Levels of heavy metals in seawater, sediment and in the tissue of <i>Crassostrea belcheri</i> in the western estuary of Ganh Rai bay
Keywords:Heavy metals, estuary, coastal area, oyster, Can Gio.
Recent studies have shown that the seawater, sediment and commercial bivalve molluscs in the studied area have been contaminated by some heavy metals Zn, Cu, Pb and Cr. Highly toxic heavy metals like As, Cd, Pb, Hg have tended to accumulate in the tissue of clams. This paper presents the levels of some heavy metals in the seawater, sediment and soft part of oyster (Crassostrea belcheri) samples collected from the western estuaries of Ganh Rai bay in 2015 and 2017. The results also showed that Ha Thanh and Rach Lo sites recorded the highest contents of most studied metals in oyster samples. Levels of metals in oyster were in the order of Zn > Cu > As > Pb > Cr > Cd > Hg and the contents of metals in oyster did not reflect a correlation with those in surrounding environment. Concerning food safety criteria, Pb, Cd and Hg contents were lower than acceptable limit given by the compilation of FAO (1983), whereas As, Cu and Zn contents exceeded the legal limit, especially Zn contents. Cu and Cr contents in sediment samples of Nga Bay and Dong Hoa estuaries were between LEL-SEL values (≥ LEL and < SEL), which may cause biological impacts at moderate level.
 Luoma, S. N., 1983. Bioavailability of trace metals to aquatic organisms–a review. Science of The Total Environment, 28(1–3), 1–22. https://doi.org/10.1016/S0048-9697(83)80004-7.
 Khaled, A., 2004. Heavy metals concentrations in certain tissues of five commercially important fishes from El-Mex Bay, Alexandria, Egypt.
 Frazier, J. M., 1979. Bioaccumulation of cadmium in marine organisms. Environmental health perspectives, 28, 75–79. https://doi.org/10.1289/ehp.792875.
 Costa-Böddeker, S., Hoelzmann, P., Huy, H. D., Nguyen, H. A., Richter, O., and Schwalb, A., 2017. Ecological risk assessment of a coastal zone in Southern Vietnam: Spatial distribution and content of heavy metals in water and surface sediments of the Thi Vai Estuary and Can Gio Mangrove Forest. Marine Pollution Bulletin, 114(2), 1141–1151. https://doi.org /10.1016/j.marpolbul.2016.10.046.
 Viet Tuan Tran, Phuoc Dan Nguyen, Khanh Duy Nguyen, Bao Phu Nguyen, Emilie Strady, Quoc Tuc Dinh, Sang Nhu Nguyen, Hanh Vu Bich Dang, Seunghee Han, 2016. Monitoring heavy metals in water, suspended particulates, sediment and clam flesh at clam farms in coastal area of Ho Chi Minh city, Vietnam; Proceedings of the 18th International Conference on Heavy Metals in the Environment.
 Pham Kim Phuong, Nguyen Thi Dung, Chu Pham Ngoc Son, 2007. Study on accumulation of heavy metals As, Cd, Pb and Hg from natural environment into bivalve molluscs. Vietnam Journal of Science and Technology, 45(5), 57–62.
 Milazzo, A. D. D., Silva, A. C. M., de Oliveira, D. A. F., and da Cruz, M. J. M., 2014. The influence of seasonality (dry and rainy) on the bioavailability and bioconcentration of metals in an estuarine zone. Estuarine, Coastal and Shelf Science, 149, 143–150. https://doi.org/10.1016/j.ecss.2014.08.013.
 Kefi, F. J., Mleiki, A., Béjaoui, J. M., and El-Menif, N. T., 2016. Seasonal variations of trace metal concentrations in the soft tissue of Lithophaga lithophaga collected from the Bizerte bay (Northern Tunisia, Mediterranean Sea). Journal of Aquaculture Research and Development, 7(6), 432–439.
 Luoma, S. N., 1990. Processes affecting metal concentrations in estuarine and coastal marine sediments. Heavy Metals in The Marine Environment, 124.
 Effendi, H., Kawaroe, M., and Lestari, D. F., 2016. Ecological risk assessment of heavy metal pollution in surface sediment of Mahakam Delta, East Kalimantan. Procedia Environmental Sciences, 33, 574–582. https://doi.org/10.1016/j.proenv.2016.03.110.
 Chen, C., and Chen, M., 2003. Investigation of Zn, Cu, Cd and Hg concentrations in the oyster of Chi-ku, Tai-shi and Tapeng Bay, Southwestern Taiwan. Journal of Food and Drug Analysis, 11(1), 32–38.
 Otchere, F. A., 2003. Heavy metals concentrations and burden in the bivalves (Anadara (Senilia) senilis, Crassostrea tulipa and Perna perna) from lagoons in Ghana: Model to describe mechanism of accumulation/excretion. African Journal of Biotechnology, 2(9), 280–287. Doi: 10.5897/AJB2003.000-1057.
 Le, T. V., Ritchelita, P. G., 2005. Effects of Nix TM grains from Huyndai - Vinashin shipyard on the quality of seawater, sediment and oyster in Van Phong bay, Vietnam. UPV Journal of Natural Sciences, University of the Philippines, 10, 153–165.
 Le, Q. D., Bach, L. G., and Arai, T., 2015. Monitoring heavy metal contamination using rocky oyster (Saccostrea glomerata) in Hai Phong - Ha Long coastal area, North Vietnam. International Journal of Environmental Research, 9(4), 1373–1378. Doi: 10.22059/ijer.2015.1031.
 de Freitas Rebelo, M., do Amaral, M. C. R., and Pfeiffer, W. C., 2003. High Zn and Cd accumulation in the oyster Crassostrea rhizophorae, and its relevance as a sentinel species. Marine Pollution Bulletin, 46(10), 1354–1358.
 Birch, G. F., Melwani, A., Lee, J. H., and Apostolatos, C., 2014. The discrepancy in concentration of metals (Cu, Pb and Zn) in oyster tissue (Saccostrea glomerata) and ambient bottom sediment (Sydney estuary, Australia). Marine Pollution Bulletin, 80(1–2), 263–274. https://doi.org/10.1016/ j.marpolbul.2013.12.005.
 Phillips, D. J. H., Thompson, G. B., Gabuji, K. M., and Ho, C. T., 1982. Trace metals of toxicological significance to man in Hong Kong seafood. Environmental Pollution Series B, Chemical and Physical, 3(1), 27–45. https://doi.org/10.1016/0143-148X(82)90 041-6.
 Riget, F., Johansen, P., and Asmund, G., 1997. Uptake and release of lead and zinc by blue mussels. Experience from transplantation experiments in Greenland. Marine Pollution Bulletin, 34(10), 805–815. https://doi.org/10.1016/S0025-326X(97)00028-3.
 Kargin, F., 1998. Metal concentrations in tissues of the freshwater fish Capoeta barroisi from the Seyhan River (Turkey). Bulletin of Environmental Contamination and Toxicology, 60(5), 822–828.
 Rojas de Astudillo, L., Chang Yen, I., and Bekele, I., 2005. Heavy metals in sediments, mussels and oysters from Trinidad and Venezuela. Revista de Biología Tropical, 53, 41–51.
 Cubadda, F., Raggi, A., and Coni, E., 2006. Element fingerprinting of marine organisms by dynamic reaction cell inductively coupled plasma mass spectrometry. Analytical and Bioanalytical Chemistry, 384(4), 887–896. https://doi.org/10.1007/s00216-005-0256-6.
 Gavrilovic, A., Srebocan, E., Pompe-Gotal, J., Petrinec, Z., Prevendar-Crnic, A., and Matasin, Z., 2007. Spatiotemporal variation of some metal concentrations in oysters from the Mali Ston bay, south-eastern Adriatic, Croatia–potential safety hazard aspect. Veterinarni Medicina, 52(10), 457–463.
 Bille, L., Binato, G., Cappa, V., Toson, M., Dalla Pozza, M., Arcangeli, G., ... and Piro, R., 2015. Lead, mercury and cadmium levels in edible marine molluscs and echinoderms from the Veneto region (north-western Adriatic Sea–Italy). Food Control, 50, 362–370. https://doi.org/10.1016/j.foodcont.2014.09.018.
 Chong, K., and Wang, W. X., 2001. Comparative studies on the biokinetics of Cd, Cr, and Zn in the green mussel Perna viridis and the Manila clam Ruditapes philippinarum. Environmental Pollution, 115(1), 107–121. https://doi.org/10.1016/ S0269-7491(01)00087-2.
 Tapia, J., Vargas-Chacoff, L., Bertrán, C., Carrasco, G., Torres, F., Pinto, R., ... and Letelier, L., 2010. Study of the content of cadmium, chromium and lead in bivalve molluscs of the Pacific Ocean (Maule Region, Chile). Food Chemistry, 121(3), 666–671. https://doi.org/10.1016/ j.foodchem.2009.12.091.