Accurate identification of nitrate (NO3-) sources is critical to address the issue of groundwater pollution. The nitrogen (N) isotopic enrichment factor (ɛp/s) is an important parameter to explain the N cycle and determine the proportional contribution of NO3- sources. Considering the isotopic fractionation effects in N transformation processes, this study quantitatively analyzed the NO3- sources in groundwater using stable isotopes (δ15N-NO3- and δ18O-NO3-) and the Bayesian isotope mixing model (SIAR). For the first time, the ɛp/s values (0.0‰, -8.7‰, -8.7‰, and 14.7‰) of atmospheric deposition (AD), soil nitrogen (SN), chemical fertilizers (CF), and manure and sewage (M&S) were calculated to determine the NO3- source apportionment in groundwater. It was proved that the isotopic fractionation effect could produce a more accurate NO3- source apportionment. We also found that the NO3- source contributions were closely related to the cropping system. In the vegetable cultivation area, CF (54.32%) and SN (37.75%) were the dominant NO3- source, while in the grain cultivation area, NO3- pollution was largely influenced by SN (33.67%), CF (33.27%), and M&S (30.16%). According to this study, the isotope fractionation is strongly recommended for NO3- source apportionment in groundwater system. Small-scale mining activities in many developing countries have caused severe environmental issues to the surrounding areas, which ultimately threatened the health of local populations. Based on detailed characterization of the local drinking water and surface soil, as well as foodstuffs, this study comprehensively assessed the public health risk of toxic metal(loid)s to the population living in three villages surrounding an abandoned small-scale polymetallic mine in southern China. The agricultural soils contained elevated levels of Cu, Zn, As, Cd, and Pb, which originated from the mining district, and as expected, the locally cultivated rice and vegetables were contaminated by As, Cd, and Pb to varying extents. Arsenic occurred in both inorganic and organic forms in the rice and vegetables, with inorganic As (i-As) accounting for 82.2% (45.4-100%) and 94.7% (65.2-100%) of the total As contents in rice and vegetables, respectively. Results of health risk assessment indicate that the residents in the impacted villages had serious non-carcinogenic and carcinogenic risk. Dietary exposure to i-As and Cd through rice and vegetable consumption was the primary cause of non-carcinogenic risk, while i-As intake was the dominant contributor of carcinogenic risk. These findings suggest that significant environmental pollution by toxic metal(loid)s could result from small-scale metal mines, even after being abandoned, and the accumulation of the toxic metal(loid)s in food crops could pose significant health risk to the local residents. Immediate actions should be taken to discourage them from consuming the locally produced food crops, while long-term control measures for containment of toxic metal(loid) pollution are being developed, and high priority should be given to the remediation of Cd and As in the contaminated soils. Sediment adsorption is one of the main fates of antibiotics in aquatic environments. However, few studies have compared the physicochemical properties of sediments from the same aquatic ecosystem but at different locations and correlated them with antibiotic adsorption efficiency. To predict the adsorption of antibiotics in water-sediment systems more accurately, this study conducted experiments with tetracycline (TC) and oxytetracycline (OTC) in tetracyclines, ciprofloxacin (CIP) in fluoroquinolones, and roxithromycin (ROX) in macrolides. Sediments from different locations in Lake Taihu, China, were collected to determine the adsorption properties of CIP, TC, OTC, and ROX. Moreover, the physicochemical properties of the sediments were measured and the correlation between these properties and antibiotic adsorption were discussed to establish a model for predicting adsorption parameter Kd. The antibiotic adsorption performance of sediments was high in heavily polluted and grassy areas but poor in estuarine areas of the lake, suggesting that adsorption effectiveness was affected by the physicochemical properties of sediments. see more Based on the established model, the specific surface area, organic carbon, and cation exchange capacity played the most significant roles. The study further determined that the predicted and actual values showed a good linear fitting relationship. Therefore, the model effectively predicted the antibiotic adsorption performance of different sediments and provided recommendations for the environmental trend and risk assessment of antibiotics. Conventionally, paddy fields are regarded as important non-point sources of nutrient pollution, while ecological ditches and ponds are developed to reduce or retain nutrient export from agricultural fields. To quantify the potential nutrient removal function of ditches and ponds that naturally existed in rice growing regions, a representative paddy irrigation and drainage unit (IDU) composed of fields, ditches and a pond in the one-season rice region of the middle Changjiang River basin, China was monitored for two years. With data and knowledge gained, a Water Quantity and Quality Model for Paddy IDUs (WQQM-PIDU) is developed and applied for 30 years simulation to produce a general view. The monitored and modelled results showed that nutrient concentration peaks after fertilization was delayed and lowered in ditches and ponds, compared to those in paddy fields. Concentrations of runoff from the IDU outlet were generally lower than from the field during the whole rice growing season except the transplanting period. If fully utilized as temporary reservoirs, ditches and ponds naturally existed in a typical paddy IDU would reduce 39% nitrogen loads from field edges with a range of 17%-93% and 28% phosphorus loads with a range of 12%-92%. Although typical paddy IDUs discharge fewer nutrient loads than the content input into them, the discharge concentrations may be risky to surface waters. For their nutrient removal function, natural ditches and ponds are recommended to be included into irrigation and drainage management with accurate water level management during drainage, which is a promising and cost-effective approach to enhance surface water quality in rice growing regions.