HEAVY METALS IN THE ENVIRONMENT OF VANPHONG - BENGOI BAY IN KHANH HOA PROVINCE
The paper represents some aspects on the heavy metals in water, sediment, oyster Saccostrea cucullata and seagrass (Thalassia hemprichii and Enhalus acoroides) at Vanphong - Bengoi bay. Results of surveys (performed in April - June 2009, dry season, and October - November 2009, rainy season) show that the heavy metal concentrations in water (Zn from 8.7 to 34.0mg/l; Cu from 0.6 to 42mg/l; Pb from 0.4 to 3.8mg/l; Cd from 0.04 to 0.32mg/l and Cr from 1.1 to 3.1mg/l) were not high. In sediment, heavy metal contents (Zn from 19.4 to 68.2mg/g; Cu from 0.4 to 11.7mg/g; Pb from 1.9 to 22.9mg/g; Cd from 0.5 to 0.21mg/g and Cr from 4.3 to 26.6mg/g) were also not high compared to critical values in criteria for Aquatic Life Protection except sediment near Huyndai Vinashin-Shipyard (HVS). In oysters, heavy metal contents (Cu from 100 to 246 mg/g wet weigh; Pb from 0.19 to 0.44mg/g wet weigh; Cd from 0.4 to 0.83mg/g wet weigh and Cr from 0.28 to 1.03mg/g wet weigh) were comparatively low compared to the maximum permissible levels for seafood safety, except Cu, especially in My Giang - near HVS. Seagrass leafs also considerably accumulated heavy metals (Fe from 54.3 to 68.2mg/g dry weigh; Zn from 29.6 to 35.3mg/g weigh; Cu from 5.0 to 5.4mg/g weigh and Pb from 1.8 to 2.6mg/g weigh).The data also indicated that there were no difference in heavy metal levels in water and oyster between two seasons.