[en] Highlights: • Land application of manure as a fertilizer can significantly contribute to the increase of ARGs and ARB. • The number of resistant bacteria to SM2 is stronger than to DOX, however, the diversity to SM2 is less than to DOX. • Bacillus and Chryseobacterium, more likely to be multi-drug-resistant bacteria, were detected in both two antibiotics. • IntI1 and intI2 genes, especially intI1 gene, may play an important role in the spreading of ARGs. -- Abstract: The increasing prevalence of antibiotic resistance genes (ARGs) and antibiotic resistant bacteria (ARB) in the soil environment represents a serious threat to public health. In this study, the diversity and abundance of ARGs and mobile genetic elements (MGEs) in different years of manure-amended vegetable soils were investigated. A total of eight genes, including four tetracycline resistance genes: tetW, tetM, tetO and tetT; two sulfonamide resistance genes: sul1 and sul2; and two MGEs: intI1 and intI2; were quantified in ten vegetable soils. The relative abundance of ARGs in soils amended with manure was significantly higher than that in soils without manure application. The relative abundance of the intI1 and intI2 genes had significantly positive correlations with the relative abundance of the tetW, tetO, sul1 and sul2 genes. Under different concentrations of antibiotics, the resistant bacteria rates of manure-amended soil were much higher than the control soil. Bacillus and Chryseobacterium, more likely to be multi-drug-resistant bacteria, were detected in both two antibiotics. Moreover, the significant correlation was found between the concentrations of Cu and Zn and the ARGs. Our findings provide empirical evidence that the dissemination risk of ARGs and ARB in long-term manure-amended vegetable soils, which might promote to the development of effective strategies to reduce the spread of ARGs in agro-ecosystems.

[en] Highlights: • Soil microbes as indicator to indicate pollution of antibiotics and heavy metals. • Used amoA gene to research the relative quantities of AOA and AOB in soil. • Single and combined pollution of ENR and Cd have inhibited the microbial activity. • There was obvious dose-effect relationship of pollutants on microbes. • Toxicity of combined ENR and Cd was greater than ENR acting alone. The negative effects of residues from antibiotics and heavy metals in agricultural soils are becoming an increasingly frequent concern. To evaluate the toxicity and interaction of antibiotics and heavy metals, enrofloxacin (ENR) and cadmium (Cd) were used as targets to study the individual effects of ENR (0.025, 0.1, 0.4 mmol/kg) and Cd (0.4 mmol/kg) and their combined effects (mole ratios of ENR to Cd of 1: 1, 1: 4 and 1: 16) on soil microbial biomass and function on days 7, 14, 21 and 28 of the study. The results demonstrated that microbial populations, which were counted during 4 sampling periods, were mainly in the order of bacteria > actinomycetes > fungi. The ammonia monooxygenase (amoA) gene copies of ammonia-oxidizing archaea (AOA) were more abundant than ammonia-oxidizing bacteria (AOB) on days 14 and 21. Soil bacteria, fungi, and actinomycetes numbers and amoA gene abundances of AOB and AOA in soils were inhibited to varying degrees by the single and combined effects of ENR and Cd; the higher the concentration of the treatments, the stronger the inhibition. The combined toxicity of ENR and Cd on soil microbes and AOA- and AOB-amoA genes was stronger than when either chemical was used alone; the interaction effects of ENR and Cd were mainly antagonistic. Moreover, the ratios of bacteria/fungi declined significantly on days 14, 21 and 28; the proportions of AOA- and AOB-amoA were altered with the addition of ENR and Cd. Thus, ENR and Cd had significant negative effects on the soil microbial community, especially when both contaminants were present.

[en] Highlights: • Chicken and swine manures have higher abundance of ARB and ARGs than cow manures. • The abundance of ARB and ARGs in fresh manures was significantly higher than that in composted manures. • Detected antibiotics and MGEs were significantly correlated with some of the target ARGs. • Acinetobacter lwoffii and Psychrobacter pulmonis are multiple resistant bacteria. -- Abstract: Livestock manure is a major reservoir of antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs). This study investigated the distribution characteristics of ARB, ARGs in fresh and composted manures of traditional breading industry in rural areas in China. Samples collected were naturally piled without professional composting, and will be applied to farmland. The real-time quantitative polymerase chain reaction (qPCR) results showed the presence of ten target ARGs and two mobile genetic elements (MGEs) in the tested manure samples. The relative abundance of tetracycline and sulfonamide resistance genes (TRGs and SRGs) was generally higher than that of macrolide resistance genes (MRGs), followed by quinolone resistance genes (QRGs). There were significant positive correlations between the abundance of sul1, sul2, tetW and MGEs (intl1, intl2). In addition, the distribution of target ARGs was associated with the residual concentrations of doxycycline (DOX), sulfamethazine (SM2), enrofloxacin (ENR) and tylosin (TYL). Overall, a total of 24 bacterial genera were identified. The resistance rates of ARB were 17.79%–83.70% for SM2, followed 0.40%–63.77% for TYL, 0.36%–43.90% for DOX and 0.00%–13.36% for ENR, which showed a significant dose-effect. This study also demonstrated that the abundance of clinically relevant ARB and ARGs in chicken, swine and cow fresh manures significantly greater than that in composted manures, and chicken and swine manures had higher proportion of ARB and higher abundance of ARGs than that in cow manures.

[en] Highlights: • Acute and chronic toxic effects of fluoxastrobin on zebrafish were investigated. • Fluoxastrobin can cause oxidative stress and oxidative damage in zebrafish. • The comet assay was the most sensitive of all biomarkers used in the present study. Fluoxastrobin is a new strobilurin fungicide, similar to azoxystrobin and pyraclostrobin. Before the wide application of fluoxastrobin, the present study was performed to assay the acute and chronic toxicity of fluoxastrobin on zebrafish (Danio rerio). The 96-hour median lethal concentration (96 h LC₅₀) after initiation of zebrafish exposure to fluoxastrobin was 0.51 mg/L with a 95% confidence interval of 0.45 to 0.57 mg/L, indicating that fluoxastrobin was highly toxic to zebrafish. As endpoints, we assayed the levels of reactive oxygen species (ROS), malondialdehyde (MDA), the activities of superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST), and the degree of DNA damage at three different doses, 0.001, 0.01, and 0.1 mg/L on days 7, 14, 21, and 28. The antioxidant enzymes partially ameliorated the ROS induced by fluoxastrobin t and were in turn inhibited by excess ROS, especially at 0.1 mg/L. Lipid peroxidation and DNA damage were stimulated by ROS. The fluoxastrobin contents of the tested solutions were also determined; at the fluoxastrobin doses of 0.001, 0.01, and 0.1 mg/L, the contents on day 28 were 3.9, 5.0, and 0.64% greater than those on day 0. Thus, fluoxastrobin was relatively stable in an aquatic environment. In addition, the present study provided more information regarding the toxic effects of fluoxastrobin and the scientific methods for selection and evaluation of fungicides in the future.

[en] Highlights: • The soil enzyme activities were used to study the toxicity of fluoxastrobin. • Biolog-ECO plate test was used to study soil microbial diversity. • Enzyme activities at each fluoxastrobin dose were lower than those of the control. • Fluoxastrobin inhibited soil microbial diversity. -- Abstract: Whether now or in the foreseeable future, agricultural production cannot do without chemical pesticides. Strobilurin fungicides, including mitochondrial inhibitors, can easily enter the soil environment and causing pollution. Fluoxastrobin is one of the top-selling strobilurin fungicides. Limited information can be found in the literature on the environmental toxicity of fluoxastrobin in soil. It is essential to understand the effects of fluoxastrobin on microorganisms in fluvo-aquic soil. The present study used a Biolog-EcoPlate method to analyze the effects of fluoxastrobin on soil microbial diversity in groups exposed to 0.1, 1.0, and 2.5 mg/kg fluoxastrobin and in control groups at exposure and on days 7, 14, 21, 28, and 48. The effects of fluoxastrobin on enzyme activities (β-glucosidase, dehydrogenase, and urease) in the soil were also evaluated. The results indicated that the three tested enzyme activities were lower at each dose to a varying degree than those of the controls. The soil microbial diversity was shown to be affected according to the results of average well color development (AWCD) experiments. The present study aimed to assess environmental risks to terrestrial ecosystems under the stress of pesticide use. These results also enrich the basic data on fungicide toxicity to the soil environment and have a guiding significance for the rational use of pesticides and the sustainable utilization of resources.

[en] Highlights: • The subchronic toxicity of fluoxastrobin to earthworms was investigated. • Fluoxastrobin can cause oxidative stress and oxidative damage in earthworms. • The comet assay was the most sensitive of the biomarkers used in the present study. Potential toxicity to soil organisms by fluoxastrobin, a new strobilurin-type fungicide has drawn increasing attention. Thus, the present study investigated the subchronic toxicity induced by exposure to several concentrations (0, 0.1, 1.0, and 2.5 mg kg⁻¹) of fluoxastrobin to earthworms on days 7, 14, 21, and 28. Biochemical indicators (e.g., reactive oxygen species (ROS) content, activities of antioxidase and detoxifying enzymes (superoxide dismutase, catalase, and glutathione S-transferase), lipid peroxidation (malonaldehyde) and degree of DNA damage) were measured. No earthworm deaths were observed during the entire experimental period. For ROS and malonaldehyde, the bioassay values of the three doses reached a maximum on day 21 and then decreased. For superoxide dismutase and glutathione S-transferase, the values increased with the exposure doses of 0.1 and 1.0 mg kg⁻¹ and then decreased. In contrast, the values for catalase were lower on days 7, 14, and 28 and greater on day 21 compared to those of the controls. In addition, the comet assay was more sensitive than other biomarkers, and the degree of DNA damage was dose and time -dependent.

[en] Antibiotics and heavy metals have long-term potential toxicity to the environment, and their residuals in agricultural soils are receiving more and more attention. To evaluate the ecotoxicological effects of enrofloxacin and cadmium on soil enzymatic activities and microbial community structure, soil samples were exposed to individual and combined contaminants over 28 days. The results indicated that the toxic effects of enrofloxacin alone on soil enzymatic activities were relatively small and showed no concentration dependence. In contrast, significant inhibition of soil enzymatic activities was observed upon cadmium contamination by itself. Overall, the combination of two contaminants also has toxic effect on enzymatic activities; an antagonism between enrofloxacin and cadmium was observed. On 14 and 21 days, individual enrofloxacin and cadmium reduced average well color development (AWCD), Shannon, McIntosh, Simpson indices, and substrate utilization, except for Shannon, McIntosh, Simpson indices of the cadmium 0.4 mmol/kg treatment were higher than the control on 21 days. In general, combined treatments led to higher value of these microbial diversity indicators than those found under separate contamination, although there were some exceptions. With the increase in enrofloxacin concentration, the utilization of any carbon source by the microorganisms gradually decreased. In addition, the AWCD value and substrate utilization decreased as time increased. In the separate and combined contaminant treatments, the order of substrate utilization by soil microorganisms was aliphatics > amino acids > saccharides > metabolites. Thus, enrofloxacin and cadmium had a variable but generally negative influence on soil enzymatic activities and microbial community structure. Graphical abstract:

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[en] Highlights: • Combined pollution caused oxidative stress and damage to the growth, tissue, and DNA in earthworms. • Analysis of the main and interaction effects of a combined pollution process were performed using a uniform design method. • ROS, MDA, weight inhibition rate, and OTM of earthworms were all affected by the interaction between imidacloprid and Cd. • Excessive ROS and MDA likely caused damage to the epidermis, midgut, and DNA of earthworms. Heavy metals pollution of soil and widespread application of neonicotinoid insecticides have caused environmental problems worldwide. To evaluate ecological toxicity resulting from the combined pollution of neonicotinoids and heavy metals, typical representatives of neonicotinoid insecticides (imidacloprid, thiamethoxam, dinotefuran) and heavy metals (cadmium, copper, zinc) were selected as soil pollutants; earthworms were used as test organisms. Analysis of the main and interaction effects of a combined pollution process were performed using a uniform design method. Results showed that the reactive oxygen species (ROS) content of earthworms in most treatment groups was higher during exposure than that of the control group. The malondialdehyde (MDA) and ROS content of earthworms demonstrated relatively low values on the 21st day and increased by the 28th day. The interaction between dinotefuran and Cd had significant antagonistic effects on ROS and MDA. The combined pollution adversely affected both the growth and genes of earthworms and also caused damage to the epidermis, midgut, and DNA. The interaction between imidacloprid and Cd was synergistic to ROS, weight inhibition rate, and Olive tail moment (OTM), but was antagonistic to MDA. Of all the single and combined exposures, Zn as a single chemical affected ROS and DNA damage the most, and MDA was significantly enhanced by imidacloprid. Composite pollutants may create different primary effects and interactions causing potential harm to soil organisms.

[en] Bisphenol A (BPA) is an environmental pollutant to disrupt endocrine system or cause cancer, thus the detection of BPA is very important. Herein, an amperometric sensor was fabricated based on immobilized CoTe quantum dots (CoTe QDs) and PAMAM dendrimer (PAMAM) onto glassy carbon electrode (GCE) surface. The cyclic voltammogram of BPA on the sensor exhibited a well-defined anodic peak at 0.490 V in 0.1 M pH 8.0 PBS. The determination conditions were optimized and the kinetic parameters were calculated. The linear range was 1.3 x 10^-8 to 9.89 x 10^-6 M with the correlation coefficient of 0.9999. The limit of detection was estimated to be 1 x 10^-9 M. The current reached the steady-state current within about 5 s. Furthermore, the fabricated sensor was successfully applied to determine BPA in real water samples.

[en] Highlights: • Two herbicides changed the number of bacteria related to the nitrogen cycle. • Cloransulam-methyl and diclosulam may inhibit the nitrification reaction. • Both of the two herbicides may promote the denitrification reaction at 0.05 mg kg⁻¹. • Diclosulam may enhance the ability to fix carbon for microbe at 0.5 mg kg⁻¹. • The toxicity of diclosulam to the soil was greater than that of cloransulam-methyl. Cloransulam-methyl and diclosulam are applied to soybean fields to control broad-leaved weeds. These herbicides have become a focus of attention because of their low application dose and high-efficiency advantages. However, the effects of these two herbicides on soil microorganisms are unknown. The present study investigated the effects of 0.05, 0.5, and 2.5 mg kg⁻¹ of cloransulam-methyl or diclosulam on soil microbes after 7, 14, 28, 42, and 56 days of exposure. The results showed that the two herbicides increased the abundances of functional bacteria related to pesticide degradation. Based on the genetic expression results, we speculated that 0.05 mg kg⁻¹ of these two herbicides inhibited the nitrification reaction but promoted the denitrification reaction. Diclosulam at a concentration of 0.5 mg kg⁻¹ may enhance the ability of microbes to fix carbon. β-glucosidase activity was activated by the two herbicides at a concentration of 2.5 mg kg⁻¹. Diclosulam had a positive effect on urease, but cloransulam-methyl activated urease activity only at concentrations of 0.05 and 0.5 mg kg⁻¹. The results of the integrated biomarker response showed that the toxicity of diclosulam was greater than that of cloransulam-methyl. Our research provides data for evaluating the environmental risks of cloransulam-methyl and diclosulam.