Classification technology of domestic waste from 2000 to 2019: a bibliometrics-based review

Waste classification is to reduce solid waste and its associated environmental pollution. This paper applied bibliometrics to assess publications related to classification technology of domestic waste from 2000 to 2019. A total of 466 publications were retrieved. The results showed the number of citations and papers increased rapidly. The major publication type regarding waste classification technology is article and English is the primary language for academic communication. The research is multidisciplinary and interdisciplinary, and its research directions are mainly divided into "Engineering," "Environmental Sciences Economics," and "Chemistry." It was identified that Waste Management (85) published most of papers in this topic. Meanwhile, China (93) contributed the most of publications, followed by the USA (42), France (40), Japan (36), and Italy (28). European countries are in the leading position in the study of garbage classification technology. Plastics and waste metals were the existing focus of waste classification technology, and waste identification and classification has become an important classification method. In addition, we also summarized the current mainstream technology progress and possible research challenges.

[Association between parental education level and left ventricular hypertrophy in childhood]

Objective: To examine the relationship between parental education level and left ventricular hypertrophy (LVH) in children. Methods: The data comes from the baseline survey of the Huantai Childhood Cardiovascular Health Cohort Study (HCCH) conducted in Huantai County, Zibo City, Shandong Province. A convenient cluster sampling method was used to select a primary school in Huantai County, Zibo City, Shandong Province as a survey point. A cross-sectional survey was conducted from November 2017 to January 2018. A total of 1 316 children aged 6-11 years with complete data were included. LVH was defined as left ventricular mass index ≥ sex-and age-specific 90th percentile values of this population. Education levels of both parents were divided into junior high school or lower, high school, university or higher, respectively. Logistic regression models were used to analyze the association between parental education level and LVH in children. Results: The age of 1 316 participants was (8.9±1.5) years old. Among them, there were 703 boys (53.4%).After adjusting for gender, age, intake of vegetables and fruits, intake of carbonated drinks, physical activity, sleep time, screen time, overweight or obesity, and occasional hypertension, the logistic regression model results show that compared with those children whose parents' education level is junior high school or below, paternal or maternal education level of college or higher was associated with odds of LVH (father: OR=0.53, 95%CI: 0.33-0.87; mother: OR=0.52, 95%CI: 0.32-0.87; father/mother: OR=0.54,95%CI: 0.32-0.91). Conclusion: Parental education level is inversely associated with LVH in childhood. The probability of LVH in childhood decreases with the increase of parental education levels.

Untangling the response of fungal community structure, composition and function in soil aggregate fractions to food waste compost addition

Soil fungi are key drivers in regulating the ecosystem function, playing a vital role in protecting the plant from phytopathogens and other biotic and abiotic pressures. However, the potential impact of compost addition and soil aggregate size on the fungal community and functional ecological guild remains uncertain. This study investigated the structure, composition, and function of soil fungal communities across aggregate fractions under food waste compost addition using Miseq sequencing and FUNGuild. Compost addition exerted a negative impact on fungal α-diversity, and shifted the structure and changed the composition of fungal community. Compost addition rates exhibited more contributions to fungal α-diversity variations (R = 0.609, 0.895, and 0.501 for Sobs, Shannon, and Chao indices, respectively, P = 0.001) and the separation of community structure than soil aggregate size (R = 0.952, P = 0.001). Biomarkers, including Chaetomiaceae, Ascobolaceae, and Sordariomycete, displayed significant superiority in compost-added soils, whereas the populations of Nectriaceae and Clavicipitaceae were significantly decreased. The relative abundances of animal and plant pathogens were significantly decreased, whereas that of saprotrophs were increased. The abundances of pathogens correlated positively with pH and negatively with nutrients (soil organic matter, dissolved organic carbon, total nitrigen, NH₄⁺, and NO₃^-), whereas those of saprotrophs showed an opposite trend. The dose of compost was the major driver for fungal functional guild variation, whereas carbon and nitrogen source exhibited more contributions to function variation than pH value. These results provide a reference for sustainable ecological agriculture by applying compost rationally under the conditions of soil health and agricultural performance.

Transport and retention of porous silicon-coated zero-valent iron in saturated porous media

Porous silicon-coated zero-valent iron (Fe⁰@p-SiO₂) is a promising material for in-situ contaminated groundwater remediation. However, investigations of factors that affect the transport of Fe⁰@p-SiO₂ remain incomplete. In the present study, Fe⁰@p-SiO₂ composites were prepared by a SiO₂-coated technology, and a series of column experiments were conducted to examine the effects of media size, ionic strength, and injection velocity and concentration on retention and transport in saturated porous media. Results showed that the obtained Fe⁰@p-SiO₂ is a core-shell composite with zero-valent iron as the core and porous silicon as the shell. Media size, injection velocity, Fe⁰ concentration, and ionic strength had a significant impact on the transport of Fe⁰@p-SiO₂. Fe⁰@p-SiO₂ effluent concentrations decreased with a smaller media size. Increasing initial particle concentration and ionic strength led to a decrease in particle transport. High particle retention was observed near the middle of the column, especially with high injection concentration. That was also observable in the condition of lower injection velocity or finer media. The results indicated that two transport behaviors during particles transport, which were "agglomeration-straining" and "detachment-re-migration". Moreover, the dominated mechanisms for Fe⁰@p-SiO₂ transport and retention in saturated porous media are hydrodynamic dispersion and interception. Given the results, in practical engineering applications, proper injection velocity and concentration should be selected depending on the pollution status of groundwater and the geochemical environment to ensure an effective in-situ reaction zone.

On the applicability of the 'humic acids' nomenclature from natural ecosystems to engineering sciences

•'HA' nomenclature can be undoubtedly applied in engineering sciences.•The real structure of NOM is still a 'black box' in natural ecosystems.•Recognition of 'HA' from natural ecosystems to engineering sciences.•Alkaline extraction on NOM link natural ecosystems to engineering sciences.

The cotreatment of old landfill leachate and domestic sewage in rural areas by deep subsurface wastewater infiltration system (SWIS): Performance and bacterial community☆

In this work, two deep subsurface wastewater infiltration systems (SWISs) were constructed and fed with domestic sewage (control system, S1) and mixed wastewater consisting of old landfill leachate and domestic sewage (experimental system, S2). S1 and S2 exhibited favorable removal efficiencies, with TP (98.8%, 98.7%), COD (87.6%, 86.9%), NH₄⁺-N (99.8%, 99.9%) and TN (99.2%, 98.9%). Even when increasing the pollutant load in S2 by adding old landfill leachate, the almost complete removal performance could be maintained in terms of low effluent concentrations and even increased in terms of load removal capabilities, which included COD (19.4, 25.9 g∙m^-2·d^-1), NH₄⁺-N (8.2, 19.9 g∙m^-2·d^-1), TN (8.9, 20.6 g∙m^-2·d^-1). To investigate the transformation of dissolved organic matter along depth, Three-Dimensional Excitation Emission Matrix fluorescence spectroscopy combined with Fluorescence Regional Integration analysis was applied. The results showed that P_Ⅰ,n and P_Ⅱ,n (the proportions of biodegradable fractions) increased gradually from 6.59% to 21.8% at S2_20 to 10.8% and 27.7% at S2_110, but P_Ⅲ,n and P_Ⅴ,n (the proportions of refractory organics) declined from 23.1% to 27.8% at S2_20 to 21.1% and 16.4% at S2_110, respectively. In addition, high-throughput sequencing technology was employed to observe the bacterial community at different depths, and the predicted functional potential of the bacterial community was analyzed by PICRUSt. The results showed that the genera Flavobacterium, Pseudomonas, Vogesella, Acinetobacter and Aquabacterium might be responsible for refractory organic degradation and that their products might serve as the carbon source for denitrifiers to achieve simultaneous nitrate and refractory organic removal. PICRUSt further demonstrated that there was a mutual response between refractory organic degradation and denitrification. Overall, the combined treatment of domestic sewage and old leachate in rural areas by SWIS is a promising approach to achieve comprehensive treatment.

Comparing the long-term responses of soil microbial structures and diversities to polyethylene microplastics in different aggregate fractions

Microplastics (MPs) alter soil aggregation stability. However, studies have yet to determine whether these alterations further affect microbial community structures and diversities within different soil aggregates and whether they influence the responses of soil microbial structures and diversities to MPs in different aggregate fractions. In this study, long-term soil incubation experiments and soil fractionation were combined to investigate the effects of polyethylene microplastics (PE-MPs) on soil aggregate properties and microbial communities in soil aggregates with different particle sizes. Results showed that the existence of PE-MPs significantly reduced the physicochemical properties of soil aggregates, inhibited the activities of soil enzymes, and changed the richness and diversity of bacterial and fungal communities. Such variations exerted notable differences in soil aggregate levels. The response sensitivity of bacteria in the silt and clay fraction was higher than that in the macroaggregate fraction, but the response sensitivity of fungi in the macroaggregate fraction was higher than that in the silt and clay fraction. Relationships and path analysis between soil aggregate properties and microbial communities after PE-MPs addition were proposed. PE-MPs affected microbial community structures by directly and indirectly influencing soil microenvironmental conditions. The relative abundances of Acidobacteria, Gemmatimonadetes, Bacteroides, Basidiomycota, Chtridiomyota, and Glomeromycota were significantly correlated with physicochemical properties and soil enzyme activities. Enzyme activities were direct factors influencing soil microbial community structures, and physicochemical properties (i.e., dissolved organic carbon, soil available phosphorus) could indirectly affect these structures by acting on soil enzyme activities. Our findings helped improve our understanding of the responses of soil microbial structures and diversities to MPs through the perspective of different soil aggregates.

Characterization of hydrogen production and microbial community shifts in microbial electrolysis cells with L-cysteine

L-cysteine is used to improve efficiency in anaerobic biological systems as an oxygen scavenger, electron shuttle and substrate source. The performance of MEC by addition of L-cysteine was investigated during start-up and operation phases, respectively. Results showed that the maximum current density of 6.36 ± 0.14 A/m², hydrogen yield of 1.08 ± 0.05 m³/m³ and energy efficiency of 130% were achieved with L-cysteine adding during operation phase. By contrast, the addition of L-cysteine during the start-up phase reduced the energy efficiency by more than 30%. The microbial community analysis revealed that a higher microbial community richness and diversity were achieved, the enrichment of Sulfuricurvum, Sulfurospirillum, Desulfovibrio and other electroactive microorganisms indicated their relative abundance could be regulated by L-cysteine during start-up phase when L-cysteine was added. This study provided an alternative method to enhanced hydrogen production and a better understanding of the mechanism of L-cysteine action in MEC performance.

Divergent response of heavy metal bioavailability in soil rhizosphere to agricultural land use change from paddy fields to various drylands

The heavy metal pollution induced by agricultural land use change has attracted great attention. In this study, the divergent response of the bioavailability of heavy metals in rhizosphere soil to different agricultural land uses was analyzed using sequential extraction, and possible influence paths were constructed. The results show that land use change can affect the heavy metal bioavailability by influencing the soil organic matter and redox potential (Eh). The average concentrations of N, P, K, Ca, Mg, S, and Fe in the soil showed no significant differences. However, the conversion direction and extent of chemical speciation of heavy metals were different across land use changes from paddy fields to various drylands. After conversion from paddy to wheat field, the bioavailability of heavy metals decreased due to an increase in permanganate oxidizable carbon (KMnO₄-C) and a decrease in Eh. The transformation from paddy to celery soil is accompanied by a change in the soil's KMnO₄-C content, increasing the proportion of the bioavailable states of heavy metals. However, the response of bioavailability to changes in the soil KMnO₄-C varied among heavy metals. In contrast, when land use changed to grapevine culture, the bioavailability of heavy metals increased due to a change in the KMnO₄-C content. Moreover, the dissolved organic carbon (DOC) content increased, which positively affected the Eh and, in turn, increased the bioavailability of heavy metals. This research is of great significance for understanding the impact of land use change on the heavy metal migration and activity in the rhizosphere microenvironment of soil.

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.