Organic carbon burial rates,and carbon and sulfur relationships in coastal sediments of the southern Baltic Sea |
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| Institution: | 1. Geotop, Université du Québec à Montréal, C.P. 8888, Montréal, QC H3C 3P8, Canada;2. Key Laboratory of Marine Geology and Metallogeny, First Institute of Oceanography, Ministry of Natural Resources, Qingdao 266061, China;3. Laboratory for Marine Geology, Pilot National Laboratory for Marine Science and Technology, Qingdao 266061, China;4. Laboratory of Coastal and Marine Geology, Third Institute of Oceanography, Ministry of Natural Resources, Xiamen 361026, China |
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| Abstract: | Organic C burial rates and C–S relationships were investigated in the Holocene sediment sequences of 3 shallow polymictic coastal lagoons in the southern Baltic Sea to better understand the biogeochemical cycling of C and S in these environmental systems. The results show that these lagoons may have a considerable influence on the environmental status of the southern Baltic Sea area in having the potential to act as a temporary sink or source for heavy metals. High organic C accumulation rates (Corg-AR) can be observed in the sediments due to a high organic matter supply from land and a high productivity of the water bodies as a result of eutrophication. However, organic C burial does not increase as a result of increasing sediment accumulation rates (SAR). Even when high sedimentation rates do occur, there appears to be a thorough recycling and resuspension of the sediment enhancing the biological decay of organic matter before burial or the removal of organic matter from the system by transport. That is why high SAR in the coastal lagoons do not enhance pyrite formation, and thereby permanent fixing of heavy metals in the sediments, to the extent that could be expected from their magnitude. Initially there is a high potential for a temporary binding of heavy metals, but the latter are likely to be subject to mobilization and redistribution within the sediments and the water column. The patterns of burial of organic and mineral matter are different from those observed in the present-day Baltic Proper, implying possible important links in deposition between the central and coastal areas of the Baltic Sea and implications for C cycling in the ecosystem of the Baltic Sea. |
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