Seasonal Changes in Settling Particulate Matter on the Eastern Turkish Coast of the Black Sea

Total mass flux (TMF), total organic matter (TOM), carbonate (CaCO3), lithogenic matter, biogenic silica (BSi), organic carbon (Corg), organic nitrogen (Norg) fluxes and sedimentation rates were determined seasonally using a sediment trap deployed in oxic layer on eastern coast of the Black Sea from July 2002 to October 2003. TOM, CaCO3, Corg and Norg percentages in surface sediment and chlorophyll-a concentration in seawater samples were also determined at the same station. The highest TMF was measured as 56.4 g m day during autumn. The maximum TOM and CaCO3 percentages and chlorophyll-a values were, respectively, determined to be 12.60, 14.06% and 5.68 μg l during spring. The highest fraction of Corg was recorded to be 2.88% during summer. C/N ratios in the settling materials suggested that nitrogen input increased during winter. Corg rates decreased in sediment cross section depth. Generally, the percentages of CaCO3, Corg and Norg were lower in the surface sediment than trap sediment samples, except TOM value at 0-2-cm sliced surface sediment, implying that organisms activity was present in the oxic layer. The lithogenic matter was the dominant component in the trap materials which ranged from 66 to 80% depending on seasonal variation related with river discharges. Evaluated with precipitation rate and wind speed data, sedimentation rate was mainly related with vertical fluxes.