EXTENT OF ARSENIC AND OTHER HEAVY METAL CONTAMINATION IN AGRICULTURAL SOILS OF GANGA DELTA REGION, INDIA

Heavy metal toxicity is one of the major current environment health problems and is potentially dangerous because of bio-accumulation through the food chain and this can cause hazardous effect on livestock and human health. Likewise the use of arsenic (As) contaminated shallow groundwater for irrigation of crops has resulted in elevated concentrations of arsenic in agricultural soils in West Bengal (India), Bangladesh, and elsewhere. Each day groundwater is being withdrawn by the village people for the fulfillment of their basic needs and for agricultural purposes. With the groundwater along with high concentration of arsenic (As), many other heavy metals are also getting introduced in the environment. In the areas with a long history of use of such groundwater, the agricultural lands have been affected severely. The concentrations of As in non-contaminated soils range from 0.1 to 10 mg/Kg. But the extent of contamination has increased to a level where the crops grown in those lands are becoming a major source for arsenic and other heavy metals poisoning and subsequently transfer to different trophic levels. Based on this a somewhat detailed study was carried out to obtain an idea about the magnitude of soil contamination of the agricultural lands irrigated with arsenic contaminated groundwater. In the study it was clearly observed that the mean concentrations (mg/kg) of As (54.40), Fe (15745.50), Mn (307.90), Cu (69.33) and Zn (44.56) were found to be in higher side, mainly arsenic which is at an alarming point. In order to check the source for arsenic accumulation in the soil, the correlation of the As concentration in soil and water was carried out. It was observed that the As concentration in soil and water were positively, specially As rich irrigation water can enrich the As level in agricultural soil up to five times than normal which was also found in several previous studies. The regression analyses were carried out between As and different heavy metals in agricultural soil. Results showed positive significant correlation between As and Fe (r² = 0.599), As and Mn (r² = 0.626), As and Zn (r² = 0.551), and As and Cu (r² = 0.580). Thus, there is a serious immediate concern for the people and other life forms living in this area regarding the poisoning through crops and drinking water as well.