Source apportionment, ecological, and human health risks of toxic metals in road dust of densely populated capital and connected major highway of Bangladesh.

Md Morshedul Haque,Shafi M Tareq,Nahin Mostofa Niloy,Sajin Sultana,Shamshad B Quraishi

doi:10.1007/s11356-021-18458-3

Abstract

This study investigates pollution levels, source apportionment, ecological, and human health risks associated with toxic metals (Pb, As, Hg, Cr, and Cd) in road dust from the most populated Dhaka city and a connected major highway in Bangladesh. The mean concentration of Pb, Hg, and Cd were 1.3, 29.3, and 13.2 times higher than their corresponding background values with spatially uneven distribution all over the study area. Metal pollution indices, the geo-accumulation index (Igeo), NIPI, and PI, indicated extreme contamination at many sites depending on local environmental factors. The potential ecological risk ([Formula: see text] revealed that 84% and 54% of samples showed the extreme ecological risk for Hg and Cd pollution, respectively. On the other hand, the potential ecological risk index (PERI) and Nemerow integrated risk index (NIRI) showed that most sampling sites suffered high to extreme ecological risk. Source apportionment using positive matrix factorization (PMF) identified coal combustion, and gasoline (50.14%), traffic exhaust (35.26%), and industrial and agriculture activity (14.60%) were the main source of toxic metals of the study area. Non-carcinogenic health risk indicated that adults are more vulnerable than children, and hazard index (HI) of Hg for both age groups and Cd for adults were significantly higher than the safe level. The carcinogenic risk (CR) levels of toxic metals were acceptable (10-6 to 10-4), although the maximum limit of Cr for children and As for adults was close to the unacceptable limit (10-4). Continual exposure to toxic metals through road dust might develop lifetime cancer risk in local inhabitants.

Highlights

Road dust is referred to as fine solid particles that are existed in the environments through diverse processes and can accumulate outdoor, especially on cemented roads and hard pavement (Lu et al 2014; Rahman et al 2019)
This study revealed that the average carcinogenic risk (CR) values of all toxic metals in road dust were fallen within the range of acceptable or tolerable cancer risk (10− 6 to 10− 4) (USEPA 2011b)
Spatial distribution of toxic metals revealed that Pb, Hg and Cr were mostly dominated in suburban areas of the highway

Summary

Introduction

Road dust is referred to as fine solid particles that are existed in the environments through diverse processes and can accumulate outdoor, especially on cemented roads and hard pavement (Lu et al 2014; Rahman et al 2019). The dust acts as the sink and source of toxic metals to its corresponding environment (especially soil and air) (Men et al 2020). The source of toxic metals in dust can be from the resuspension and erosion of surrounding natural environment (soil parent materials) as well as anthropogenic activities such as fossil fuel combustion, traffic activities (e.g., brake lining, tire, and asphalt wear), industrial activities, construction and demolition, waste dumping, and domestic emission (Ali et al 2017; Hou et al 2019; Wang et al 2020). Spatial analysis is a prerequisite to control and manage pollution through exploring the patterns, hotspots, and sources of toxic metals in road dust (Qin et al 2020; Wang et al 2020). 0.3 Akbor et al, 2020; Turekian and Wedepohl, 1961

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