Multi-year monitoring of atmospheric dust fall as a sink for lead in an agro-industrial and petrochemical city of Argentina.Geo-accumulation and ecological risk assessment

摘要

A multi-year monitoring data set of potentially harmful elements(PHEs),which are pre-sent in the chemical composition of atmospheric set-tleable particulate matter(SPM)in the urban,indus-trial and port areas in Bahia Blanca,was studied in order to assess potential ecological risk.The selected PHEs were metal elements of local and regional envi-ronmental importance(Cd,Cr,Cu,Ni,Pb,and Zn).Seventeen sampling campaigns were carried out between April 2013 and September 2019.After the microwave-assisted acid digestion of samples,the total contents of the PHEs were determined by ICP-OES.The annual dry deposition rate,the indexes associated with the potential ecological risk(RI)and the degree of geo-accumulation(Igeo)of each PHE were calculated.The results indicated that:(a)there are 3 groups(Ⅰ,Ⅱ,Ⅲ)of PHEs with differentiated concentration levels,ranked Ⅰ(Pb＞Zn＞Cu)＞Ⅱ(Cr a Ni)＞Ⅲ(Cd)(p＜0.01)in all the studiedareas;(b)the median of the total deposition rate was 1 mg cm-2.month-1 with a significant relative contri-bution of Pb;(c)a considerable increase in geo-accu-mulation of Pb indicated that SPM was functioning as a sink for Pb,and also reflected a significant pro-gressive increase in the potential ecological risk in all sites(p＜0.01);and(d)there were chemometrically identified potential sources of Pb,Cu and Zn emis-sions that would be associated mainly to the resus-pension of dust from geogenic,industrial and urban origin,and to a lesser extent,to other gaseous emis-sions of the industrial sector.This work highlights three major aspects of environmental assessment:(a)the value of continuous monitoring as an important tool to detect long-term trends;(b)the importance of the role of dust fall as a useful environmental indica-tor of lead geo-accumulation;and(c)the great util-ity of geo-accumulation and potential ecological risk indices as rapid quantitative assessment tools of envi-ronmental pollution.