| Environmental Hormone is a class of chemical compounds in the environment, known as endocrine disrupting chemicals(EDCs). It may disrupt the human endocrine system and cause reproductive, developmental and behavioral disorder. Phthalic acid esters(PAEs) is a kind of material of environmental hormone, mainly used as plasticizer. In recent years, due to extensive production and use of plastic, PAEs have entered the environment constantly, polluting the environment and harming animals and plants health. Therefore, PAEs have become a focus pollutants of global concern.As a kind of sewage treatment, constructed wetlands have been widely used in the world.At present, there are many achievements about the removal of conventional pollutants in wastewater by constructed wetlands, while there are few studies about the organic micropollutants which are harmful to human. The phthalic acid asters have potential threat to human which is the most common environmental hormones.In the research, we chose two representative wetland systems in the constructed wetland of Zaohe river into Weihe river mouth as sample plots, among which one is the bulrush wetland system and another is cattail wetland system. Water, sediments and plants were sampled along at the places of different distances from the inlet water. Four PAEs(DMP,DEP,BBP,DBP) were measured by high performance liquid chromatography. The research aims to analyze the concentration and total accumulation of PAEs in the wastewater, sediments and plants, and the corelation between them and analyze the distribution characteristics, removal efficiency and removal pathways of the PAEs. The main conclusions are as follows:(1)The optimum condition for analysis of PAEs were established based on high performance liquid chromatography(HPLC). In this paper the conditions of the HPLC were as follows: C18 chromatographic column(4.6*250mm, 5um); UV-Detector(275nm); Mobile phase, methanol-H2O(85:15,v/v); Column temperature, ambient temperature; Sample size, 20 ul. The average recoveries of four PAEs were between 90.80%~110.00%, and the relative standard deviation(RSD) ranged from 3.05%~4.54%. The recovery of this experiment is high and its relative standard deviation(<5%) is low,representing excellent accuracy and precision.(2)The removal efficiency of PAEs in wetland system was analyzed. The influent concentration of four PAEs in Zao River Estuary Constructed Wetland was between 6.63~22.34ug/L, and the effluent concentration of them were both below 7ug/L. The removal efficiency of four PAEs in wetland system was between 58.96%~84.24%; the bulrush and cattail wetland system had some effect on the removing four PAEs, and it showed a decreasing trend in the concentration of the PAEs in the wetland water in the direction of flow; while the removal efficiency of PAEs in the bulrush wetland system was 44.91%~68.25%, the removal efficiency of PAEs in the cattail wetland system was 29.22%~39.97%. On the whole, the removal efficiency of PAEs in the bulrush wetland system was slightly higher than the cattail wetland system.(3)The distribution characteristics of PAEs in the substrates and plants were analyzed. The concentration of the 4 kinds of PAEs decreased in the vertical and horizontal substrate of both bulrush and cattail wetland system, and the content of the four PAEs in the bulrush and cattail had a similar trend. In addiction, the removal of PAEs by the bulrush was slightly better than the cattail.(4)The differences of PAEs concentration in different plant wetland systems were analyzed. There was no significant difference in the removal efficiency of the four PAEs between the bulrush wetland system and the cattail wetland system; significant difference existed in the content of DEP between the 0-10 cm and 10-20 cm substrate of the wetland systems, while others didn’t; there were no significant differences in the removal of the four PAEs by the bulrush or cattail.(5)The accumulation of PAEs in the substrate and plants of the wetland system have been detected, and the PAEs concentration relativity in wastewater, aquatic plants, substrate have been analyzed. Accumulation of PAEs in substrate was much larger than in plants, so the contribution of substrate to the removal of PAEs was much greater than plants. Besides, 74.6% of DBP removal was contributed by substrate absorption by calculation, while 25.4% of DBP removal was contributed by plant absorption and microbial degradation. On the whole, the approaches to removal of PAEs were the substrate adsorption, plants uptake, and the microbial degradation. What is more, the removal effect of substrate adsorption was much greater than that of the plant uptake. |
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