Image: Markus Nordin
Research project Sediment is a large reservoir for a number of toxic organic chemicals and we therefore need to protect the Baltic Sea and human health. The project focuses on measures and includes identifying toxic substances and their biological effects, developing virtual methods for identifying toxic substances in new samples and studying a non-destructive laboratory-scale decontamination method that has been successfully used on polychlorinated biphenyls. Finally, we will make field trials with the method.
Due to human activities, chemicals are everywhere and serious concern about adverse effects on aquatic organisms have been raised for a long time. Even at trace levels, certain of these contaminants pose an environmental, economic, and health risk. Millions of chemicals are commercially available, but only a minuscule fraction is internationally regulated and monitored (e.g. polycyclic aromatic hydrocarbons, flame retardants, some pesticides, and pharmaceuticals). It is therefore hardly surprising that the compounds that are regulated and monitored cannot explain observed toxic effects. In order to protect aquatic environments and human health, the identification of toxic compounds is of great importance. However, it is a difficult task due to limited knowledge on chemicals reaching the environment and the effects of a multitude of unmonitored and unknown chemicals. Because environmental samples can contain thousands of compounds, it is clear that focus has to be made on the compounds that have not been detected yet and can be responsible for toxic effects.
When chemicals are released, they encounter various biogeochemical processes determining their fate and distribution into the aquatic environment. Sediments are known to be a major sink for a myriad of organic chemicals, but can also represent a significant risk for benthic organisms and coastal ecosystems, including consumption fish species as they can become themselves a source of pollution if remobilized to the water phase. Management of such contaminated sediments includes reducing emissions, monitoring and classifying polluted sediments by risk for humans and ecosystems, as well as in situ remediation measures for polluted sediments.
This project will develop tools to establish causal links between sample constituents in highly complex mixtures and toxic effects, identify toxicants in aquatic environments, and will provide:
We will work on contaminated sediments from the Baltic Sea, associated with pulp and paper mills, fiber banks, oil depots and primary aluminium producers. On these samples we will perform bioassays enabling to determine toxic effects produced by different mechanisms of action (mutagenicity, estrogenic activity, dioxin-like activity and thyroid hormone disruption activity). These different mode of action can provide information on the class of compounds that are responsible for the toxic effects. The next step of great importance is to identify these compounds exhibiting toxic effects. We will use mass spectrometry for this step. The identification will use a combination of fractionation (to reduce the complexity of the sample), bioassays (to know which fraction(s) contain the toxicant(s)) and chemical analysis by mass spectrometry (to put a name on the toxicant(s)).
Knowing which areas are of hazard for the environment and human health is important, the methods described above will help in “mapping” the Baltic Sea, but we need to think on methods to decontaminate these sites. To date dredging (sediments are removed and disposed somewhere else) or capping (sediments are covered by a layer of clean material) are the common methods. However, they are expensive and can be harmful for the aquatic life. We will work on new devices looking like big nails that are pushed into the sediments, where they act as sponges. The contaminants are transferred into the plastic nails that contain a solvent. Thus the contaminants are trapped and nails can be easily removed from the sediments when depolluted. We will have some laboratory experiments with real world sediments in order to understand how it works, for which compounds and how long it needs to be deployed. The final aim will be to deploy in the field as a large scale experiment.
