Karol Kuliński

Distribution and origin of organic matter in the Baltic Sea sediments dated with 210Pb and 137Cs

Organic carbon deposited in marine sediments is an important part of the global carbon cycle. The knowledge concerning the role of shelf seas (including the Baltic Sea) in the carbon cycle has increased substantially, however organic carbon accumulation rates in the Baltic sediments still require clarification.This paper describes methods used for assessing organic carbon and nitrogen accumulation rates in six sediment cores collected in the sediment accumulation areas in the Baltic Sea. Mass sediment accumulation rates were based on 210Pb method validated by 137Cs measurements. The organic carbon accumulation rates ranged from 18 to 75 g·C·m−2·yr−1. The C/N ratios and δ13C were used to access sedimentary organic matter provenance. The C/N ratios in the investigated cores vary in the range from 7.4 to 9.6, while δ13C ranged from −24.4‰ to −26.4‰. Results of the terrestrial organic matter contribution in the sedimentary organic matter were calculated basing on δ13C using the end member approach. Large proportion (41–73%) of the sedimentary organic carbon originates on land.The obtained results indicate the Baltic Sea sediments as an important sink for organic carbon. Substantial fraction of the sedimentary load originates on land.

Mercury in suspended matter of the Gulf of Gdańsk: Origin, distribution and transport at the land–sea interface

The coastal regions of inland seas are particularly vulnerable to Hg pollution. An important carrier of toxic Hg in the marine environment is suspended matter originating from multiple sources. The present study was conducted in the Gulf of Gdańsk and its adjoining land in the years 2011-2013. The results indicated that the HgSPM (Hg bound with suspended particulate matter) concentrations varied horizontally and vertically and were dependent on the water dynamics and the composition of organic matter. Conditions favourable for the accumulation of matter and adsorption of reactive gaseous mercury led to increasing HgSPM levels, which are especially hazardous in the case of semi-enclosed areas such as estuaries. These conditions also increase the Hg loads into the trophic chain through suspension feeders. Moreover, the HgSPM concentration was significantly affected by seasonal phenomena (mainly coastal erosion) and the quantity and quality of primary production (phytoplankton blooms, mainly Mesodinium rubrum).

Benthic foraminifera contribution to fjord modern carbon pools: A seasonal study in Adventfjorden, Spitsbergen

The aim of this study was to determine the amount of organic and inorganic carbon in foraminifera specimens and to provide quantitative data on the contribution of foraminifera to the sedimentary carbon pool in Adventfjorden. The investigation was based on three calcareous species that occur commonly in Svalbard fjords: Cassidulina reniforme, Elphidium excavatum and Nonionellina labradorica. Our results show that the species investigated did not contribute substantially to the organic carbon pool in Adventfjorden, because they represented only 0.37% of the organic carbon in the sediment. However, foraminiferal biomass could have been underestimated as it did not include arenaceous or monothalamous taxa. Foraminiferal carbonate constituted up to 38% of the inorganic carbon in the sediment, which supports the assumption that in fjords where non-calcifying organisms dominate the benthic fauna foraminifera are among the major producers of calcium carbonate and that they play crucial roles in the carbon burial process. The results presented in this study contribute to estimations of changes in foraminiferal carbon levels in contemporary environments and could be an important reference for palaeoceanographic studies.

Low virus to prokaryote ratios in the cold: benthic viruses and prokaryotes in a subpolar marine ecosystem (Hornsund, Svalbard).

The density and spatial distribution of benthic viruses and prokaryotes in relation to biotic and abiotic factors were investigated in sediment cores collected in Hornsund, a permanently cold fjord on the West coast of Svalbard, Norway. The cores were obtained from the mouth of the fjord to the central basin, along a longitudinal transect. The results of our analyses showed lower densities of viruses (0.2 x 10(8) to 5.4 x 10(8) virus-like particles/g) and lower virus-to-prokaryote ratios (0.2-0.6, with the exception of the uppermost layer in the central basin, where the ratio was about 1.2) at the study site than generally found in the temperate areas, despite the relatively high organic matter content in subpolar sediments. Variations in benthic viral and prokaryote abundances along gradients of particle sedimentation rates, phytopigment concentrations, and macrobenthic species composition together suggested the influence of particle sedimentation and macrobenthic bioturbation on the abundance and spatial distribution ofprokaryotes and viruses in cold habitats.

Research on Carbon Cycling in the Baltic: Quantification of the Carbon Fluxes

Considerations presented in this chapter are based on the comprehensive study performed by Kulinski et al. (2011). The details of the methodology used for the quantification of carbon exchange between the Baltic Sea and the North Sea are presented in Sect. A.1 (this volume, Appendixes).

Climate and Carbon Cycle

Climate, as defined by IPCC, is the “average weather” at a given period of time and space. In a more statistical understanding, this period of time, ranging in various reports from months to thousands of years, was eventually adopted by the World Meteorological Organization (WMO) to be 30 years.

Watershed characteristics and climate factors effect on the temporal variability of mercury in the southern Baltic Sea rivers

Mercury (Hg) is a neurotoxic metal which can enter into the human organism mainly by fish consumption, skin and transpiration. In the coastal zone of the southern Baltic Sea, rivers are the main source of Hg. The Polish region represents the largest proportion of the Baltic Sea catchment and this research included four rivers of the Baltic watershed: the Reda, Zagórska Struga, Kacza and Gizdepka. The samples were collected in the years 2011-2013. Total and particulate Hg concentration in these rivers were measured. Due to intensive rain, deposited mercury on the catchment area was washed out into the riverines water and introduced into the Baltic Sea. Consequently, the load of Hg increased three times. Additionally, the intensive dry atmospheric deposition during heating season caused the increase of the concentration of particulate Hg in the river water even by 85%. The research confirmed the role of the river flow magnitude in the load of mercury introduced into the sea by rivers. Moreover, a high variability of mercury concentration was connected to the additional sources such as the chemicals containing Hg and no municipal sewage system. The analysis of stable isotopes indicated that the SPM contained terrestrial organic matter; however, there was no clear correlation between Hgtot, Corg and Ntot concentrations and δ13C, δ15N, C/N in particulate matter.

Research on Carbon Cycling in the Baltic: Aims and Scope

The main goal of the study is to present a quantitative and qualitative description of the Baltic Sea carbon cycle. In order to achieve the goal, a quantitative annual budget of the basin carbon inflows and outflows was constructed. The balance was then used to determine the direction and extent of CO2 exchange between the seawater and the atmosphere for the entire Baltic Sea surface.

Research on Carbon Cycling in the Baltic: Discussion

The carbon fluxes quantified in chapter “Research on Carbon Cycling in the Baltic: Quantification of the Carbon Fluxes” give a complete outlook of the carbon sources (positive values) and sinks (negative values) in the Baltic Sea. The Baltic carbon cycle is characterized by a balance between carbon inflows and outflows to/from the basin. Thus, quantifying carbon fluxes and substituting appropriate values, one gets the total carbon inflow exceeding the total outflow by 1.14 Tg C year−1. The obtained difference is associated with the CO2 net exchange between the seawater and the atmosphere. Therefore, the estimates indicate the Baltic Sea as a net source of CO2 to the atmosphere amounting to −1.14 Tg C year−1, which corresponds to −4.18 Tg CO2 year−1.