AVALIATION OF BIOACCUMULATIVE EFECTS OF METALS IN OYSTERS Crassostrea brasiliana EXPOSED TO PRODUCED WATER DISCARD AT THE SEA
oysters, metals, ICP OES, marine water, produced water
The Produced Water (PW) is one of the oil industry main problems due to its large production volume and high complexity. To carry out its disposal in marine environments it is necessary the removal of toxic substances present in the environment, among these substances are metals. Metals when present in the aquatic environment, even at low concentrations, are capable to provocate bioaccumulating in organisms, mainly the filter bivalve molluscs, such as oysters. The present study aimed to evaluate the metal quantification in bivalve molluscs (Crassostrea brasiliana), which serve as marine's waters contamination bioindicators by metals. For this purpose, it was simulated a real produced water discard from the Potiguar Basin, using distinct concentrations in sea water from the Areia Preta / RN beach. The physical-chemical parameters of the water, such as pH, temperature, salinity, dissolved oxygen, total dissolved solids and conductivity were evaluated daily, as well as the tissue of oysters exposed to this citaded conditions. In order to determine the metals Cadmium, Cobalt, Copper, Nickel and Lead, the samples were decomposed with a closed system assisted by microwave radiation using Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) for quantification. A decrease in the concentration of all metals in water over time was observed, as expected, according to evidenced by their absorption by oysters. In an environment with higher water content, this absorption is limited. In aquaria containing the highest concentration of produced water, survival was only 70 hours. It was also observed that with a lower concentration of PW and metals in the medium, higher was removal's rate. The results obtained after oyster analysis showed that how lower metal's concentration in water, greater the oysters absorption potential. Therefore, it is concluded that oyster exposure tests in front of the produced water show that these can function as indicative species for contamination of aquatic environments and Inductively Coupled Plasma Optical Emission Spectrometry technique was efficient in determination of metals in the studied matrixes, showing good linearity (r2>0.998 for all metals determined with DPR <5%) and quantification limits between 0.0003 and 0.0045 mg.L-1.