The Ecological Effects And Health Risk Of Typical Organic Pollutants In Coastal Wetland Soils

With the rapid industrialization, urbanization in recent years, many pollutants were released into the environment by human activities. And the pollution in wetlands has been both serious and widespread in China. Due to their persistence and hydrophobic nature, some organic pollutants are prone to enrichment in soils and eventually cause some adverse effects to the ecological environment and human health. Hence, a comprehensive understanding of the ecological effects and risk of organic pollutants in coastal wetland soils is of great importance in protecting the environment and human health.In order to evaluate the ecological effects of organic pollutants in coastal wetland soils, we select the typical organic pollutants polycyclic aromatic hydrocarbons (PAHs) and Pentachlorophenol (PCP) as the research target. Soil microorganisms (bacteria, fungus and actinomycetes) and soil enzyme (urease and sucrase) activities were investigated were measured to assess the ecological effects of organic pollutants (Pyr, Phe and PCP). In order to evaluate the health risks of organic pollutants in coastal wetland soils, we select two typical coastal wetlands (Liaohe estuary wetland and Jiaozhou Bay wetland) as the reserrch target. The concentrations of PAHs and PCP in these two wetland soils were measured. And the carcinogenic risk via three different exposure pathways (soil ingestion, dermal contact and inhalation) were evaluated. In the carcinogenic risk assessment, two different carcinogenic risk assessment models (ILCR model and RAGS model) were used. The differences between these two models were also discussed in this study. In order to minimize the uncertainties of risk assessment, a probability-based approach (Monte Carlo simulation) was successfully applied in this study. A sensitivity analysis was performed to determine the greatest effect of input variables on the risk assessment. We can improve the accuracy of the health risk assessment based on the results of sensitivity analysis. The main contents are as follows:(1) PCP will promote the growth of bacteria and will promote the growth of fungus when PCP concentration lower than 100×103 ng/g, and will inhibit when PCP concentration was 150×103 ng/g. For actinomycetes, PCP will inhibit the growth even at low concentration level. Phe will inhibit the growth of bacteria and will promote the growth of fungus when Phe concentration lower than 300 ng/g, and will inhibit when Phe concentration higher than 600 ng/g. For actinomycetes, PCP will promote the growth. Phe will inhibit the growth of bacteria and actinomycetes. For fungus, Pyr will inhibit the growth.(2) PCP will inhibit the activity of urease and sucrase. For Phe, the activity of urease and sucrase will be promoted when the concentration lower than 300 ng/g, and will be inhibited when the concentration was higher than 600 ng/g. Pyr will inhibite the activity of urease even at low concentration level. Pyr will promote the activity of sucrase when Pyr concentration lower than 150 ng/g, and will inhibit when higher than 300 ng/g.(3) The carcinogenic risk for three age groups caused by coastal wetland soils (Liaohe estuary wetland and Jiaozhou Bay wetland) were lower than 10-6, there is no potential carcinogenic risk. BaP and DBahA contributed most to the total carcinogenic risk. Soil ingestion and dermal contact were the main exposure pathways. PAHs concentration and exposure duration were the most sensitive parameters. The carcinogenic risks for PCP in coastal wetland soils were lower than 10-6, indicating no potential carcinogenic risk. The carcinogenic risk calculated based on RAGS model were lower than ILCR model, which can be explained by the difference of cancer slop factor (CSF) in these two models.