Rapeseed (Brassica napus L.) is a winter oil crop and biodiesel resource that has been widely cultivated in the southern part of China. Applying rapeseed residue (RSD) to summer rice fields is a common agricultural practice under rice−rapeseed double cropping systems. However, in Cd−contaminated paddy fields, the influence mechanisms of this agricultural practice on the migration and distribution of Cd fractions in soil are not clear. Therefore, a field experiment was carried out to analyse the changes in soil pH, organic matter (OM), microbial biomass carbon (MBC) and nitrogen (MBN), enzyme activity (urease (UA), acid phosphatase (ACP), and dehydrogenase (DH)), Cd distribution fractions, and Cd concentration in rice tissues after RSD application. The results showed that RSD treatment significantly increased the soil OM and MBC concentrations and UA, ACP, and DH activities, decreased the soil acetic acid−extractable fraction of Cd (ACI–Cd), and increased the reducible fraction of Cd (Red–Cd). The formation of stable organic complexes and chelates upon application of RSD is a result of the high affinity of Cd for soil OM. The activities of soil ACP, DH and MBC can well reflect Cd ecotoxicity in soil, particularly the DH activity. In addition, RSD application was helpful in inducing iron plaque formation. The “barrier” effect of iron plaque resulted in reduced Cd accumulation in different tissues of rice. The health risk of rice consumption also decreased as a result of RSD application; it decreased by 0.89–30.0% and 24.1–51.7% in the two tested fields. Overall, the application of RSD was increased soil OM, microbial biomass, and enzyme activity, and these changes was instrumental in reduce the risk of cadmium pollution in rice fields.

Currently the Chinese government has adopted World Health Organization interim target-1 values as the national ambient air quality standards values. However, the population-based evidence was insufficient, especially for the oldest old (aged 80+). We evaluated the association of fine particulate matters (PM₂.₅) exposure and incidence of disability in activities of daily living (ADL) in 15 453 oldest old in 886 counties/cities in China from 2002 to 2014 using Cox model with penalized splines and competing risk models to evaluate the linear or non-linear association. After adjusting for potential confounders, a J-shaped association existed between PM₂.₅ exposure with a threshold concentration of 33 μg/m³, and incident disability in ADL. Above this threshold, the risk magnitude significantly increased with increase of PM₂.₅ concentrations; compared to 33 μg/m³, the hazard ratio ranged from 1.03 (1.00–1.06) at 40 μg/m³ to 2.25 (1.54–3.29) at 110 μg/m³. The risk magnitude was not significantly changed below this threshold. Each 10 μg/m³ increase in PM₂.₅ exposure corresponded to a 7.7% increase in the risk of disability in ADL (hazard ratio 1.077, 95% CI 1.051–1.104). Men, smokers, and participants with cognitive impairment might be more vulnerable to PM₂.₅ exposure. The study provided limited population-based evidence for the oldest old and detected a threshold of 33 μg/m³, and supported that reduction to current World Health Organization interim target-1value (35 μg/m³) and Chinese national ambient air quality standards (35 μg/m³) or lower may be associated with lower risk of disability in ADL.

Environmental emissions of perfluoroalkyl acids (PFAAs) often contaminate aquatic ecosystems and accumulate in the species therein. This can represent an exposure pathway for human populations where seafood is consumed. Concentrations of PFAAs in water breathing animals may be a function of many different factors, however, little is known about how these different factors impact contaminant accumulation in estuarine and marine species. This study explores the relationships between PFAA accumulation and two key variables, animal size and sediment concentrations, for a number of important seafood species. Sixty Dusky Flathead (Platycephalus fuscus), 58 Mulloway (Argyrosomus japonicus) and 53 Giant Mud Crab (Scylla serrata) were tested for perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA) and perfluorohexane sulfonate (PFHxS) in edible tissues, and the concentrations compared with animal size and sediment concentrations at the location of capture. PFAAs showed a high degree of variation among species, and PFOA and PFHxS were only common in Giant Mud Crab. Log-transformed PFOS concentrations in all three species showed negative correlations with animal size (weight). There was limited evidence for relationships between PFOS muscle tissue concentration and sediment PFOS concentration. The patterns observed are potentially explained by changes in trophic position, relative growth rate, consumption rate and metabolic rate, throughout the species life history. The results contrast with observations for other persistent organic pollutants, whereby larger individuals tend to carry greater contaminant loads. Future work is required to establish whether these patterns are evident for PFAAs in other species and contaminant sources.

Exposure to metal nanoparticles causes both pulmonary and systemic effects. Nanoparticles can enter the circulation and act directly or indirectly on blood cells, such as monocytes. Monocytes/macrophages are among the first cells to home to inflammatory sites and play a key role in the immune response. Here we investigated the effects of nickel nanoparticles (Nano-Ni), partially [O]-passivated Nano-Ni (Nano-Ni-P), and carbon-coated Nano-Ni (Nano-Ni-C) on MMP-2 and MMP-9 production in mouse primary monocytes both in vitro and in vivo and explored the potential mechanisms involved. The dose- and time-response studies showed that exposure of primary monocytes from wild-type (WT) mice to 30 μg/mL of Nano-Ni for 24 h caused significant MMP-2 and MMP-9 production; therefore, these dose and time point were chosen for the following in vitro studies. Nano-Ni and Nano-Ni-P caused miR-21 upregulation, as well as MMP-2, MMP-9, TIMP-1 and TIMP-2 upregulation in monocytes from WT, but not miR-21 knock-out (KO), mice, indicating the important role of miR-21 in Nano-Ni-induced MMPs and TIMPs upregulation. However, Nano-Ni-C did not cause these effects, suggesting surface modification of Nano-Ni, such as carbon coating, alleviates Nano-Ni-induced miR-21 and MMPs upregulation. These results were further confirmed by in vivo studies by intratracheal instillation of nickel nanoparticles into WT and miR-21 KO mice. Finally, our results demonstrated that exposure of primary monocytes from WT mice to Nano-Ni and Nano-Ni-P caused downregulation of RECK, a direct miR-21 target, suggesting the involvement of miR-21/RECK pathway in Nano-Ni-induced MMP-2 and MMP-9 production.

Little is known about fine particulate matter (PM2.5) exposure among pregnant women in rural China. This study aims to characterize exposure to PM2.5 among pregnant women in rural China, and investigate potential risk factors of personal exposure to PM2.5. The data were obtained from a birth cohort study that enrolled 606 pregnant women in Xuanwei, a county known for its high rates of lung cancer. The personal exposure to PM2.5 was measured using small portable particulate monitors during each trimester of pregnancy. Participants were interviewed using structured questionnaires that sought information on risk factors of PM2.5 exposure. The daily exposure to PM2.5 among the pregnant women ranged from 19.68 to 97.08 μg/m3 (median = 26.08). Exposure to PM2.5 was higher in winter and autumn than other seasons (p < 0.05); higher during the day than during the night (p < 0.001); and greater during cooking hours than during the rest of the day (p < 0.001). Using a mixed effects model, domestic solid fuel for cooking (β = 1.75, p < 0.001), winter and autumn (β = 2.96, p < 0.001), cooking ≥ once per day (β = 1.58, p < 0.05), heating with coal (β = 1.69, p < 0.001), secondhand smoke exposure (β = 1.59, p < 0.001) and township 1(β = 2.39, p < 0.001) were identified as risk factors for personal exposure to PM2.5 of pregnant women throughout pregnancy. Indirect effects of season and township factors on personal PM2.5 exposure were mediated by heating, cooking and domestic fuel using. In conclusion, PM2.5 levels in Xuanwei exceeded WHO guidelines. Seasonal and township factors and individual behaviors like domestic solid fuel using for cooking, heating with coal and secondhand smoke exposure are associated with higher personal PM2.5 exposure among pregnant women in rural China.

Cylindrospermopsin (CYN) is an important cyanobacterial toxin posing a major threat to surface waters during cyanobacterial blooms. Hence, methods for cyanotoxin removal are required to confront seasonal or local incidences to sustain the safety of potable water reservoirs. Non-thermal plasmas provide the possibility for an environmentally benign treatment which can be adapted to specific concentrations and environmental conditions without the need of additional chemicals. We therefore investigated the potential of two different non-thermal plasma approaches for CYN degradation, operated either in a water mist, i.e. in air, or submerged in water. A degradation efficacy of 0.03 ± 0.00 g kWh⁻¹ L⁻¹ was found for a dielectric barrier discharge (DBD) operated in air, while a submerged pulsed corona-like discharge resulted in an efficacy of 0.24 ± 0.02 g kWh⁻¹ L⁻¹. CYN degradation followed a pseudo zeroth order or pseudo first order reaction kinetic, respectively. Treatment efficacy of the corona-like discharge submerged in water increased with pH values of the initial solution changing from 5.0 to 7.5. Notably, a pH-depending residual oxidative effect was observed for the submerged discharge, resulting in ongoing CYN degradation, even without further plasma treatment. In this case hydroxyl radicals were identified as the dominant oxidants of CYN at acidic pH values. In comparison, degradation by the DBD could be related primarily to the generation of ozone.

This study evaluated three biochars derived from bioenergy by-products — manure-based anaerobic digestate (DIG), distillers’ grains (DIS), and a mixture thereof (75G25S) — as amendments to stabilize Hg in contaminated floodplain soil under long-term saturated (up to 200 d) and cyclic drying and rewetting conditions. Greater total Hg (THg) removal (72 to nearly 100%) and limited MeHg production (<65 ng L⁻¹) were observed in digestate-based biochar-amended systems under initial saturated conditions. Drying and rewetting resulted in limited THg release, increased aqueous MeHg, and decreased solid MeHg in digestate-based biochar-amended systems. Changes in Fe and S chemistry as well as microbial communities during drying and rewetting potentially affected MeHg production. Digestate-based biochars may be more effective as amendments to control Hg release and minimize MeHg production in floodplain soils under long-term saturated and drying and rewetting conditions compared to distillers’ grains biochar.

New environmental regulations are mandating cleaner fuels and lower emissions from all maritime operations. Natural gas (NG) is a fuel that enables mariners to meet regulations; however, emissions data from maritime operations with natural gas is limited. We measured emissions of criteria, toxic and greenhouse pollutants from a dual-fuel marine engine running either on diesel fuel or NG as well as engine activity and analyzed the impacts on pollutants, health, and climate change. Results showed that particulate matter (PM), black carbon (BC), nitric oxides (NOₓ), and carbon dioxide (CO₂) were reduced by about 93%, 97%, 92%, and 18%, respectively when switching from diesel to NG. Reductions of this magnitude provide a valuable tool for the many port communities struggling with meeting air quality standards. While these pollutants were reduced, formaldehyde (HCHO), carbon monoxide (CO) and methane (CH₄) increased several-fold. A health risk assessment of exhaust plume focused on when the vessel was stationary, and at-berth showed the diesel plume increased long-term health risk and the NG plume increased short-term health risk. An analysis of greenhouse gases (GHGs) and BC was performed and revealed that, on a hundred year basis, the whole fuel cycle global warming potential (GWP) per kWh including well-to-tank and exhaust was 50% to few times higher than that of diesel at lower engine loads, but that it was similar at 75% load and lower at higher loads. Mitigation strategies for further reducing pollutants from NG exhaust are discussed and showed potential for reducing short-term health risks and climate impacts.

Cigarette butts (CBs) are the most common litter item on Earth but no long-term studies evaluate their fate and ecological effects. Here, the role of nitrogen (N) availability and microbiome composition on CBs decomposition were investigated by a 5-years experiment carried out without soil, in park grassland and sand dune. During decomposition, CBs chemical changes was assessed by both ¹³C CPMAS NMR and LC-MS, physical structure by scanning electron microscope and ecotoxicity by Aliivibrio fischeri and Raphidocelis subcapitata. Microbiota was investigated by high-throughput sequencing of bacterial and eukaryotic rRNA gene markers. CBs followed a three-step decomposition process: at the early stage (∼30 days) CBs lost ∼15.2% of their mass. During the subsequent two years CBs decomposed very slowly, taking thereafter different trajectories depending on N availability and microbiome composition. Without soil CBs showed minor chemical and morphological changes. Over grassland soil a consistent N transfer occurs that, after de-acetylation, promote CBs transformation into an amorphous material rich in aliphatic compounds. In sand dune we found a rich fungal microbiota able to decompose CBs, even before the occurrence of de-acetylation. CBs ecotoxicity was highest immediately after smoking. However, for R. subcapitata toxicity remained high after two and five years of decomposition.

Di(2-ethylhexyl) phthalate (DEHP), the most extensively used plasticizer in plastic formulations, is categorized as a priority environmental contaminant with carcinogenic, teratogenic, and mutagenic toxicities. Many isolated microorganisms exhibit outstanding performance as pure cultures in the laboratory but are unable to cope with harsh environmental conditions in the field. In the present study, a microbial consortium (CM9) with efficient functionality was isolated from contaminated farmland soil. CM9 could consistently degrade 94.85% and 100.00% of DEHP (1000 mg/L) within 24 h and 72 h, respectively, a higher efficiency than those of other reported pure and mixed microorganism cultures. The degradation efficiencies of DEHP and di-n-butyl phthalate were significantly higher than those of dimethyl phthalate and diethyl phthalate (p < 0.05). The primary members of the CM9 consortium were identified as Rhodococcus, Niabella, Sphingopyxis, Achromobacter, Tahibacter, and Xenophilus. The degradation pathway was hypothesized to include both de-esterification and β-oxidation. In contaminated soil, bioaugmentation with CM9 and biochar markedly enhanced the DEHP removal rate to 87.53% within 42 d, compared to that observed by the indigenous microbes (49.31%) (p < 0.05). During simulated bioaugmentation, the dominant genera in the CM9 consortium changed significantly over time, indicating their high adaptability to soil conditions and contribution to DEHP degradation. Rhodococcus, Pigmentiphaga and Sphingopyxis sharply decreased, whereas Tahibacter, Terrimonas, Niabella, Unclassified_f_Caulobacteraceae, and Allorhizobium-Neorhizobium-Pararhizobium-Rhizobium showed considerable increases. These results provide a theoretical framework for the development of in situ bioremediation of phthalate (PAE)-contaminated soil by composite microbial inocula.