Abstract
Deposits of fibrous sediment, which include fiberbanks and fiber-rich sediments, are known to exist on the Swedish seafloor adjacent to coastally located former pulp and paper industries. These deposits contain concentrations of hazardous substances that exceed national background levels and contravene national environmental quality objectives (EQOs). In this study of metal fluxes from fibrous sediments using benthic flux chamber measurements (BFC) in situ we obtained detected fluxes of Co, Mo, Ni and Zn, but no fluxes of Pb, Hg and Cr. The absence of fluxes of some of the analyzed metals indicates particle bound transport of Pb, Cr and Hg from fiberbanks even though Hg might become methylated under anoxic conditions and, in that case, may enter the food chain. We found less metal fluxes than expected and thus emphasize the importance of in-situ flux measurements as a compliment to sediment metal concentrations within risk assessments of contaminated sediments.
Highlights
The forest industry is prominent in Sweden and plays an important role in the national economy
Surveys of coasts and lakes in northern Sweden established that fiber affected sediments cover at least approximately 29 km2 and of these relatively thick deposits cover an area of about 2.6 km2 (Apler et al, 2014; Norrlin et al, 2016)
Fiberbanks are characterised by elevated organic carbon content, low bulk density, and levels of metals and persistent organic pollutants that are frequently classified as high compared to national background values (Apler et al, 2019)
Summary
The forest industry is prominent in Sweden and plays an important role in the national economy. Large deposits of fibrous waste that accumulated prior to legislation have been identified by marine geological surveys (Apler et al, 2014; Norrlin et al, 2016). Surveys of coasts and lakes in northern Sweden established that fiber affected sediments cover at least approximately 29 km and of these relatively thick deposits cover an area of about 2.6 km (Apler et al, 2014; Norrlin et al, 2016). Apler et al (2019) differentiate between (i) fiberbanks, which are relatively thick deposits of fibrous residues and wood ships often found close to the industrial source and (ii) fiber-rich sediments, which are a mixture of fibrous residues and natural sediment that exist in river beds or marine accumulation areas. We emphasize that fiberbanks are thought to derive from earlier than 1969, when the waste discharge from the pulp and paper industry was unregulated
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