Insights into the effects of heavy metal pressure driven by long-term treated wastewater irrigation on bacterial communities and nitrogen-transforming genes along vertical soil profiles

Irrigation with treated wastewater (TWW) influences soil ecological function due to the accumulation of heavy metals (HMs) and nutrients in soils. However, the interaction between HMs and microbial processes in TWW-irrigated soil has not been fully explored. We investigated the effect of HMs on bacterial communities and nitrogen-transforming (N-transforming) genes along vertical soil profiles irrigated with domestic TWW (DTWW) and industrial TWW (ITWW) for more than 30 years. Results indicate that long-term TWW irrigation reshaped bacterial community structure and composition. Irrigation with ITWW led to increased accumulation of Cd, Cr, Cu, Pb, Zn, and Ni in soils than DTWW. Accumulation of inorganic N, soil organic carbon, and HMs in topsoil irrigated with ITWW contributed to the activities of Micrococcaceae. The effect of the activation of nutrient factors on Bacillus, which was the dominant species in DTWW-irrigated soils, was greater than that of HMs. HM pressure driven by ITWW irrigation changed the vertical distribution of N-transforming functional genes, increasing the abundance of amoA gene and decreasing that of nifH through soil depth. ITWW irrigation enhanced the denitrification capacity in topsoil; ammonia-oxidizing capacity in deeper soil was increased after long-term irrigation with DTWW and ITWW, suggesting a potential risk of nitrogen loss.

Metal type and aggregate microenvironment govern the response sequence of speciation transformation of different heavy metals to microplastics in soil

Microplastics change the physical, chemical, and biological processes in soil, and these changes further affect the transformations of heavy metal speciation in soil. Whether this influence mechanism differs between heavy metals is unknown on the soil aggregates level. In this study, 5 months incubation experiments and soil fractionation were conducted to evaluate the effect of microplastic addition on the chemical speciation of seven heavy metals (Zn, Cu, Ni, Cd, Cr, As, and Pb) in the three soil aggregate fractions. The results show that 28% concentration of polyethylene microplastics with size 100 μm reduces and increases the heavy metal content in the bioavailable and organic-bound fractions, respectively, indicating that microplastics promote the transformation from bioavailable to organic-bound species. The transformation in the larger-sized aggregate fractions is more dramatic than that of smaller-sized aggregate fractions within the incubation period. This indicates that the extent of the response of the different heavy metals to microplastics is significantly different in the three aggregate-size fractions. Soil physicochemical factors affected different heavy metals in different pathways, and microplastics have different adsorption or complexation effects on different heavy metals. These processes result in heterogeneous responses of different heavy metals to microplastic addition. In addition, the microplastics have different extents of influence on the different chemical speciation of the heavy metals, having the greatest influence on the exchangeable and carbonate-bound of Cu and Zn, FeMn oxide-bound of As, and organic-bound of Cr, Ni, Cd, and Pb. This phenomenon is relatively consistent among the three aggregate-size fractions. Our findings provide more accurate management information for soil environmental quality management with different heavy metal pollution and different soil types.

Heavy metal pollution, ecological risk, spatial distribution, and source identification in sediments of the Lijiang River, China

The Lijiang River is of great ecological and environmental importance for Guilin City, which is located in the karst area of southeast China. Given its importance, a detailed evaluation of the heavy metals (HMs) in the river sediment is required. For the first time, 61 sediment samples were collected along the entire Lijiang River to determine pollution level and ecological risk posed by 10 HMs (Co, Cr, Cu, Mn, Ni, Pb, Zn, As, Hg, and Cd). These were assessed using the geo-accumulation index, potential ecological risk index, and modified degree of contamination. The results showed that the mean concentrations of the majority of HMs exceeded their corresponding background values and followed the trend: midstream > downstream > upstream. Based on the spatial distributions and pollution indices of the 10 HMs, the Lijiang River was found to have a high accumulation of Cd, Hg, Zn, and Pb in the sediments. The midstream area was the most polluted with respect to Cd and Hg, and also posed a relatively higher potential ecological risk than the downstream and upstream areas. The sources of the assessed HMs were inferred based on a correlation analysis and principal component analysis, which identified both natural and anthropogenic sources. A higher pollution potential was associated with Cd, Hg, Pb, and Zn in the midstream and downstream areas due to higher organic and carbonate content, urbanization, agricultural activities, and leisure activities (e.g., boating and cruises). In contrast, natural erosion and weathering processes were responsible for the HM concentrations in the upstream area. The findings of this study will help the local authorities to protect the important water resource of the Lijiang River.

The maturity period is the main stage of antibiotic resistance genes reduction in aerobic composting process of swine manure in sub-scale farms

This study was focused on the changes of antibiotic resistance genes (ARGs) and their potential host bacteria during the swine manure composting on sub-scale farms. Eight target ARGs increased 427% on average, with a trend of increase at early stage and decrease at later stage, and the main reduction stage appeared in maturity stage. The abundance of ARGs was mainly affected by the community succession of potential host bacteria. Composting could reduce the abundance of potential host bacteria of ARGs as well as pathogens such as Pseudomonas, and reduce the environmental risks of swine manure. N/C and S levels had a positive effect on the potential host of most ARGs. Prolonging the maturity period would inhibit the growth of potential host bacteria of ARGs during composting, therefore inhibiting the transmission of ARGs.

Effects of hydrological and climatic variables on cyanobacterial blooms in four large shallow lakes fed by the Yangtze River

Shallow lakes, one of the most widespread water bodies in the world, are easily shifted to a new trophic state due to external interferences. Shifting hydrologic conditions and climate change can cause cyanobacterial harmful algal blooms (CyanoHABs) in shallow lakes, which pose serious threats to ecological integrity and human health. This study analyzed the effects of hydrologic and meteorological variables on cyanobacterial blooms in Yangtze-connected lakes (Lake Dongting and Poyang) and isolated lakes (Lake Chao and Tai). The results show that (i) chlorophyll-a (Chl-a) concentration tends to decrease exponentially with increasing relative lake level fluctuations (RLLF) and precipitation, but to increase linearly with increasing wind speed and air temperature; (ii) Chl-a concentrations in lakes were significantly higher when RLLF < 100, precipitation < 2.6 mm, wind speed > 2.6 m s^-1, or air temperature > 17.8 °C; (iii) the Chl-a concentration of Yangtze-isolated lakes was more significantly affected by water level amplitude, precipitation, wind speed and air temperature than the Yangtze-connected lakes; (iv) the RLLF and the ratio of wind speed to mean water depth could be innovative coupling factors to examine variation characteristics of Chl-a in shallow lakes with greater correlation than single factors.

[Elevated blood pressure in childhood or adolescence and early cardiovascular damage]

With the increase of overweight and obesity, elevated blood pressure (BP) in children and adolescents has been an important public health issue globally. Many studies have assessed the association between elevated BP and early cardiovascular damage in children and adolescents. A majority of these studies have highlighted the effects of elevated BP on cardiovascular damage, but with partly inconsistent findings. The studies of biological mechanisms played important roles in illuminating the potential mechanisms of cardiovascular damage caused by elevated BP. In addition, studies on the interventions, including losing weight and lowing BP were beneficial to reduce the occurrence of or reverse early cardiovascular damage. In this review, we reviewed articles on the association between elevated BP and early cardiovascular damage (including structural and functional damage of cardiac and vessels) in children and adolescents, underlying biological mechanisms, and the effectiveness of interventions to provide a reference for the prevention and intervention of early cardiovascular damage caused by elevated BP in children and adolescents and then reduce the occurrence of cardiovascular disease in adulthood.

[Design of huantai childhood cardiovascular health cohort study]

Cardiovascular disease (CVD) has been an important public health issue in China. Recently, the prevalence of obesity, elevated blood pressure, hyperglycemia, dyslipidemia, and unhealthy lifestyles was high in Chinese children and adolescents, which might increase the risk of short-term target organ damage and adult CVD. Therefore, we selected one primary school in Huantai County, Zibo City between November 2017 and January 2018 to establish the Huantai Childhood Cardiovascular Health Cohort Study. The aim of this project was to investigate the effects of childhood exposures on short-term target organ damage and adult CVD, and to provide evidence to curb the epidemic of CVD in China from the source. A total of 1 515 children aged 6-11 years old were included at the baseline. In this paper, we will introduce the overall design of the survey, including participants, methods, quality control, basic characteristics of the participants, study limitations, and future directions, which might provide some useful implications for similar researches in the future.

[Establishing longitudinal cohort studies based on domestic and foreign experiences and promoting the prevention and control of cardiovascular diseases in childhood]

There is a "trajectory" of cardiovascular risk factors from childhood to adulthood, and cardiovascular disease in adulthood originates in childhood. Several childhood cardiovascular follow-up cohorts have been established at home and abroad and participants have been followed up to middle-age or early old-age period, which have provided evidence support for prevention of cardiovascular disease in adulthood. However, at present, Chinese residents are in nutritional transition period. Given the evolving socio-economic context in China and the differences in growth and development patterns between contemporary Chinese children and western children or Chinese children in the 1990s, it is necessary to establish new childhood cardiovascular follow-up cohorts with Chinese features, to inform prevention of cardiovascular disease in Chinese adults.

[Association between elevated blood pressure and high carotid intima-media thickness in children according to different blood pressure references]

Objective: To analyze the association between elevated blood pressure (BP) and carotid intima-media thickness (cIMT) in children according to four BP references. Methods: Study population came from"Huantai Childhood Cardiovascular Health Cohort Study"in Huantai County, Zibo City, Shandong Province. A convenient cluster sampling method was used to conduct a cross-sectional survey on 1 515 children from November 2017 to January 2018 in a primary school. A total of 1 431 children aged 6-11 years old with complete data were included in this study. Data on demographic characteristics, BP and cIMT were collected through questionnaire survey, physical examination and ultrasound examination. High cIMT was defined as the level of cIMT ≥ age-and sex-specific 90^th percentile of this study population. Based on the Chinese Guideline reference, the Health Industry reference, the International reference and the U.S. reference, all participants were divided into three subgroups: the normal BP, high normal BP and, elevated BP. The multivariate logistic regression models were used to examine the association between BP status and high cIMT in children. Results: The age of children was (8.9±1.5) years, and boys accounted for 53.4% (n=682). The multivariate logistic regression models showed that after adjusting for relevant confounding factors, the risk of high cIMT in elevated BP group was increased compared with the normal BP group according to the four references (all P values<0.05) Conclusion: Elevated BP according to the four BP references is associated with high cIMT in children.

[Association of abdominal obesity in childhood with high carotid intima-media thickness]

Objective: To examine the association of abdominal obesity assessed by waist circumference (WC) with carotid intima-media thickness (cIMT) in children. Methods: The study participants were from the "Huantai Childhood Cardiovascular Health Cohort Study" conducted in Huantai County, Zibo City, Shandong Province. A convenient cluster sampling method was used to select a primary school in Huantai County to conduct the baseline survey from November 2017 to January 2018. A total of 1 515 children aged 6-11 years old were included. The first follow-up survey was conducted from November to December 2019, and a total of 981 children aged 8-13 years old were finally included after exclusion of those with high cIMT at baseline. Questionnaire survey, physical examination and ultrasonic examination were used to collect general demographic characteristics, WC and cIMT information. According to the status of WC at baseline, the participants were divided into normal WC group and abdominal obesity group. Covariance analysis was used to compare the cIMT levels of children between normal WC group and abdominal obesity group. Multivariable logistic regression models were used to evaluate the association between baseline abdominal obesity and high cIMT during the follow-up. Results: The age of 981 children was (8.5±1.5) years at the baseline. The follow-up age was (10.5±1.5) years, and 520 boys accounted for 53.0%. The cIMT of children in the abdominal obesity group was 0.54 mm, which was higher than that in the normal WC group (0.51 mm) (P<0.001). Similarly, the prevalence of high cIMT in children with abdominal obesity (23.9%) was higher than that of normal WC group (3.9%) (P<0.001). After adjusting for potential covariates at the baseline and during the follow-up period, compared with the normal WC group, abdominal obesity was significantly associated with high cIMT (OR=5.78, 95%CI:3.43-9.74). Conclusion: The abdominal obesity in children could increase the risk of high cIMT.

Inhibitory effect of microplastics on soil extracellular enzymatic activities by changing soil properties and direct adsorption: An investigation at the aggregate-fraction level

Microplastics (MPs), as a new type of environmental pollutant, pose a serious threat to soil ecosystems. The activities of soil extracellular enzymes produced by microorganisms are the potential sensitive indicators of soil quality. However, little is known about the response mechanism of enzyme activities toward MPs on a long-term scale. Moreover, information on differences in enzyme activities across different soil aggregates is lacking. In this study, 150 days of incubation experiments and soil aggregate fractionation were combined to investigate the influence of MPs on extracellular enzyme activities in soil. 28% concentration of polyethylene with size 100 μm was adopted in the treatments added with MPs. The results show that MPs inhibited enzyme activities through changing soil nutritional substrates and physicochemical properties or through adsorption. Moreover, MPs competed with soil microorganisms for physicochemical niches to reduce microbial activity and eventually, extracellular enzyme activity. Enzyme activities in different aggregate-size fractions responded differently to the MPs exposure. The catalase in the coarse particulate fraction and phenol oxidase and β-glucosidase in the micro-aggregate fraction exerted the greatest response. With comparison, urease, manganese peroxidase, and laccase activities showed the greatest responses in the non-aggregated silt and clay fraction. These observations are believed to stem from differences in the key factors determining the enzyme activities in different aggregate-size fractions. The inhibitory pathway of microplastics on activities of extracellular enzymes in soil varies significantly across different aggregate fractions.

Tracing bacterial and fungal necromass dynamics of municipal sludge in landfill bioreactors using biomarker amino sugars

The dynamics of microbial necromass of municipal solid waste over long-term landfill remain unknown. This study presents the first investigation on the dynamics of bacterial and fungal necromass of municipal sludge in non-aeration versus alternating aeration landfill bioreactors by using amino sugar biomarkers. Results showed that under non-aeration treatment, the decomposition rate of muramic acid derived from bacteria is higher than that of fungal-derived glucosamine. The relative change in glucosamine and muramic acid in the early period of landfills under the alternating aeration treatment is consistent with that under non-aeration treatment. However, with the increase in alternating aeration cycles, bacterial necromass muramic acid exerts a lower decomposition rate than fungal necromass glucosamine. Throughout the entire landfill period, galactosamine is the amino sugar with the slowest decomposition rate under non-aeration mode but the amino sugar with the fastest decomposition rate under alternating aeration mode. The present work fills the knowledge gap of microbial necromass dynamics of municipal solid waste in landfills.

A comparative study on the treatment of 2,4-dinitrotoluene contaminated groundwater in the combined system: efficiencies, intermediates and mechanisms

In this study, scrap irons (SI)/granular activated carbons (GAC) micro-electrolysis treatment and persulfate-releasing materials (PRM) treatment were employed to construct the combination reduction and oxidation system to treat 2,4-dinitrotoluene (2,4-DNT) contaminated groundwater. The 2,4-DNT treatment efficiencies in the PRM pre-treatment before SI/GAC micro-electrolysis treatment (FM-1 = PRM + SI/GAC) and SI/GAC micro-electrolysis pre-treatment before the PRM treatment (FM-3 = SI/GAC + PRM) were investigated in two separated columns. As control groups, the separated SI and GAC instead of the SI/GAC mixture were used in another two separated columns (FM-2 = PRM + SI + GAC; FM-4 = SI + GAC + PRM). The highest treatment efficiencies of 2,4-DNT in the FM-1 and FM-3 systems reached 79% and 93% during 5 PV, respectively. We found that the filling position of SI, GAC and PRM significantly affected the variations of pH, oxidation-reduction potential, Fe²⁺ and S₂O₈^2- concentrations in the combined systems. These results indicated that the SI/GAC micro-electrolysis pre-treatment of 2,4-DNT before the PRM treatment (FM-3) is more beneficial. The fifteen main intermediates in the combined system were identified by the detection of liquid chromatograph mass spectrometer. Furthermore, the possible treatment pathways of 2.4-DNT were proposed on the basis of identified intermediates. The treatment mechanisms in the FM-1 and FM-3 systems were proposed with the reduction mechanism in the SI/GAC micro-electrolysis system and the oxidation mechanism in the PRM treatment. Therefore, the combination of the reduction pre-treatment with the SI/GAC micro-electrolysis system and the oxidation post-treatment with persulfate can effectively treat the nitroaromatic compounds contaminated groundwater.

[Prevention of cardiovascular disease in adulthood should attach importance to related risk factors in childhood]

Most cardiovascular disease (CVD) related risk factors are prevalent in children and adolescents, especially obesity, elevated blood pressure (BP) and increased unhealthy lifestyle. To prevent CVD in adulthood, it is necessary to attach importance to the prevention and control of CVD risk factors in childhood. Of note, the prevention of childhood obesity is key measure, the control of childhood BP is the first goal, and the development of healthy lifestyle is important basis. The prevention and control of CVD risk factors in childhood can benefit the future prevention and treatment of CVD in adulthood, provide scientific base for the prevention and intervention of cardiovascular risk factors in childhood, and provide new perspective for the early prevention of cardiovascular diseases in adulthood.

[Association of abdominal obesity and obesity types with carotid intima-media thickness in children in China]

Objective: To evaluate the association of abdominal obesity and obesity types with carotid intima-media thickness (cIMT) in children and provide scientific evidence for the prevention of abnormal vascular structure. Methods: Based on the "Children's Cardiovascular Health Cohort" conducted in Huantai county of Zibo, Shandong province from November 2017 to January 2018, a total of 1 240 children, including 657 boys (53.0%), who had completed data of sex, age, physical examinations, blood biochemical indices and lifestyle variables (collected by questionnaires) were included for the analysis. Covariance analysis was used to compare the levels of cIMT in groups with normal waist circumference, pre-abdominal obesity and abdominal obesity. Logistic regression analysis was used to evaluate the association of pre-abdominal obesity and abdominal obesity with high cIMT, and the association of combined effect of general overweight or obesity and abdominal obesity or pre-abdominal obesity with high cIMT. Results: The levels of cIMT in children with pre-abdominal obesity (0.47±0.03) mm and abdominal obesity (0.50±0.04) mm were higher than that in children with normal waist circumference (0.45±0.05) mm, the difference was significant (P<0.001). The detection rates of high cIMT in children with pre-abdominal obesity(20.8%) and abdominal obesity (49.5%) were higher than that in children with normal waist circumference (8.8%), the difference was significant (P<0.001). Compared with normal waist circumference, pre-abdominal obesity and abdominal obesity were significantly associated with high cIMT (pre-abdominal obesity: OR=2.53, 95%CI: 1.67-3.84; abdominal obesity: OR=8.56, 95%CI: 5.97-12.29) after adjustment for potential covariates. Compared with normal body mass index and normal waist circumference, abdominal obesity or pre-abdominal obesity alone (OR=2.24, 95%CI: 1.36-3.69), and mixed overweight and obesity (OR=6.94, 95%CI: 4.87-9.90) were significantly associated with high cIMT. Conclusions: The association between abdominal obesity and high cIMT was significant in children, and the association was stronger between mixed overweight or obesity and high cIMT, suggesting that we should consider mixed overweight and obesity in the prevention of abnormal vascular structure.

[Detection of hypertension based on measurements at three occasions in different days and its relationship with obesity in children]

Objective: To analyze the trends in blood pressure (BP) values and the elevated BP based on the measurements at three occasions in different days and its relationship with obesity in children and provide scientific evidence for the identification and prevention of hypertension in children. Methods: A public primary school in Huantai county of Zibo, Shandong province, was selected as the investigation field by using a convenient cluster sampling method. The baseline survey of "Children's Cardiovascular Health Cohort" was carried out from November 2017 to January 2018. All the students with willingness and informed consent in this school were included in the survey, and the valid sample size was 1 505 children (aged 6-11 years). Children with elevated BP at the measurement of the first occasion should had a second measurement 2 weeks later, and a third measurement was given 2 weeks later if BP was still high at the measurement of the second occasion. Hypertension was confirmed if elevated BP was detected in the measurements at all the three occasions in different days. Multivariate linear regression model was used to assess the trend in BP values in children in the measurements at three occasions in different days, Cochran-Armitage trend analysis was used to evaluate the trend of elevated BP, and logistic regression model was used to analyze the relationship of elevated BP with obesity at three occasions in different days. Results: In this study, with the increase of follow-up visits, the BP levels continued to rise (trend P<0.05). The elevated BP rates at three occasions were 15.5%, 4.0% and 1.9%, respectively, showing a significantly downward trend (trend P<0.05). Compared with both normal weight and normal waist circumference, the association between obesity types (general obesity only, abdominal obesity only, and mixed obesity) and elevated BP at three occasions increased (the first occasion: OR=3.62, 95%CI: 2.65-4.96; the second occasion: OR=9.50, 95%CI: 4.95-18.22; and the third occasion: OR=8.94, 95%CI: 3.48-22.96; all P<0.05). Stratified analysis by gender showed similar results. Conclusions: The elevated BP rates based on the measurements at three occasions in different days in children aged 6-11 years showed a significant decrease trend. The association between different types of obesity (especially mixed obesity) and elevated BP in children became stronger gradually with the progress of the follow up.

Insights into the removal efficiencies of aged polycyclic aromatic hydrocarbons in humic acids of different soil aggregate fractions by various oxidants

Chemically oxidative removal of polycyclic aromatic hydrocarbons (PAHs) in soil is related to their occurrence state. Whether the heterogeneity of natural organic matter has an effect on the occurrence of PAHs in soil and, if there is an effect, on the oxidative removal efficiency of PAHs remains unknown. In this study, the removal efficiencies of 16 priority PAHs aged in humic acids (HAs) of different soil aggregate fractions by various oxidants were investigated by combining soil fractionation and microreaction experiments. Results showed that the accumulations of PAHs in particulate HA (P-HA) and microaggregate occluded HA (MO-HA) mainly occurred in the early period of the aging time frame. In contrast, PAH accumulation in non-aggregated silt and clay associated HA (NASCA-HA) was relatively slow and tended to saturate in the late period of the aging time frame. The cumulative contents of PAHs throughout the entire aging period in MO-HA and NASCA-HA were significantly greater than that in P-HA. The aged PAHs in P-HA and NASCA-HA exhibited the highest and lowest removal efficiencies, respectively. This ranking was mainly governed by the molecular size and polarity of HAs. Sodium persulfate and potassium permanganate had the highest removal efficiencies in total PAHs in HAs, with average efficiencies of 85.8% and 79.1%, respectively, in P-HA. Hydrogen peroxide had the lowest degradation efficiency in PAHs. In particular, the degradation efficiency of total PAHs in NASCA-HA was lowered to 31.0%. PAH congeners in HAs showed a large difference in oxidative removal efficiency. Low-ring PAH was more easily degraded than medium- and high-ring PAHs, and in most treatments, fluoranthene and pyrene in the medium ring and benzo[a]pyrene in the high ring demonstrated higher efficiencies than other PAHs with the same number of rings. Our findings are useful in promoting the accurate and green remediation of PAH-contaminated soils.

Dissolved Silicate Enhances the Oxidation of Chlorophenols by Permanganate: Important Role of Silicate-Stabilized MnO2 Colloids

Dissolved silicate is an important background constituent of natural waters, but there is little clarity regarding the effect of silicate on the oxidizing capability of permanganate (Mn(VII)) and on its efficiency for remediation applications. In the present study, we found that dissolved silicate, metasilicate or disilicate (DS), could significantly promote the oxidation of 2,4-dichlorophenol (2,4-DCP) by Mn(VII), and the extent of the promoting effect was even more evident than that of pyrophosphate (PP). The experiments showed that, unlike PP, DS was not capable of coordinating with Mn(III) ions, and the promoting effect of DS was not due to the oxidizing capability of complexed Mn(III). Instead, DS ions, as a weak base, could combine with the hydroxyl groups of MnO₂ via hydrogen bonding to limit the growth of colloidal MnO₂ particles. The DS-stabilized colloidal MnO₂ particles, with hydrodynamic diameters less than 100 nm, could act as catalysts to enhance the oxidation of 2,4-DCP by Mn(VII). The best promoting effect of DS on the performance of Mn(VII) oxidant was achieved at the initial solution pH of 7, and the coexisting bicarbonate ions further improved the oxidation of 2,4-DCP in the Mn(VII)/DS system. Sand column experiments showed that the combined use of Mn(VII) and DS additive could mitigate the problem of permeability reduction of sand associated with the retention of MnO₂ particles. This study not only deepens our understanding on the role of dissolved silicate in a Mn(VII) oxidation process but also provides an effective and green method to enhance the oxidizing capacity of Mn(VII)-based treatment systems.

Biogas slurry as an activator for the remediation of petroleum contaminated soils through composting mediated by humic acid

Soil pollution caused by petroleum hydrocarbons is a widespread environmental problem. Composting is one of the cost-effective solutions for petroleum hydrocarbons removal but limited by low efficiency of bioremediation, leading to high phytotoxicity. Given that biogas slurry as nutrients can alter the microbial activity, the aim of this study was to investigate the role of biogas slurry on the remediation of petroleum contaminated soils in composting. Herein, we added biogas slurry into the composting of hydrocarbon contaminated soil to investigate its effect on the biodegradation of petroleum hydrocarbons, humic acid (HA) transformation and the safety of product. The results showed that biogas slurry addition improved the degradation of organic matter and total petroleum hydrocarbons (TPH) (especially C > 16), but also increased 18.0% of germination index and the humification degree of HA. The estrone from biogas slurry was removed during composting and did not affect the phytotoxicity level of compost. Redundancy analysis and structural equation modeling indicated that TPH degradation was significantly related to the humification of HA components and total nitrogen from biogas slurry, which contributed to composting safety. Therefore, biogas slurry could be a possible activator for the remediation of petroleum contaminated soils through composting mediated by HA transformation, which is beneficial to obtain the composts with a lower phytotoxicity and higher maturity for soil application.

[Relationship between parental history of hypertension and childhood hypertension]

To explore the relationship between parental hypertension history and hypertension in children and adolescents based on the relevant data of 6 049 children and adolescents aged 6 to 17 years old in Jinan city from September 2012 to September 2014. The results showed that the history of hypertension in parents was positively correlated with systolic blood pressure in children and adolescents, with the value of coefficient β (95%CI) about 0.91 (0.23-1.59). Compared with children and adolescents whose parents had no history of hypertension, those with history of hypertension in one parent and both parents were more likely to develop hypertension, with OR values (95%CI) about 1.28 (1.01-1.61) and 2.24 (1.09-4.61), respectively. Therefore, it is suggested that prevention and intervention measures should be taken as soon as possible for children and adolescents whose parents have a history of hypertension.

Decrease in bioavailability of soil heavy metals caused by the presence of microplastics varies across aggregate levels

Microplastics can alter the physicochemical and biogeochemical processes in soil, but whether these alterations have further the effects on the transformation of soil heavy metal speciation, and if so, whether these effects vary across soil aggregate levels remain unknown. Herein, long-term soil culture experiments and soil fractionation are combined to investigate the effects of microplastics on chemical speciation of Cu, Cr, and Ni with different particle-size soil aggregates. Results show that microplastics in soil decrease the exchangeable, carbonate-bound, and Fe-Mn oxide-bound fractions of metals but increase their organic-bound fractions via direct adsorption and indirect effects on the soil microenvironment conditions. The findings suggest that microplastics can promote the transformation of heavy metal speciation from bioavailable to organic bound. Such promotion exerts notable differences across soil aggregate levels. The transformation of soil heavy metal speciation is greater in larger aggregates than in smaller aggregates in the early incubation period with microplastics but shows the opposite trend in the later incubation period. Therefore, this process is more sensitive to long-term microplastic pollution in smaller aggregates than in larger aggregates, most likely owing to the lag in the influence of microplastics on metal speciation transformation in the smaller aggregates.

A study of layered-unlayered extraction of benzene in soil by SVE

With the aim to improve the pollution removal efficiency, a layered extraction simulation device for the removal of benzene-contaminated soil via soil vapor extraction was constructed. The removal of benzene from soils by both layered extraction and unlayered extraction was explored based on the factors of extraction flow, extraction time, initial contaminant content, initial soil moisture content, and extraction method. Under the same conditions, layered extraction improved the repair efficiency, shortened the repair time, and decreased the cost of repair. Different factors exerted different influences on the extraction effect, but overall, compared with unlayered extraction, the removal rate of layered extraction can be increased by 2-20%. In particular, when the content of benzene was high, layered and intermittent extraction could remove more than 90% of benzene from the soil. When layered extraction was adopted, the pressure loss in the lower part of the soil layer was small and the air flow into the soil was large, which can promote the volatilization of benzene and thus improve its removal rate.

Accumulation characteristics and biological response of ginger to sulfamethoxazole and ofloxacin

The potential risk to human health of antibiotics that pass through the food chain has become an important global issue, but there are few reports on the response of ginger (Zingiber officinale) to antibiotic pollution. In this study, we investigated the enrichment characteristics and biological response of ginger to sulfamethoxazole (SMZ) and ofloxacin (OFL) residues, which are common in the environment. Lower levels of SMZ, OFL and their combined duplex treatment (SMZ+OFL) promoted the growth of ginger, but the critical doses necessary to stimulate growth differed among treatments: 10 mg L-1 SMZ, 1 mg L-1 OFL and 1 mg L-1 (SMZ+OFL) had the strongest stimulating effects. At higher dosages, the root growth and light energy utilization efficiency of ginger were impaired, and (SMZ+OFL) had the strongest inhibitory effect. Treatments with lower levels of antibiotics had no significant effect on reactive oxygen species and antioxidant enzyme activities. However, when SMZ, OFL and SMZ+OFL concentrations exceeded 10 mg L-1, the contents of H2O2, O2- and MDA continued to increase, while the activities of SOD, POD, CAT first increased and then decreased, especially in SMZ+OFL. Ginger accumulated more SMZ and OFL in rhizomes and less in leaves, and accumulation increased significantly as antibiotic concentration increased. When SMZ concentration was 1 mg L-1, the SMZ concentrations in rhizomes, roots, and leaves were 0.23, 0.15, and 0.05 mg kg-1, respectively, and the residual SMZ in the rhizome was 2.3 times higher than the maximum residue limit. The abundance of the resistance genes sul1, sul2, qnrS, and intI1 increased with increasing antibiotic concentrations, and intI1 abundance was the highest. OFL induced higher levels of intI1 expression than did SMZ.

Influence of surface properties and antecedent environmental conditions on particulate-associated metals in surface runoff

Particulate-associated trace metals have been regarded as an important pollution source for urban surface runoff. Cd, Pb, Cu, Zn and total solids (TS) washed off two different surfaces (low-elevated facade and road surfaces) under two kinds of antecedent environmental conditions (dry and snow-melting) were determined in this study. Wet-vacuuming sweeping (WVS) and surface washing (SW) methods, representing the maximum pollution potential and common rainfall-induced wash-off condition respectively, were used to collect the particulate matters. The result shows that the wash-off concentrations of trace metals were found in the order of Cd (2.28 ± 2.08 μg/l) < Pb (435.85 ± 412.61 μg/l) < Cu (0.93 ± 0.61 mg/l) < Zn (2.52 ± 2.30 mg/l). The snow-melting process had a considerable influence on the wash-off concentrations of the trace metals on both road and facade surfaces. It reduced >38% and >79% of metals and TS concentrations in the facade surface and road surface runoff respectively. The wash-off concentrations of Cd, Cu, and Zn on the road surface 45-780% higher than those on the facade surfaces. The sensitivity analysis based on the Bayesian network indicates that the wash-off concentrations of metals were mainly dependent on the antecedent environmental conditions or the surface properties while the sampling methods had a minor influence. Therefore, to accurately model the pollutant migration in the surface runoff requires an improving method considering different surfaces and antecedent environment conditions.