Mobility of arsenic in fiber banks off the coast of Västernorrland

Off the coast of Västernorrland lies a large number of fiber banks and fiber-rich sediments. These banks and sediments originate from the many sawmills and pulp and paper industries located along the coast and streams. These industries not only emitted residues of wood and cellulose but also heavy metals and organic pollutants such as DDT, PCBs and dioxins.

Arsenic is present in most of the fiber banks that have been studied, and at levels that are considered to be “highly contaminated”. Arsenic is toxic to humans and animals and, given the levels, would pose a threat if it began to leak from these fiber banks. There are several reasons why arsenic and other toxic compounds would start to spread from the banks, e.g. due to increased agitation of the seawater, as a result of the land rise combined with more extreme weather, warmer seas or increased boat traffic. It can also occur as a result of the influence of microorganisms. Microorganisms are known to guard themselves against toxic substances by making them more water soluble so that they are easily transported away from their immediate environment. This can be achieved by producing complexing agents that bind to metal ions. Examples of complexing agents are so-called siderophores, but also simpler organic acids such as oxalic acid or citric acid. The fact that microorganisms can produce molecules capable of binding toxic metals can be perceived as means of potential bioremediation of contaminated soil, but also as a threat of undesirable leakage of toxic compounds from the aforementioned fiber banks.

In the project the presence of naturally occurring complexing agents that have the potential to bind arsenic will be examined. The study will mainly be carried out by means of liquid chromatography analysis coupled to mass spectrometry.