{"id":345,"date":"2014-11-19T02:00:06","date_gmt":"2014-11-19T02:00:06","guid":{"rendered":"http:\/\/faculty.engineering.ucdavis.edu\/ginn\/?page_id=345"},"modified":"2014-11-19T02:12:01","modified_gmt":"2014-11-19T02:12:01","slug":"biogeochemical-cycling","status":"publish","type":"page","link":"https:\/\/faculty.engineering.ucdavis.edu\/ginn\/projects\/biogeochemical-cycling\/","title":{"rendered":"Biogeochemical cycling"},"content":{"rendered":"

Biogeochemical Cycling<\/strong><\/p>\n

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Prior Funding: <\/span><\/strong>Biogeochemical Cycling of Heavy Metals in Lake Coeur d’Alene Sediments: The Role of Indigenous Microbial Communities, NSF-EAR Project 0628258 2002-2009.<\/span><\/p>\n

Students\/Postdocs: <\/span><\/strong>Sevinc Sengor, Arash Massoudieh, Prof. Petros Gikas\/ Tech. U. Crete, Eileen Belding (graduated MSCE), KC Curthoys (graduated BSCE, Valedictorian), Karen Lam Fat Cheong Him (graduated MSCE), Montarat Na Issangkarun (graduated MSCE).<\/p>\n

Collaborators: <\/span><\/strong>Brent Peyton\/ Montana State; Rajesh Sani\/S. Dakota SMT; Nic Spycher\/LBL; Petros Gikas\/Tech. U. Crete; Dusan Zagar\/J. Stefan Inst., Ljubljana, Slovenia; Sevinc Seng\u00f6r\/ SMU; Arash Massoudieh\/Catholic Univ. America.<\/p>\n

\"droppedImage_2\" \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0\u00a0<\/a> \"LCDABenthicmineralXRF\" \u00a0 \u00a0 \u00a0 \u00a0 \u00a0<\/a> \"droppedImage\"<\/a><\/p>\n

Redox Sequence\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 micro-XRF image of lake sediments\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 Sampling at Lake Coeur d’Alene<\/p>\n<\/div>\n<\/div>\n<\/div>\n

Project Summary:<\/strong> The mobility of metals in riverine, estuarine, and lacustrine sediments is affected by multiple coupled biotic and abiotic geochemical processes that reflect redox disequilibrium and cannot be modeled using conventional equilibrium-based models.\u00a0 Competing mechanisms in these environments include the mobilization of sorbed metals by reductive dissolution of Fe(III) (hydr)oxides and the precipitation of metal sulfides upon reaction with biogenic sulfide.\u00a0 In addition, the toxicity of metals in polluted environments can have a significant effect on microbial activity and thus indirectly affect metal biogeochemical behavior.\u00a0 We are investigating these processes with mathematical modeling and data from several locations including Lake Coeur d\u2019Alene, Idaho (e.g., Moberly et al., 2009), an area heavily impacted by upstream mining activities, and sediments from several DOE-managed sites including Rifle, Colorado.\u00a0 Model results for Benthic cycling of heavy metals at Lake Coeur d’Alene (e.g., Seng\u00f6r et al., 2007) indicate that the relative rates of Fe(III) versus sulfate reduction may be an important factor controlling pH and types of Fe(II) minerals precipitation at depth.\u00a0 Upon reductive dissolution of Fe(III) hydroxides, numerical experiments indicate that a delicate balance takes places between FeS and FeCO3 precipitation, which compete for aqueous Fe(II), and the formation of aqueous (bi)sulfide complexes, which compete with the precipitation of FeS and other metal sulfides for biogenic sulfide.<\/p>\n

We have extended this modeling approach that seeks to incorporate comprehensive chemical and microbially-mediated transformations to interpret lab data on U reoxidation (Singh et al., 2014; Spycher et al., 2011), as well as data from lab experiments in toxic effect of exposure of microbial species to heavy metals (Sani et al., 2010; Seng\u00f6r et al., 2012).\u00a0 These simulations utilize the exposure-time concept developed in Ginn (1999) for the accounting of cumulative dose acquired by motile microbial species that undergo attachment\/detachment to solid surfaces.<\/p>\n

\u00a0Important Papers in this Topic<\/strong>:<\/p>\n