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Special Session 2: Changing ocean environment: from the sedimentary perspective -- processes and records |
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Mercury footprint of the anthropocene in the sedimentary record of Galicia Continental Shelf
Wednesday 11th @ 1550-1605
Room 4
Luz-Eva, F. F.* , Departamento de Geociencias Marinas, Universidad de Vigo, 36310 Vigo, Spain
Rubio, B., Departamento de Geociencias Marinas, Universidad de Vigo, 36310 Vigo, Spain
Böttcher, M.E., Leibniz Institute for Baltic Sea Research, Seestrasse 15, 18119 Warnemünde, Germany
Leipe, T., Leibniz Institute for Baltic Sea Research, Seestrasse 15, 18119 Warnemünde, Germany
Schmiedinger, I., Leibniz Institute for Baltic Sea Research, Seestrasse 15, 18119 Warnemünde, Germany
Scherff, I., Leibniz Institute for Baltic Sea Research, Seestrasse 15, 18119 Warnemünde, Germany
Rey, D., Departamento de Geociencias Marinas, Universidad de Vigo, 36310 Vigo, Spain
Presenter Email: luz.fernandez@uvigo.es
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| Mercury is an important trace element to assess the environmental quality of ecosystems. Anthropogenic Mercury can also contribute to the identification of the Anthropocene or become a local dating tool by age equivalence. The study of Hg concentrations is particularly relevant for human health in highly productive fishing areas like the Galician continental shelf, our study area, where its knowledge in the sedimentary record is scarce. Here we have measured the total Hg content in six box-cores of recent sediments from the Galicia continental shelf, between North latitudes of 41° and 43°. Mercury was analyzed on freeze-dried samples using a DMA-80 analyzer from MLS Company. Data calibration was done with CRM (BCR) 142R certified reference material and MBSS sediment standard. The detection limit of this analyzer is about 0.15 μg kg-1, four orders of magnitude below the Hg concentration found in local recent marine sediments, and below the reference generic levels that guarantee the protection of these galician environments (DOGA 57/60/2009). Additionally we have also measured total CNS and Total Reduced Inorganic Sulfur. Hg values ranged between 3.5 and 29.8 μg kg-1 for sand dominated cores and between 20 and 72.8 μg kg-1 for mud dominated cores. The highest concentrations were detected at the uppermost 25 cm and 15 cm, respectively. We found Hg positive correlations with C/S and C/N ratios and negatively correlatios with total S, reflecting its relationship with organic matter. The highest values of 72.8 μg kg-1 and 29.8 μg kg-1, found at 0.5 and 4.5 cm depth in sediment respectively, are attributed to the influence of the Minho River. These values are well under the legally established safety limits (1 μg g-1) therefore we conclude that recent sediments from the middle and outer Galicia continental shelf are not polluted by mercury. We have also assessed the chronological value of these peaks as age marker in the area in base of their source. Sediment mixing is deduced in some cores whereas others indicate a better reflection of the contamination history in the Iberian peninsula. |
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