Spatial Distribution And Environmental Effects Of Polycyclic Aromatic Hydrocarbons And Heavy Metals In Snowpack In Harbin

With the rapid development of economic and social and the continuous acceleration of urbanization,human production and living activities have produced a large number of pollutants,causing environment pollution,and causing harm to human health and animals and plants.In this study,the China's northern alpine city-Harbin as the research area,we analyzed 16 polycyclic aromatic hydrocarbons(PAHs)(Nap,Acy,Ace,Flu,Phe,Ant,Fla,Pyr,Ba A,Chr,Bb F,Bk F,Ba P,Icd P,Dah A and Bghi P)and heavy metals(Cr,Cu,Zn,As,Cd and Pb)in the snowpack samples that were controlled in February 2018.The research contents include:the content characteristics and spatial distribution characteristics of PAHs and heavy metals in snowpack were analyzed,and their sources were explored;a residual inventory of PAHs and heavy metals in snowpack were established,the spatial distribution characteristics were analyzed;the environmental effects of PAHs during the snowmelt period were explored by a multi-media environment model;and a residual inventory of heavy metals in the snowpack-soil system was established for pollution assessment.Research indicates:(1)The average concentration of?PAHs in the snowpack of Harbin is 1433.39 ng/L,mainly 3-4 rings PAHs.Among them,and the content of Phe is the highest in the monomer.?PAHs are mostly distributed in the particle phase,about accounting for 96.84%.The content of?PAHs in different areas is significantly different.The concentration of?PAHs in the suburbs(4221.35 ng/L)is 26times that in urban and 4 times that in rural.Most high-sampling points of?PAHs are located in the downwind area of Harbin.The average concentrations of Cr,Cu,Zn,As,Cd,and Pb in the snowpack of Harbin are 13.40,26.28,146.42,23.32,1.70,and 30.65?g/L;Cr,Cu,As,and Pb are mainly distributed in the particle phase,and Zn and Cd is more balanced in the dissolved phase and the particle phase.The spatial distribution of heavy metals generally appears as urban>suburbs>rural.Source analysis results show that the sources of LWM-PAHs and HWM-PAHs may be different.In addition,the sources of Phe and Dah A may differ from other PAHs.PAHs in snowpack may come from the combustion of coal and biomass and motor vehicle emissions.As and Cd may be different from other heavy metals.The heavy metals in snowpack mainly from industrial pollution and traffic pollution,followed by coal pollution and farmland pollution.(2)The average residual inventory of?PAHs in the snowpack of Harbin is 52.43?g/m~2,and residual inventory of Phe is the highest.Spatial differences in?PAHs residues in snowpack are obvious.The?PAHs residues in suburbs(119.80?g/m~2)are 22 times that in urban and 4 times that in rural.Sampling points with higher?PAHs are mainly distributed in the downwind direction area of Harbin,such as UR1 in urban,SU3 and SU4 in suburbs,and RU7 and RU8 in rural.The average residual inventories of Cr,Cu,Zn,As,Cd and Pb are 415.58,806.18,4451.60,703.85,51.90,940.53?g/m~2,respectively.The overall appearance is urban>suburbs>rural.The highest points of residual inventory of heavy metals all appear at the UR5,while the lowest points appear in rural.This may be because the heavy metals mainly come from transportation and living pollutions.(3)During the snowmelt period,73.2%of the Phe content in snowpack of Harbin discharge into the atmospheric environment and 21.5%snowmelt runoff;23.1%of the Pyrene(Pyr)content discharge into the atmospheric environment,36.2%snowmelt runoff,31.2%soil infiltration;94.1%Benzo[a]Pyrene(Ba P)content into the soil infiltration.The degradation of Phe,Pyr and Ba P accounte for 5%,10%and 3%of the total,respectively.The toxic equivalent concentration of the SU4 in Harbin exceed the Surface Water Environmental Quality National Standard,and the pollution is very serious.The assessment of the health risks of respiratory exposure to PAHs during the snowmelt period in Harbin show that SU1,SU3 and SU4 in suburbs,and RU7 in rural all pose carcinogenic risks to the population;the remaining areas are potentially carcinogenic.(4)The average residual inventories of Cr,Cu,Zn,As,Cd,and Pb in the snowpack-soil system of Harbin are 58.789,20.366,72.723,7.620,0.110,and 24.628 mg/kg,respectively;the average cumulative percentage are 0.32%,1.83%,2.86%,4.38%,27.43%,and 1.77%,respectively,of which the cumulative percentages of Cd and As are relatively high,and we should pay more attention to them.The spatial distribution of heavy metals residual inventories in the snowpack-soil system of Harbin are presented as urban>suburbs>rural.The results of the Nemerow comprehensive index method show that the average of the heavy metals pollution index from high to low is:Cu>Cr>Zn>Pb>Cd>As,and the soil under the snow-covered conditions in Harbin is in an uncontaminated state.The research results will provide reference value and scientific basis for regional air pollution control,the evaluation of surface water and soil under the conditions of snow-covered,as well as the formulation of environmental pollution control measures and management policies.