[Research Status and Trend Analysis of Environmental and Health Risk and Control of Persistent, Mobile, and Toxic Chemicals].

Persistent, mobile, and toxic or very persistent and very mobile (PMT/vPvM) chemicals have been widely detected in surface water, groundwater, and drinking water around the world and are important emerging contaminants that may significantly affect human health and the environment in the future. According to the identification criteria proposed by the European Union, there are thousands of PMT/vPvM substances in existing chemicals, covering a wide range of applications, including dozens of high-yield industrial chemicals such as melamine. PMT/vPvM chemicals can be discharged into the environment through farmland runoff, industrial wastewater, and domestic sewage, and sewage treatment plants are currently considered to be their main discharge route. It is difficult to effectively remove PMT/vPvM chemicals through the current conventional water treatment technology; they can exist in the water circulation system of the urban human settlement environment for a long time, endangering the safety of drinking water and the ecosystem. The European Union has taken the lead in introducing PMT/vPvM chemicals specifically into the priority areas of the current chemical risk management system. At present, there are still many potential PMT/vPvM chemicals in the environment, and their monitoring methods need to be further improved. It will take time for the identification of substances, the scope of categories, and the establishment of lists. Studies on the environmental fate and exposure of PMT/vPvM in various regions of the world are still very limited, and research on the potential, long-term ecotoxicity, and human health hazard effects remains scarce. At the same time, the research and development of substitute or alternative technologies, as well as environmental engineering treatment technologies such as sewage treatment and contaminated site remediation, will become an urgent need for future PMT/vPvM risk scientific research and management decisions.

Emission and fate of antibiotics in the Dongjiang River Basin, China: Implication for antibiotic resistance risk.

Antibiotics used for human and veterinary purposes are released into the environment, resulting in potential adverse effects, including the development and spread of antibiotic resistant bacteria. Here we investigated the dynamic fate of 36 antibiotics in a large river basin Dongjiang in South China, and discussed their potential antibiotic resistance selection risk. Based on the usage, excretion rate, wastewater treatment rate, human population and animal numbers the emissions of 36 frequently detected antibiotics were estimated for the Dongjiang River Basin. The total usage of the 36 antibiotics in the basin was 623.4 tons, which included 37% for human use and the rest for veterinary purposes. After being metabolized and partially treated, the amount of antibiotics excreted and released into the environment decreased to 267.6 tons. By allocating the high-precision antibiotic discharge inventory to 42 sewage plants and 17 livestock farms, an improved GREAT-ER (Geography referenced Regional Exposure Assessment Tool for European Rivers) model for the Dongjiang River Basin, with a well calibration river flow network based on the SWAT (Soil and Water Assessment Tool), was established to simulate the dynamic fate of 36 antibiotics. The simulation results showed that antibiotics contaminated >50% of the river sections. The modelled concentrations in water were almost within an order of magnitude of the measured concentrations. Antibiotic contamination in the dry season was obviously higher than that in the wet season. The concentrations of the antibiotics were always higher at the discharge zones and lower reaches of the river basin than the other reaches. The antibiotic resistance risk assessment showed that 23 out of the 36 antibiotics (nearly 65%) could pose high risks in the river basin. For those river reaches with high risks, the risk levels could mostly be reduced to low risk levels with a certain distance (15 km) from the pollution source. Therefore, more attention should be paid to those impact zones in term of antibiotic resistance.

Emission estimation and fate modelling of three typical pesticides in Dongjiang River basin, China.

Pesticides are widely and intensively used in the world for crops protection. High pesticide loadings can potentially pollute the water resource. However, little is known about the usage, environmental emission and fate of pesticides in river basins. Here, we firstly established a pesticide emission estimation method, and investigated the environmental fate of three commonly used pesticides (chlorpyrifos, triazophos, and isoprothiolane) in Dongjiang River basin, southern China using mathematical modelling approach in combination with field monitoring. The distributed hydrological model SWAT (Soil and Water Assessment Tool) was applied to model the emission of the target pesticides from farmland to stream water, and their fate in the basin. A satisfactory model calibration for flow and suspended sediment was obtained based on eight-year observation data of four hydrological monitoring stations in Dongjiang River basin. The differences between the simulation and observation of pesticides were almost within an order of magnitude, including more than 53% differences within 0.5 order of magnitude. In the river basin, 78860 kg of chlorpyrifos, 54990 kg of triazophos and 35320 kg of isoprothiolane were sprayed onto the crops, the estimated annual emissions of the basin come up to 1801 kg, 3779 kg, and 2330 kg under the conditions of rainfall, surface runoff and percolation. After a series of environmental processes including settlement and degradation within the channels, the predicted export masses for chlorpyrifos, triazophos and isoprothiolane were reduced to 266 kg, 1858 kg, 1350 kg, respectively. Successful prediction suggests that the reliable estimation method combing the SWAT modelling can help us understand the source, concentration levels and fate of pesticides in river basin in different scales. Combing the method of emission and fate modelling method we proposed, countries and regions lacking pesticide-application database can facilitate better management of pesticides.

Expression and functional characterization of a recombinant targeted toxin with an uPA cleavable linker in Pichia pastoris.

A recombinant targeted toxin (Disintegrin-Conj-Mel) was developed that contained a disintegrin connected to cytotoxic melittin by a urokinase plasminogen activator (uPA)-cleavable linker. This recombinant targeted toxin was designed to target tumor cells expressing integrin αvß3. The fusion gene was expressed under the control of the promoter AOX1 in Pichia pastoris. Electrophoresis by SDS-PAGE and Western blotting assays of culture broth from a methanol-induced expression strain, demonstrated that an approximately 13 kDa fusion protein was secreted into the culture medium. The molecular weight was that calculated from the predicted amino acid sequence. After optimizing the growth and expression conditions of the transformant strain, about 160 mg/L of the recombinant protein was achieved. The recombinant protein was purified to more than 95% purity by SP Sepharose ion exchange chromatography and Sephadex G-75 gel filtration chromatography. The hemolysis bioactivity test revealed that the fusion had no hemolytic activity or cytotoxicity against uPA non-expressing 293 cells, but exerted dose-dependent inhibition on uPA-expressing A549 cell proliferation.