PM09 Sediment Quality Assessment Cases
Exhibit Hall
8:00 AM - Monday
(PM127) In search of reference material for sediment toxicity testing.
Beg, M.1, Al-Ghadban, A.1, Beg, K.1, 1 Kuwait Institute for Scientific Research, P.O. Box 24885, Safat-13109, Kuwait
ABSTRACT- Sediment toxicity is one of the most difficult aspect of overall ecological risk assessment of water bodies. In majority of cases chemical analysis of contaminants is used in predicting the toxicity. However, chemical analysis is mostly restricted to known priority pollutants and suffers a drawback that new or different stressors may not be identified that may cause an affect. Therefore, toxicity defined as biological response is considered a best measure. The toxicity of sediment has been determined by whole sediment, pore water, elutriate, and extracts bioassays. Microtox solid phase test is one of the methods currently used in discriminating contaminated and clean sediment. However, no natural sediment is totally uncontaminated and has the same physical features as the chemically corrupted sediment, also formulated sediment do not represent natural sediment. Therefore, this study was focused on the characterization of sediment samples that can be used as reference material in toxicity testing to ensure quality control of the method. Surface sediments were collected from the high and low contaminated coastal area in Kuwait, freeze dried, sieved with 500 
m mesh and subjected to sequential extraction with organic solvent of increasing polarity to remove petroleum hydrocarbons. Both natural and solvent washed sediments were characterized for organic and inorganic contaminants and subjected to whole sediment toxicity assay using Microtox solid phase toxicity test. The toxicity was not reduced in solvent extracted sediment indicating factors other than the adhered petroleum hydrocarbons exerted major toxic effects. The ash left on incineration of sediments was found to be extremely toxic. Therefore, amendment of sediment by solvent extraction or incineration was not necessary. The difference in Microtox toxicity between high- and low- contaminated natural sediment was around 30-fold, suggesting that the two samples can be used as positive and negative reference sediments, as no such reference sediment samples are available for the toxicity assays of marine sediment from the Gulf region.
Key words: toxicity, microtox, sediment, reference material