Seasonal Variations of Heavy Metals in the Soil Around a Coal-Fired Thermal Power Plant, South-West Coast of India

This study focuses on seasonal variations of heavy metals in the soil around a coal fired thermal power plant in Udupi district, which is a densely populated town in the tropical southwest coast of India. This study, pertaining to 48 soil samples, collected during the pre-monsoon, early-monsoon, monsoon and post-monsoon seasons for one year, reveals that the chemistry of collected soil samples is influenced by non-pedogenic (anthropogenic) sources such as fly-ash deposition from the thermal power plant and vehicular emissions. This was concluded based on grouping of similar behaved elements through correlation-regression analysis. The distance-wise distribution of heavy metals and backward wind-trajectory analysis suggests that pre-monsoon and post-monsoonal samples are more influenced by anthropogenic activities compared to rest of the seasons. This is supported by high concentration of Zn in pre-monsoon (25.21 mg/kg) and post-monsoon (21.32 mg/kg) seasons compared to early-monsoon (17.05 mg/kg) and monsoon (8.60 mg/kg) seasons.

Occurrence of polycyclic aromatic hydrocarbons (PAHs) in air and soil surrounding a coal-fired thermal power plant in the south-west coast of India

This investigation focused on the potential sources of polycyclic aromatic hydrocarbons (PAHs) in different matrices and their temporal variations surrounding a coal-fired thermal power plant in India. Samples were collected in different seasons for 1 year. Gas chromatography-mass spectroscopy (GC-MS) was used to perform the measurement of 16 priority PAHs. Average PAH concentrations were ranged from 0.71 to 2.99 ng/m³ in air and 1.59-22.7 ng/g in soil respectively. High levels of PAHs were found in soil compared to air, which indicated deposition in soil. This could be because of the fallout of high-molecular-weight compounds. During the monsoons, PAH concentrations in the air were the lowest compared to the other seasons because of the dilution effect. Phenanthrene, fluoranthene, and pyrenes were dominant in the air, contributing up to 32.5%, 22.7%, and 19.2% of total PAHs, respectively. On the other hand, soils contained fluoranthene (12.3%), pyrene (10.7%), benzo[b]fluoranthene (10%), chrysene (9.82%), and indeno[123-c,d]pyrene (9.64%) compounds. The occurrence of indeno[1,2,3-cd]pyrene (9.14 ng/g) indicated that the soil is contaminated from fly ash and diesel emissions from the thermal power plant and vehicular emission. The diagnostic ratios, thematic maps, and principal component analysis revealed that the fly ash, diesel emissions from the thermal power plant, vehicles, and biomass burning were the probable sources of PAHs in the study area. The human health risk assessment studies reveal that the soil samples are more prone to carcinogenicity than air samples. As per our knowledge, this is the first report on the impact of PAHs on air and soil in this region.