Analysis and assessment of heavy metals in soils around the industrial areas in Mettur, Tamilnadu, India.

Abstract

Industrialization and extraction of natural resources have resulted in large-scale environmental contamination and pollution. We have collected the soil samples from five different industrial areas of Mettur (Chemplast Sanmar Limited, SIDCO-1, SIDCO-2, SIDCO-3, thermal power plant), Salem district, Tamil Nadu, India, and estimated the physical properties (pH, EC, and alkalinity), chemical properties (major and minor elements), and heavy metal analysis. Thermal power plant soil sample showed higher pH5.01, EC 29.33μmhos/cm compared with rest of the samples. Acidic nature of the soil samples near thermal power plant was due to the effect of ash disposal. The high electrical conductivity is due to the disposal of soluble electrolytes and deposition of dust particles released from Thermal Power Plant.Alkalinity of the SIDCO-2 soil (410ppm) was higher than that of rest of the soil samples. Soil samples show higher concentrations of chloride (10,400ppm) from thermal power plant when compared with soil sample collected from all 15 sample areas. It was found that heavy metal concentrations lie in the following ranges: Cu (3.780-86.360ppm) > Pb (0.018-1.710ppm) > As (0.053-0.342ppm) in Mettur area. The maximum concentration of copper (Cu) found in SIDCO-1 (86.360ppm) was due to electroplating industry, smelting and refining, mining, and biosolids. Maximum concentrations of arsenic (As) recorded (0.342ppm) in thermal Power plant was due to ash disposal from the coal-fired thermal power plant. And maximum concentrations of lead (Pb) (1.710ppm) in Chemplast area are due to the effluent discharge of manufacturing units like PVC resins, chlorochemicals, and piping systems in Chemplast which are main source of heavy metal pollutants. Therefore, major mining and smelting of metalliferous ores, burning of leaded gasoline, municipal sewage, industrial wastes enriched with Pb, and paints, which exceeded WHO (2011) and BIS (2003) recommended standard for lead (0.090ppm) and arsenic (0.010ppm). The geo-accumulation index (Igeo) study indicates that there is no significant contamination with lead and arsenic but there is a moderate contamination with copper (86.360ppm). According to the calculated values of PLI, area 1 (0.061) has been contaminated high compared with other areas.