A comparative biogeochemical study of sediments from Kandalaksha Bay, White Sea, Russian Arctic

Abstract

Major (Al, Fe), minor (Mn), and trace (Li, Cu, Ni, Cr, Cd, Zn, Pb) metals along with nutrients (TOC, TON, TS, TP) and enzymatic activities were determined in 18 surface sediment and two soil samples collected in six small bays of the Karelian shore of Kandalaksha Bay, White Sea, Russian Arctic. The studied sediments tended to be marine, with a major input of organic matter from autochthonous sources. Marine organic material might be an important carrier of trace metals in the examined sediments. According to sediment quality guidelines, all tracemetal contents were below the threshold levels. The results of azocasein-trypsin tests also suggested no significant contamination of analysed sediments and soils. A comparison of the trace-metal contents in the sediments examined with those of the western Arctic shelf showed higher levels of Zn and Cr in the Karelian shore. Presumably these disparities were related to regional differences in sediment chemistries rather than to any enhanced pollution within the studied area. Both geochemical composition and enzymatic-activities patterns among sites studied are largely controlled by the sediment granulometry. The evolution of sediments in the restricted exchange environments under investigation is caused by depositional conditions, which are strongly affected by small-scale hydrodynamic processes specific for each particular area. The most vivid examples are separating basins, where the fine-grained sediments enriched in organic matter -and thus in nutrients and metals -are formed under calm hydrodynamic conditions enhanced by severely restricted water exchange.

Ecological Research of Arctic Restricted Exchange Environments (Kandalaksha Bay, White Sea, Russian Arctic)

“…The most fine-grained organic-rich and sometimes hydrosulfuric sediments are found in separating basins (Koukina et al, 2010). The evolution of sediments here is caused by specific depositional conditions, which are strongly affected by small-scale hydrological, hydrodynamic and hydrochemical processes unique for each particular area, of which the hypoxia is of most importance (Koukina et al, 2003).…”

“…trace heavy metals) can both be present in the sediments f r o m d e p o s i t i o n i n t h e p a s t a n d c a n a r r i v e w i t h c u r r e n t d e p o s i t s , w h i l e s e d i m e n t resuspension and subsequent reaction and transport in the water column can be an important mechanism for redistribution of trace contaminant metal. Within the Karelian coastline, the small-scale geochemical patterns and disparities complicate the assessment of natural geochemical background of the region under investigation (Koukina et al, 2003). Therefore, the found mean trace heavy metal content values were compared with those found in previous studies for surface sediments from the other White Sea regions, where the anthropogenic trace heavy metal contamination was not detected.…”

“…In the coastal zone, tidal and wind generated currents form coarse sediments, of which well sorted fine-grained sands are of most importance. In the small bays of the rugged coast, the hydrodynamic and thus sedimentary conditions are very calm, leading to accumulation of fine-grained silty material (Koukina et al, 2003). These sediments are mainly comprised of aleurite silts, which often have a high content of coarse fragments transported by ice.…”

“…In the recent decades significant research efforts have been undertaken to evaluate concentration of potential contaminants (such as trace metals, oil pollutants, and chemically resistant anthropogenic substances) in sea waters, sediments, and food chains of the White Sea with special attention devoted to shallow areas and enclosed estuarine systems (Koukina et al, 2001, Savenko, 2006. Most of these areas were found to be characterized by very active fronts and biogeochemical barriers creating small scale variability in hydrodynamic, lithological and geochemical patterns that significantly complicates the differentiation of sites of natural element accumulation from sites of anthropogenic contamination (Koukina et al, 2003, Pantiulin, 2001). …”

“…The upper sediment column in estuarine and coastal environments can be regarded as a slowly stirred reactor to which substrates are added at the top and mixed downward (Martin, 2010). The comparative biogeochemical study of Karelian shore coastal basins showed the pronounced enrichment of sediments from separating bays in clay fraction, organic matter and in nutrients and metals in comparison to the neighboring open shallow sea (Koukina et al, 2003(Koukina et al, , 2006. Further study of the region revealed the extreme high total Fe (160000 µg/g) as well as enhanced content of labile (acid soluble) Fe, Mn and Cr in sediments from central parts of two separating lagoons of Chernorechenskaya Bay (Koukina et al, 2010).…”