Investigation of pollutant metals in road dust in a post-industrial city: Case study from Detroit, Michigan

Abstract

Inhalation and/or ingestion of toxic heavy metals enriched in road dust have toxic effects on humans. From inhalation and ingestion of dust, release of readily bioavailable elements sorbed on to dust, could lead to health issues such as lung or skin cancer, kidney dysfunction, hypertension, dermal lesions, peripheral neuropathy, and vascular disease. On 49 road dust and soil samples collected in the Metro Detroit area, we analyzed a suite of trace metals in <63 μm and size-separated fractions to quantify the extent of metal enrichment and contamination status. We evaluated Enrichment Factor (EF), Pollution Index (PI), Geoaccumulation Index (GI), and Pollution Load Index (PLI). The average Chromium (Cr) concentration of 198 ppm is the highest reported for any global city in literature while in ∼80% samples, Barium (Ba), Cr, Lead (Pb), and Zinc (Zn) concentrations exceeded the USEPA limit. The EF for Barium (Ba) was found to be ≥9 in all samples, and for the rest of other elements was >1.5. The PI values for Cr, Ba, Zinc (Zn), Lead (Pb), and Selenium (Se) indicate elevated levels and for Ba, Cr, and Zn up to a moderate level. PLI values in >50% of road dusts were ≥3, indicating many sites are ‘heavily polluted’. The PLI value in Detroit road dust is higher than those reported for some other global cities including Shanghai. Observed strong correlations between Cr-Zn and Cadmium (Cd)-Silver (Ag) likely indicate a common metal source. Cluster analysis of data for Cd, Arsenic (As), Pb, and Zn appears to be distinct between different proximally related clusters, while Nickel (Ni) and Ba are potentially more distinct between property type clusters. In general, metal concentrations of industrial samples are more commonly distinct with over half of metals (≥6 of 11) differing from residential and/or soil samples. Three generalized “groups” were identified from the combination of hierarchical cluster and PCA analyses followed by varimax rotation: Group 1 characterized by Cr, Cd, Ni, Ag, Zn, and Copper (Cu); Group 2 characterized by Pb, As, Mercury (Hg), and minor Ba; and Group 3 characterized by Se. This is the first study to report all four metrics of metal pollution along with rigorous statistical analysis.

Metal Element Traces Sampled from Peri-Urban Road Verge Particulate Matter

“…Excessive interaction with heavy metals can precipitate a range of detrimental health effects, encompassing impacts on the nervous, skeletal, circulatory, enzymatic, endocrine, and immune systems. A case in point is the inhalation of soil dust enriched with cadmium (Cd), which is associated with chronic health outcomes including lung cancer, chronic obstructive pulmonary disease, and compromised lung function [20].…”

Pollution and Health Risk Assessments of Potentially Toxic Elements in the Fine-Grained Particles (10–63 µm and <10 µm) in Road Dust from Apia City, Samoa

“…Cr is used for the wheels of vehicles, and many parts of vehicles are plated with Cr as it has an aesthetic appearance and is not easily corroded. Many studies have reported that Cr contamination in road dust and soil is due to traffic and industrial activities [63][64][65][66].…”

Spatial Analysis of Heavy Metal Pollution in Road-Deposited Sediments Based on the Traffic Intensity of a Megacity

“…These studies have been fundamental to adapt those indices to the integral analysis of HMs in the RDS, through criteria such as the level of toxicity, persistence in the environment, and biological accumulation. This has also allowed an ecological and public health risk assessment to take place due to HMs associated with the RDS, with ecological risk, and non-carcinogenic and carcinogenic risk indices [27,33]. In different studies, there were also joint evaluations between indices.…”