Current understanding of biochar's effect on antibiotic resistance genes (ARGs) in soil is limited, and whether the effect could change after long-term field aging remains largely unknown. In this study, we employed high-throughput quantitative PCR to assess the effect of biochar amendment on soil resistome as affected by three years of field aging. Application of fresh biochar significantly elevated the number and abundance of ARGs in the manured soil, but did not show such effect under pakchoi cultivation. The presence of aged biochar caused a marked reduction of ARGs only in the planted manured soil. Results of principal coordinate analysis and structural equation modeling indicate that biochar's effect on soil ARG profile was changed by field aging through altering soil microbial composition. These results highlight the necessity of considering aging effect of biochar during its on-farm application to mitigate soil antibiotic resistance.

Evidence of the effects of long-term household air pollution (HAP) on human mental health is limited. This study aimed to explore the longitudinal relationship between long-term household air pollution exposure from solid fuel use and depression based on nationally representative follow-up dataset. A total of 7005 middle- and old-age adults from the latest four waves (2011, 2013, 2015, and 2018) of China Health and Retirement Longitudinal Study (CHARLS) were involved. The Center for Epidemiologic Studies Depression scale (CES-D 10) was used to measure depressive symptoms and individuals who got more than 12 points were considered to have depression symptoms. We conducted Cox proportional hazards regression models to examine the association between household air pollution and depression in overall population, and subgroup stratified by socio-demographic factors, lifestyle behaviors, chronic diseases, and residential environments. We found long-term household air pollution exposure from solid fuel use was significantly associated with higher depression risk among Chinese older adults (HR 1.27, 95% CI 1.14–1.42 in heating; 1.26, 1.13–1.40 in cooking). Longer duration of household air pollution exposure (1.47, 1.28–1.68 in heating; 1.36, 1.19–1.56 in cooking) and household air pollution from crop residue/wood burning (1.66, 1.41–1.94 in heating; 1.37, 1.23–1.53 in cooking) was correlated with higher depression risk. For subgroups analysis, the effect of household air pollution from solid fuel on depression varied. Compared with those who using clean fuel, older adults living in small size houses or houses with small number rooms had increasing depression risks if they used solid fuel for heating or cooking. Our findings indicate long-term household air pollution exposure from solid fuel use is associated with higher depression risk. Reducing household air pollution by restricting solid fuel use can be effective ways to prevent depression for Chinese older adults and decrease related public health burden.

COVID-19 pandemic has led to concerns on the circulation of SARS-CoV-2 in the environment, its infectivity from the environment and, the relevance of transmission via environmental compartments. During 31 weeks, water samples were collected from a heavily contaminated stream going through an urban, underprivileged community without sewage collection. Our results showed a statistically significant correlation between cases of COVID-19 and SARS in the community, and SARS-CoV-2 concentrations in the water. Based on the model, if the concentrations of SARS-CoV-RNA (N1 and N2 target regions) increase 10 times, there is an expected increase of 104% [95%CI: (62–157%)] and 92% [95%CI: (51–143%)], respectively, in the number of cases of COVID-19 and SARS. We believe that differences in concentration of the virus in the environment reflect the epidemiological status in the community, which may be important information for surveillance and controlling dissemination in areas with vulnerable populations and poor sanitation. None of the samples were found infectious based cultures. Our results may be applicable globally as similar communities exist worldwide.

Nitrate is the most common contaminant in groundwater in Korea, as well as across the world. Reduction of nitrate to ammonia is one of the options available to remediate groundwater. In this study, nitrate in groundwater was removed using a zero-valent iron (ZVI) containing biochar synthesized by co-pyrolyzing iron oxide and sawdust biomass. Among the various biogases generated during the pyrolysis of biomass, CO and H₂ act as reducing agents to transform iron oxides to ZVI. Approximately 71% of nitrate was reduced to ammonium by ZVI-biochar at initial pH 2.0, and the reduction decreased sharply by the increase in pH. The mass of nitrate-N decreased is exactly same with the mass of ammonia-N formed. However, ammonium remained in the aqueous phase after reduction by ZVI-biochar, and the total nitrogen was not lowered. Acid-washed zeolite adsorbed most ammonium reduced by the ZVI-biochar and maintained the pH to acidic condition to facilitate the reduction of nitrate. The results of this study imply that nitrate-contaminated groundwater can be properly treated within the guidelines of water quality by synthesized ZVI-containing biochar.

As the largest tributary flowing into Chaohu Lake, China, the Hangbu–Fengle River (HFR) has an important impact on the aquatic environment security of the lake. However, existing information on the potential risks of heavy metals (HMs) in HFR sediments was insufficient due to the lack of bioavailability data on HMs. Hence, geochemical fractionation, bioavailability, and potential risk of five HMs (Cr, Cu, Zn, Cd, and Pb) in HFR sediments were investigated by the combined use of the diffusive gradient in thin-films (DGT), sequential extraction (BCR), as well as the physiologically based extraction test (PBET). The average contents of Cd and Zn in the HFR Basin were more than the background values in the sediments of Chaohu Lake. A large percentage of BCR-extracted exchangeable fraction was found in Cd (8.69%), Zn (8.12%), and Cu (8.05%), suggesting higher bioavailability. The PBET-extracted fractions of five HMs were all almost closely positively correlated with their BCR-extracted forms. The pH was an important factor affecting the bioavailability of HMs. The average DGT-measured contents of Zn, Cd, Cr, Cu, and Pb were 28.07, 7.7, 3.69, 2.26, 0.5 μg/L, respectively. Only DGT-measured Cd significantly negatively correlated with Eh, indicating that Cd also had a high release risk under reducing conditions, similar to the risk assessment results. Our results could provide a reference for evaluating the potential bioavailabilities and ecological hazards of HMs in similar study areas.

Intestines contain a large number of microorganisms that collectively play a vital role in regulating physiological and biochemical processes, including digestion, water balance, and immune function. In this study, we explored the effects of ammonia stress on intestinal inflammation, the antioxidant system, and the microbiome of the Asian clam (Corbicula fluminea). Exposure to varying ammonia concentrations (10 and 25 mg N/L) and exposure times (7 and 14 days) resulted in damage to C. fluminea intestinal tissue, according to histological analysis. Furthermore, intestinal inflammatory responses and damage to the antioxidant system were revealed through qPCR, ELISA, and biochemical analysis experiments. Inflammatory responses were more severe in the treatment group exposed to a lower concentration of ammonia. High-throughput 16S rDNA sequencing showed that ammonia stress under different conditions altered intestinal bacterial diversity and microbial community composition, particularly impacting the dominant phylum Proteobacteria and genus Aeromonas. These results indicate that ammonia stress can activate intestinal inflammatory reactions, damage the intestinal antioxidant system, and alter intestinal microbial composition, thereby impeding intestinal physiological function and seriously threatening the health of C. fluminea.

Fish cultivation in rice fields is a valuable resource in some rural areas of the world. Fish is a source of protein and an additional source of income for local farmers. However, the use of pesticides may impact fish and consumer health. The aim of this study was to evaluate exposure and effect biomarkers in native fish inhabiting a rice field during a production cycle. Samples of fish, water and sediment from a rice field in Santa Fe, Argentina were collected during a cultivation season (at the beginning: November 2017, in the middle: December 2017 and at the end: February 2018). At each sampling period, fish biomarkers of effect (biometric indices, hematological parameters, energy reserves, oxidative stress and neurotoxicity) were assessed together with pesticide screening in water, sediment, and fish samples. Only herbicides were present in water and sediment samples in agreement with land treatment before rice sowing stage, where only herbicides were applied. In general, the greatest water concentrations of bentazone, glyphosate and aminomethylphosphonic acid (AMPA), and the lowest sediment glyphosate and AMPA levels were observed at the beginning of the farming cycle. Fish bioaccumulated AMPA residues at all sampling periods and showed biological responses to cope with a stressful environment. Alterations in hematological parameters, mobilization of energetic reserves and activation of the antioxidant system were detected. However, no oxidative damage nor neurotoxic effects were present along the production cycle. Under a real exposure scenario, the present work demonstrates that biological changes are induced in fish to cope with stressors present in a rice field. Fish-rice coculture is an efficient and ecologically sustainable approach to increase food supplies, and a better understanding of the effect of this particular environment on fish would allow a greater and safer development of this promising productive activity in South American rice producing countries.

Ants are eusocial insects and have evolved sensitive chemosensory systems for social communication. However, the effect of heavy metal contamination on the olfactory sensitivity of ants remains largely unknown. Here, we investigated the survival and olfactory response of Solenopsis invicta under cadmium (Cd) exposure. As a result, exposure to dietary Cd at different concentrations (100, 300 and 500 mg/L) caused higher Cd accumulation and lower survival of the ants compared with the control (0 mg/L). Cd exposure induced diverse expression patterns of odor binding protein genes (SiOBPs) in S. invicta antenna. Specifically, the expression of SiOBP4, SiOBP11, SiOBP12 and SiOBP16 was increased by 1.84-, 1.14-, 0.83- and 1.76-fold, respectively, at 300 mg/L Cd, while SiOBP7 and SiOBP9 were suppressed as Cd concentration increased. Electroantennography (EAG) and behavioral bioassays were performed to further evaluate the effect of Cd contamination on the olfactory sensitivity of S. invicta workers to 2, 4, 6-trimethylpyridine (TMP) and 2-ethyl-3,6(5)-dimethylpyrazine (EDP), the two frequent functional semiochemicals for S. invicta. The results showed that under no Cd exposure, S. invicta workers exhibited strong EAG response and apparent residing repellence to TMP and EDP, but Cd exposure suppressed EAG response and deprived the behavioral repellence to TMP and EDP of the workers, suggesting that Cd exposure decreases the olfactory sensitivity of S. invicta to these two functional semiochemicals. Further fluorescence competitive binding assay revealed that SiOBP7 had strong binding affinity to TMP and EDP, suggesting that the decrease in olfactory sensitivity may be attributed to the inhibitory effect of Cd exposure on SiOBP7. Overall, our results suggest that Cd exposure may not only directly decrease the survival of ants, but also affect their olfactory recognition.

Neonicotinoid pesticide use is widespread and highly debated, as evidenced by recent attention received from the public, academics and pesticide regulatory agencies. However, relatively little is known about the physiological effects of neonicotinoid insecticides on aquatic vertebrates. Amphibians (larval stages in particular) are excellent vertebrate bioindicators in aquatic systems due to their risk of exposure and sensitivity to environmental stressors. Previous work with wood frog (Rana sylvatica) tadpoles exposed to formulated products containing thiamethoxam or clothianidin in outdoor mesocosms found significant shifts in leukocyte profiles, suggesting the tadpoles were physiologically stressed. The main objective of the present study was to characterize this stress response further using complementary measures of stress after exposure to clothianidin on northern leopard frogs (Rana pipiens) during their aquatic larval stages. Laboratory static-renewal exposures were conducted over eight weeks with the technical product clothianidin at 0, 0.23, 1, 10 and 100 μg/L, and diquat dibromide at 532 μg/L was used as a positive control. We assessed tadpole leukocyte profiles and measures of oxidative stress as these sub-lethal alterations could affect amphibian fitness. We found changes in several types of leukocytes at 1 and 10 μg/L, suggesting that these tadpoles exhibited signs of mild physiological stress. Clothianidin also induced an oxidative stress response at 0.23, 1 and 100 μg/L. However, we found no differences in survival, growth, development time or hepatosomatic index in frogs exposed to clothianidin. Our study indicates that tadpoles chronically exposed to clothianidin have increased stress responses, but in the absence of concentration-response relationships and effects on whole-organism endpoints, the implications on the overall health and fitness of these changes are unclear.

Cyanobacterial blooms have considerable effects on lacustrine microbial communities. The current study explored the temporal pattern of sedimentary archaea and bacteria during cyanobacterial bloom in a eutrophic lake. With the sampling period divided into bloom phase, interval phase and end phase according to the variation of physicochemical parameters, the structures and functions of both kingdoms presented a significant difference among phases. Bloom phases could be characterized with the lowest diversity and up-regulated functions in biodegradation of cyanobacterial metabolites driven by bacteria. Archaeal community showed an increased metabolic function during interval phases, including active methanogenesis sensitive to carbon input. The highest diversity and an enrichment of hub genera in microbial network were both observed in end phase, allowing for closer cooperation among groups involved in cyanobacteria-derived organic matter transformation. Although the archaeal community was less variable or diverse than bacteria, methanogenic functions dramatically fluctuated with cyanobacterial dynamics. And microbial groups related to methane cycling played an important role in microbial network. The results provided new insights into temporal dynamics of lacustrine microbial communities and microbial co-occurrence, and highlighted the significant ecological role of methane cycling-related microbes in lake sediments under the influence of cyanobacterial blooms.