Modeling diagenesis of lead in sediments of a Canadian Shield lake

Methylmercury cycling in estuarine sediment pore waters (Penobscot River estuary, Maine, USA)

“…PROFILE models of pore-water dynamics assume the absence of a significant advective flux and that the system is, at least, at quasi-steady state (i.e., LC Lt < 0). Although steady-state assumptions may not be strictly valid for environments subject to variations in salinity, bottomwater dissolved O 2 , or temperature, diagenetic models such as PROFILE have allowed exploration of the depthspecific parameters that facilitate either sequestration or mobilization of sediment contaminants (Gallon et al 2004;Goulet et al 2007;Merritt and Amirbahman 2007).…”

Lead isotopes as particulate contaminant tracers and chronostratigraphic markers in lake sediments in northeastern North America

“…This assumption is typically verified by analyzing sediment cores obtained from lakes whose benthic regions are deep enough so that they may be assumed to be permanently or seasonally anoxic, with little bioturbation. A study by Gallon et al (2004) showed that diagenetic processes have negligible impact on the Pb flux profile in a Canadian Shield Lake, however other studies by Nriagu et al (1982) and Marcantonio et al (2002) discovered that certain lakes are affected by post-depositional mobilization. Nriagu et al (1982) saw that lakes that are highly acidified can undergo post-depositional leaching from the surface sediments, and a lake analyzed by Marcantonio et al (2002) had been dredged in a previous decade, making age-dated Pb isotope analysis impossible.…”

“…The utility of lake sediments to provide trace metal concentration profiles and Pb isotope profiles relies on the assumption that these profiles are not affected by diagenetic processes, including remobilization, molecular diffusion, bioturbation, and bioirrigation (Gallon et al, 2004). This assumption is typically verified by analyzing sediment cores obtained from lakes whose benthic regions are deep enough so that they may be assumed to be permanently or seasonally anoxic, with little bioturbation.…”

Organic matter mineralization in sediment of a coastal freshwater lake and response to salinization

“…In these depositional settings, aerobic degradation of C org may be limited by O 2 consumption due to secondary oxygenation reactions, particularly the oxidation of CH 4 (Sweerts et al, 1991). Furthermore, reactive Fe(III) mineral phases are often preserved in fresh water sediments (Wersin et al, 1991;Gallon et al, 2004;Hyacinthe and Van Cappellen, 2004), while low SO 4 2À concentrations in freshwater environments limit sulfate reduction (Holmer and Storkholm, 2001). As a consequence, methanogenesis is generally a dominant C org degradation process (Capone and Kiene, 1988;Peretyazhko et al, 2005).…”