The microbial mercury link in oligotrophic lakes: Bioaccumulation by picocyanobacteria in natural gradients of dissolved organic matter

SOTO CÁRDENAS, CAROLINA; QUEIMALIÑOS, CLAUDIA; RIBEIRO GUEVARA, SERGIO; GEREA, MARINA; DIÉGUEZ, MARÍA C.

CHEMOSPHERE

PERGAMON-ELSEVIER SCIENCE LTD

Año: 2019 vol. 230 p. 360 - 368

0045-6535

Andean Patagonian lakes are oligotrophic systems characterized by low dissolved organic carbon (DOC) levels and moderate to high Hg concentration that determine naturally high Hg/DOC ratios andbioavailability. In these lakes, microbial food webs are extremely important in Hg trophodynamics, being that the picophytoplankton fraction is a major entrance path of Hg2+ into pelagic food webs. This studyanalyzed the bioaccumulation of Hg2+ by the picocyanobacteriaSynechococcus sp. using the radiotracer 197Hg2+ and water from four Andean Patagonian lakes presenting a natural gradient of DOM concen-tration and quality. Hg2+ bioaccumulation by Synechococcus was calculated as the uptake of Hg2+ per biovolume unit (volume concentration factor VCF; pLmm3). Hg uptake showed a wide variation(13