Environmental emissions and pollution characteristics of mosquitocides for the control of dengue fever in a typical urban area.

Mosquitocides are frequently used to control the spread of dengue fever in tropical and sub-tropic urban regions worldwide, resulting in their discharge into the environment via rainfall runoff, causing adverse effects on ecological health. This study quantitatively evaluated mosquitocide emissions and environmental pollution in a typical urban district in China affected by the dengue fever epidemic, using a method combining market surveys, monitoring campaigns and SWMM (storm water management model) modelling tools. During the assessment period, the total mosquitocide usage in the urban district reached 6334 kg, with an estimated load of 56.55 g entering the receiving environment via rainfall runoff, 91.04 % of which occurred in the rainy season. Monitoring results indicated that the initial 0.5-1 h was the main period of mosquitocide wash off into the receiving water. Environmental mosquitocide pollution levels were found to be affected by the mosquitocide type and the time interval between mosquitocide application and precipitation events. The measured environmental concentrations of mosquitocides in this study were generally higher than those areas unaffected by the dengue fever epidemic. The modelled mosquitocide concentrations were in accordance with monitoring results. The finding of this study are important for assessing the environmental impact of dengue fever control activities, while also providing valuable baseline data for the effective environmental management of mosquitocides.

Antibiotic pollution in lakes in China: Emission estimation and fate modeling using a temperature-dependent multimedia model.

The high use of antibiotics worldwide has poses a serious threat to both human and environmental health. Lakes are served as reservoirs for antibiotics, however, there is a lack of information available on antibiotics emissions and the subsequent pollution. Here, the emission and fate of 34 frequently detected antibiotics were studied in 226 Chinese lakes, via the built emission estimation method and a temperature-dependent multimedia lake model. It has been estimated that totally 5711 tons antibiotic were discharged into the lakes of China in 2019. Antibiotics emissions are due to human activities, with 3800-fold higher emissions in the Eastern China than that in Western China. The antibiotic fate in lakes has been successfully modelled by simulating the lake stratification, freeze-melt cycles and the stable condition throughout the year. Both stratification and freeze-melt cycles can lead to increased antibiotic concentrations in lake water. Deep-water lakes were shown to serve as a highly effective natural storage medium for antibiotics. The reliability of the model was confirmed by published measured concentrations and Monte Carlo method. This is the first study to comprehensively investigate the antibiotic fate in lakes of China, providing valuable guidance for the remediation of contaminated lakes.

Hypothetical scenarios estimating and simulating the fate of antibiotics: Implications for antibiotic environmental pollution caused by manure application.

The application of animal manure containing antibiotic residues as an organic fertilizer to farmlands, poses a major threat to the health of river basin ecosystems. Waste treatment processes can help reduce antibiotic pollution levels in river basins following manure application, but the overall influence of these processes remains unclear. This study evaluates the impact of manure treatment methods on the emission and subsequent river pollution caused by 14 frequently detected antibiotics in a typical pig breeding area in China, by using hypothetical scenarios method. Three scenarios were constructed based on possible fate pathways of antibiotics, representing in 47.0, 55.3, and 81.6 ton·yr-1 antibiotic emissions into the river basin. The soil and water assessment tool (SWAT) model successfully simulated the transport of antibiotics from farmland to surface water, with calibration and verification performed using hydrological station monthly data over 8 consecutive years. Field measured concentrations also verified the reliability of the model and were used to determine the most realistic scenario. In basins applied with manure, environmental antibiotic pollution is most affected by the wastewater treatment process and manure applied patterns, followed by changes in streamflow. The antibiotic pollution in manure applied areas showed significant spatial and temporal differences, resulting from the different manure application patterns. The simulated total outflow of antibiotics in the river basin accounted for 18.1% of the inflow, with the loss of target antibiotics by degradation, volatilization and sedimentation deposition in the river basin being 0.23, 0.01 and 33.2 ton·yr-1, respectively. This study can help to clarify the environmental fate of antibiotics in the basin following manure application, provide guidance for policy makers and help to design the effective corrective interventions for reducing the environmental pollution.