Understanding the Sources of Heavy Metal Pollution in Ambient Air of Neighboring a Solid Waste Landfill Site

Abstract

With growing urbanization and industrialization, problems such as poor disposal practices of solid waste and ensuing uncontrolled air pollution adjacent to landfill pose threats to human and environmental wellbeing. Ahmedabad is highly polluted urban city in India and unregulated burning of solid waste further aggravates already appalling situation caused by a large number of industries and vehicle fleets. The present work was carried out to understand sources of metals in ambient air surrounding a municipal landfill known as Pirana. For the study, surrounding area of the landfill was divided into 100 rectangular cells covering almost 5 km distance from its outer boundary. A location representing major land-use feature of each cell was classified. Sampling was carried out at these locations. A total of 100 PM_5.0 samples were collected. Sampling was conducted for 3 h at each sampling location with samples collected on quartz filter paper. Measurements were performed over approximately 6 months from August to February, 2018. The filters were analyzed for metals using an Atomic Absorption Spectrometer. These measurements were used to identify pollution sources using positive matrix factorization technique and locate the hotspots of emission sources of heavy metals pollution. Five major sources namely, ferrous industry, nonferrous industry, vehicular emissions, re-suspended dust and solid waste burning/industrial coal combustion were identified and quantified. The average contributions of these sources to heavy metals were 20.7 ± 16.2, 18.4 ± 14.3, 19.9 ± 13.6, 21.4 ± 17.6, and 19.6 ± 10.6%, respectively. The average contribution from solid waste and industrial coal combustion is only 19.6% against the total from the combined remaining sources (~ 80.4), which means contribution from former will be lesser. Thus, solid waste burning is minor contributor for degradation of air quality; presence of many other sources around the site is actually the dominant cause of pollution.