Phytoremediation potential of some naturally grown weeds for arsenic contaminated soils of bangladesh

Abstract

Abstract : With the aim of verifying a phytoremediation option for the farmers of arsenic affected areas of Bangladesh, a study was undertaken in the field laboratory of Department of Agricultural Chemistry, Bangladesh Agricultural University, Mymensingh with eight weed species commonly grown in Bangladesh. The weeds are barnyard grass, Yellow nut sedge, ‘joina’, ‘chesra’, ‘topapana’, Water taro, Water cress and ‘malancha’. Initially the soil was treated with seven As levels viz. 0, 10, 20, 30, 50, 70 and 100 mg/kg arsenic from sodium arsenite (NaAsO?) and used for phytoremediation study by the weeds. The soils after two steps of phytoremediation study were used for the present experiment. In all the weeds, the concentration of arsenic increased significantly with increasing soil arsenic levels. On the other hand, the biomass of all weeds gradually decreased with increased soil As level. Among the weeds, the highest As concentration was found in the root of barnyard grass (Echinochloa crusgalli) (53.1 mg/kg) when soil arsenic concentration was 6.8 mg/kg. In all the weeds, the concentration of arsenic was found much higher in root than in shoot. The highest recovery of arsenic (211.97 pg/pot) was found in water taro (.Monochoria hastata) followed by barnyard grass {E. crusgalli) (125.40 pg/pot) and water cress (Enhydra fluctuans) (110.10 pg/pot). The reason of highest As absorption by water taro might be due to its highest biomass production. Considering the present findings, it could be tentatively said that, among the weeds under study, barnyard grass and water taro have the potentiality to remedy As from contaminated soils.