SEASONAL VARIATION ON ARSENIC & TRACE ELEMENTS MOVEMENT IN AGRICULTURAL SOIL OF GANGETIC DELTA REGION OF INDIA

The extensive and prolonged use of agro-chemicals in agricultural field is one of the major causes of accumulation of trace metals in soil. Distribution of arsenic and heavy metals in soil and determining their status of relative abundance in soil and plants provide a valuable access to the knowledge of soil pollution and soil health. Contamination by high concentration of arsenic in groundwater increases total content of arsenic in agricultural field and this results into crops uptaking those metals depending on the availability rather than total content of metal in soil. Presence of high level of arsenic and heavy metals in agricultural fields of lower region has an adverse effect on crop productivity and quality being a potential health risk factor too. The present study shows the seasonal impact on arsenic and other trace elements dispersal in agricultural soil in Chakdaha region during two different paddy cultivation, Boro and Amon cultivation. The results show the concentration of selected metals in a respective year on the same sampling site. The study tried to find out the concentration (mg/kg) of arsenic (As) and iron (Fe) of soil samples along with four other trace metals (Copper, Zinc, Lead and Cadmium).The mean concentration of Fe, As, Zn, Pb, Cd, Cu are 6746.85 , 7.93 , 80.27 , 2.42 , 0.15 , 38.63 present in control field whereas, 11379.39 , 57.98 , 118.84 , 9.77 , 0.41 and 84.65 present in experimental field in boro season and 32722 , 11.09 , 113.81 , 4.029 , 0.324, 64.24 in control field and 37785, 36.78, 112.31, 4.92 , 0.57 and 63.29 in experimental field in monsoon season. A mix trend has been observed in both type of irrigation viz monsoonal and groundwater irrigation. During analysis of pollution indices, contamination factor (CF), Pollution Load Index (PLI), geo-accumulation index (I_geo), enrichment factor (EF), all shows the range of low to moderate to considerable amount of contamination. This study is quite important to show the movement of trace metals through water to soil accumulating in a higher degree. The concentration (mg/kg) of studied metals of soil samples help to assume the situation of agricultural soil in respect of increasing metal(loid)s changing with time due to the continuous use of contaminated groundwater.