Mercury (Hg) is a toxic and persistent pollutant and has long-term impacts on ecological systems and human health. Coal-fired power plants (CFPPs) are the main source of anthropogenic Hg emission, and the emitted atmospheric Hg is deposited to the surrounding environments which causes soil pollution. To assess the effects of atmospheric Hg from CFPPs in China on the temperate steppe, Hg contents in the topsoil and subsoil were analyzed for samples collected from 80 sites in central Inner Mongolia during 2012–2015. The average content of Hg in topsoil and subsoil were 14.9 ± 10.4 μg kg⁻¹ and 8.9 ± 5.8 μg kg⁻¹, respectively. The principal components analysis (PCA) indicated that the soil organic matter content and atmospheric deposition were the main factors determining soil Hg content in Inner Mongolia. We used the power plant impact factor (PPIF) to evaluate the impacts of the surrounding CFPPs. The PPIF results showed the most positive correlation with Hg content in topsoil at more than 400 km distances, indicating that the contribution of the long-range transport of Hg emitted from CFPPs is regional in scale. Considering the potential of Hg accumulation in soil, long-term and regional measurements of soil Hg and stricter emission-limit standards for power plants should be implemented to control soil Hg pollution in China.

The optical properties of light-absorbing carbonaceous aerosols have caused increasing concerns due to their significant impacts on local and regional climates. In this study, particles from biomass burning in home stoves were collected and evaluated for their optical properties. The absorption Ångström exponent (AAE) values ranged from 1.17 to 2.92 and negatively correlated with the modified combustion efficiency, indicatinging more brown carbon in combustion emissions with relatively low combustion efficiencies. The average contribution of brown carbon to the total aerosol absorption at 370 nm was equally as important as that of black carbon (BC), with the average relative contribution fraction of 50% varying from 10% to 84% for different biomasses. The average value of the mass absorption efficiency (MAE) of BC (MAEBC) at 880 nm was positively correlated with the ratio of organic carbon to elemental carbon, indicating the significant coating effects of organic aerosols. The MAE values of BrC at 370 nm were in the range of 1.1–11.3 m²/g, with an average of 5.1 ± 2.2 m²/g. The estimated absorption emission factors at 370 nm and 880 nm were 3.75 ± 3.45 and 0.84 ± 0.78 m²/kg, respectively. Optical property information of particles emitted from real-world biomass burning are imperative in future modeling studies of biomass burning impacts on climate. The limitation of the relatively small sample size for each subgroup fuel calls for more field- and lab-based emission characterization research.

The biological effects of nanoplastics are a growing concern. However, most studies have focused on exposure to high concentrations or short-term exposure. The potential effects of exposure to low environmental nanoplastic concentrations over the long-term and across multiple generations remain unclear. In the present study, Daphnia pulex was exposed over three 21-day generations to a typical environmental nanoplastic concentration (1 μg/L) and the effects were investigated at physiological (growth and reproduction), gene transcription and enzyme activity levels. Chronic exposure did not affect the survival or body length of D. pulex, whereas the growth rate and reproduction were influenced in the F2 generation. Molecular responses indicated that environmental nanoplastic concentrations can modulate the response of antioxidant defenses, vitellogenin synthesis, development, and energy production in the F0-F1 generations, and prolongation resulted in inhibitory effects on antioxidant responses in F2 individuals. Some recovery was observed in the recovery group, but reproduction and stress defenses were significantly induced. Taken together, these results suggest that D. pulex recovery from chronic exposure to nanoplastic may take several generations, and that nanoplastics have potent long-term toxic effects on D. pulex. The findings highlight the importance of multigenerational and chronic biological evaluations to assess risks of emerging pollution.

Civilization development is associated with the use of plastic. When plastic was introduced to the market, it was assumed that it was less toxic than glass. Recently, it is known that plastics are serious ecological problem they, do not degrade and remain in the environment for hundreds of years.Plastic may be degraded into micro-particles < 5000 nm in diameter, and further into nanoparticles (NPs) < 100 nm in diameter. NPs have been detected in air, soil, water and sludge.One of the most commonly used plastics is polystyrene (PS) - a product of polymerization of styrene monomers. It is used for the production of styrofoam and other products like toys, CDs and cup covers. In vivo and in vitro studies have suggested that polystyrene nanoparticles (PS-NPs) may penetrate organisms through several routes i.e. skin, respiratory and digestive tracts. They can be deposited in living organisms and accumulate further along the food chain. NPs are surrounded by “protein corona” that allows them penetrating cellular membranes and interacting with cellular structures. Depending on the cell type, NPs may be transported through pinocytosis, phagocytosis, or be transported passively. Currently there are no studies that would indicate a carcinogenic potential of PS-NPs. On the other hand, the PS monomer (styrene) was classified by the International Agency for Research on Cancer (IARC) as a potentially carcinogenic substance (carcinogenicity class B2).Despite of the widespread use of plastics and the presence of plastic NPs of secondary or primary nature, there are no studies that would assess the effect of those substances on human organism. This study was aimed at the review of the literature data concerning the formation of PS-NPs in the environment, their accumulation along the food chain, and their potential adverse effects on organisms on living various organization levels.

Light absorbing carbonaceous aerosols (LACA) consisting of black carbon (BC) and brown carbon (BrC) have received considerable attention because of their climate and health implications, but their sources, characteristics and fates remain unclear in Southeast Asia (SEA). In this study, we investigated spatio-temporal characteristics of LACA, their radiative properties and potential sources in Singapore under different weather conditions. Hourly BC concentrations, measured from May 2017 to March 2018, ranged from 0.31 μg/m³ to 14.37 μg/m³ with the mean value being 2.44 ± 1.51 μg/m³. High mass concentrations of BC were observed during the south-west monsoon (SWM, 2.60 ± 1.56 μg/m³) while relatively low mass concentrations were recorded during the north-east monsoon (NEM, 1.68 ± 0.96 μg/m³). There was a shift in the Absorption Ångström exponent (AAE) from 1.1 to 1.4 when the origin of LACA changed from fossil fuel (FF) to biomass burning (BB) combustion. This shift is attributed to the presence of secondary BrC in LACA, derived from transboundary BB emissions during the SWM. Lower AAE values were observed when local traffic emissions were dominant during the NEM. This explanation is supported by measurements of water-soluble organic carbon (WSOC) in LACA and the corresponding AAE values determined at 365 nm using a UV–vis spectrophotometer. The AAE values, indicative of the presence of brown carbon (BrC), showed that photochemically aged LACA contribute to an enhancement in the light absorption of aerosols. In addition, spatio-temporal characteristics of BC in the intra-urban environment of Singapore were investigated across diverse outdoor and indoor microenvironments. High variability of BC was evident across these microenvironments. Several air pollution hotspots with elevated BC concentrations were identified. Overall, the results stress a need to control anthropogenic emissions of BC and BrC in order to mitigate near-term climate change impacts and provide health benefits.

Microplastics are a complex group of ubiquitous environmental contaminants of emerging concern. These particles degrade slowly, release plasticizers, and can be transferred between trophic levels. In aquatic systems, they have been identified suspended in the water column, along shorelines, and within sediment. However, the abundance and distribution of microplastics in vegetated wetlands, which are transitional ecosystems between terrestrial and aquatic environments, are poorly understood. Here we describe the spatial distribution of soil microplastics in habitats of varying vegetation density in an urban tidal wetland. Samples were wet-sieved, organic matter was oxidized using hydrogen peroxide, and microplastics separated under a dissecting microscope, counted, and weighed. A fraction (n = 175) were analyzed via FTIR for validation. Positive microplastics identification was 81%–93%. Dominant polymers were polystyrene (29%) and polyethylene and synthetic rubber (both 8%). Average microplastic number to a 5-cm depth (23,200 ± 2,500 m−2 or 1,270 ± 150 kg−1) varied between habitat types, where mudflat, channel edge, and drift line habitats all had significantly more total microplastics than the interior of dense stands of vegetation, suggesting that emergent wetland plants are a highly effective filter of microplastics. Microfibers were about eight times as abundant as microfragments, and fibers and fragments differed in their distribution patterns, with microfibers most abundant in vegetation-free mudflats and microfragments in vegetated channel edges. Our results demonstrate that vegetated wetlands are important locations for microplastic accumulation and that wetland vegetation and hydrodynamics affect spatial distribution of microplastics between habitats.

Heavy metal pollution is widespread, and has an increasing trend in some countries and regions. It can be easily accumulated in plants, leading to plant species loss and affecting plant community composition. Artificial restoration can conserve plant diversity in contaminated soils and accelerate the recovery of polluted ecosystems. The application of nitrogen (N) and phosphorus (P) is inexpensive and convenient, which can increase the resistance of plants to adversity and promote the growth of plants in heavy metal polluted soils. In order to examine the effect of N and P nutrition on the conservation of plant community, we conducted a comparison experiment in greenhouse using soil with low N and P concentration, and set five treatments: C (soil with no heavy metals and fertilizer addition), H (soil with heavy metals addition but with no fertilizer), HN (soil with heavy metals and N addition), HP treatment(soil with heavy metals and P addition), HNP treatment (soil with heavy metals, N and P addition). Our results showed that heavy metal pollution reduced plant species by 300%, and significantly decreased plant diversity (P < 0.05). N addition increased the richness of plant species and increased the dominance of Euphorbia peplus, but had no significant effect on plant diversity and community structure, while reduced the evenness of plant species. P addition of HP and HNP treatments restored plant species richness and increased plant diversity under heavy metal pollution. The plant community structures of these two treatments were more similar to that of group C. Compared with N addition, P addition had a better performance to restoring the species composition and relative dominance of plant communities. Our results provided a guidance for the restoration of plant communities and the conservation of plant species in low N and P concentration soils with the context of heavy metal pollution.

Production of chrysanthemum (Dendranthema grandiflora) in greenhouses often requires intensive pesticide use, which raises serious concerns over food safety and human health. This study investigated uptake, translocation and residue dissipation of typical fungicides (metalaxyl-M and fludioxonil) and insecticides (cyantraniliprole and thiamethoxam) in greenhouse chrysanthemum when applied in soils. Chrysanthemum plants could absorb these pesticides from soils via roots to various degrees, and bioconcentration factors (BCFLS) were positively correlated with lipophilicity (log Kₒw) of pesticides. Highly lipophilic fludioxonil (log Kₒw = 4.12) had the greatest BCFLS (2.96 ± 0.41 g g⁻¹), whereas hydrophilic thiamethoxam (log Kₒw = −0.13) had the lowest (0.09 ± 0.03 g g⁻¹). Translocation factors (TF) from roots to shoots followed the order of TFₗₑₐf > TFₛₜₑₘ > TFfₗₒwₑᵣ. Metalaxyl-M and cyantraniliprole with medium lipophilicity (log Kₒw of 1.71 and 2.02, respectively) and hydrophilic thiamethoxam showed relatively strong translocation potentials with TF values in the range of 0.29–0.81, 0.36–2.74 and 0.30–1.03, respectively. Dissipation kinetics in chrysanthemum flowers followed the first-order with a half-life of 21.7, 5.5, 10.0 or 8.2 days for metalaxyl-M, fludioxonil, cyantraniliprole and thiamethoxam, respectively. Final residues of these four pesticides, including clothianidin (a primary toxic metabolite of thiamethoxam), in all chrysanthemum flower samples were below the maximum residue limit (MRL) values 21 days after two soil applications each at the recommended dose (i.e., 3.2, 2.1, 4.3 and 4.3 kg ha⁻¹, respectively). However, when doubling the recommended dose, the metabolite clothianidin remained at concentrations greater than the MRL, despite that thiamethoxam concentration was lower than the MRL value. This study provided valuable insights on the uptake and residues of metalaxyl-M, fludioxonil, cyantraniliprole and thiamethoxam (including its metabolite clothianidin) in greenhouse chrysanthemum production, and could help better assess food safety risks of chrysanthemum contamination by parent pesticides and their metabolites.

It is of environmental significance to study the leaching performance of additives from microplastics (MPs) and further evaluate the toxicity of leachate to microalgae. Here, we investigated the effects of accelerated aging on characteristics, leaching, and toxicity of commercial lead chromate pigmented MPs. Results show that aging of MPs caused surface cracks and fragmentation, increased their surface area and carbonyl contents, and promoted the release of lead chromate pigment. Chromium (Cr) and lead (Pb) tend to leach under acidic condition, rather than neutral and alkali environment. Aging treatment facilitates the leaching performance and a high concentration of NaCl solution also favors the leaching process. Toxicology experiments demonstrate that only high concentration of leachate (>10 μg L⁻¹) exerted significant inhibitory influence (p < 0.005) on cell photosynthesis of Microcystis aeruginosa. The growth inhibition of algal cells remarkably increased with increasing leachate concentrations. We observed more inhibiting effects on cell growth and photosynthesis using the leachates of aged MPs. Longer aging time leads to more release of Cr and Pb, rendering higher toxicity to microalgae. These novel findings will benefit us from assessing the leaching behavior of additives in MPs and their toxicological risks to aquatic organisms.

This study assessed the sources, magnitudes, and chemical compositions of household air pollution (HAP) and personal exposure in traditional Tibetan households. We measured 24-h personal exposures to PM₂.₅ and kitchen area black carbon (BC) concentrations, using MicroPEMs and microAeths, respectively. Particulate polycyclic aromatic hydrocarbon (PAH) and inorganic element concentrations were quantified via post analyses of a subset of MicroPEM sample filters. Household surveys regarding participant demographics, cookstove usage, household fuel, cooking behaviors, and lifestyles were collected. The results reaffirm that burning firewood and yak dung, mainly for cooking, leads to high PM₂.₅ and BC exposures. The geometric mean concentration (95% confidence interval, CI) was 74.3 (53.6, 103) μg/m³ for PM₂.₅ and the arithmetic mean ± standard deviation (SD) concentration was 4.90 ± 5.01 μg/m³ for BC and 292 ± 364 ng/m³ for 15 identified PAHs, respectively. The arithmetic mean ± SD of mass concentrations of 24 detected elements ranged from 0.76 ± 0.91 ng/m³ (Co) to 1.31 ± 1.35 μg/m³ (Si). Our statistical analyses further illustrated that the high concentrations of PM₂.₅, BC, and most PAHs and metals, are significantly associated with nomadic village, poorer stove/chimney conditions and yak dung burning. The results from this study show that substantial HAP exposure is prevalent in Tibetan households and requires immediate actions to mitigate potential negative environmental health impacts. The observational data also revealed the possibility of other important sources (e.g. traffic and garbage burning) that have contributed to personal exposures. These findings improve our understanding of HAP exposure and potential health risks in Tibetan communities and will help inform strategies for reducing HAP in Tibetan households and beyond.