Assessment of bioaccumulation and biomagnification of arsenic in paddy fields

In the present study, arsenic fluxes at sediment-water interface, distribution, bioaccumulation, biomagnification and factors affecting those were determined. The present study was conducted by sampling from ponds in Crowley, LA, USA where crayfish and rice farming in common. Different characteristics of water sources, sediment, and vegetation of three stations were selected. Water, sediment, vegetation and crayfish (Procambarus clarkii) samples were collected from the stations once bimonthly, over the season (November 2013-April 2014). Arsenic concentrations were determined in crayfish tissues and in all the other samples. The most important factors that control arsenic mobility in sediment were determined as pH, ORP and Fe-Al (hidr)oxides. Arsenic concentration in rice, straw and weed were ranged 0.33-0.41 mg kg-1, 3.14-4.93 mg kg-1, and 3.26-5.89 mg kg-1, respectively. Arsenic accumulation levels in the crayfish tissues were gill (S)>hepatopancreas (H)> exoskeleton (D)>muscle (K). Arsenic in muscle tissues showed positive correlation (R2=0.59-0.65) with body weight. The highest biomagnifications in crayfish were occurred in hepatopancreas and gill tissues. Pattern of arsenic accumulation in crayfish was S>H>D>K, after 14 days of exposure of different concenrations of arsenic.