Chemical Fractionation in Environmental Studies of Potentially Toxic Particulate-Bound Elements in Urban Air: A Critical Review.

Ryszard Świetlik,Marzena Trojanowska

doi:10.3390/toxics10030124

Ryszard Świetlik, Marzena Trojanowska

Open Access

https://doi.org/10.3390/toxics10030124

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Abstract

In recent years, studies of heavy metal air pollution have increasingly gone beyond determining total concentrations of individual toxic metals. Chemical fractionation of potentially toxic elements in airborne particles is becoming an important part of these studies. This review covers the articles that have been published over the last three decades. Attention was paid to the issue of atmospheric aerosol sampling, sample pretreatment, sequential extraction schemes and conditions of individual extractions. Geochemical forms of metals occurring in the air in urban areas were considered in detail. Based on the data sets from chemical fractionation of particulate matter samples by three sequential extraction procedures (SEPs)—Fernández Espinosa, BCR and Chester’s—the compilation of the chemical distribution patterns of As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn was prepared. The human health risk posed by these toxic and/or carcinogenic elements via inhalation of atmospheric particles was estimated for two categories of polluted urban areas: the commonly encountered pollution level and the high pollution level.

Highlights

The goal of this paper is to review the present state of knowledge on the distribution of chemical forms of potentially toxic elements in airborne particles
The distribution pattern developed on the basis of the results of the chemical fractionation by Chester’s procedure is similar, while the operational speciation of Co based on the results of the chemical fractionation according to the BCR scheme is different in character
In order to assess the risk in an environment polluted by potentially toxic elements (PTEs), it is common to use a number of individual and complex indices, the most important being the following: geoaccumulation index (Igeo ); enrichment factor (EF); bioavailability index (BI); individual and global contamination factor (ICF and GCF); risk assessment code (RAC); pollution load index (PLI); degree of contamination (Cdeg ); and potential ecological risk (RI) [12,16,92]

Summary

Introduction

Among the primary air pollutants (CO, CO2 , CH4 , VOCs, NO, N2 O, NH3 , H2 S, SO2 and particulate matter) and the secondary air pollutants (NO2 , HNO3 , O3 , H2 SO4 , sulfate, nitrate and organic aerosols), atmospheric particulate matter (APM) is of special interest to researchers due to its adverse effect on human health [1]. The goal of this paper is to review the present state of knowledge on the distribution of chemical forms of potentially toxic elements in airborne particles. The results of operational studies of PTE speciation in urban air have not been the subject of review elaborations so far. The most frequent subject of these studies was a group of toxic metals: As, Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn (50–90% of the papers) [9,12,13,16,21,27,30,33–35]. The elements such as Al [15,18,20,26,32,33], Co [9,12,14,17,21,23,26–30], V [23,26,27,33,57–60], Ti [10,19,20,23, 26,27,32,33], Sb [10,11,14,20,27,28,32], Mo [20,32,33,59–61], Se [11,14,28,47,55,56,62,63] and. The complementary goals were the assessment of the uniformity of the terminology and the laboratory procedures used

Terminology

Chemical Fractionation Procedures

Procedure

M H2O2 (pH 2–3), shaking, 85 °C, 1 h, (c) 1 M AcONH4 (pH 2, HNO3), shaking, RT, 16 h

Water-Soluble

Mean proportion of water-soluble ofpollution

Environmental Risk Assessment

Health Risk Assessment

Findings

Conclusions