The present research used zebrafish (5–28 days post-fertilization; dpf) as a model organism to investigate the effects of chronic exposure to environmentally relevant sub-lethal concentrations of waterborne (261 μg/L) and dietary zinc (Zn) (1500 mg Zn/kg dw), either independently or simultaneously, during development. The results showed that whole body contents of Zn were increased in all Zn treatment groups, with the highest accumulation of Zn observed in larvae simultaneously exposed to elevated waterborne and dietary Zn. In addition, exposure to elevated levels of Zn, either through the water or the diet, led to a decrease in whole body calcium (Ca) contents at 28 dpf. The findings also suggested that exposure to elevated levels of Zn resulted in a significant reduction in whole body manganese (Mn) contents. More importantly, the magnitude of decrease in Mn contents by Zn exposure was markedly higher than that in Ca and appeared to mirror the increases in whole body Zn accumulation. These results indicate that Mn regulation is more sensitive than Ca to disruption by Zn exposure in developing fish. Further examination of the Zrt-Irt-Like Protein (ZIP) family of transporters using droplet digital PCR technologies revealed that several zip transporters exhibited temporal and exposure route-specific changes following Zn exposure. In particular, the level of zip4 was influenced by Zn exposure regardless of the exposure routes, while changes in zip7 and zip8 levels were predominantly driven by waterborne exposure. Overall, our findings demonstrated that zebrafish during the developmental periods are sensitive to elevated levels of Zn seen in the environment, particularly following co-exposures to waterborne and dietary Zn. Future toxicological assessment of elevated Zn exposure should consider both the exposure routes and the life stages of fish.

Residential greenspace quality may be more important for people's mental health than the quantity of greenspace. Existing literature mainly focuses on greenspace quantity and is limited to exposure metrics based on an over-head perspective (i.e., remote sensing data). Thus, whether greenspace quantity and quality influence mental health through different mechanisms remains unclear. To compare the mechanisms through which greenspace quantity and quality influence mental health, we used both remote sensing and street view data. Questionnaire data from 1003 participants in Guangzhou, China were analysed cross-sectionally. Mental health was assessed through the World Health Organization Well-Being Index (WHO-5). Greenspace quantity was measured by both remote sensing-based Normalized Difference Vegetation Index (NDVI) and Street View Greenness-quantity (SVG-quantity). Greenspace quality was measured by both Street View Greenness-quality (SVG-quality) and questionnaire-based self-reported greenspace quality. Structural equation models were used to assess mechanisms through which neighbourhood greenspace exposure has an influence on mental health. Stress, social cohesion, physical activity and life satisfaction were found to mediate both SVG-quality - WHO-5 scores and self-reported greenspace quality - WHO-5 scores associations. However, only NO₂ (nitrogen dioxide) mediated the association between NDVI and WHO-5 scores, while NO₂, perceived pollution and social cohesion mediated the association between SVG-quantity and WHO-5 scores. The mechanisms through which neighbourhood greenspace exposure influences mental health may vary across different exposure assessment strategies. Greenspace quantity influences mental health through reducing harm from pollution, while greenspace quality influences mental health through restoring and building capacities.

Continuous tightening emission standards (ESs) facilitate the reduction of organic gas emissions from gasoline vehicles. Correspondingly, it is essential to update the emissions and chemical speciation of total organic gases (TOGs), including volatile organic compounds (VOCs), intermediate volatility organic compounds (IVOCs), CH₄, and unidentified non-methane hydrocarbons (NMHCs) for assessing the formation of ozone and secondary organic aerosol (SOA). In this study, TOG and speciation emissions from 12 in-use light-duty gasoline vehicle (LDGV) exhausts, covering the ESs from China II to China V, were investigated on a chassis dynamometer under the Worldwide Harmonized Light-duty Test Cycle (WLTC) in China. The results showed that the most effectively controlled subgroup in TOG emissions from LDGVs was VOCs, followed by the unidentified NMHCs and IVOCs. The mass fraction of VOCs in TOGs also reduced from 61 ± 9% to 46 ± 18% while the IVOCs gently increased from 2 ± 0.4% to 8 ± 4% along with the more stringent ESs. For the VOC subsets, the removal efficiency of oxygenated VOCs (OVOCs) was lower than those of other VOC subsets in the ESs from China IV to V, suggesting the importance of OVOC emission controls for relatively new LDGVs. The IVOC emissions were mainly subject to the ESs, then driving cycles and fuel use. The formation potentials of ozone and SOA from LDGVs decreased separately 96% and 90% along with the restricted ESs from China II-III to China IV. The major contributor of SOA formation transformed from aromatics in the VOC subsets for China II-III vehicles to IVOCs for China IV/V vehicles, highlighting that IVOC emissions from LDGVs are also needed more attentions to control in future.

Benthic microbes play a crucial role in maintaining the biogeochemical balance of aquatic ecosystems especially the material cycling during plant decomposition. However, those systems in agricultural area are always threatened by agricultural run-off containing a mass of typical pathogenic invader- Escherichia coli. It is therefore vital to clarify the turnover, assembly, and geochemical functions of the E. coli invaded benthic prokaryotic microbial community during plant decomposition. During the decaying process, the key filtering factors of benthic community assembly were NH₄⁺-N (P < 0.001), NO₂⁻-N (P < 0.01), and Organic-N (P < 0.05). The E. coli colonized significantly in sediments (P < 0.001) and drove the turnover of the bacterial community (P = 0.001), which enhanced archaeal dominance in the benthic microbial network. E. coli also triggered niche structural variations. The biomass (%) of benthic nutrient cycling genera including Dechloromonas, Pseudomonas, Bacteroides, Candidatus_Methanofastidiosum, and Desulfomicrobium (P < 0.05) was altered by E. coli stress. The structural equation model illustrated that E. coli critically affected the benthic microbial geochemical functions in multiple pathways (P < 0.05). Our results provide new insights into benthic prokaryotic microbial community assembly and nutrient cycling and management under pollution stress.

In addition to being historically intentionally manufactured as commercial products, polychlorinated biphenyls (PCBs) can be unintentionally released as by-products from industrial processes. Recent studies have emphasized the importance of unintentionally produced PCBs (UP-PCBs) and have even identified them as major contributors to atmospheric PCBs. However, little is known about contributions of UP-PCBs in current soils. In this study, all 209 PCB congeners were analyzed in agricultural soils on a national scale to investigate the influence of unintentional sources on Chinese soil. The concentration of Σ₂₀₉PCBs in soils across China was in the range of 64.3–4358 pg/g. Four non-Aroclor congeners, i.e., PCB11, PCB44 + 47+65, PCB68, and PCB209, were dominant among all PCBs, averagely accounting for 26.3%, 8.83%, 3.03%, and 2.80% of total PCBs, respectively. PCB11 and PCB209 were found to be higher in East China, while PCB44 + 47+65 and PCB68 were higher in South China. Their spatial distributions were largely dependent on local sources. The results of source apportionment indicated that the legacy of historically produced and used commercial PCB mixtures was the dominant contributor to seven indicator PCBs in Chinese agricultural soils, especially high-chlorinated congeners. However, unintentional sources (i.e., pigment/paint, combustion-related sources, and polymer sealant), which contributed 57.4% of the total PCBs, are controlling PCB burdens in agricultural soils across China.

This meta-analysis systematically evaluated the effects of water improvement and defluoridation on fluorosis-endemic areas in North and South China. The study used PubMed, Embase, China National Knowledge Infrastructure, and Wanfang to retrieve relevant research studies published between January 2000 and October 2019. The data included water fluoride levels, dental fluorosis prevalence in children 8–15 years of age, urinary fluoride levels in children and adults, and skeletal fluorosis prevalence in adults. Fixed-effects and random-effects models were used in the meta-analysis. A total of 17 research articles met the inclusion criteria and had an average water improvement period of 15.8 years. With water improvement, water fluoride levels decreased from 2.72 mg/L to 0.54 mg/L (95% confidence intervals: −2.75, −1.58), which was below the standard for drinking water (1.5 mg/L). Additionally, after water improvement, the prevalence of dental fluorosis decreased from 54.5% to 36.2% (95% confidence intervals: 0.12, 0.31) in children, and the prevalence of skeletal fluorosis decreased from 13.7% to 4.2% (95% confidence intervals: 0.16, 0.40) in adults. Urinary fluoride levels decreased from 3.06 mg/L to 1.70 mg/L (OR = −2.03, 95% confidence intervals: −2.77, −1.30) in children and from 2.29 mg/L to 1.72 mg/L (OR = −0.57, 95% confidence intervals: 0.65, −0.49) in adults. The results showed that the prevalence of dental fluorosis and skeletal fluorosis and urinary fluoride levels were significantly reduced by water improvement. This study findings revealed that the effects of water improvement and defluoridation were greater in South China than in North China, and it is obviously related to the time of water improvement and reducing fluoride.

Black carbon (BC) reacts with different substances to form secondary pollutants called aged black carbon, which causes inflammation and lung damage. BC and aged BC may enhance IL-33 in vivo, which may be derived from macrophages. The pro-inflammatory effect of IL-33 makes it essential to determine the source of IL-33, so it guides us to explore how to alleviate lung injury. In this study, a human bronchial epithelial cell line of 16HBE cells was selected, and aged BC (1,4-NQ coated BC and ozone oxidized BC) was used. We found that both BC and aged BC were able to up-regulate the mRNA expression of IL-1β, IL-6, and IL-8 except IL-33. However, the Mitogen-activated protein kinases (MAPKs) and Phosphatidylinositol 3-kinase (PI3K)/Protein kinase B (AKTs) pathways remained inactive. After pretreatment with Lipopolysaccharide (LPS), IL-33 mRNA expression was significantly increased in 16HBE cells and MAPKs and PI3K/AKT were activated. These results suggested that MAPKs and PI3K/AKT pathways were involved in the elevation of IL-33. Furthermore, epithelial cells are unlikely to be the source of lung inflammation caused by elevated IL-33 in BC and aged BC.

Seafood is an important source of arsenic (As) exposure for humans. In this study, 34 seafood samples (fishes, shellfishes, and seaweeds) collected from different markets in China were analysed for total and speciated As before and after boiling. Furthermore, the As bioaccessibility was also assessed using a physiologically based extraction test combined with the Simulator of Human Intestinal Microbial Ecosystems. The results showed that the total As (tAs) contents of seaweeds (raw: 44.12; boiled: 31.13, μg·g⁻¹ dw) were higher than those of shellfishes (raw: 8.34; boiled: 5.14, μg·g⁻¹ dw) and fishes (raw: 6.01; boiled: 3.25, μg·g⁻¹ dw). Boiling significantly decreased the As content by 22.24% for seaweeds, 32.27% for shellfishes, and 41.42% in fishes, respectively (p < 0.05). During in vitro digestion, the bioaccessibility of tAs and arsenobetaine (AsB) significantly varied between the investigated species of seafood samples in gastric (G) and small intestinal phases (I) (p < 0.05). Higher tAs bioaccessibility (G: 68.6%, I: 81.9%) were obtained in fishes than shellfishes (G: 40.9%, I: 52.5%) and seaweeds (G: 31%, I: 53.6%). However, there was no significant differences in colonic phase (C) (p > 0.05). With the effect of gut microbiota, arsenate (AsⅤ) was transformed into monomethylarsonic acid (MMA) and arsenite (AsⅢ) in C. Moreover, as for seaweeds, an unknown As compound was produced.

Water pollution is an urgent problem that needs to be controlled via green transformation and the development of the Yangtze River Economic Belt (YREB). Based on the water pollutant discharge and socio-economic database of prefecture-level cities in the YREB from 2011 to 2015, this study explores the spatiotemporal variations in water pollutant discharge in the YREB via two main indicators: chemical oxygen demand (COD) and ammonia nitrogen (NH₃–N). Further, the spatial effects and determinants of water pollutant discharge are quantitatively estimated. The results show that (1) the water pollutant discharge in the YREB has decreased significantly, with the COD and NH₃–N discharge reduced by 10.46% and 10.79%, respectively, and the discharge reduction in the lower reaches was the most prominent; (2) the spatial pattern of water pollutant discharge in the YREB was generally stable and partially improved, and cities with a high rate of water pollutant reduction in the YREB were distributed in the main stream region of the Yangtze River and the intersection of the main stream and tributaries; (3) spatial effects had a significant impact on water pollutant discharge in the YREB, with regional cooperation and economic radiation through environmental management and control initially showing a combined reduction trend in regional water pollutants; and (4) determinants of population size and agricultural economic share declined to varying degrees at the end of the study period, although the urbanization level continued to increase, indicating that urbanization in the YREB occurred too quickly and that water pollutant discharge reduction was limited. However, economic development leading to the deterioration of the water environment was alleviated. In addition, foreign direct investment (FDI) inflows and rapid industrialization processes must be monitored to increase the reduction in characteristic water pollutants.

The oxidative potential (OP) of atmospheric fine particulate matter (PM₂.₅) has been linked to organic content, which includes polycyclic aromatic hydrocarbons (PAHs). The OP of 135 individual PAHs (including six subclasses) was measured using the dithiolthreitol (DTT) consumption assay. The DTT assay results were used to compute the concentration of each PAH needed to consume 50% of the DTT concentration in the assay (DTT₅₀), and the reduction potential of the PAHs (ΔGᵣₓₙ). Computed reduction potential results were found to match literature reduction potential values (r² = 0.97), while DTT₅₀ results had no correlations with the computed ΔGᵣₓₙ values (r² < 0.1). The GINI equality index was used to assess the electron distribution across the surface of unreacted and reacted PAHs. GINI values correlated with ΔGᵣₓₙ in UPAH, HPAH, and OHPAH subclasses, as well as with all 135 PAHs in this study but did not correlate with DTT₅₀, indicating that electron dispersion is linked to thermodynamic reactions and structural differences in PAHs, but not linked to the OP of PAHs. Three ambient PM₂.₅ filters extracts were measured in the DTT assay, alongside mixtures of analytical standards prepared to match PAH concentrations in the filter extracts to test if the OP follows an additive model of toxicity. The additive prediction model did not accurately predict the DTT consumption in the assay for any of the prepared standard mixtures or ambient PM₂.₅ filter extracts, indicating a much more complex model of toxicity for the OP of PAHs in ambient PM₂.₅. This study combined computed molecular properties with toxicologically relevant assay results to probe the OP of anthropogenically driven portions of ambient PM₂.₅, and results in a better understanding of the complexity of ambient PM₂.₅ OP.