Pollution Characteristics And Health Risk Of Phthalate Esters In Soils Of The West Lake Scenic Area

Phthalates（PAEs）are commonly known as plasticizers.They are one of the world’s largest and most widely used synthetic organic compounds.Their main use is to add to plastic products to increase Its plasticity and flexibility.With the development of the plastics industry,the advantages of convenient,durable and low-cost plastic products have been accepted,and the demand for plastic products has been greatly enhanced.The production and use of PAEs are increasing rapidly.Due to the relative independence of PAEs and plastic molecules,a large number of PAEs can easily migrate from plastic products to environmental media such as the atmosphere,water and soil.PAEs are not only persistent toxic substances（PTSs）,but also endocrine disrupting compounds（EDCs）,which are extremely harmful to human health and the ecological environment.Therefore,it is of great significance to study the pollution characteristics and health risks of PAEs in the soil of the West Lake Scenic Area to protect the health of scenic spots and surrounding residents and the ecological environment of scenic spots.In this study,42 soil samples from 4 different land uses in the West Lake Scenic Area were collected,and accelerated solvent extraction-solid phase extraction purification-gas chromatography tandem triple quadrupole mass spectrometry was used to determine the priority of the US Environmental Protection Agency.The detection limits,recovery rates and precision of the method were investigated.This method was used to analyze the content and composition of six PAEs in all samples.The source and spatial distribution of PAEs in different land-use types were analyzed by Principal Component Analysis and Ordinary Kriging interpolation.A detailed discussion was carried out.At the same time,the human health risk model recommended by the US Environmental Protection Agency was used to evaluate the carcinogenic and non-carcinogenic risks of six PAEs in the soil of the West Lake Scenic Area.The main conclusions are as follows:（1）Optimized accelerated solvent extraction method,using 1:1 extraction solvent of dichloromethane and acetone,extraction pressure 10.3MPa,extraction temperature120°C,static extraction for 300s,purge time 90s,rinse volume 60%,Cycle 2 times.The detection limit of this method is 0.1⁰.6μg·kg^-1,the recovery range is72.8%¹11.6%,and the relative standard deviation range is 1.9%⁹.0%.The reproducibility meets the quality control standard.In general,this method saves time and solvent compared with the traditional Soxhlet extraction method,and has better extraction effect,and can effectively,quickly and accurately determine PAEs in soil.（2）ΣPAEs were detected in 42 soil samples in the West Lake Scenic Area.The content ofΣPAEs ranged from 597.6μg·kg^-1 to 7360.1μg·kg^-1,with an average of2963.3μg·kg^-1.The content of PAEs in the soil of the scenic spot was:DEHP>DBP>DMP>DEP>DNOP>BBP.Among them,DMP,DBP and DEHP are the main components of PAEs pollutants in the soil of West Lake Scenic Area,and the total content contribution rate ranges from 95.7%to 99.2%.DEHP is the most important pollutant,and the monomer contribution rate is 42.3%⁷7.9%.The content of PAEs in the soil of West Lake Scenic Area is at a medium level compared with other regions at home and abroad.（3）The distribution of PAEs in soils with different land uses is quite different.According to the content ofΣPAEs:Road side>Greenbelt>Tea garden>Woodland,the main sources of PAEs in different land use types are different,and the traffic in the traffic area is dense.Transportation,a large number of tourists in scenic spots,seasonal agricultural activities in tea gardens,and atmospheric dry and wet deposition of forest land are the main sources of PAEs in their respective types of soil.（4）The spatial distribution of PAEs in the West Lake Scenic Area is closely related to its source.The PAEs pollution in the scenic soil is mainly concentrated in the northeastern region,showing a decreasing trend from north to south and from east to west.The surrounding area of the northeastern region and the northern mountainous area are close to many urban main roads and urban commercial centers.The traffic activities and population are extremely dense,and they are close to the main pollution sources,thus becoming a serious pollution area for soil PAEs in the West Lake scenic area.（5）The non-carcinogenic risk of PAEs in adults and children in the West Lake scenic area does not exceed the USEPA recommended non-carcinogenic level and is acceptable.The carcinogenic risk of BBP and DEHP for adults and children does not exceed the USEPA-recommended carcinogenic level and is acceptable.