Tunnel vision in current chemicals management cannot deal with the unknown risk of synthetic chemicals in aquatic systems
Chemicals management is focused around the hazard, exposure and risk assessment
of single chemicals. This is a slow process which cannot keep pace with chemical innovation and
development of use. Environmental monitoring focuses on few, and well-known, chemicals. As a
consequence, the majority of all chemicals emitted to the aquatic environment remain unstudied, and
so does their risk. We conclude that to understand how chemical pollution affects aquatic ecosystems,
requires reformation of current chemicals management, moving away from the single chemical
approach. It requires increased transparency regarding chemical content in materials, products and
articles, and importantly, a management system that covers different aspects of the many unknowns
related to chemical pollution of aquatic systems. This implies for instance, environmental monitoring
that screens for a wide range of chemicals and effects, and that is able to detect more unexpected
effects of chemical pollution than what is possible today.
How Important is Bioturbation for Sediment‐to‐Water Flux of Polycyclic Aromatic Hydrocarbons in the Baltic Sea?
In the present study a recently developed benthic flow‐through chamber was used to assess the sediment‐to‐water
flux of polycyclic aromatic hydrocarbons (PAHs) at 4 sites on the Swedish Baltic Sea coast. The flow‐through chamber allows for assessment of the potential effect of bioturbation on the sediment‐to‐water flux of hydrophobic organic contaminants. The sediments at the 4 investigated sites have both varying contamination degree and densities of bioturbating organisms. The flux of individual PAHs measured with the flow‐through chamber ranged between 21 and 510, 11 and 370, 3 and 9700, and 62 and 2300 ngm–2 d–1 for the 4 sites. To assess the potential effect of bioturbation on the sediment‐to‐water flux, 3
flow‐through and closed chambers were deployed in parallel at each site. The activity of benthic organisms is attenuated or halted because of depletion of oxygen in closed benthic chambers. Therefore, the discrepancy in flux measured with the 2 different chamber designs was used as an indication of a possible effect of bioturbation. A potential effect of bioturbation on the sediment‐to‐water flux by a factor of 3 to 55 was observed at sites with a high density of bioturbating organisms (e.g., Marenzelleria spp., Monoporeia affinis, and Macoma balthica of approximately 860–1200 individuals m–2) but not at the site with much lower organism density (<200 individuals m–2). One site had a high organism density and a low potential effect of bioturbation, which we hypothesize to be caused by the dominance of oligochaetes/polychaetes at this site because worms (Marenzelleria spp.) reach deeper into the sediment than native crustaceans and mollusks.