Profiles and risk assessment of legacy and current use pesticides in urban rivers in Beijing, China

Pesticide residues in agricultural end-products and risk assessment for consumers in North China

This study investigated pesticide residues in market-sold vegetables and fruits in Hebei Province, China, over 5 years (2018-2022). A modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) method was applied to gas chromatography with triple-quadrupole mass spectrometer (GC-MS/MS). The analytical methods were validated with respect to matrix effect (ME), recovery rate (78.9~105.5%), limit of quantitation (LOQ, 2.93~9.73 μg/kg), and linear correlation coefficient (0.9982~0.9997). Residues of 10 pesticides in 12 categories of vegetable and fruit were detected. 31.9% of the samples were detected pesticide residues; 15.5% of samples were detected multi-component pesticide residues. Twenty-seven positive detections of pesticide residues exceeded the corresponding maximum residue limit (MRL), accounting for 2.33%. The most types of pesticide residues were detected in cherry, with the number of 7. Procymidone was the most detected pesticide, and it was detected in 8 categories of samples. The hazard index (HI) of omethoate was the highest and the procymidone was the lowest. The HI of all the vegetables and fruits were less than 100%. The effects of pesticide residues are within an acceptable range for human. Adequate attention and further monitoring are still needed.

Micropollutants but high risks: Human multiple stressors increase risks of freshwater ecosystems at the megacity-scale

Micropollutants in water environments have attracted widespread attention, but how human and natural stressors influence the risks of micropollutants has not been comprehensively revealed. A megacity-scale study of the ecological risks of micropollutants in the surface water of Beijing, China is presented to illustrate the magnitudes of the influences of multiple anthropogenic and natural stressors. A total of 133 micropollutants representing typical land use patterns in Beijing, were quantified with the mean concentration range of ND (not detected) to 272 ng·L-1. The micropollutant concentrations in the south were obviously higher than those detected in the northern areas, and neonicotinoid pesticides showed the highest mean concentration of 311 ng·L-1. The chronic and acute risks of micropollutants to algae, invertebrates, and fishes were determined, and herbicides, organophosphorus esters, and insecticides account for the primary risks to algae, invertebrates, and fishes, respectively. The cropland and impervious cover cause the differences in the pollution and risks of micropollutants. The land use in riparian zones greater than 2 km shows a great influence on the chronic chemical risks (CCRs) for the three groups of species, indicating that too local scale does not explain the local pollution status. Climate conditions and human land use are important drivers explaining the CCRs to which various trophic levels of species are exposed. Results demonstrate that multiple categories of micropollutants pose adverse risks to freshwater in the megacity of Beijing, while climate conditions, pollution discharge, and human land use induce the chemical risk of micropollutants to aquatic organisms, and the land use in different riparian zones show different effects on the risks.

Heat/PMS Degradation of Atrazine: Theory and Kinetic Studies

The degradation effect of heat/peroxymonosulfate (PMS) on atrazine (ATZ) is studied. The results show that the heat/PMS degradation for ATZ is 96.28% at the moment that the phosphate buffer (PB) pH, temperature, PMS dosage, ATZ concentration, and reaction time are 7, 50 °C, 400 μmol/L, 2.5 μmol/L, and 60 min. A more alkaline PB is more likely to promote the breakdown of ATZ through heat/PMS, while the PB alone has a more acidic effect on the PMS than the partially alkaline solution. HO• and SO4−• coexisted within the heat/PMS scheme, and ATZ quantity degraded by HO• and SO4−• in PB with pH = 7, pH = 1.7~1. HCO3− makes it difficult for heat/PMS to degrade ATZ according to inorganic anion studies, while Cl− and NO3− accelerate the degradation and the acceleration effect of NO3− is more obvious. The kinetics of ATZ degradation via heat/PMS is quasi-first-order. Ethanol (ETA) with the identical concentration inhibited ATZ degradation slightly more than HCO3−, and both of them reduced the degradation rates of heat/PMS to 7.06% and 11.56%. The addition of Cl− and NO3− increased the maximum rate of ATZ degradation by heat/PMS by 62.94% and 189.31%.