9thInternational Symposium on Environmental Geochemistry
Aveiro, 15th– 21th July 2012
CHARACTERISATION OF HEAVY METAL POLLUTION IN SPENT ABRASIVE MATERIAL AND NEARBY MARINE SEDIMENTBY USING SEDIMENT QUALITY INDICES AND SINGLE EXTRACTIONS IN VAN PHONG BAY – VIETNAM.
1,2Tran Thi Thu Dung, 2,3Valérie Cappuyns, 4Nguyen Ky Phung, 2Rudy Swennen
1.Faculty of Environment, University of Science, 227 Nguyen Van Cu St, W4 D5, Ho Chi Minh City, Vietnam. Email:
2. Geology, Earth and Environmental Sciences, K.U.Leuven, Celestijnenlaan 200E, B-3001 Heverlee, Belgium
3.Hogeschool-Universiteit Brussel, Warmoesberg 26, B-1000 Brussels, Belgium
4.Institue of Hydrometeorology and Environment, 19 Nguyen Thi Minh Khai St, W Ben Nghe D1, Ho Chi Minh City, Vietnam
Abstract
In recent years, the shipping industrial activities developed in Van Phong bay, located inthe South-Central partof Vietnam, have raised an urgent environmental concern relating to theuse of copper slag as abrasive material for removing rust and marine deposits from ships.This study was conducted to investigate the characteristics of the spent copper slag used as abrasive material and sediment samples collected nearbythe area of the shipping company in Van Phong bay. Moreover, some single extractionswere performed to examine under which conditions heavy metals may leach out from the spent copper slag and sediment.The obtained results indicated that sediments at Van Phong bay were characterized by a low clay mineral and organic matter content anda low cation exchange capacity. The carbonatecomponent (inferred from Ca content) was dominant in all sediments (25%). A strongpositive correlation was found between Al, Fe, K and organic matter content and some heavymetals (As, Pb and Zn).A combined approach using sediment quality guidelines (SQGs) and differentquantitative indices (Geo-accumulation Index- Igeo, Enrichment Factor- EF, PollutionLoad Index – PLI and Risk assessment Code – RAC) was used to investigate thepollution status by heavy metals in the studied area. Among the heavy metals,As shows the greatest concern because of its high EF and Igeo. Concerning to results of RAC, Zn, Cu, Pb and As possess a“high risk” in the sediment and spent copper slag to environment due to the high RAC. Somemarine sediment samples adjacent to the abrasive blasting working area can be considered as hot spots of pollution in thestudied area because of the high value of all quantitative indices and classified in thehighest class of “adverse biological effects” ( as SQGs).The results from the single extractions suggest that heavy metals in both sediment andspent copper slag show a low actual mobility (according to CaCl2 extraction) and were noteasily mobilized by sea water (extractability < 1% of total concentration by NaClextraction) and organic complexion agent (extractability < 10% of total concentration byEDTA extraction). The acidification processes based on CH3COOH extraction showed amore pronounced effect on heavy metal release in sediments (except Cd and Pb) and spent copper slag.