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The OTC degradation rates in the soils were significantly lower than for TC and CTC. TCs (150-1350 mg·kg-1) significantly inhibited urease and rhizosphere catalase activity in soil and reduced the number of soil culturable bacteria and fungi.To explore the effects of water management and silicon application on the bioavailability of soil arsenic (As) and cadmium (Cd), and the accumulation of As and Cd in rice, pot experiments were carried out using As/Cd co-contaminated paddy soil from a field in Kaiyang County, Guizhou Province. The experimental treatments had the following five water application modes with and without silicon additionflooding during the entire growth period (T1); flooding for three weeks (0-105 d) after transplanting with wet irrigation (moisture content 50%-60%) during other growth periods (T2); flooding for three weeks before heading (0-65d), three weeks after heading (84-105d), and wet irrigation during other growth periods (T3); flooding from heading to three weeks after heading (84-105d) and wet irrigation during the other growth periods (T4); and wet irrigation during the entire growth period (T5). The results showed that compared with flooding and wet irrigation, flooding combined with wet irrigation was more conducive tnt and silicon application regimes according to the level of As/Cd pollution can effectively decrease the bioavailability of As/Cd in the soil, thereby reducing the accumulation of As/Cd in rice.Using Fe3O4 and hydroxyapatite as raw materials, superparamagnetic nanometer-sized Fe3O4-phosphate functionalized materials (MFH) were prepared. Soil was subsequently magnetically repaired by adding MFH to cadmium-contaminated paddy field soil. Two kinds of rice with high (Yuzhenxiang) and low (Xiangwanxian-13) cadmium enrichment were selected for conduct pot experiments to study the effect of MFH magnetic separation on soil microorganisms and enzymes, and explore the possibility of application in the remediation of cadmium-polluted farmland. The results showed that MFH application improved the soil remediation effect, with significantly reduced total Cd (38.9%) and available Cd (27.3%) contents. In addition, the Cd content of the two kinds of rice grain was significantly reduced. After MFH magnetic separation, soil microbial community diversity and richness were decreased during the jointing, heading, and maturing stages of the two rice varieties. Treatment of cultivated Yuzhenxiang rice with high concentrations of Cd significantly increased the abundance of dominant Firmicute bacteria in the rice field during the jointing and heading stages. With the use of MFH in the magnetic separation, urease, catalase, and soil peroxidase activity were improved during the jointing, heading, and maturing stages of the two rice soils. The POD enzyme activity in the soil planted with Yuzhenxiang was slightly higher than that planted with Xiangwanxian-13, while urease activity showed the opposite trend.To understand the main factors influencing the translocation and accumulation of cadmium (Cd) in soil-crop systems in typical karst areas, 68 sets of paddy soil and rice grain samples were collected in Guangxi Province. These were used to analyze Cd concentrations and soil properties (pH, organic matter (OM) content, oxide content, and texture). Spearman's correlation coefficients and principal component analysis (PCA) were used to examine the effects of soil properties on Cd concentrations and identify the main influencing factors. The studied soils were highly enriched in iron oxide (TFe2O3), aluminum oxide (Al2O3), and manganese oxide (MnO) compared to background levels, with average concentrations of 20.2%, 19.0%, and 0.2%, respectively. However, the soils are relatively depleted in silica (SiO2), with an average concentration of 41.0%. The soils are strongly weathered and leached in study area, giving rise to rich occurrences of Fe-Mn nodules. The concentrations of TFe2O3 and MnO in the study soils were significantly correlated with soil Cd, rice seed Cd, and the Cd bioconcentration factor (BCF). The PCA analysis further showed that TFe2O3 and MnO in soils were the main factors affecting the migration and enrichment of Cd while soil pH, OM, and Al2O3 had less of an influence. Furthermore, SiO2 and soil texture indirectly affected the migration and enrichment of Cd. It is suggested that the Fe-Mn nodules effectively adsorb and immobilize Cd in the study area soils, acting as a heavy metal scavenger that reduced the biological accessibility of Cd.The Bayan Obo deposit is the largest light rare earth ore deposit in the world, which releases rare earth elements (REEs) to the surrounding environment through long-term mining processes. read more To inform restoration plans, it is necessary to investigate the concentration, spatial distribution, pollution level, and ecological risk of REEs. Sample analyses showed that the average total concentration of REEs in this area is 6064.95 mg·kg-1, which was higher than the background levels of control soils (207.44 mg·kg-1), Inner Mongolia (150.95 mg·kg-1), and China (184.72 mg·kg-1). Light REEs (LREEs) accounted for 83%-99% of the detected REE, and Ce was the dominant element. Areas with high REE concentrations were mainly located near the source bed, and the distribution was extremely inhomogeneous, being greatly affected by external interference. Chondrite normalized REE patterns of different functional areas were similar and normalized curves inclined to the right, indicating district fractionation between the LREE and 6376.46, with REEs in soils posing high strong risk, very strong risk, strong risk, moderate risk, and low risk in 33%, 16%, 12%, 30%, and 9% of the sampling sites, respectively. Based on these findings, measures for controlling current pollution and potential ecological risks from REE in the soils of the Bayan Obo mining region are urgently needed.Ephedrine (EPH) is an alkaloid commonly used to relieve nasal congestion caused by colds, allergic rhinitis, rhinitis, and sinusitis, and to control bronchial asthma. It is also be used as a raw material in the manufacture of methamphetamine. Although the distribution of EPH in surface waters has been widely studied, its uptake, internal distribution, and toxicokinetic processing in exposed organisms have not been well investigated. In this study, we investigated the uptake, disposition, and toxicokinetics of EPH in zebrafish (Danio rerio) in a semi-static exposure system. EPH was consistently detected in zebrafish biological samples, with the highest concentrations of 84.97 ng·g-1 detected in the brain tissue of fish in the high treatment group. Over the 14-d exposure period, the relative abundance of mean concentrations of EPH in biological samples generally followed the order of brain > ovary > liver > intestine > muscle. The uptake rate constants (Ku), elimination rate constants (Ke), and half-lives of EPH in the biological tissues were in the ranges 0.23-570.31 L·(kg·d)-1, 1.22-6.11 d-1, and 0.12-0.57 d, respectively. The observed bioconcentration factor (BCFo) and kinetically-derived bioconcentration factor (BCFk) were similar, ranging 0.24-337.33 L·kg-1 and 0.13-316.43 L·kg-1, respectively. These results are helpful for understanding the behavior of psychoactive substances in aquatic organisms and have directive significance for studying their toxicity and ecological risks to aquatic organisms.Wastewater treatment plants (WWTPs) have different treatment effects during different seasons due to changes in water quality and temperature. To understand bacterial community structure and diversity dynamics in the WWTPs, this study employed high-throughput sequencing technology during winter and summer. A total of 60 activated sludge samples were collected in five WWTPs in Beijing with different treatment processes in summer (temperature=28℃±2℃, water temperature=24.9℃±1.1℃) and winter (temperature=0℃±3℃, water temperature=16.8℃±1.3℃). The relative abundances of dominant bacterial genera in activated sludge varied significantly between the WWTPs but microbial community structure was typically similar between different treatment units (i.e., the anaerobic tank, anoxic tank, and aerobic tank) at each WWTP. At the same time, different bacteria dominated in winter and summer, when the relative abundance of SJA-15, Ferruginibacter, and Blasocatellaceae was 6.07%, 4.50%, and 4.44% respectively, when the relative abundance of Nitrospira, Methylotenera, and RBG-13-54-9 in winter was 10.17%, 3.96%, and 3.28%, respectively. Correlation analysis showed that temperature, total nitrogen (TN), NH4+-N, total phosphorus (TP), and chemical oxygen demand (COD) were the main environmental factors affecting microbial community structure, of which temperature had the greatest effect on species composition followed by TN. Furthermore, a predictive analysis of functional enzymes indicated that the abundance of key enzymes involved in the nitrogen cycle in the activated sludge of WWTPs is higher in winter than that in summer. These results show that temperature, water quality, and treatment process affect bacterial community structure (i.e., dominance and abundance) in WWTP activated sludge.Sulfate reduction with ammonium oxidation (SRAO) in laboratory ANAMMOX reactors was considered as an autotrophic process mediated by ANAMMOX bacteria (AnAOB), in which ammonium, as an electron donor, was oxidized by the electron acceptor sulfate. This process was developed based on the transformations of nitrogenous and sulfurous compounds observed in natural environments. Reported results vary widely for conversion mole ratios (ammonium/sulfate) as do intermediate and final products of the sulfate reduction. Thus, hypotheses surrounding biological conversion pathways of ammonium and sulfate in ANAMMOX consortia are implausible. In this study, continuous reactor experiments and batch tests were conducted under micro-aerobic (-100 mV less then ORP less then 0 mV, 0.5 mg·L-1 less then DO less then 1 mg·L-1), anoxic (-300 mV less then ORP less then -100 mV, 0.2 mg·L-1 less then DO less then 0.5 mg·L-1) and anaerobic (ORP less then -300 mV, DO less then 0.2 mg·L-1) conditions with different inoculated sludge (ANAMMOX sludge and mixed sludge) to verify the SRAO phenomena and identify possible pathways of substrate conversion. The key findings were that SRAO occurred only where SRB existed under anoxic condition, and was absent under anaerobic conditions with ANAMMOX consortia. The analysis of the microbial community and functional gene expression showed that ammonium oxidation by AAOB coupled with sequential ANAMMOX is possibly responsible for the loss of ammonium under anoxic condition. Organic substances released through microbial decay contributed to heterotrophic sulfate conversion by SRB. AnAOB do not possess the ability to oxidize ammonium with sulfate as the electron acceptor. SRAO could, in fact, involve a combination of aerobic ammonium oxidation, ANAMMOX, and heterotrophic sulfate reduction processes, which are mediated via AOB, AnAOB, and SRB.Properties of landfill leachate are complex. Therefore, leachate should be treated by combined processes with both biological and advanced methods. Due to the shortage of engineering-scale assessment data about the pollutant treatment contribution of individual process units, existing optimization methods still lack theoretical support. Here, a membrane biological reactor (MBR)+nanofiltration (NF) system with a capacity of 800 m3·d-1 was examined. Conventional physiochemical parameters and fluorescent parameters were examined to analyze the contribution of each process unit to treating mature landfill leachate. Furthermore, the transformation of dissolved organic matter (DOM) was evaluated using excitation emission matrix fluorescence spectroscopy-parallel factor (EEMs-PARAFAC). Results showed that the biological treatment removed soluble nitrogen (dissolved nitrogen, DN) by 74.7%, 54.6% occurred in the first-stage denitrification unit. The external ultrafiltration unit reduced dissolved chemical oxygen demand (COD) and dissolved organic carbon (DOC) by 92.