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

Pesticide Pollution Reduces the Functional Diversity of Macroinvertebrates in Urban Aquatic Ecosystems

Urbanization accelerates innovation and economic growth but imposes significant ecological challenges, particularly to aquatic biodiversity and ecosystem functionality. Among urban stressors, pesticide-driven chemical pollution represents a critical, yet under-recognized, global threat. Quantifying the causes and consequences of pesticides on biodiversity loss and ecosystem degradation is vital for ecological risk assessment and management, offering insights to promote sustainable societal development. This study evaluated anthropogenic stressors and macroinvertebrate communities at 42 sites across two major drainages in Beijing using chemical analysis and environmental DNA (eDNA), focusing on macroinvertebrate responses to pesticide exposure in the context of multiple anthropogenic stressors. Pesticides significantly impacted the α- and β-functional diversity of macroinvertebrates, accounting for 18.46 and 14.6% of the total observed variation, respectively, underscoring the role of functional groups in pesticide risk assessment. Land use and flow quantity directly influenced pesticide levels, which in turn affected macroinvertebrate functional diversity, while basic water quality had a less pronounced effect. These results provide empirical evidence of pesticide pollution's impact on macroinvertebrate functional diversity at the watershed scale under field conditions in a highly urbanized area. The findings highlight the importance of considering multiple stressors and sensitive taxa in pesticide risk assessment and management for urban aquatic ecosystems.

Occurrence and risk assessment of current-use pesticides in a tropical drinking water source reservoir in Hainan Province, China

The agricultural sector plays a pivotal role in Hainan Province, China; therefore, the utilization of pesticides is indispensable. The current ban on traditional pesticides and ongoing replacement of current-use pesticides (CUPs) have not been accompanied by extensive research on the presence of CUPs in reservoirs, which are vital centralized sources of drinking water. In this study, 26 CUPs was investigated in a drinking water source reservoir, the surrounding watershed, and the surrounding agricultural and domestic discharge water in Hainan Province. The predominant detected CUPs in the study area were clothianidin (CLO), thiamethoxam (THM), acetamiprid (ACE), imidacloprid (IMI), and dichlorvos (DCH). Neonicotinoids (NNIs) were the primary type of pesticide contamination in the study area, with a concentration ranging from not detected (n.d.) to 755 ng L-1 (median of 71.0 ng L-1). The upstream watersheds of the reservoir were primarily contaminated due to agricultural activities, and the highest concentration of individual CUPs, ranging from 102 to 821 ng L-1 (median of 468 ng L-1), was found in agricultural source water. Source identification analysis revealed that the presence of CUPs in the reservoir primarily stemmed from three types of activities: the cultivation of fruit trees around the reservoir, the daily activities of residents, and the agricultural practices in the upstream watershed basin. Risk assessment indicated that DCH, IMI, and THM posed moderate or high risks to aquatic organisms, with an emphasis on the effects of NNIs. The chronic cumulative risk assessment of NNIs was conducted by the relative potency factor approach, and it indicated that infants and young children were the most vulnerable groups and exhibited heightened susceptibility. The potential exposure to NNIs through drinking water was below the recommended relative chronic reference dose, thereby posing no discernible health risks. The results of this study will support the regulation of CUPs in drinking water sources.

Impact of land covers on pesticide contamination and the associated ecological risk in a major tributary of the Pearl River, South China

Pesticide contamination in the river basins is closely associated with land covers. However, the impact of land covers on the pesticide contamination remains unclear. In this study, concentrations of 14 pesticides (10 insecticides, 3 fungicides, and 1 herbicide) in water were investigated along a major tributary of the Pearl River in wet and dry seasons in 2023. Thirteen pesticides were found in wet season, while all for dry season. Correlation analyses indicated that herbaceous cropland and grassland covers predominantly positively affected the overall pesticide concentrations in both seasons. Irrigated cropland cover positively affected the concentrations of 3 pesticides only in wet season, suggesting their use for the crops. Closed evergreen broadleaved forest cover negatively affected the overall pesticide concentration in only wet season, indicating the mitigation effect of forest. In dry season, positive effect of open evergreen broadleaved forest was found only for malathion, suggesting its usage in the forest. Additionally, ecological risks of the pesticides were low to moderate, with similar dominant pesticides in both seasons. Finally, the investigation of pesticide used in croplands, grasslands, and forests, and forest protection are recommended for pesticide contamination management. These outcomes will deepen our understanding of pesticide contamination control in the river basins.

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%.