| With the rapid development of urbanization,industrialization and agricultural modernization,agricultural soil pollution is becoming more and more serious,which poses potential harm to ecological environment quality and human health.In recent years,due to the extensive use of greenhouses and agricultural film,the use of phthalates(PAEs)has been increasing.PAEs are easily released from the plastic into the atmosphere,water,and soil.The purpose of this study is to understand the levels and distribution characteristics of PAEs in Urban and rural ecotonel cities in northeast China and the possible risks to the ecological safety brought by pollutants.This will provide scientific basis for controlling the environmental discharge of PAEs and protecting the local ecological environment.In this study,four types of agricultural soils(green belt,field,greenhouse,plastic sewage irrigation area)were selected to determine the basic physical and chemical properties of the soil.dimethyl phthalate(DMP),Diethyl phthalate(DEP),dibutyl phthalate(DBP),and diethylhexyl phthalate(DEHP)were used as target contaminants.The contents of four kinds of PAEs in four different types of agricultural soils were determined by LC-MS,and the distribution characteristics of these four pollutants were analyzed.The contents of four kinds of PAEs were compared with American soil PAEs standard and environmental risk limits(ERLs)so as to examine whether these four PAEs are exceeded and whether they have environmental risks.The results showed that the order of ?4PAEs in four types of agricultural soils was plastic sewage irrigation area>years of facilities>field>green belt.In general,the levels of DEHP were the highest in the four PAEs,and the level of DEP was the lowest.Comparing the contents of four kinds of PAEs in the soil of the plastic soil with those of other cities in China,We found that the contents of the four PAEs in the soils of were at a low level.According to the American soil PAEs control standard,the contents of DMP,DEP and DBP compounds in the four types of agricultural soils exceeded the standard.Although the content of DEHP did not exceed the standard,it was very close to the control standard and should be paid attention.The DBP and DEHP contents of the green belt were lower than the environmental risk limit,and there were no environmental risks.DBP and DEHP in the field,greenhouse and plastic sewage irrigation area were higher than the environmental risk limit,and there were environmental risks.We have selected DBP for further study.The transformation rule of DBP in soil was studied and effects on soil microbial biomass with different concentrations of DBP was measured.Finally,the effects of different concentrations of DBP on soil microbial community diversity were studied by DGGE.The results showed that under low concentrations of DBP,the microbial biomass carbon and nitrogen changed a little,while at high concentrations of DBP,microbial biomass carbon and nitrogen dropped sharply.In general,microbial biomass carbon and nitrogen decreased with increasing DBP concentrations.By analyzing the DGGE map,we founded that the higher the DBP concentration was,the less the numbers of bands were in the lane,indicating that the high concentration of DBP would reduce the diversity of microorganisms in the soil,and the band brightness was negatively related to DBP concentration in general,indicating that high-concentration DBP would reduce the microbial biomass,which had a negative effect on the soil microbial ecology. |
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