Correlation among toc and heavy metals in groundwater used for irrigation in Bangladesh

Abstract

A comparative study was conducted in this current experiment to correlate Total Organic Carbon (TOC) with arsenic (As), iron (Fe), manganese (Mn), calcium (Ca), Alkalinity and Electric Conductivity (EC) by determining their concentration in groundwater extracted from irrigation wells. Three locations in three different districts Munshiganj, Comilla and Bogra were selected as sampling sites, the first two was known as the area laden with high arsenic concentration in groundwater where the last one is known as the arsenic unaffected area. For samples collected from agricultural land in Munshiganj, TOC was found at a median concentration of 14 ppm with a range from 2.4 – 31.4 ppm. TOC value ranged from 0.03-7.2 ppm with median value of 2 ppm in Comilla and 0.04-1.6 ppm with median value of 0.17 in Bogra. The study shows that TOC is correlated with arsenic when concentration of both is much lower. The correlation between TOC and arsenic is moderate to mild in Munshiganj, Comilla and Bogra. Moreover, TOC is moderately correlated with alkalinity and EC with correlation coefficient greater than 0.5 in Munshiganj and Bogra. On the other hand, no significant correlation was found between TOC with Fe, Mn and Ca.