Influence of dissolved organic matter character on mercury incorporation by planktonic organisms： An experimental study using oligotrophic water from Patagonian lakes

• Published in: Journal of environmental sciences (China) Vol. 25; no. 10; pp. 1980 - 1991
• Main Authors: Diéguez, María C., Queimaliños, Claudia P., Guevara, Sergio Ribeiro, Marvin-DiPasquale, Mark, Cárdenas, Carolina Soto, Arribére, María A.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.10.2013
• Subjects: absorption; Adsorption; Algae; Animals; Argentina; bioaccumulation; Bioavailability; Boeckella; Brachionus; Brachionus calyciflorus; Copepoda - metabolism; Cryptomonas; Cryptomonas erosa; Cryptophyta - metabolism; Dissolved organic matter; food webs; Foods; Freshwater; humic substances; laboratory experimentation; Lakes; Lakes - chemistry; ligands; Marine; Mercury; Mercury (metal); Mercury - chemistry; Mercury - metabolism; mercury incorporation; molecular weight; Patagonian lakes; plankton; Plankton - metabolism; Rotifera - metabolism; Signatures; Webs; zooplankton; 塔; 实验室实验; 有机物性质; 汞; 湖泊; 生物利用度; 生物溶解; 营养水; Argentina; Patagonian lakes; dissolved organic matter; Argentina; plankton; mercury incorporation; mercury
• ISSN: 1001-0742; 1878-7320
• DOI: 10.1016/S1001-0742(12)60281-2

Ligands present in dissolved organic matter （DOM） form complexes with inorganic divalent mercury （Hg^2＋） affecting its bioavailability in pelagic food webs. This investigation addresses the influence of a natural gradient of DOM present in Patagonian lakes on the bioaccumulation of Hg^2＋ （the prevailing mercury species in the water column of these lakes） by the algae Cryptomonas erosa and the zooplankters Brachionus calyciflorus and Boeckella antiqua. Hg^2＋ accumulation was studied through laboratory experiments using natural water of four oligotrophic Patagonian lakes amended with^197Hg^2＋. The bioavailability of Hg^2＋ was affected by the concentration and character of DOM. The entrance of Hg^2＋ into pelagic food webs occurs mostly through passive and active accumulation. The incorporation of Hg^2＋ by Cryptomonas, up to 27% of the Hg^2＋ amended, was found to be rapid and dominated by passive adsorption, and was greatest when low molecular weight compounds with protein-like or small phenolic signatures prevailed in the DOM. Conversely, high molecular weight compounds with a humic or fulvic signature kept Hg^2＋ in the dissolved phase, resulting in the lowest Hg^2＋ accumulation in this algae. In Brachionus and Boeckella the direct incorporation of Hg from the aqueous phase was up to 3% of the Hg^2＋ amended. The dietary incorporation of Hg^2＋ by Boeckella exceeded the direct absorption of this metal in natural water, and was remarkably similar to the Hg^2＋ adsorbed in their prey. Overall, DOM concentration and character affected the adsorption of Hg^2＋ by algae through competitive binding, while the incorporation of Hg^2＋ into the zooplankton was dominated by trophic or dietary transfer.