Movement of Arsenic in Amon(monsoon) Rice Plants Cultivated on Arsenic Contaminated Agricultural Fields of Nadia District, West Bengal

Mandraha, Shivanand (2014) Movement of Arsenic in Amon(monsoon) Rice Plants Cultivated on Arsenic Contaminated Agricultural Fields of Nadia District, West Bengal. Masters thesis, Indian Institute of Science Education and Research Kolkata.

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Abstract

Agriculture in West Bengal (WB) is the means of livelihood of about 65% of the population of the state living in villages. The agricultural economy of the state is heavily dependent on the vagaries of monsoon with an average annual rainfall of 195.98 cm. Arsenic (As) contamination in soil and irrigation water elevates As concentration in rice grains, so rice consumption is changing into a very important As intake route for populations in south and south-east Asia. The study area comes in one of the eight districts in West Bengal, India where groundwater contains arsenic above the prescribed limit by WHO (10μg/l). Each day groundwater is being withdrawn by the village people for the fulfillment of their basic needs and for agricultural purposes.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 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 concern a somewhat detailed study was carried out to obtain an idea about the magnitude of rice paddy, soil and water contamination in the areafor the rice growing period. It was found that the mean concentration (mg/kg) of As (36), Cu (125.27) and Mn (223.90) were higher than the prescribed limits for agricultural soil. The quantities of heavy metals (Ni, Cr, Cu, Pb, Zn, As, Mn, and Mg) were also determined in different parts of rice plants. Results revealed that the mean levels ofheavy metals in different parts of rice plant (root, straw, husk and grain) showed the common trend of bioaccumulation. The content of Cu, Pb, Zn, As, and Mn were significantly higher in root than in aerial parts of the rice (straw, husk and grains). And also the metal transfer factors from soil to rice plants were significant for these heavy metals. Mainly the mean arsenic concentration (mg/kg) in root of the matured plant was around 36 followed by straw, husk and grains as 16.28, 1.65 and 0.52 respectively.

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