Mercury concentration and solid phase speciation changes in the course of early diagenesis in marine coastal sediments (Southern Baltic Sea)
Jacek Beldowski A B and Janusz Pempkowiak AA Department of Marine Chemistry and Biochemistry, Institute of Oceanology, Polish Academy of Sciences, ul. Powstańców Warszawy 55, 81-712 Sopot, Poland.
B Corresponding author. Email: hyron@iopan.gda.pl
Marine and Freshwater Research 60(7) 745-757 https://doi.org/10.1071/MF08060
Submitted: 29 February 2008 Accepted: 11 February 2009 Published: 28 July 2009
Abstract
On reaching the sea, mercury discharged into the environment is deposited on and buried in marine sediments. Diagenetic processes in sediments lead to changes in both mercury concentration and speciation; they may enhance mercury bioavailability and/or lead to mercury remobilisation. Total concentrations and speciation of mercury were measured in dated sediment samples from sites covering a range of different environmental conditions and mercury concentrations. In the course of ~200 year-long diagenetic processes, the dominant changes in mercury speciation have involved diffusion of labile mercury to the overlying water, transformation of organic-bound mercury to HgS under anoxic conditions or to insoluble humin-bound Hg under oxic conditions, and dismutation of HgS into soluble polysulfides under hyperanoxic conditions. Rate constants of labile-to-stable mercury species transformations and the return flux of mercury were calculated on the basis of sediment core geochronology obtained by the 210Pb method. Although the study was performed in a specific area, we believe that the observed processes are valid for other shallow, coastal seas and that the results enable mercury stability in sediments to be assessed in similar areas worldwide.
Additional keywords: budget, kinetics, labile, rate constants, remobilisation, species, stable, transformation processes.
Acknowledgement
The study was carried out as part of the statutory activities of the Institute of Oceanology, Sopot, grant No. II.2.04. Authors would like to express their gratitude to the guest editor and anonymous reviewers, for thorough comments which have greatly improved the quality of this manuscript.
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