Heavy metals in bulk and particle size fractions from street dust of Kathmandu city as the possible basis for risk assessment

Abstract

Street dust has been sampled from eight major locations of Kathmandu city. The samples were separated into three particle size fractions (<425, 425-600 and >600 μm) and analyzed for Pb, Cu, Zn and Fe using Atomic Absorption Spectrophotometric method. Results revealed that the bulk samples as well as all particle size fractions under investigation were found to have the metal abundance order as Fe > Zn > Cu > Pb. However, the trace metal concentrations increased with the decrease of dust particle size in all samples. About 35-68% of heavy metals were associated with the small particle size fraction (<425 μm) and this particle size accounted for 64-81% of the total mass of street dust from all locations. The smaller particle size fraction has a higher heavy metal content, low density, high mobility in runoff, and thus is a higher risk for the residents of Kathmandu city. From the present study, we conclude that a monitoring plan and a suitable risk assessment are necessary to evaluate the evolution of metal concentration in dust in order to develop the proper measures for reducing the risk of inhalation and ingestion of dust for humans and environment.

Determination and Contamination Assessment of Heavy Metals in Street Dust from Different Types of Land-Use in Kathmandu District, Nepal

“…This is consistent with the findings of Herath et al (2013) who also reported high organic matter content in Colombo metropolitan region due waste disposal, leakage of lubricants and vehicle oil. Further, the present study is also in agreement with the work of Karmacharya and Shakya (2012) and Acosta et al (2011) who reported similar results in properties of street dust.…”

“…Results revealed that dust particle size of 425-150 µm was the main dominant fraction in all the studied areas and varied from 49.17 % (urban) to 56.53 % (residential) of the total fraction. This finding is also supported by the work of Karmacharya and Shakya (2012) who reported dust particle of 425-150 µm mesh size as the major fraction by percentage in street dust. However, the composition of dust may vary depending on climate, human activities, soils and rocks of the surrounding areas etc (Amato et al 2010).…”

“…The alkaline nature of the dust samples reflects the richness of carbonate and/or bicarbonate salts (Yaalon 1997) and also from the aging road and building materials (Sutherland & Tolosa 2000). Alkaline nature of dust was also reported by Christoforidis & Stamatis (2009) and Karmacharya & Shakya (2012) in their studies.…”

Evaluation of the Levels of Some Heavy Metal Contents of Street Dust in Some Parts of Yola Metropolis, Adamawa State, Nigeria

“…The ingestion of dust particles with high concentration of potentially toxic metals, possess a potential threat to human health. For instance, in California, 5-10% of allergen city for atmospheric total suspended particulate matter was attributed to paved road dust emissions [10]. Heavy metals are persistent pollutant that can be biomagnified in the food chain, becoming increasingly dangerous to humans and wild life.…”