Experimental Studies on the Bioaccumulation of Selected Heavy Metals and Radionuclides in the Blood Cockle Anadara granosa of the Bang Pakong Estuary
KANITHA SRISUKSAWAD AND NIKOM PRASERTCHIEWCHAN
Thailand Institute of Nuclear Technology (TINT), Chatuchak District, Bangkok, Thailand
Biokinetic experiments of essential metal (65Zn), heavy metals (51Cr, 203Hg) and anthropogenic radionuclides (57Co, 85Sr, and 134Cs) on Anadara granosa from Bang Pakong estuary were performed under controlled conditions (salinity 30 psu, temperature 28.5±1.5oC and pH 8.0±0.1). The results showed that A. granosa accumulates studied metals and radionuclides efficiently, except 85Sr and 134Cs. Uptake of 51Cr, 57Co and 65Zn in A. granosa displayed saturation kinetics with estimated whole-body steady-state concentration factors (CFss) of 24, 730, and 90, respectively. Accumulation of 203Hg by A. granosa followed a simple linear model (R2 = 0.83), with maximum concentration factor (CFM) of 166. Loss kinetics of 57Co, 65Zn and 203Hg were best described by a 2-component exponential model, with computed half lives for long-lived component ranging from 99 to 125 d, whereas loss kinetics of 51Cr was best described by a single exponential model with computed half life of 16 d. 51Cr, 57Co and 65Zn were distributed rather similarly between shells and soft parts whereas 203Hg was mostly detected in the soft parts. Overall these experiments indicate that A. granosa could be used as a bioindicator species for monitoring environmental contamination by 51Cr, 57Co, 65Zn and 203Hg, but not 85Sr and 134Cs. Hence, the use of A. granosa as a bioindicator of possible releases from nuclear facilities in which Sr and Cs are important radio-contaminants may not be appropriate. The results obtained from these experiments demonstrate how nuclear detection techniques may be useful for regulators and managers dealing with the marine coastal zone.
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