Influence of historical industrial epochs on pore water and partitioning profiles of polycyclic aromatic hydrocarbons and polychlorinated biphenyls in Oslo Harbor, Norway, sediment cores

Abstract

Contaminant levels in urban harbor sediments vary with contaminant emission levels, sedimentation rates, and sediment resuspension processes such as propeller wash. Levels of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) are decreasing in many urban harbors, as heavily contaminated sediments that accumulated during past decades are being buried by less-contaminated sediments. However, PAHs and PCBs remain a concern in areas where burial is slow or resuspension processes re-expose heavily contaminated older layers. Chronostratigraphic sediment core studies typically characterize contaminant level histories by using total sediment concentrations, C(sed) , and do not determine the freely dissolved porewater concentrations, C(pw) , which provide a better measure of bioavailability. Here both C(sed) and C(pw) profiles were established for PAHs and PCBs in dated sediment cores from diverse areas of Oslo Harbor, Norway. Sediment-porewater partitioning profiles were established alongside profiles of various sorbing carbonaceous phases, including total organic carbon (TOC), black carbon, and diverse carbonaceous geosorbents identified by petrographic analysis. Stratigraphic trends in carbonaceous phases and C(sed) could be associated with different industrial epochs: hydropower (post-1960, approximately), manufactured gas (∼1925-1960), coal (∼1910-1925), and early industry (∼1860-1910). Partitioning was highly variable and correlated best with the TOC. Hydropower-epoch sediments exhibit decreasing C(sed) with time and a relatively strong sorption capacity compared with the manufactured-gas epoch. Sediments from the manufactured-gas epoch exhibit substantial PAH and metal contamination, large amounts of coke and char, and a low sorption capacity. Reexposure of sediments of this epoch increases risks to local benthic species. Implications on natural recovery as a sediment management strategy are discussed.

Linking Geology and Microbiology: Inactive Pockmarks Affect Sediment Microbial Community Structure

“…Our results suggest that TC/TOC concentrations decrease with depth, while NPOC concentrations remain fairly constant, but this remains speculative since we did not measure the intermediate depths. Nonetheless, TOC concentrations found in another study from the Oslofjord did decline with depth, however only after an initial increase at the top sediments [84]. Nonetheless, we find similar values for the surface as well as the deeper sediments in our study as in Arp et al, (2011) suggesting the same concentration pattern in our sediments.…”

“…Regarding different hydrodynamic regimes within and outside the inactive pockmarks, it is known that different deposition rates of organic matter can influence the microbial community richness, but so far this has only been shown in oligotrophic marine surface (0–5 cm) sediments [33]. The Oslofjord is not an oligotrophic environment, and in line with Bienhold et al, (2012) a difference between the 0–4 cm microbial communities of the pockmarks and the references sediments was not found, which indicates that organic matter deposition rates are similar at both sites [84]. An additional factor influenced by different sedimentation rates could be the grain size of the pockmark sediments [14].…”

Release of dissolved trace metals and organic contaminants during deep water disposal of contaminated sediments from Oslo harbour, Norway

“…Sediment data does, however, show decreasing trends for trace metals (Lepland et al 2010) and PCBs (Arp et al 2011). Decreased input has been confirmed by Berge et al (2008) who showed that during the period 1992-2008, the concentration of PCBs within the top layer of the sediments in the inner Oslofjord had decreased by an average factor of 8.6 at 22 stations.…”

Influence of anthropogenic activities on PAHs in sediments in a significant gulf of low-latitude developing regions, the Beibu Gulf, South China Sea: Distribution, sources, inventory and probability risk

“…This implies that the higher emission intensity of PAHs in mid-latitudes (N) than those in low-latitudes was due to more developed countries distributed in mid-latitudes (N). This hypothesis is also supported by the high correlations between PAH concentration profiles and socioeconomic indexes (such as energy consumption, population and GDP) both in developing areas such as China, and developed regions such as Europe and the USA (Arp et al, 2011;Lima et al, 2003;Liu et al, 2012). Despite higher PAHs emissions in the mid-latitude (N) developed regions, current and historical contaminations of PAHs in the low-latitude developing regions are also important for comprehending the global setting.…”