Genetic effects and radioactive contamination of large mammals, including wild boar (Sus scrofa), have been studied in Japan because of dispersal of radionuclides from the Fukushima Dai-ichi Nuclear Power Plant in 2011. Such studies have generally demonstrated a declining trend in measured radiocesium body burdens in wildlife. Estimating radiation exposure to wildlife is important to understand possible long-term impacts. Here, radiation exposure was evaluated in 307 wild boar inhabiting radioactively contaminated areas (50–8000 kBq m⁻²) in Fukushima Prefecture from 2016 to 2019, and genetic markers were examined to assess possible germline mutations caused by chronic radiation exposures to several generations of wild boar. Internal Cs activity concentrations in boar remained high in areas near the power plant with the highest concentration of 54 kBq kg⁻¹ measured in 2019. Total dose rates to wild boar ranged from 0.02 to 36 μGy h⁻¹, which was primarily attributed to external radiation exposure, and dose rates to the maximally exposed animals were above the generic no-effects benchmark of 10 μGy h⁻¹. Using the estimated age of each animal, lifetime radiation doses ranged from <0.1 mGy to 700 mGy. Despite chronic exposures, the genetic analyses showed no significant accumulation of mutation events. Because wild boar is an occasional human dietary item in Japan, effective dose to humans from ingesting contaminated wild boar meat was calculated. Hypothetical consumption of contaminated wild boar meat from radioactively contaminated areas in Fukushima, at the per capita pork consumption rate (12.9 kg y⁻¹), would result in an average effective annual dose of 0.9 mSv y⁻¹, which is below the annual ingestion limit of 1 mSv y⁻¹. Additionally, a consumption rate of about 1.4 kg y⁻¹ of the most contaminated meat in this study would not exceed annual ingestion limits.

Widespread use of fungicides has raised the concern of exposure to them among the general population. However, there are extremely limited studies reporting the occurrence of fungicides in indoor dust in China. This study aimed to determine ten agricultural fungicides in indoor dust samples collected in three cities of China from 2016 to 2019, assess spatial and seasonal variations, and estimate the related exposure via dust ingestion. Six out of ten fungicides including difenoconazole, prochloraz, tebuconazole, tricyclazole, azoxystrobin, and pyraclostrobin were frequently detected in the dust samples (ranged 65.8–97.7%) and the concentrations of some fungicides showed a strong correlation with each other. Difenoconazole was the most abundant one among the selected fungicides. The highest level of the selected fungicides was observed in the indoor dust collected from Wuhan in summer 2019 (median cumulative concentration of the fungicides: 62.6 ng/g), while the relatively low concentrations of fungicides were found in the dust from Taiyuan (2.08 ng/g). Heavier fungicide contamination was observed in urban districts compared to that in rural districts. Seasonal variations in the fungicide residuals were also identified. The exposure assessment suggested that intake of the selected fungicides via dust ingestion was much lower than dietary intake reported in other studies. This study filled the data gap of fungicide residuals in the indoor dust in China and further studies are needed to identify the sources and determinants of indoor fungicide contamination.

Batch sorption of metformin hydrochloride (MET) onto a specially designed biochar mix consisting of both macro (MAC) and micro (MIC) algae, rice husk and pine sawdust was conducted. Pyrolysis of both MAC and MIC algae mixture was done followed by chemical activation with hydrogen-peroxide. Additionally, sorption of MET under the influence of pH was separately investigated. Batch studies of isotherms were well described by Freundlich model with high non-linearity and Freundlich exponent values ranged anywhere from 0.12 to 1.54. Heterogeneity of MET adsorption to the bonding sites was attributed to the surface functional groups of the modified biochar. Amongst the four biochars, the activated macroalgae biochar (MACAC) and microalgae biochar (MICAC) depicted favourable adsorption of MET with maximum adsorption at pH 7. Up to 76% of MET removal from the environment was obatained using the MACAC biochar. Scanning electron micrographs coupled with energy dispersive X-ray, as well as elemental analyses confirmed formation of oxygen containing surface functional groups due to activation strengthening chemisorption as the main sorption mechanism. Further, Fourier transform infra-red spectroscopy and other surface functional group analyses along with Zeta potential measurements reinforced our proposed sorption mechanism. Lowest zeta potential observed at pH 7 enhanced the electrostatic force of attraction for both the biochars. Negative zeta potential value of the biochars under different pH indicated potential of the biochars to adsorb other positively charged contaminants. From a techno-economic perspective, capital expenditure cost is not readily available, however, it is envisaged that production of pyrolyzed biochar from algal biomass could make the process economically attractive especially when the biochar could be utilised for high-end applications.

Ice is an important physical and chemical sink for various pollutants in cold regions. The photodegradation of emerging fluoroquinolone (FQ) antibiotic contaminants with dissolved organic matter (DOM) in ice remains poorly understood. Here, the photodegradation of ciprofloxacin (CIP) and fulvic acid (FA) in different proportions as representative FQ and DOM in ice were investigated. Results suggested that the photodegradation rate constant of CIP in ice was 1.9 times higher than that in water. When CFA/CCIP ≤ 60, promotion was caused by FA sensitization. FA increased the formation rate of cleavage in the piperazine ring and defluorination products. When 60 < CFA/CCIP < 650, the effect of FA on CIP changed from promoting to inhibiting. When 650 ≤ CFA/CCIP ≤ 2600, inhibition was caused by both quenching effects of 143.9%–51.3% and light screening effects of 0%–48.7%. FA inhibited cleavage in the piperazine ring for CIP by the scavenging reaction intermediate of aniline radical cation in ice. When CFA/CCIP > 2600, the light screening effect was greater than the quenching effect. This work provides new insights into how DOM affects the FQ photodegradation with different concentration proportions, which is beneficial for understanding the environmental behaviors of fluorinated pharmaceuticals in cold regions.

The coexistence of nitrate and endocrine substances (EDCs) in groundwater is of global concern. Herein, an efficient and stable polypyrrole@corn cob (PPy@Corn cob) bioreactor immobilized with Zoogloea sp. was designed for the simultaneous removal of 17β-estradiol (E2), nitrate and Mn(II). After 225 days of continuous operation, the optimal operating parameters and enhanced removal mechanism were explored, also the long-term toxicity and microbial communities response mechanisms under E2 stress were comprehensively evaluated. The results showed that the removal efficiencies of E2, nitrate, and Mn(II) were 84.21, 82.96, and 47.91%, respectively, at the optimal operating conditions with hydraulic retention time (HRT) of 8 h, pH of 6.5 and Mn(II) concentration of 20 mg L⁻¹. Further increased of initial E2 (2 and 3 mg L⁻¹) resulted in the inhibiting effect of denitrification and manganese oxidation, but excellent E2 removal efficiencies maintained, which were associated with the formation and continuous accumulation of biomanganese oxides (BMO). Characterization analysis of biological precipitation demonstrated that adsorption and redox conversion on the BMO surface played key roles in the removal of E2. In addition, different levels of E2 exposure are decisive factors in community evolution, and bioaugmented bacterial communities with Zoogloea as the core group can dynamically adapt to E2 stress. This study offers the possibility to better utilize microbial metabolism and to advance opportunities that depend on microbial physiology and material characterization applications.

Arctic tundra soils store a globally significant amount of mercury (Hg), which could be transformed to the neurotoxic methylmercury (MeHg) upon warming and thus poses serious threats to the Arctic ecosystem. However, our knowledge of the biogeochemical drivers of MeHg production is limited in these soils. Using substrate addition (acetate and sulfate) and selective microbial inhibition approaches, we investigated the geochemical drivers and dominant microbial methylators in 60-day microcosm incubations with two tundra soils: a circumneutral fen soil and an acidic bog soil, collected near Nome, Alaska, United States. Results showed that increasing acetate concentration had negligible influences on MeHg production in both soils. However, inhibition of sulfate-reducing bacteria (SRB) completely stalled MeHg production in the fen soil in the first 15 days, whereas addition of sulfate in the low-sulfate bog soil increased MeHg production by 5-fold, suggesting prominent roles of SRB in Hg(II) methylation. Without the addition of sulfate in the bog soil or when sulfate was depleted in the fen soil (after 15 days), both SRB and methanogens contributed to MeHg production. Analysis of microbial community composition confirmed the presence of several phyla known to harbor microorganisms associated with Hg(II) methylation in the soils. The observations suggest that SRB and methanogens were mainly responsible for Hg(II) methylation in these tundra soils, although their relative contributions depended on the availability of sulfate and possibly syntrophic metabolisms between SRB and methanogens.

The cationic degradable polymer poly(lactic acid) choline iodide ester methacrylate, poly(PLA₄ChMA), can be used to flocculate particles and dewater sediments from tailings ponds and wastewater. A suitable bioaccessibility method is required to characterize the interactions of this novel flocculant in the human gastrointestinal system. To this end, a physiologically based extraction test (PBET) was modified to evaluate the bioaccessibility of flocculants. Bioaccessibility (bioaccessible fraction) is a measure of the solubility of a contaminant in gastrointestinal fluids and that may be available for systemic absorption. The flocculants poly(PLA₄ChMA), SNF C3276, and FLOPAM A3338 were tested at a solid-to-liquid ratio of 1:200 in the absence and presence of kaolin clay, which is used as a model sediment compound. Bioaccessible fractions were characterized by proton nuclear magnetic resonance spectroscopy and estimated by gravimetry. The bioaccessibility of poly(PLA₄ChMA) in gastric and intestinal PBET solutions decreases from 78% and 100%, respectively, in the absence of kaolin to approximately 0% with kaolin, indicating that poly(PLA₄ChMA) remains adsorbed onto the clay surface throughout the PBET, a result confirmed by thermogravimetric analysis. The bioaccessibility of cationic SNF C3276 and anionic FLOPAM A3338 in gastric solution is approximately 76% and 26%, respectively, and is not affected by the presence of kaolin. However, in intestinal solutions, the bioaccessibility of SNF C3276 and FLOPAM A3338 (60–85% in the absence of kaolin) changes to 0% and 100%, respectively, in the presence of kaolin. These results, interpreted in terms of solution pH and surface charge, demonstrate that interactions with kaolin influence the solubility of flocculants and must be considered in the evaluation of bioaccessibility. In future works, such bioaccessibility methods can be applied to assess the human-health safety of using flocculants in wastewater treatments.