Leaching behaviour of sintered contaminated marine sediments

Contaminated marine sediments from Cantabrian es¬tuaries have been compacted and fired to produce sintered ceramic materials. The effect of sintering on the leaching behaviour has been investigated by means of the compari¬son of concentrations of species proposed by the European Waste Landfill Directive present in leachates and regula¬tory limits for them. The impact of the specimens on the environment is assessed. In order to reach this objective, unfired and fired sam¬ples of marine sediments and clay were subjected to the Compliance Leaching Standard Tests EN 12457 1-2 using different liquid to solid ratios (L/S = 2 and 10). The con¬centrations of Se, As, Cr, Sb, Zn, Cd, Pb, Ni, Ba, Mo, Cu, fluoride, chloride and sulphate in leachates were analyzed, and the results compared with regulatory limits collected in 2003/33/CE Directive. The results revealed that the firing process decreases the leaching of the species analyzed, except for As. The comparison of the metal and metalloid concentrations in leachates and regulatory limits showed that all species fulfilled them, excepting As, fluoride, chlo¬ride and sulphate in unfired specimens. Thus, the potential environmental risk in relation to the leaching behaviour associated to the sintered contaminated marine sediments can be considered to be low versus to commercial clay.Peer reviewe

Toxicity bioassays in core sediments from the Bay of Santander, Northern Spain

Δημοσίευση σε επιστημονικό περιοδικόSummarization: The use of Vibrio fischeri as luminescence bacteria is particularly effective in evaluating contaminated sediment. In this study, the ecotoxicity of five core sediments from the Bay of Santander, northern Spain, utilising V. fischeri as marine bacterium, was carried out. Different toxicity assay procedures were applied in order to study the influence of the mobility and bioavailability of the pollutants. Basic Solid Phase Test (BSPT) in whole sediment and acute toxicity test, using pore water and three leaching test procedures as liquid extracts, were applied. In addition, the study of the influence of the pH value on the toxicity results of the leaching tests was conducted. The obtained results show toxicity units (TU50) values in BSPT test ranging from 0.42 to 39.06 with a decrease with depth as general trend and TU50 values from 0.010 to 0.389 in the liquid extracts, where TU50 is calculated as the inverse of EC50 (%). The obtained data show the historical toxicity trends of the Bay of Santander and provides a technical database for the management of contaminated sediments. Moreover, these results showed evidence that each sediment test procedure provided independent and complementary ecotoxicological responses useful for a sediment classification. In order to analyse the correlations between chemical parameters (both organic and inorganic) and the toxicity results, the self-organising map (SOM) neural network and regression equations were applied. Satisfactory correlations (R=0.93) between chemical concentrations of sum of five heavy metals and 16 PAHs and BSPT toxicity were obtained.Presented on: Environmental Researc