Exposure to benzene is inevitable, and concerns regarding the adverse health effects of benzene have been raised. Most investigators found that benzene exposure induced hematotoxicity. In this regard, Our study aimed to explore a novel potential biomarker of adverse health effects following benzene exposure and the toxic mechanisms of benzene metabolites in vitro. This study consisted of 314 benzene-exposed workers and 288 control workers, an air benzene concentration of who were 2.64 ± 1.60 mg/m3 and 0.05 ± 0.01 mg/m3, respectively. In this population-based study, miR-34a expression was elevated in benzene-exposed workers. The correlation of miR-34a with the airborne benzene concentration, S-phenylmercapturic acid (S-PMA) and trans, trans-muconic acid (t, t-MA), all of which reflect benzene exposure, was found. Correlation analysis indicated that miR-34a was associated with peripheral blood count, alanine transaminase (ALT) and oxidative stress. Furthermore, multivariate analysis demonstrated that miR-34a expression was strongly associated with white blood cell count (structure loadings = 0.952). In population-based study, miR-34a had the largest contribution to altered peripheral blood counts, which reflect benzene-induced hematotoxicity. The role of miR-34a in benzene toxicity was assessed using lentiviral vector transfection. Results revealed that 1,4-benzoquinone induced abnormal cell apoptosis and simultaneously upregulated miR-34a accompanied with decreased Bcl-2. Finally, inhibition of miR-34a elevated Bcl-2 and decreased 1,4-benzoquinone-induced apoptosis. In conclusion, miR-34a was observed to be involved in benzene-induced hematotoxicity by targeting Bcl-2 and could be regarded as a potential novel biomarker for benzene toxicity.

In our earlier work, Tigriopus japonicus were subjected to different mercuric chloride treatments (0–50 μg/L in the seawater) for five generations (F0–F4), and they were subsequently resumed under clean environments for one generation, i.e., F5. Accumulative effects were hypothesized to participate in mercury (Hg) multigenerational toxicity, however phenotypic plasticity could be responsible for metal resistance in this copepod against the long term exposure. Here, we specifically investigated the proteome profiles in the F0, F2, and F5 copepods of the control and 50 μg/L metal treatment, respectively, so as to elucidate the action mechanisms for Hg toxicity/tolerance in T. japonicus under the long term exposure. Functional enrichment analysis showed that a quite different proteomic response was observed in F5 compared with F0 and F2. Namely, the vast majority of enrichments were correlated with the down-regulated proteins in F0 and F2, whereas the enrichments for F5 were mostly attributable to the up-regulated proteins, suggesting that different mechanisms are responsible for Hg toxicity and tolerance (i.e., phenotypic plasticity). Hg toxicity prohibited many proteins in F0 and F2 which are related to several critical processes/pathways, e.g., protein translation, macromolecule metabolic process, DNA replication, cell cycle, cuticle organization, vitellogenesis, etc. In F5, many up-regulated proteins were enriched into compensatory systems, such as carbohydrate metabolism, myosin reorganizations, and stress-related defense pathway. Notably, glycolysis (an oxygen-independent pathway) was enhanced for energy allocation into metal detoxification and tolerance. Taken together, proteomics provides novel mechanistic insights into phenotypic plasticity used by T. japonicus when challenged with cumulative effects due to Hg multigenerational toxicity.

Methylmercury (MeHg), a neurotoxin, is a global concern because of its potential risk to human and ecological health. Elevated mercury (Hg) concentrations were recently reported in the Tibetan Plateau (TP) due to increasing Hg input from distant regions, yet little is known about MeHg production and distribution in the terrestrial ecosystems of the TP. Here, we report longitudinal occurrence of MeHg and the factors regulating net MeHg production in 23 grassland sites from eastern to western TP. The soil MeHg content varied from 0.002 to 0.058 ng g−1, with different distribution patterns between the eastern and western TP. There was a positive correlation between the MeHg concentration and the longitude after 90 °E, which is similar to the distribution patterns of the total mercury (THg), water and organic carbon in this region. Average MeHg concentration in topsoil is generally higher than that in subsoil. Our results show that MeHg concentration in soils of the TP is directly affected by soil water, potential microbial methylators and THg, while indirectly regulated by soil organic carbon through the microbial community and the longitude-dependent precipitation through soil water. Our study suggests that soil water is the most important driver regulating net MeHg production in the grasslands of the TP. These findings have important implications for unraveling the mechanism of net production of MeHg in high-altitude environments.

Estimating the burden of mortality associated with particulates requires knowledge of exposure-response associations. However, the evidence on exposure-response associations is limited in many cities, especially in developing countries. In this study, we predicted associations of particulates smaller than 10 μm in aerodynamic diameter (PM10) with mortality in 73 Chinese cities. The meta-regression model was used to test and quantify which city-specific characteristics contributed significantly to the heterogeneity of PM10-mortality associations for 16 Chinese cities. Then, those city-specific characteristics with statistically significant regression coefficients were treated as independent variables to build multivariate meta-regression models. The model with the best fitness was used to predict PM10-mortality associations in 73 Chinese cities in 2010. Mean temperature, PM10 concentration and green space per capita could best explain the heterogeneity in PM10-mortality associations. Based on city-specific characteristics, we were able to develop multivariate meta-regression models to predict associations between air pollutants and health outcomes reasonably well.

This paper provides a process-oriented perspective on the combined effects of ozone (O3), climate change and/or nitrogen (N) on vegetation. Whereas increasing CO2 in controlled environments or open-top chambers often ameliorates effects of O3 on leaf physiology, growth and C allocation, this is less likely in the field. Combined responses to elevated temperature and O3 have rarely been studied even though some critical growth stages such as seed initiation are sensitive to both. Under O3 exposure, many species have smaller roots, thereby enhancing drought sensitivity. Of the 68 species assessed for stomatal responses to ozone, 22.5% were unaffected, 33.5% had sluggish or increased opening and 44% stomatal closure. The beneficial effect of N on root development was lost at higher O3 treatments whilst the effects of increasing O3 on root biomass became more pronounced as N increased. Both responses to gradual changes in pollutants and climate and those under extreme weather events require further study.

Chemical and toxicological characterization of the water-soluble fraction of size-segregated urban particulate matter (PM) (<0.49, 0.49–0.97, 0.97–1.5, 1.5–3.0, 3.0–7.2 and >7.2 μm) was carried out at two urban sites, traffic and urban background, during the cold and the warm period. Chemical analysis of the water-soluble PM fraction included ionic species (NO3−, SO42−, Cl⁻, Na⁺, NH4⁺, K⁺, Mg²⁺, Ca²⁺), water-soluble organic carbon (WSOC), and trace elements (Al, As, Ba, Cd, Cr, Cu, Fe, Pb, Mn, Ni, Zn, Pt, Pd, Rh, Ru, Ir, Ca, and Mg). The dithiothreitol (DTT) assay was employed for the abiotic assessment of the oxidative PM activity. Cytotoxic responses were investigated in vitro by applying the mitochondrial dehydrogenase (MTT) and the lactate dehydrogenase (LDH) bioassays on human lung cells (MRC-5), while DNA damage was estimated by the single cell gel electrophoresis assay, known as Comet assay. The correlations between the observed bioactivity responses and the concentrations of water-soluble chemical PM constituents in the various size ranges were investigated. The results of the current study corroborate that short-term bioassays using lung human cells and abiotic assays, such as the DTT assay, could be relevant to complete the routine chemical analysis and to obtain a preliminary screening of the potential effects of PM-associated airborne pollutants on human health.

Among other climate changes in the southern Baltic, there is a tendency towards warming, especially in autumn-winter. As a result, the ice cover on the coastal zone often fails to occur. This is conducive to the thriving of phytoplankton, in which metals, including mercury, can be accumulated. The dry deposition of atmospheric Hg during heating seasons is more intense than in non-heating seasons, owing to the combustion of fossil fuels for heating purposes. This has resulted in studies into the role of phytoplankton in the introduction of Hg into the first link of trophic chain, as a function of autumn and winter warming in the coastal zone of the lagoon. The studies were conducted at two stations in the coastal zone of the southern Baltic, in the Puck Lagoon, between December 2011 and May 2013. The obtained results show that, in the estuary region, the lack of ice cover can lead to a 30% increase and during an “extremely warm” autumn and winter an increase of up to three-fold in the mean annual Hg pool in phytoplankton (mass of Hg in phytoplankton per liter of seawater). The Hg content in phytoplankton was higher when Mesodinium rubrum was prevalent in the biomass, while the proportion of dinoflagellates was small.

Though rainfall is recognized as one of the main mechanisms to reduce atmospheric particulate pollution, few studies have quantified this effect, particularly the corresponding lag effect and threshold. This study aimed to investigate the association between rainfall and air quality using a distributed lag non-linear model. Daily data on ambient PM2.5 and PM2.5–10 (particulate matter with an aerodynamic diameter less than 2.5 μm and from 2.5 to 10 μm) and meteorological factors were collected in Guangzhou and Xi'an from 2013 to 2014. A better washout effect was found for PM2.5–10 than for PM2.5, and the rainfall thresholds for both particle fractions were 7 mm in Guangzhou and 1 mm in Xi'an. The decrease in PM2.5 levels following rain lasted for 3 and 6 days in Guangzhou and Xi'an, respectively. Rainfall had a better washout effect in Xi'an compared with that in Guangzhou. Findings from this study contribute to a better understanding of the washout effects of rainfall on particulate pollution, which may help to understand the category and sustainability of dust-haze and enforce anthropogenic control measures in time.

We evaluated three types of functionalized, graphene-based materials for activating persulfate (PS) and removing (i.e., sorption and oxidation) sulfamethoxazole (SMX) as a model emerging contaminant. Although advanced oxidative water treatment requires PS activation, activation requires energy or chemical inputs, and toxic substances are contained in many catalysts. Graphene-based materials were examined herein as an alternative to metal-based catalysts. Results show that nitrogen-doped graphene (N-GP) and aminated graphene (NH2-GP) can effectively activate PS. Overall, PS activation by graphene oxide was not observed in this study. N-GP (50 mg L−1) can rapidly activate PS (1 mM) to remove >99.9% SMX within 3 h, and NH2-GP (50 mg L−1) activated PS (1 mM) can also remove 50% SMX within 10 h. SMX sorption and total removal was greater for N-GP, which suggests oxidation was enhanced by increasing proximity to PS activation sites. Increasing pH enhanced the N-GP catalytic ability, and >99.9% SMX removal time decreased from 3 h to 1 h when pH increased from 3 to 9. However, the PS catalytic ability was inhibited at pH 9 for NH2-GP. Increases in ionic strength (100 mM NaCl or Na2SO4) and addition of radical scavengers (500 mM ethanol) both had negligible impacts on SMX removal. With bicarbonate addition (100 mM), while the catalytic ability of N-GP remained unaltered, NH2-GP catalytic ability was inhibited completely. Humic acid (250 mg L−1) was partially effective in inhibiting SMX removal in both N-GP and NH2-GP systems. These results have implications for elucidating oxidant catalysis mechanisms, and they quantify the ability of functionalization of graphene with hetero-atom doping to effectively catalyze PS for water treatment of organic pollutants including emerging contaminants.

Superfund sites with sediments contaminated by hydrophobic organic compounds (HOCs) can be difficult to characterize because of the complex nature of sorption to sediments. Porewater concentrations, which are often used to model transport of HOCs from the sediment bed into overlying water, benthic organisms, and the larger food web, are traditionally estimated using sediment concentrations and sorption coefficients estimated using equilibrium partitioning (EqP) theory. However, researchers have begun using polymeric samplers to determine porewater concentrations since this method does not require knowledge of the sediment's sorption properties. In this work, polyethylene passive samplers were deployed into sediments in the field (in situ passive sampling) and mixed with sediments in the laboratory (ex situ active sampling) that were contaminated with polychlorinated biphenyls (PCBs). The results show that porewater concentrations based on in situ and ex situ sampling generally agreed within a factor of two, but in situ concentrations were consistently lower than ex situ porewater concentrations. Imprecision arising from in situ passive sampling procedures does not explain this bias suggesting that field processes like bioirrigation may cause the differences observed between in situ and ex situ polymeric samplers.