Chronological evaluation of polycyclic aromatic hydrocarbons in sediments of tangxun lake in central China and impacts of human activities.

This study sheds light on the contamination of polycyclic aromatic hydrocarbons (PAHs) in Tangxun Lake sediments, an urban lake reflecting environmental changes in Central China. By analyzing sediment cores from both the inner and outer areas of the lake, we determined the historical trends and sources of PAHs over the past century. The results reveal a significant increase in PAHs concentrations, particularly since the 1980s, coinciding with China's rapid urbanization and industrialization. Using diagnostic ratios and Absolute principal component score-multivariate linear regression (APCS-MLR) methods, we identified petroleum combustion, coal combustion, and biomass combustion as the primary sources of PAHs in the lake sediments. The spatial analysis indicates higher PAHs levels in the inner lake, likely due to its closer proximity to industrial activities. Moreover, by comparing PAH trends in Tangxun Lake with those in other urban, suburban, and remote lakes across China, based on data from 49 sedimentary cores, we highlight the impact of regional socio-economic dynamics on PAH deposition. These insights are crucial for developing effective pollution mitigation strategies and promoting sustainable development in rapidly urbanizing regions.

[Occurrence and Risk Assessment of N-nitrosamines and Their Precursors in Qingjiang River Basin].

N-nitrosamines are a type of nitrogen-containing organic pollutant with high carcinogenicity and mutagenicity. In the main drinking water sources of small and medium-sized towns in China, the contamination levels of N-nitrosamines remain unclear. In addition, there is still lack of research on the concentration of N-nitrosamines and their precursors in tributary rivers. In this study, eight N-nitrosamines and their formation potentials （FPs） were investigated in the Qingjiang River, which is a primary tributary of the Yangtze River. The sewage discharge sites were also monitored, and the environmental influencing factors, carcinogenic and ecological risks caused by N-nitrosamines, and their precursors were evaluated. The results showed that six N-nitrosamines were detected in water samples of the Qingjiang River, among which NDMA [（10 ±15） ng·L-1], NDEA [（9.3 ±9.3） ng·L-1], and NDBA [（14 ±7.8） ng·L-1] were the dominant N-nitrosamines, whereas seven N-nitrosamines were detected in chloraminated water samples, among which NDMA-FP [（46 ±21） ng·L-1], NDEA-FP [（26 ±8.3） ng·L-1], and NDBA-FP [（22 ±13） ng·L-1] were the dominant N-nitrosamine FPs. The concentrations of N-nitrosamines in the middle reaches of the Qingjiang River were higher than those in the upper and lower reaches. Furthermore, the concentrations of N-nitrosamines in the sample sites of sewage discharge and tributaries were significantly higher than those in other sampling sites. The monitoring results at the direct sewage discharge points indicated that the main source of N-nitrosamines in river water was the sewage carrying N-nitrosamines and their precursors. In addition, the concentrations of the three dominant N-nitrosamines including NDMA, NDBA, and NDEA were positively correlated with each other, mainly because of their similar sewage sources. The average carcinogenic risk to residents due to N-nitrosamine in drinking water sources was 2.4×10-5, indicating a potential carcinogenic risk. Moreover, due to the high concentrations of N-nitrosamine formation potentials in the Qingjiang River, the carcinogenic risk of drinking water may be even higher. The ecological risk assessment showed that the ecological risk quotient values of N-nitrosamines in the Qingjiang River watershed were lower than 0.002, which was negligible.

Serum Folate and Vitamin B12 Modify the Associations of N6AMT1 Genetic Variants with Gestational Diabetes Mellitus: A Cross-Sectional Study in Chinese Pregnant Women.

Purpose: This study aimed to explore the association between N-6 adenine-specific DNA methyltransferase 1 (N6AMT1) single nucleotide polymorphisms (SNPs) and gestational diabetes mellitus (GDM) and the modification of the relationship by folate and vitamin B12. Methods: A cross-sectional study involving 1303 pregnant women (262 GDM and 1041 non-GDM) was performed in Tianjin, China. Nine SNPs in N6AMT1 were genotyped, and serum folate, vitamin B12, and homocysteine (Hcy) levels were measured. The logistic regression models determined the odds ratios (ORs) for SNPs in N6AMT1 and the gene-nutrition interactions on GDM. Results: N6AMT1 rs7282280, rs1048546, and rs1997605 were related to GDM under the dominant model after adjusting for multiple covariates. Individuals carrying the N6AMT1 rs7282280 TC/TT genotypes had a lower risk of developing GDM, regardless of serum folate and vitamin B12 levels. However, rs1048546 TG/GG genotypes were associated with lower GDM risk when serum folate ≥ 6.0 ng/mL. Pregnancies with the risk genotypes in N6AMT1 and higher serum folate or lower vitamin B12 are more prone to GDM. The study also showed a statistically significant additive interaction between N6AMT1 rs1997605 GG genotypes and lower vitamin B12 (RERI: 2.54; 95% CI: 0.17, 4.92). Conclusion: SNPs in N6AMT1 were found to be associated with GDM, and serum folate and vitamin B12 levels can modify their associations.

Atmospheric deposition is an important pathway for inputting microplastics: Insight into the spatiotemporal distribution and deposition flux in a mega city.

Microplastics (MPs) refer to plastic particles with a size less than 5 mm, which attracted widespread attention as an emerging pollutant. The monitoring of atmospheric microplastics (AMPs) in a megacity was carried out to study the characteristics and spatiotemporal distribution of AMPs, explore the sources and estimate the deposition flux. The results showed that the annual average abundance of AMPs in Wuhan was 82.85 ± 57.66 n·m-2·day-1. The spatiotemporal distribution characteristics of AMPs show that spring was the highest season, followed by autumn, winter, and summer; the city center was higher than the suburbs. Fiber was the main type of AMPs in Wuhan, followed by fragment, film and pellet. The proportion of AMPs were mainly small (<0.5 mm) and medium (0.5-1.0 mm). Transparent and white were the main colors of AMPs, followed by red, brown. A total of 10 types polymers were detected, polyethylene terephthalate (PET) was dominant. There are positive correlations between AMPs and SO2, NO2 in the atmosphere, indicating that they might be influenced by intense human activity. The polycyclic aromatic hydrocarbons (PAHs) and AMPs in spring showed an extremely significant positive correlation (p < 0.05). AMPs might mainly originate from the wear and tear shedding of textiles, the aging of agricultural films and plastic waste based on their polymer types and main uses. The potential geographical sources of AMPs were mainly the surrounding cities. The annual deposition flux of AMPs was about 308 tons if there were no remove processes, which highlighted the importance of atmospheric transport and deposition of MPs. The analysis of the abundance, morphological characteristics and sources of AMPs can provide data support and reference for mega-cities with high global population activities, or cities in global mid-latitude regions.

Insight into the effect mechanism of sedimentary record of polycyclic aromatic hydrocarbon: Isotopic evidence for lake organic matter deposition and regional development model.

Deciphering the temporal patterns of polycyclic aromatic hydrocarbons (PAHs) in sediment cores, and the effect mechanism of sedimentary organic matter (OM) and regional development model on PAHs are crucial for pollution control and environmental management. Herein, sediment core was collected from Chenhu international wetland in Wuhan, central China. Meanwhile, historical trend and source of PAHs and sedimentary OM were presented, respectively. Result demonstrated that the most significant growth of PAHs (increased by 158.8%) was attributed to the significant enhancement of traffic emission (5.57 times), coal combustion (4.59 times), and biomass burning (8.09 times). Similarly, the percentage of phytoplankton (stage Ⅲ: 37.9%; stage Ⅳ: 31.2%) and terrestrial C3 plants (stage Ⅲ: 24.6%; stage Ⅳ: 29.2%) to sedimentary OM hold the dominant position after the stage Ⅱ. The obvious shifts of historical trend and sources in PAHs were highly related to economic development models (r = 0.72, p < 0.001) and sedimentary OM (r = 0.82, p < 0.001). It demonstrated that eutrophication of lake accelerated the burial of PAHs. Redundancy analysis results suggested that TOC was dominating driver of sedimentary PAHs (16.56%) and phytoplankton occupied 9.58%. To further confirm the significant role of economic development models, three different historical trends of PAHs in different regions of China were presented. The result of this study provides the new insight into the geochemistry mechanism of lake sedimentary OM and PAHs. Meanwhile, the relationship of regional development model and sedimentary PAHs was highlighted in this study. Significantly, the main environmental implications of this study are as follows: (1) lake eutrophication of phytoplankton OM accelerated the burial of PAHs in lake sediment; (2) economic development models and energy structure significantly influence the sedimentary PAHs. This study highlights the coupling relationship between OM burial and PAHs sedimentation, and the importance of accelerating the transformation of economic energy structure.

Comparison of the 2009 Institute of Medicine and 2021 Chinese guidelines for gestational weight gain: A retrospective population-based cohort study.

OBJECTIVE: To analyze the associations between gestational weight gain (GWG) and perinatal outcomes based on the GWG guidelines of the Chinese Nutrition Society (CNS) and the Institute of Medicine (IOM). METHODS: This was a retrospective study with 9075 low-risk singleton pregnant women. Logistic regression model was used to analyze associations between GWG categories and perinatal outcomes. Sensitivity analyses were performed based on pre-pregnancy body mass index (calculated as weight in kilograms divided by the square of height in meters). RESULTS: Excessive GWG as defined by the two guidelines was associated with a higher risk of adverse perinatal outcomes. Inadequate GWG was associated with higher risks of small for gestational age (adjusted odds ratio [aOR] 1.34, 95% confidence interval [CI] 1.10-1.64) and preterm birth (aOR 1.70, 95% CI 1.22-2.36), but a lower risk of large for gestational age (LGA) (aOR 0.77, 95% CI 0.63-0.95) according to the IOM guidelines. When using the CNS guidelines, inadequate GWG was associated with only a lower risk of preterm birth (aOR 1.80, 95% CI 1.19-2.70). Sensitivity analyses suggested that excessive GWG was associated with a higher risk of LGA in underweight women. CONCLUSIONS: Both guidelines could demonstrate the relationship between GWG and adverse perinatal outcomes. The CNS guidelines were more suitable for the Chinese population with underweight or normal weight before pregnancy, whereas IOM was more suitable for pregnant women with inadequate GWG.

Distribution, sources, and ecological risk assessment of polycyclic aromatic hydrocarbons in agricultural and dumpsite soils in Sierra Leone.

This study investigates the concentration and distribution of polycyclic aromatic hydrocarbons (PAHs) in soils, potential sources, risk assessment, and soil physicochemical properties influencing PAH distribution in developed and remote cities in Sierra Leone. Seventeen topsoil samples (0-20 cm) were collected and analyzed for 16 PAHs. The average concentrations of Σ16PAH in soils in the surveyed areas were 1142 ng g-1 dw, 265 ng g-1 dw, 79.7 ng g-1 dw, 54.3 ng g-1 dw, 54.2 ng g-1 dw, 52.3 ng g-1 dw, and 36.6 ng g-1 dw in Kingtom, Waterloo, Magburaka, Bonganema, Kabala, Sinikoro, and Makeni, respectively. Based on the European soil quality guidelines, Kingtom and Waterloo soils were categorized as heavily and weakly contaminated soil PAHs respectively. The main PAH compounds of this study were 2-ring, 4-ring, and 5-ring PAHs. High molecular weight PAHs (4-6 rings) made up 62.5% of the total PAHs, while low molecular weight PAHs (2-3 rings) was 37.5%. In general, HMWPAHs were predominant in Kingtom, followed by Waterloo. The appointment of PAH sources using different methods revealed mixed sources, but predominantly pyrogenic sources (petroleum, biomass, coal, and fossil fuel contributions). Soil pH has a significant impact on PAH distribution. The toxicity equivalent quantity (TEQBaP) levels in soils pose a potential health risk to residents in developed cities but pose a negligible health risk to residents in remote cities. This study is significant as its findings reveal the status of PAH soil contamination in Sierra Leone. The results have important implications for policymakers and stakeholders to identify high-risk zones and establish proper environmental monitoring programs, pollution control measures, and remediation strategies to prevent future risks.

[Pollution Characteristics of Organochlorine Pesticides in Water and Sediments of Huixian Karst Wetland in Guilin].

Karst wetland plays an important role in the ecological environment; however, due to the existence of karst pipeline, pollutants can threaten the underground environment through the highly developed karst pipeline. Therefore, understanding the pollution characteristics of the karst surface environment is the premise of pollution ecological risk assessment and prevention. In this study, 24 organochlorine pesticides (OCPs) were analyzed to study the concentration, composition, source, and risk of OCPs in water and surface sediments in the Huixian Wetland of Guilin. The results showed that:the concentration of OCPs in water ranged from 3.17 ng·L-1 to 92.50 ng·L-1, and the concentration of OCPs in sediment ranged from 1.16 ng·g-1 to 219.52 ng·g-1, showing the main pollution characteristics of HCHs and DDTs. The concentration of OCPs in water was higher in the wet season than that in the dry season. The concentration of OCPs in sediments was higher in the dry season than that in the wet season. The isomer ratios revealed that OCPs in the study area were mainly derived from long-term degradation residues, and some sites had new input of lindane. Based on Monte Carlo simulation, the human health risk assessment of the study area showed that the 95% quantile carcinogenic risk of OCPs in water was greater than 1×10-6, with potential but acceptable health risk. The non-carcinogenic risk was lower than 1, which indicated that the level of OCPs residues in the water in the study area was not enough to cause non-carcinogenic risk to the human body.

New insight into the geochemical mechanism and behavior of heavy metals in soil and dust fall of a typical copper smelter.

The desorption mechanism of heavy metals (HMs) in soil around the mining region are complex and affected by multiple pollution sources, including sewage discharge and atmospheric deposition. Meanwhile, pollution sources would change soil physical and chemical properties (mineralogy and organic matter), thus affecting the bioavailability of HMs. This study aimed to investigate the pollution source of HMs (Cd, Co, Cu, Cr, Mn, Ni, Pb, and Zn) in soil near mining, and further evaluate influence mechanism of dust fall on HMs pollution in soil by desorption dynamics processes and pH-dependence leaching test. Result presented that dust fall is the primary pollution source to HMs accumulation in soil. Additionally, the result of mineralogical analysis in dust fall revealed that quartz, kaolinite, calcite, chalcopyrite, and magnetite are the major mineralogical phases by XRD and SEM-EDS. Meanwhile, the abundance of kaolinite and calcite in dust fall is higher than in soil, which is the primary reason of higher acid-base buffer capacity of dust fall. Correspondingly, the weakened or disappeared of hydroxyl after the adding acid extraction (0-0.4 mmol· g-1) demonstrated that hydroxyl is the main participants of HMs absorption in soil and dust fall. These combined findings suggested that atmospheric deposition not only increases the pollution loading of HMs in soil, but also changes the mineral phase composition of soil, which would increase the adsorption capacity and bioavailability of HMs in soil. This is very remarkable that heavy metals in soil influenced by dust fall pollution could be released preferentially when soil pH is changed. The present results of this study would provide efficient and scientific targeted strategies for pollution control of HMs in soil near mining areas.

[Characteristics and Source Analysis of Heavy Metals in Farmland Soil on the South of Dongting Lake].

Based on the grid distribution method, 1589 topsoil samples were collected from farmland on the south side of Dongting Lake from April to August 2020. The content, potential ecological risk, spatial distribution characteristics, and source analysis of heavy metals in the soil were studied. The concentrations and pH of As, Cd, Pb, Cu, Zn, Ni, Cr, and Hg in the soil were determined using ICP-MS, ICP-OES, HG-AFS, and ISE methods. The results showed that the average concentrations of Zn, Cr, Pb, Cu, Ni, As, Cd, and Hg were 118.18, 82.21, 52.1, 33.76, 32.81, 18.25, 0.42, and 0.13 mg·kg-1, respectively. All heavy metals had medium or high variability. The soil was mainly weakly acidic with a pH between 3.96 and 7.90. Hg and Cd had high ecological risks. The spatial distribution of heavy metals showed a tendency of being high in the southwest and low in the northeast. The PMF and PCA methods were used to analyze the sources and calculate the contribution rates of the eight types of heavy metals. The PMF results showed that the contribution rates of soil heavy metals in the study area were as follows:agricultural activity sources (36.98%), natural sources (32.94%), water and soil exchange sources (17.05%), and atmospheric dry and wet deposition sources (13.03%). The PCA results showed that the soil heavy metals in the study area mainly came from agricultural activity sources (68.04%), natural sources (31.02%), and atmospheric deposition sources (0.94%). The conclusions of the two source analysis methods tended to be consistent, that is, agricultural activities were the main source of soil heavy metals in the study area. The vertical profile analysis showed that the contents of Cd, Hg, and Pb elements were high in the surface layer and low in the deep layer, and the phenomenon of anthropogenic input was obvious. These results can provide a scientific basis for the formulation of prevention and control countermeasures of farmland soil heavy metal pollution around Dongting Lake.

Occurrence, distribution and risk assessment of microplastics and polycyclic aromatic hydrocarbons in East lake, Hubei, China.

The pollution of microplastics (MPs) and polycyclic aromatic hydrocarbons (PAHs) in the environment is a global problem, which has attracted extensive attention of many researchers. In present study, MPs and PAHs are investigated to study the impact of human activities and their possible relationship in China's second largest urban lake, East Lake. The abundance of MPs are 3329.19 ± 2059.26 particles/m3 and 2207.56 ± 1194.04 particles/kg in water and sediment, respectively. MPs are predominantly characterized by fibers, polypropylene (PP) and polyethylene (PE), colorlessness in water and sediment. The abundance of MPs in water with frequent human activities is higher, which is reversed in sediments, indicating that disturbance is not conducive to the enrichment of MPs in sediments. The concentration of 16 PAHs are 36.95 ± 13.76 ng/L and 897.08 ± 232.34 ng/g in water and sediment, respectively. PAHs in water are mainly 2-3-ring, while there are 4-ring PAHs in sediments. The good corresponding relationship between MPs and PAHs indicates that human activities have an important impact on the distribution of pollutants compared to the interaction of pollutants. In addition, the significant positive correlation between lakeshore length and water MPs abundance indicates that surface runoff may be an important source of water MPs. The pollution load index shows that MPs in sediment has reached moderate to severe pollution level, while the water is slightly polluted level. The potential ecological risk assessment results show that more than half of the sediment sites are at dangerous to very dangerous ecological risk level.

Occurrence and exposure risk assessment of organochlorine pesticides in two waterbird species from Honghu Lake Wetland, Central China.

Monitoring and evaluating bird exposure to hazardous pollutants in wetlands are receiving considerable attention. In this study, the occurrence of 18 organochlorine pesticides (OCPs) in the muscle of bean geese (Anser fabalis) and common teals (Anas crecca) collected from Honghu Lake Wetland (HLW), Central China was studied. Additionally, an exposure risk assessment model was applied to obtain risk levels of OCPs to these birds through three oral routes (food intake, water drinking and soil ingestion). The results suggested that the most abundant OCPs detected in the muscle of waterbirds were DDTs (7.68-602 ng/g lipid weight), followed by HCHs (1.39-89.8 ng/g lipid weight). A significant difference (p < 0.05) existed between two species, but most of OCPs exhibited no statistically relationship with age or gender (p > 0.05). The compositional patterns of OCPs combined with ratios of certain metabolites to their parent compounds indicated that all OCPs in the HLW were largely from historical usage except heptachlor. The exposure risk assessment revealed that common teals with lighter weight had greater exposure risks than bean geese. Of the OCPs analyzed, DDTs could probably cause harm to target birds studied here. Exposure via food intake was identified to be significant while soil ingestion and water drinking contributed least, but they should still be concerned.

Bioavailability and regional transport of PM2.5 during heavy haze episode in typical coal city site of Fenwei Plain, China.

Despite the decrease in anthropogenic emissions, haze episodes were still frequent in the Fenwei Plain, which was identified as one of the three key areas for air pollution control. Herein, PM2.5 samples were collected to investigate the influence of festival effect during the Chinese Spring Festival from February 2rd to 13th, 2019, in Linfen on the Fenwei Plain. The characteristics of element pollution, enrichment factor, source apportionment, regional transport of PM2.5, and health risk assessment were discussed. Meanwhile, the simulated lung fluid method (SLF) was carried out to accurately assess the inhalation risks of heavy metals (HMs). Results indicated that the average concentration of PM2.5 was 195.6 µg·m-3 during the studying period. Road fugitive dust (15.6%), firework burning source (25.6%), industrial emission (30.5%), and coal combustion (28.3%) were identified by positive matrix factorization (PMF) modeling. Using the HYSPLIT trajectory model, air masses from the central Shaanxi, southern Hebei, and northern Henan were the dominant transport paths during the Spring Festival, which contributed 21.9 and 41.2% of total trajectories, respectively. The findings that high PSCF and CWT levels were found in central Shaanxi, southern Hebei, and northern Henan were confirmed. The SLF mean bioaccessibility (%) of the solubility of particulate metals was in order of Mn > Ni > Sb > Ba > Zn > Pb > Cr. However, the carcinogenic risk value of Cr was the highest, exceeding the maximum acceptable risk. The present study provided important information for further analyzing the air pollution cause of Fenwei Plain.

Influence of temperature and precipitation on the fate of polycyclic aromatic hydrocarbons: simulation experiments on peat cores from a typical alpine peatland in Central China.

The corresponding relationships between temperature, precipitation, and polycyclic aromatic hydrocarbon (PAH) concentration in a typical ombrotrophic peatland in Dajiuhu, Shennongjia, were quantitatively characterized by field sampling tests validated with simulation experiments. The PAH concentrations of peat cores in Dajiuhu peatland ranged from 262 to 977 ng·g-1, with a mean value of 536 ± 284 ng·g-1. PAHs were mainly composed of 2-3 ring PAHs, accounting for 31.7% ± 2.00% and 31.7% ± 5.00%, respectively. The concentration of PAHs in peat cores showed a significant decrease with increasing temperature, while the low molecular weight PAHs (LMW-PAHs) were more sensitive to temperature changes compared to the high molecular weight PAHs (HMW-PAHs). Besides, with the increase of quantity and velocity of leaching liquid, PAHs in peat were first transferred in the form of attached large-size particles and then gradually entered the aqueous phase. According to the IPCC projections of global warming, Dajiuhu peatland will release 956 ± 26.3 kg·°C-1 PAHs into gas phase during 2030-2052, and a conservative projection based on local temperature trends showed that 459 ± 12.6 kg·°C-1 PAHs will be released into gas phase by 2047 in Dajiuhu peatland. The projected release fluxes of PAHs in Dajiuhu peatland with precipitation volume and precipitation velocity are 381 ± 201 kg·100 mm-1 and 1052 ± 167 kg·min·mL-1, respectively, which are primarily from peat into particulate and aqueous phase.

The characteristics of polycyclic aromatic hydrocarbons and heavy metals in water and sediment of dajiuhu subalpine wetland, shennongjia, central China, 2018-2020: Insights for sources, sediment-water exchange, and ecological risk.

Polycyclic aromatic hydrocarbons (PAHs) and heavy metals (HMs) are persistent environmental issues. Secondary emissions are produced as a result of climate change and human activity. To observe spatio-temporal variations of PAHs and HMs and to discuss the sources as well as the source or sink of PAHs for sediment and peat, twelve surface sediment and surface water sites were chosen along the direction of the flow to down hole in the Dajiuhu area, simultaneously, surface peat and water samples were collected in peatland. Samples were continuously taken for three years (Sep. 2018, Sep. 2019, and Sep. 2020, respectively). The results showed that PAHs and HMs are common in sediment and peat. PAHs concentration is generally higher in peat and water, while HMs concentration is relatively higher in water and relatively low in sediment and peat, and the ecological risk of sediment was low. HMs in sediment are mainly affected by rock weathering, while PAHs are mainly affected by atmospheric deposition, biomass and coal combustion and vehicle emission. HMs and PAHs can be used as an indicator of rock weathering and human activity in Dajiuhu area, respectively. A water-sediment fugacity analysis revealed that peat is a sink for PAHs, confirming that it has a high capacity for adsorbing organic contaminants, and that sediments are secondary sources of PAHs that can release them into water. Attention should be paid to the increased fugacity fraction (ff) value in peatland, indicating that peat might be converted from a sink to a source of PAHs.

Impact of short-term control measures on air quality: A case study during the 7th Military World Games in central China.

The 7th Military World Games held in Wuhan (WH) in Oct 2019 provided an opportunity to clarify the impact of short-term control measures on air quality. Fine particulate matters (PM2.5) were collected in WH, Huangshi (HS), and Huanggang (HG) during the control (Oct 13-28, 2019) and non-control periods (Oct 29- Nov 5, 2019). The results showed that air quality was good during the control period, with the concentrations of PM2.5 and gaseous pollutants being below the Grade Ⅱ of China Ambient Air Quality Standard. Concentrations of PM2.5 and its major chemical components in the control period were significantly lower than those in the non-control period, with reductions ranging from 17% (trace elements) to 46% (elemental carbon). However, higher contributions of secondary components such as SO42-, NO3-, NH4+ and secondary organic carbon (SOC) to PM2.5 were observed during the control period, suggesting the important role of secondary transformation. Potential source contribution function (PSCF) of PM2.5 showed that the main source regions were potentially located in surrounding cities Hubei Province, but regional transport can't be ignored. Six sources were identified by positive matrix factorization (PMF) for both control and non-control period. The contributions of combustion emissions and vehicle emissions were amplified in the control period, while the contribution of construction dust increased significantly when the control measures ended. Emission reductions contributed more to PM2.5 concentration decrease in WH (55%) than that in HS (51%) and HG (49%), which was consistent with the stricter control measures implemented in WH. These results indicated that short-term controls were effective at lowering PM2.5 concentration. However, the elevated contributions of secondary aerosols and the influence of regional transport on the study areas also need to be paid attention for air quality improvement in the future.

Huge quantities of microplastics are "hidden" in the sediment of China's largest urban lake-Tangxun Lake.

Microplastics (MPs) pollution in Tangxun Lake, the largest urban lake in China, was investigated. The average MPs pollution in sediment (1.81 ± 1.75 × 104 items kg-1) is at a high level, while the MPs in lakeshore water (917.77 ± 742.17 items m-3) is in the middle to low level compared with existing studies, which is related to the government's protection. Fragments and fibers are the most common shapes in sediment and water, respectively. MPs size <1 mm dominates in the sediment, while the MPs in water has a larger size. The distribution of MPs in the inner lake shows that pellets tend to "hidden" in sediments. Suspected MPs are randomly selected for polymer detection by Micro-Raman microscopy. Polypropylene (PP), polyethylene (PE) and polyethylene terephthalate (PET) are the most common polymer types in water, sediment and atmospheric deposition MPs samples. The input of wastewater, fishery and surrounding human activities are the main sources of MPs in sediment. Atmospheric deposition has a great impact on the distribution of MPs, while the contribution of surface runoff to lake MPs is not remarkable. In addition, MPs in sediments have exceeded the environmental carrying capacity. More attention should be focused on the sediment, where huge amounts of MPs are "hidden".

Variation of pollution sources and health effects on air pollution before and during COVID-19 pandemic in Linfen, Fenwei Plain.

Stringent pollution control measures are generally applied to improve air quality, especially in the Spring Festival in China. Meanwhile, human activities are reduced significantly due to nationwide lockdown measures to curtail the COVID-19 spreading in 2020. Herein, to better understand the influence of control measures and meteorology on air pollution, this study compared the variation of pollution source and their health risk during the 2019 and 2020 Spring Festival in Linfen, China. Results revealed that the average concentration of PM2.5 in 2020 decreased by 39.0% when compared to the 2019 Spring Festival. Organic carbon (OC) and SO42- were the primary contributor to PM2.5 with the value of 19.5% (21.1%) and 23.5% (25.5%) in 2019 (2020) Spring Festival, respectively. Based on the positive matrix factorization (PMF) model, six pollution sources of PM2.5 were indicated. Vehicle emissions (VE) had the maximum reduction in pollution source concentration (28.39 µg· m-3), followed by dust fall (DF) (11.47 µg· m-3), firework burning (FB) (10.39 µg· m-3), coal combustion (CC) (8.54 µg· m-3), and secondary inorganic aerosol (SIA) (3.95 µg· m-3). However, the apportionment concentration of biomass burning (BB) increased by 78.7%, indicating a significant increase in biomass combustion under control measures. PAHs-lifetime lung cancer risk (ILCR) of VE, CC, FB, BB, and DF, decreased by 44.6%, 43.2%, 34.1%, 21.3%, and 2.0%, respectively. Additionally, the average contribution of meteorological conditions on PM2.5 in 2020 increased by 20.21% compared to 2019 Spring Festival, demonstrating that meteorological conditions played a crucial role in located air pollution. This study revealed that the existing control measures in Linfen were efficient to reduce air pollution and health risk, whereas more BB emissions were worthy of further attention. Furthermore, the result was conducive to developing more effective control measures and putting more attention into unfavorable meteorological conditions in Linfen.

The mechanistic investigation of geochemical fractionation, bioavailability and release kinetic of heavy metals in contaminated soil of a typical copper-smelter.

Identifying the bioavailability and release-desorption mechanism of heavy metals (HMs) in soil is critical to understand the release risk of HMs. Simultaneously, the mechanistic investigation of affecting the bioavailability of HMs in soil is necessary, such as the grain-size distribution and soil mineralogy. Herein, the bioavailability of HMs (Cu, Cd, Ni, Pb, and Zn) in different area soils near a typical copper-smelter was evaluated by the sequential extraction technique (BCR), diffusive gradients in thin-films (DGT), and DGT-induced fluxes in sediments (DIFS) model. Results showed that the HMs proportion of the residual fraction in all soils was the highest. The average bioavailability concentration (CDGT) of Cu and Cd in industrial soil was the highest, with 45.12 µg· L-1 and 9.06 µg· L-1. The result of DIFS model revealed that the decreased order of the mean value of desorption rate constant (K-1) was Cd > Zn > Ni > Cu > Pb, 5.91 × 10-5, 4.96 × 10-5, 2.89 × 10-5, 9.64 × 10-6, and 8.69 × 10-6, respectively. According to the spatial distribution of release potential (R-value), the release potential of labile-Cu in agricultural soil was the highest, which was mainly attributed to fertilizer application in farmland. Simultaneously, the reduced hydroxyl was also related to the agricultural activities, resulting in the weakened adsorption capacity of HMs by soil. Redundancy analysis (RDA) results showed that the bioavailability of Cd, Ni, and Zn was mainly driven by soil pH, while the bioavailability of Cu and Pb was primarily driven by dissolved organic carbon (DOC). Meanwhile, carbonate minerals had a positive correlation with the bioavailability of Cd, Ni, and Zn, which could promote the release of HMs in mining soil as chemical weathering progresses. In conclusion, this study provides a structured method which can be used as a standard approach for similar scenarios to determine the geochemical fractionation, bioavailability, and release kinetics of heavy metals in soils.

Status and prospects of atmospheric microplastics: A review of methods, occurrence, composition, source and health risks.

The global pollution of microplastics (MPs) has attracted widespread attention, and the atmosphere was an indispensable media for the global transmission of MPs. With the growing awareness of MPs, atmospheric microplastics (AMPs) have been proposed as a new topic in recent years. Compared with the extensive studies on MPs in Marine and terrestrial environments, the studies of AMPs remain limited. In this study, sampling and analysis methods, occurrence, source analysis and health risk of AMPs were summarized and discussed. According to the different sampling methods, AMPs can be divided into suspension microplastics (SAMPs) and deposition microplastics (DAMPs). Previous studies have shown that SAMPs and DAMPs differ in composition and abundance, with SAMPs generally having a higher fraction of fragments. The mechanism of the migration of AMPs between different media was not clear yet. We further collated global data on the composition characteristics of MPs in soil and fresh water, which showed that the fragment MPs in soil and fresh water was higher than that in the atmosphere. Polymers in soil and fresh water were mainly PP and PE, while AMPs in the atmosphere were mainly PET. The shape composition of the MPs in both atmospheric and freshwater systems suggests that there may be the same dominant factor. The transport of AMPs and source apportionment were the important issues of current research, but both of them were at the initial stage. Therefore, AMPs needs to be further studied, especially for the source and fate, which would be conducive to understand the global distribution of AMPs. Furthermore, a standardized manual on sampling and processing of AMPs was also necessary to facilitate the comparative analysis of data between different studies and the construction of global models.