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One of the major aims of th EU-INCO-CUULONG project is the evaluation of level and fate of key contaminants in the Mekong Delta and its associated Coastal Zone. Therefore, the concentration of trace elements in sediment, suspended matter and dissolved phase were measured in samples taken during dry and wet seasons (March and October 1997). All measurements have been carried out under controlled conditions. The dissolved fraction of Ni (7.5 nM March, 8.4nM October), Cu (14.5;13.4), Cd (0.07;0.1),Cr(2.8; n.d.),Pb(0.77;0.4),As(10;n.d.),Co(1;n.d.), Hg(0.01;n.d.) and Mn (n.d;81) have measured in a clean room. The results obtained in the river delta area show a constant behaviour during the two seasons, except for Zn which was found approximately 25 times higher in March (187 nM, October 7 nM) probably due to contamination problems during the sampling. The element concentrations in the dissolved fraction decrease in the near share area, and the values are comparable for the two seasons. All the trace element concentrations are comparable with the values measured in major unpolluted world rivers such as Arctic rivers. The average particulate values of as(37.5 mg kg (-1) March and 31.6 October ),Cd(0.61 and 0.8) and Co (18.4 and 22.8) are of the same order of magnitude during both seasons. On the contrary, the average values for Ni, Pb and Cr in October exceed 1.5 -3 times those of March. The Cu was measured during the first cruize only, while Zn (224 mg kg(-1), Al (85000 mg kg(-1)) and Fe (44600 mg kg (-1) have been only analysed in October. A general decrease of particulate concentration from the river to the sea is observed in October whilst the concentration remain rather constant in March, with a noticeable increase in marine water. This was most likely due to the increase of primary production in offshore direction. The space-temporal concentration of trace elements in superficial sediments I.e. Cd (1.3 mg kg (-1) ),Cu (49), Mn (719),Ni (32), Pb (38), Zn (147) and Ti

Additional information

Authors: CENCI R, Instituto dell Ambiente - CCR, Ispra (IT);BARBERO P, Instituto dell Ambiente - CCR, Ispra (IT);TRINCHERINI P R, Instituto dell Ambiente - CCR, Ispra (IT);FACCHETTI S, Instituto dell Ambiente - CCR, Ispra (IT);MARTIN J M, Instituto dell Ambiente - CCR, Ispra (IT)
Bibliographic Reference: Paper presented: International Workshop on the Mekong Delta, Chiang Rai (TH), February 23-27th, 1998
Availability: Available from DG XIII as Paper EN 41253 ORA
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