丹江口库区地表水中多环芳烃的污染特征、来源及生态风险评价

Pollution characteristics,sources and ecological risk assessment of polycyclic aromatic hydrocarbons in surface water of Danjiangkou Reservoir

为探究丹江口水库地表水体中多环芳烃(PAHs)的污染特征、来源及潜在的生态风险,2020年9月(丰水期)及12月(枯水期)分别对丹江口水库20个采样点的地表水中16种优先控制的PAHs进行调查和分析.研究发现丹江口库区丰水期共检出PAHs 6种,质量浓度为64.64~360.21 ng/L,均值为170.46 ng/L,枯水期共检出PAHs 9种,质量浓度为23.05~202.11 ng/L,均值为74.17 ng/L;丰水期总PAHs质量浓度略高于枯水期.在丹江口库区不同水期,均未检出蒽(Ant)、[艹屈](Chr)、苯并[a]蒽(BaA)、二苯并[a,h]蒽(DbA)、茚并[1,2,3-cd]芘(IcdP)和苯并[g,h,i]苝(BghiP),其余10种有不同程度的检出,其中,萘(Nap)、芴(Flu)及菲(Phe)为丹江口库区检出率最高的PHAs.从空间分布情况来看,丹江口库区库湾各点位PAHs含量最高,丹库、汉库及坝前均显著低于库湾.采用主成分分析法对丹江口库区PAHs来源进行解析发现,丹江口库区丰水期及枯水期的PAHs来源相似,主要来源为煤及汽油燃烧或汽车尾气排放.采用熵值法对丹江口水库不同时期PAHs进行生态风险评价发现,丹江口水库枯水期20个采样点位均为低风险;丰水期除S19为中风险外,其他采样点位均为低风险.综合来看丹江口水库地表水中PAHs处于较低风险状态.

To investigate the pollution characteristics,sources and potential ecological risks of polycyclic aromatic hydrocarbons(PAHS)in surface water of Danjiangkou Reservoir,16 priority control PAHs were investigated and analyzed in surface water from 20 sampling sites of Danjiangkou Reservoir in September(abundant water period)and December 2020(dry water period),respectively.It was found that six PAHs were detected in the Danjiangkou reservoir area during the abundant water period,with mass concentrations ranging from 64.64 to 360.21 ng/L and a mean value of 170.46 ng/L,and nine PAHs were detected during the dry water period,with mass concentrations ranging from 23.05 to 202.11 ng/L and a mean value of 74.17 ng/L.The mass concentrations of the total PAHs were slightly higher during the abundant water period than the dry water period.In different water periods in Danjiangkou Reservoir Area,Anthracene(Ant),perylene(Chr),benzo[a]onion(BaA),dibenzo[a,h]onion(DbA),indeno[1,2,3-cd]pyrene(IcdP),and benzo[g,h,i]pyrene(BghiP)were not detected,and the remaining 10 were detected with varying degrees of intensity,of which naphthalene(Nap),fluorene(Flu)and phenanthrene(Phe)were the most detected PHAs.In terms of spatial distribution,the PAHs content was highest at each point in Danjiangkou Reservoir Bay,and was significantly lower in Dankou,Hankou and in front of the dam than in the Reservoir Bay.By using principal component analysis to analyze the sources of PAHs in the Danjiangkou reservoir area,it was found that the sources of PAHs in the Danjiangkou reservoir area were similar during the abundant water period and the dry water period,and the main sources were the combustion of coal and gasoline or automobile exhaust emissions.The entropy value method was used to evaluate the ecological risk of PAHs in Danjiangkou Reservoir in different periods,and it was found that the 20 sampling sites in Danjiangkou Reservoir were all at low risk during the dry water period,and that all the other sites were at low risk during the abundant water period,except for S19,which was at medium risk.In summary,PAHs in surface water of Danjiangkou Reservoir are at low risk.