Emission Estimation, Multimedia Fate Modeling And Risk Assessment Of Typical Emerging Pollutants At River Basin Scale In China

With the development of society and economy, more chemical categories come into exist. At the same time, with the help of modern efficient analysis and test method, more and more emerging pollutants, which are closely related to our daily life, are detected and found. China is a contury with the world’s largest chemical production and usage, however research and management of these emerging pollutants was only set up in recent years, especially for the basin scale chemical research. With little knowledge on the presence, frequency of occurrence, and sources, as well as the risks on the human and environment, it is essential to understand the basin scale emissions and contamination profiles associated their ecology risks.The emission estimation methods for three typial emerging pollutants(steroids, antibiotics, and biocides) have been well developed based on the emission characteristic for different chemicals. At the same time, a lot of references have been consulted for data collected for parameters about the chemical and environment. Based on fugacity method, both Level III and Leve IV fugacity multimedia model have been developed as well as the sensitivity and uncertainty analysis(Monte Carlo) method. The model was run using a build-in function in Matlab R2010. The identification of the most influential parameters and processes responsible for the fate of chemicals was performed with a sensitivity analysis. Uncertainty analysis is concerned with propagation of the various sources of uncertainty to the model output. Basd on the built-in model, the emission estimations, multimedia fate and environmental risks for those selected chemicals at all of the 58 river basins in China were evaluated. The main results are as follows:The emissions of seven steroids(estrone, 17β-estradiol, estriol, testosterone, androsterone, progesterone, and cortisol) and their multimedia fate as well as the risk assessment were comprehensively estimated in 58 river basins of whole China. The total excretion of steroids by humans and animals in China was estimated to be 3071 t/yr. The excretion of steroids from animals was two times larger than that from humans. After various treatments, the total emission of steroids was reduced to 2486 t/yr, of which 84% was discharged into the water compartment by through the wastewater dishcharge and the rest dishcharged into the soil compartment by through the land application and wastewater irrigation. The emission density map showed that higher emission densities for the steroids were found in the river basins of east China than in west China, which was found generally similar to the distribution of Gross Domestic Product(GDP) across China. The simulated concentrations in water were within an order of magnitude of the measured concentrations available in the literature. The uncertainty analysis further verified the reliability of the modelling using Monte Carlo simulation. Aquatic risks from the steroids with estrogenic and androgenic activities showed that estrogenic risks are expected to be widespread for the water compartment, and high risks were mostly located in north China. In contrast, the androgenic risks in China are expected to be quite low. If the treatment rate for wastewaters in each basin were increased to 80% and the removal efficiency for each steroid in wastewater treatment plants were greater than 95%, no high aquatic risks from steroids would be expected in almost all of the rivers in China.National consumptions, emissions and environmental fate of 36 frequently detected antibiotics in the environment in whole China were investgated by market survey, data analysis and level III fugacity modelling tools. Potential linkage of the antibiotic usages and PECs to the bacterial resistance in the hospitals and aquatic environments of China was also evaluated. The total antibiotic usage in China in 2013 was estimated to be approximately 160000 tons. Human consumption accounted for about 48% of the total antibiotics, and the rest were shared by animals. The total usage for the 36 chemicals was 92665 tons in 2013, including 84.3% for veterinary use and 15.6% for human use. An estimated 54003 tons of the antibiotics was excreted by human and animals through urine and feces, and eventually 53756 tons of them entering into the receiving environment following various wastewater treatments. The average usage densities for the basins located in east and south China were more than 6 times higher than those in west China, with the basins being separated into two different regions by the Chinese geographic “Hu Huanyong line”. The fugacity model successfully predicted environmental concentrations(PECs) in all 58 river basins of China, which are comparable to the reported measured environmental concentrations(MECs) available in some basins, with more than 50% difference(between the MECs and PECs) within one order magnitude. Antibiotic contamination in the aquatic environment of north China was found more severe than in the other regions of China. The transfer fluxes analysis showed that source emission and degradation shared most in various environmental compartments, and antibiotics emissions from the animals contributed much more than the humans. Statistical analysis showed certain linkage of the PECs and antibiotic usages to the bacterial resistance rates in the hospitals and aquatic environments, especially for those antibiotics used in the latest time. This comprehensive study demonstrated an alarming usage and emission of various antibiotics in China, resulting in a nationwide high contamination of antibiotics and associated bacterial resistance. Proper management measures should be taken immediately to control overuse of antibiotics and contamination of the environment.Emission and multimedia fate as well as potential risks of typical biocides(triclosan and climbazole) in all of 58 basins in China were investigated. The total usage of tirclosan and climbazole in whole China were 100 and 345 t/yr, and the discharge to the receiving environment was estimated to be 66.1 and 254 t/yr, respectively. The biocides emission levels in east China were found generally higher than in west China. The predicted triclosan and climbazole concentrations by the level III fugacity model were within an order of magnitude of the reported measured concentrations. The sensivitity and uncertainty analysis(Monte Carlo simulation) further verified the reliability of the model. The transfer fluxes analysis showed that both triclosan and climbazole were prone to the sediment. The mass inventory of triclosan in whole China was estimated to be 75.3 t, with 2.4% in water, 96.7% in sediment, 0.9% in soil, and remaining in air. In contrast, the mass inventory of climbazole in whole China was estimated to be 294 t, with 6.79% in water, 83.7% in sediment, 9.49% in soil, and 0.002% in air. A level IV fugacity modelling for triclosan showed that seasonal and regional variations existed and those variations make great impact on the degradation and advection fluxes. The input flux for triclosan to seawater was largely attributed to the seasonal variations in advection flows. Preliminary risk assessment showed that medium to high ecological risks for TCS would be expected in the eastern part of China due to the high population density. Higher risks were located in the Bohai Bay Rim and Pearl River delta region when compared with other basins. Although the predicted risks for the biocides were relative low, higher aquatic risks are expected from this group of chemicals as co-occurrence of other biocides with climbazole and triclosan in surface water, which were with similar ecotoxicological effects to the aquatic organisms.