Search

Background, aim, and scope It is well known that contaminated sediments represent a potential long-term source of pollutants to the aquatic environment. To protect human and ecosystem health, it is becoming common to remediate contaminated sites. However, the great cost associated with,e.g., dredging in combination with the large numbers of contaminated sites makes it crucial to pinpoint those sites that are in greatest need of remediation. In most European countries, this prioritization process has almost exclusively been based on chemical analyses of known substances; only seldom toxicity data has been considered. The main objective of the current study was therefore to develop a tool for hazard identification of sediment by ranking potential toxicity of organic sediment extracts in a crustacean and a fish. A secondary objective was to investigate the difference in potential toxicity between compoundswith different polarities. Materials and methods Early life stages of the crustacean Nitocra spinipes and the fish Oncorhynchus mykiss, which represent organisms from different trophic levels (primary and secondary consumer) and with different routes of exposure(i.e., ingestion through food, diffusive uptake, and maternal transfer), were exposed to hexane and acetone fractions(semi-polar compounds) of sediment from five locations,ranging from heavily to low contaminated. Preliminary tests showed that the extracts were non-bioavailable to the crustacean when exposed via water, and the extracts were therefore loaded on silica gel. Rainbow trout embryos were exposed using nano-injection technique. Results and discussion Clear concentration–response relationships of both mortality and larval development were observed in all tests with N. spinipes. Also for rainbow trout,the observed effects (e.g., abnormality, hemorrhage, asymmetric yolk sac) followed a dose-related pattern. Interestingly, our results indicate that some of the locations contained toxic semi-polar compound

Part of urn:nbn:se:su:diva-8143

In a series of bio-effect-directed fractionation experiments, we investigated the potential toxicity of sediment extracts from a contaminated bay. A previous study investigated abnormalities and hepatic ethoxyresorufin O-deethylase (EROD) activities in rainbow trout (Oncorhynchus mykiss) larvae by exposing newly fertilized eggs to the total extract and to fractions separated by degree of aromaticity. A major part of the potential toxicity was isolated in a fraction containing polycyclic aromatic compounds (PACs). In this study, we prepared a synthetic PAC mixture with 17 commonly analyzed polycyclic aromatic hydrocarbons (PAHs) in amounts equimolar to those found in the sediment PAC fraction. The 17 PAHs, which included 11 of the 16 United States Environmental Protection Agency (US EPA) priority PAHs, were unable to account for the toxicopathic effects observed and could explain less than 4% of the total EROD induction. The lack of a clear relationship between toxicopathic effects and EROD induction underlines the need for a battery of biomarkers for estimating environmental risk. These results reveal the limits of our knowledge regarding compounds responsible for potential toxicity in field situations., Part of urn:nbn:se:su:diva-510

Part of urn:nbn:se:su:diva-510