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Abstract: In this work, sixteen U.S. EPA priority PAH compounds in the dated sediment cores were detected from five lakes in western China. In most lakes, the concentrations of the total PAHs (ΣPAHs) increased from the deep layers to the surface sediments. Two source categories, i.e. vehicular emission and biomass & domestic coal combustion were identified by Unmix, a factor analysis receptor model to explore the source contributions of PAHs in the dated sediments. The source apportionment results showed that biomass & domestic coal combustion contributed larger proportion of PAHs in the five lakes. The toxicities of PAHs in the dated sediments, assessed by BaP equivalent (BaPE) values showed that the BaPE increased gradually from the deep layers to the surface sediments in most lakes. For the first effort, the contribution of each source to BaPE was apportioned by Unmix–BaPE method, and the result indicated that the vehicular emission posed the highest toxic risk. The percentage contribution of vehicular emission for PAHs and BaPE also increased from the deep layers to the surface sediments, while biomass & domestic coal combustion exhibited the opposite tendency. [Copyright &y& Elsevier]

Abstract: Four typical freshwater fish species in Lake Taihu (TH), China, were collected and analyzed for the residue levels of DDT and its metabolites DDD and DDE (sum of o,p′- and p,p′-DDT, DDD, and DDE is designated as DDTs). The DDTs concentrations ranged from 3.24 to 37.1ng/g, and p,p′-DDE was the dominant isomer, followed by p,p′-DDD and o,p′-DDT. Source identification indicated that DDTs in TH was mostly stemmed from the historical usage of technical DDT mixture, but a new source of DDT, i.e., dicofol-type DDT, also occurred. The results from the present work, together with previously published data, clearly indicate that dicofol-type DDT was widespread and was an important continual source of DDTs in China. [Copyright &y& Elsevier]

Abstract Evidence suggesting an association between ozone exposure and stroke risk remains inconsistent; variations in the distributions of susceptibilities of the study populations may explain some of it. We examined the hypothesis in a general Chinese population. During 2013–2015, 1356 first-ever stroke events were selected from a large representative sample, the China National Stroke Screening Survey (CNSSS) database; daily maximal 8-hour ozone concentrations were obtained from spatiotemporally interpolated estimates of in-situ observations over China. We conducted a time-stratified case-crossover design to assess associations between stroke risk and ambient ozone exposure. Next, potential effect modifiers were identified using interaction analyses. Final, a well-established approach was applied to estimate individual-level susceptibility (i.e., the individual-specific effect given a certain combination of multiple effect-modifiers) and its probability distribution among all the CNSSS participants (n = 1,292,010). With adjustments for temperature, relative humidity and ambient fine particulate matter exposure, a 10-μg/m3 increment in mean ozone levels 2–3 day prior to symptom onset was associated with a 3.0% change in stroke risk (95% confidence interval: −1.2%, 7.3%). This association was statistically significantly enhanced by male gender, rural residence and low vegetable and fruit consumption. The subgroup results suggested that a fraction of the population might be considerably affected by ozone, regardless of the insignificant association in average level. The analysis of susceptibility distribution further indicated that the ozone-stroke association was statistically significantly positive in 14% of the general population. Susceptibility to ozone-related stroke significantly varied among Chinese adults. Characterizing individual-level susceptibility reveals the complexity underlying the weak average effect of ozone, and supports to plan subpopulation-specific interventions to mitigate the stroke risk. Graphical abstract Unlabelled Image Highlights • Probability distribution of ozone-related stroke susceptibility remained unknown. • We included a representative sample of 1,292,010 Chinese adults nationwide. • We explored 14 individual-level potential modifiers of ozone-stroke associations. • Susceptibility to ozone-related stroke varied largely among the entire population. • Acute effects of ozone on stroke were significant only in specific subpopulations. [ABSTRACT FROM AUTHOR]

High levels of dissolved arsenic (As) have been reported in many rivers running though the Tibetan Plateau (TP), the "Water Tower of Asia". However, the source, spatiotemporal variations, and geochemical behavior of dissolved As in these rivers remain poorly understood. In this study, hot spring, river water, and suspended particulate material samples collected from the Yarlung Tsangpo River (YTR) (upper reaches of the Brahmaputra River) system in 2017 and 2018 were analyzed. Spatial results shown that the upper reaches of YTR (Zone I) have comparatively high levels of dissolved As ([As] dissolved : mean 31.7 μg/L; 4.7–81.6 μg/L; n = 16), while the tributaries of the lower reaches (Zone II) have relatively low levels (mean 0.54 μg/L; 0.11–1.3 μg/L; n = 7). Seasonal results shown that the high [As] dissolved (6.1–22.4 μg/L) were found in September to June and low [As] dissolved (1.4–3.7 μg/L) were observed in July to August. Geothermal water is suspected as the main source of the elevated As levels in YTR due to the extremely high [As] dissolved in hot springs (1.13–9.76 mg/L) and abundance of geothermal systems throughout TP. However, the seasonal results suggested that weathering of As-containing rocks and minerals is also a key factor affecting the [As] dissolved in the river water in July to August (wet-season). Natural attenuation of As in main channel is dominated by dilution process due to the lower As concentrations in tributaries, but mostly occurred by both dilution and adsorption (or co-precipitation) processes in tributaries. This work highlights that the weathering process may have an important contribution to the dissolved As in the river waters in wet-season, and the geochemical behavior of As is largely transported conservatively in the main channel and relative non-conservatively in the tributaries in YTR system. Unlabelled Image • High levels of dissolved As are observed in YTR system. • Hot springs are main source of dissolved As in the upper reaches of YTR. • Natural attenuation of dissolved As in main channel is mainly due to dilution. • Lowest dissolved As is observed in July and August due to dilution process. • Weathering of As-containing minerals inputs much of As in rivers in wet-season. [ABSTRACT FROM AUTHOR]

Results from recent studies on associations between blood pressure (BP) and short-term exposure to fine particulate matter (PM 2.5) have been inconsistent. Most studies have been evaluations of small geographic areas, with no national study in China. This study aimed to examine the acute BP responses to ambient PM 2.5 among the general population of Chinese adults. During 2012–2015, systolic and diastolic BP levels were obtained from a large national representative sample, the China Hypertension Survey database (n = 479,842). Daily PM 2.5 average exposures with a spatial resolution of 0.1° were estimated using a data assimilation that combines satellite measurements, air model simulations, and monitoring values. Overall, a 10-μg/m3 increase in daily PM 2.5 was associated with a 0.035 (95% confidence interval: 0.020, 0.049) mmHg change in systolic BP and 0.001 (−0.008, 0.011) mmHg in diastolic BP after adjustments. Stratified by geographic regions, the systolic and diastolic BP levels varied from −0.050 (−0.109, 0.010) to 0.242 (0.176, 0.307) mmHg, and from −0.026 (−0.053, 0.001) to 0.051 (0.020, 0.082) mmHg, respectively. Statistically significant positive BP-PM 2.5 associations were only found in South and North China for systolic levels and in Southwest China for diastolic levels. We further explored the regional study population characteristics and exposure-response curves, and found that the geographic variations in BP-PM 2.5 associations were probably due to different population compositions or different PM 2.5 exposure levels. Our study provided national-level evidence on the associations between ambient PM 2.5 exposure and elevated BP levels. The magnitude of the estimated associations varied substantially by geographic location in China. The Clinical trial registration name was Survey on prevalence of hypertension in China; the registration number was ChiCTR-ECS-14004641. http://www.chictr.org.cn/showproj.aspx?proj=4932 Unlabelled Image • Association between blood pressure and PM 2.5 was spatially varied in China. • Significant associations were found in some regions and in national level. • The exposure-response curves flattened out at higher PM 2.5 concentrations. • Some sub-populations were more susceptible to PM 2.5 exposure. • Sublinear curves and susceptibility may explain the spatially-varied associations. [ABSTRACT FROM AUTHOR]