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Sulfachloropyridazine (SCP) is a common sulfonamide antibiotic pollutant found in animal excreta. Finding highly efficient degrading bacterial strains is an important measure to reduce SCP antibiotic pollution. Although some strains with degradation capabilities have been screened, the degradation pathways and biotransformation mechanisms of SCP during bacterial growth are still unclear. In this study, a strain capable of efficiently degrading SCP, named Bacillus sp. DLY-11, was isolated from pig manure aerobic compost. Under optimized conditions (5 % Vaccination dose, 51.5 ℃ reaction temperature, pH=7.92 and 0.5 g/L MgSO 4 ), this strain was able to degrade 97.7 % of 20 mg/L SCP within 48 h. Through the analysis of nine possible degradation products (including a new product of 1,4-benzoquinone with increased toxicity), three potential biodegradation pathways were proposed. The biodegradation reactions include S-N bond cleavage, dechlorination, hydroxylation, deamination, methylation, sulfur dioxide release, and oxidation reactions. This discovery not only provides a new efficient SCP-degrading bacterial strain but also expands our understanding of the mechanisms of bacterial degradation of SCP, filling a knowledge gap. It offers important reference for the bioremediation of antibiotic pollutants in livestock and poultry farming., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

Groundwater from different aquifers in the Zhanjiang area suffers from different degrees of nitrogen pollution, which poses a serious threat to the health of urban and rural residents as well as the surrounding aquatic ecological environment. However, neither the water chemistry and microbial community characteristics in different aquifer media nor the sources of inorganic nitrogen pollution have been extensively studied. This study integrated water quality parameters, dual isotopes (δ 15 N-NO 3 - and δ 18 O-NO 3 - ), and 16S rRNA data to clarify the hydrochemical and microbial characteristics of loose rock pore water (LRPW), layered bedrock fissure water (LBFW), and volcanic rock pore fissure water (VRPFW) in the Zhanjiang area and to determine inorganic nitrogen pollution and sources. The results show that the hydrochemistry of groundwater in different aquifers is complex and diverse, which is mainly affected by rock weathering and atmospheric precipitation, and the cation exchange is strong. High NO 3 - concentration reduces the richness of the microbial community (VRPFW). There are a large number of bacteria related to nitrogen (N) cycle in groundwater and nitrification dominated the N transformation. A quarter of the samples exceeded the relevant inorganic nitrogen index limits specified in the drinking water standard for China. The NO 3 - content is highest in VRPFW and the NH 4 + content is highest in shallow loose rock pore water (SLRPW). In general, NO 3 - /Cl - , dual isotope (δ 15 N-NO 3 - and δ 18 O-NO 3 - ) data and MixSIAR quantitative results indicate manure and sewage (M&S) and soil organic nitrogen (SON) are the main sources of NO 3 - . In LRPW, as the depth increases, the contribution rate of M&S gradually decreases, and the contribution rate of SON gradually increases. The results of uncertainty analysis show that the UI 90 values of SON and M&S are higher. This study provides a scientific basis for local relevant departments to address inorganic nitrogen pollution in groundwater., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Sulfonamides (SAs) are ubiquitous antibiotics that are increasingly detected in aquatic environments and can react with free available chlorine to produce transformation products (TPs) during disinfection. However, the TPs generated during chlorination remains poorly understood. Here, a non-target screening method based on the PyHRMS program was used to assess the transformation pathways of five SAs, particularly the transient NCl intermediates, during a simulated chlorination process. We observed 210 TPs during SA chlorination using a non-target screening method based on high-resolution mass spectrometry, and the reaction mechanisms mainly included chlorine substitution, desulfonation, and hydroxylation. Among the TPs, 87 were tentatively proposed to be NCl intermediates as they instantly disappeared after quenching with Na 2 S 2 O 3 . The MS 2 spectra of 13 of these potential NCl intermediates were obtained, and all displayed an [M-Cl] + fragment. A diagnostic fragment ion (DFI) strategy was applied to explore the structural relationship between parent compounds and TPs. Based on the result, five SAs and 101 TPs (if their MS 2 spectra were available) could be connected through the same fragments, and this method was also proved effective in a real wastewater treatment plant effluent sample. We believe this novel method can help explore the TPs of organic compounds during chlorination in drinking water plants., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

To improve the prediction accuracy of soil heavy metals (HMs) by spatial interpolation, a novel interpolation method based on genetic algorithm and neural network model (GANN model), which integrates soil properties and environmental factors, was proposed to predict the soil HM content. Eleven soil HMs (Cu, Pb, Zn, Cd, Ni, Cr, Hg, As, Co, V and Mn) were predicted using the GANN model. The results showed that the model had a good prediction performance with correlation coefficients (R 2 ) varying from 0.7901 to 0.9776. Compared with other traditional interpolation methods, including inverse distance weighting (IDW), ordinary kriging (OK), universal kriging (UK), and spline with barriers interpolation (SBI) methods, the GANN model had a relatively lower root mean square error value, ranging from 0.0497 to 77.43, suggesting that the GANN model might be a more accurate spatial interpolation method and the soil properties together with the environmental geographical factors played key roles in prediction of soil HMs., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Biogas slurry has the problems of having a low concentration, having a large production volume, and containing many small-molecule organic pollutants. During the fertigation process of biogas slurry, many small-molecule organic pollutants may pose potential pollution risks to groundwater. In this study, the ultrafiltration membrane technology was used to separate small-molecule organics in the biogas slurry to prepare ultrafiltration concentrated biogas slurry (UCBS). To research the impact of UCBS and raw biogas slurry (RBS) on the small-molecule organic pollution of groundwater, a laboratory soil column simulation leaching device was used to conduct leaching experiments with 4 types of UCBS and RBS in acric ferralsols and hydragric anthrosols for two quarters (8 fertilization periods). The results of the study show that both UCBS and RBS caused nitrate pollution to groundwater. UCBS has a lower risk of organic pollution to groundwater than RBS. Irrigating UCBS in hydragric anthrosols has a higher risk of organic pollution of groundwater than that in acric ferralsols. Analysis of the molecular weight distribution of dissolved organic matter (DOM) in the leaching solution showed that the organic pollutants were mainly small molecules <10 kDa. According to 3D excitation-emission matrix (3D-EEM) analysis, the main organic pollutants in the leaching solution were fulvic acid, microbial protein metabolites and humic acid organic compounds. The research results show that the pretreatment of biogas slurry by ultrafiltration can reduce the risk of small-molecule organic pollution of groundwater in land application, which can provide a new scientific basis to standardize biogas slurry land application technical guidelines and reduce groundwater pollution., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)