied populations. In addition, the genetic distribution of rs174570 in Daur was significantly different from Manchu and Korea, and the frequency of rs7115739 in Ewenki was significantly different from the other populations. The results also showed that the frequencies of the three SNPs in the six minorities were different from those of Greenlandic Inuit and Siberian population.

CONCLUSIONS

Our results showed the distributions of the three cold resistance-related SNPs from six populations that included 1093 individuals in northern China. Distributions of the allele frequencies for the cold resistance-related SNPs in northern China were statistically different from those in southern China. These data help to establish the DNA genome database for the six populations and fully preserve existing minority genetic information.

Nitrogen-Fixing Heterocystous Cyanobacteria in the Tonian Period

Cyanobacteria were the ultimate ancestor of all plastids and, for much of Earth's history, the only source of biogenic oxygen and a major source of fixed carbon and nitrogen. One cyanobacterial clade, subsections IV+V, is characterized by multicellularity and cell differentiation, with many members bearing specialized nitrogen-fixing (or diazotrophic) heterocysts and encysting akinetes [1-3]. Molecular clock estimates of the divergence time of this clade are highly variable, ranging from ∼2,000 Ma (mega-annum) [4-9] to ∼500 Ma [10]. The older estimates are invariably calibrated by putative akinete fossils from Paleoproterozoic-Mesoproterozoic rocks around 2,100-1,400 Ma [3, 11, 12]. However, the interpretation of these fossils as akinetes has been questioned [13], and the next oldest akinete and heterocyst fossils are ∼410 Ma [14]. Thus, the scarcity of reliable heterocystous cyanobacterial fossils significantly hampers our understanding of the evolution of complex multicellularity among cyanobacteria, their role in regulating geochemical cycles in the geological past, and our ability to calibrate cyanobacterial molecular clocks. Here, we report Tonian (∼1,000-720 Ma) filamentous cyanobacteria that are characterized by large cells, binary fission (for filament elongation), hormogonia (for asexual reproduction and dispersal), probable akinetes (for survival in adverse conditions), and by implication, diazotrophic heterocysts. The new fossils provide a minimum age calibration on the divergence of subsections IV+V and place a firm constraint on the evolution of akinetes and heterocysts.

Assessing on toxic potency of PM2.5-bound polycyclic aromatic hydrocarbons at a national atmospheric background site in North China

A total of 76PM_2.5 samples collected at Tuoji Island from November 2011 to January 2013 were used to analyze 15 congeners of polycyclic aromatic hydrocarbons (∑₁₅PAHs) and assess their toxic potency. The average ∑₁₅PAHs was 15.34±8.87ngm^-3, ranging from 4.24 to 40.62ngm^-3 over the sampling period. BkF, BbF, Phe and BaP were dominant PAH congeners, contributing together 60.64% of the ∑₁₅PAH concentration. The highest monthly ∑₁₅PAHs concentration was in January 2012, followed by the next January, which was closely four times greater than the lowest level occurred in July 2012. Wheat straw burning was responsible for the high PAH concentrations in June 2012. The averaged BaP toxicity equivalent (TEQ-BaP) concentration was 2.70±1.88ngm^-3 over the sampling period. BaP and DaA were the largest contributors, which contributed 58.5% and 14.7% of totals, respectively. The high TEQ-BaP and TEQ-BaP value per unit of ∑₁₅PAHs concentration (TEQ-BaP(U)) values occurred in the cold season and the low levels presented in the warm period. The heaviest monthly TEQ-BaP was 5.28±2.84ngm^-3, which appeared in January 2012; the lowest value was 0.86±0.33ngm^-3, which occurred in July 2012. The potential source contribution function (PSCF) showed the occurrence of the high health risk associated with PAHs in the middle of Liaoning and the south of Shandong Peninsula.