Development of a Mercury Speciation, Fate and Biotic Uptake (Biotranspec) Model: Application to Lahontan Reservoir, Nevada, Usa

Gandhi, Nilima; Bhavsar, Satyendra; Diamond, M.; Kuwabara, James S.; Marvin-DiPasquale, Mark C.; Krabbenhoft, David P.

doi:10.1897/06-468

Cited by 7 publications

(11 citation statements)

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“…The assumption of chemical equilibrium between water and air allowed for the use of the partial pressure of CO 2 when calculating the dissolution of CO 2 into carbonate species. WHAM and other geochemical models assume that metal species are at chemical equilibrium; that is, the model does not consider kinetically controlled reactions such as microbial methylation as done by Gandhi et al [27]. We believe this is a reasonable approach because few kinetic rates are known, and including such complexity is not consistent with other simplifications made in the UWM.…”

Section: Speciation Model-whammentioning

confidence: 99%

Critical load analysis in hazard assessment of metals using a Unit World Model

Gandhi

Bhavsar

Diamond

2011

Environmental Toxicology and Chemistry

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A Unit World approach has been used extensively to rank chemicals for their hazards and to understand differences in chemical behavior. Whereas the fate and effects of an organic chemical in a Unit World Model (UWM) analysis vary systematically according to one variable (fraction of organic carbon), and the chemicals have a singular ranking regardless of environmental characteristics, metals can change their hazard ranking according to freshwater chemistry, notably pH and dissolved organic carbon (DOC). Consequently, developing a UWM approach for metals requires selecting a series of representative freshwater chemistries, based on an understanding of the sensitivity of model results to this chemistry. Here we analyze results from a UWM for metals with the goal of informing the selection of appropriate freshwater chemistries for a UWM. The UWM loosely couples the biotic ligand model (BLM) to a geochemical speciation model (Windermere Humic Adsorption Model [WHAM]) and then to the multi-species fate transport-speciation (Transpec) model. The UWM is applied to estimate the critical load (CL) of cationic metals Cd, Cu, Ni, Pb, and Zn, using three lake chemistries that vary in trophic status, pH, and other parameters. The model results indicated a difference of four orders of magnitude in particle-to-total dissolved partitioning (K(d)) that translated into minimal differences in fate because of the short water residence time used. However, a maximum 300-fold difference was calculated in Cu toxicity among the three chemistries and three aquatic organisms. Critical loads were lowest (greatest hazard) in the oligotrophic water chemistry and highest (least hazard) in the eutrophic water chemistry, despite the highest fraction of free metal ion as a function of total metal occurring in the mesotrophic system, where toxicity was ameliorated by competing cations. Water hardness, DOC, and pH had the greatest influence on CL, because of the influence of these factors on aquatic toxicity.

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Section: Speciation Model-whammentioning

confidence: 99%

Critical load analysis in hazard assessment of metals using a Unit World Model

Gandhi

Bhavsar

Diamond

2011

Environmental Toxicology and Chemistry

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“…Previous research of the CRLR has focused primarily on hydrodynamics and sediment transport of nonpoint source loading of total inorganic Hg (THg 2+ ) and total methylated Hg, or methylmercury (TMeHg) in the river (Warwick and Carroll, ). In contrast, only steady state models of the system have addressed dissolved species in the receiving reservoir (Diamond et al ., ; Gandhi et al ., ), and there has been little/no focus in this system, or others, on dissolved species under transient conditions spanning an entire river‐reservoir system with nearly two decades of data. Yet it is the dissolved species that may be bioavailable to plankton and transferred to higher trophic levels causing ecologic concern.…”

Section: Introductionmentioning

confidence: 99%

Modeling the Highly Dynamic Loading of Mercury Species in the Carson River and Lahontan Reservoir System, Nevada

Carroll

Warwick

2016

J American Water Resour Assoc

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The semiarid Carson River — Lahontan Reservoir system in Nevada, United States is highly contaminated with mercury (Hg) from historic mining with contamination dispersed throughout channel and floodplain deposits. Work builds on previous research using a fully dynamic numerical model to outline a complete conceptualization of the system that includes transport and fate of both sorbed and dissolved constituents. Flow regimes are defined to capture significant mechanisms of Hg loading that include diffusion, channel pore water advective flux, bank erosion, and overbank deposition. Advective flux of pore water is required to reduce dilution and likely represents colloidal‐mediated transport. Fluvial concentrations span several orders of magnitude with spatial and temporal trends simulated within 10‐24% error for all modeled species. Over the simulation period, 1991‐2008, simulated loads are 582 kg/yr (THg2+), 4.72 kg/yr (DHg2+), 0.54 kg/yr (TMeHg), and 0.07 kg/yr (DMeHg) with bank erosion processes the principal mechanism of loading for both total and dissolved species. Prediction error in the reservoir is within one‐order of magnitude and considered qualitative; however, simulated results indicate internal cycling within the receiving reservoir accounts for only 1% of the reservoir's water column contamination, with river channel sediment sources more influential in the upper reservoir and bank erosion processes having greater influence in the lower reservoir.

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“…A study performed by the North Carolina Department of Natural Resources revealed that 75% of the total mercury load present in the Cashie River Watershed resulted from eroded sediments [26]. A study on the development of a mercury speciation applied to the Lohatan Reservoir in Nevada, showed that 90% of the mercury released into the system was maintained within the sediments and constituted a continuous source of pollution [27]. [11].…”

Section: Modeling Applicationsmentioning

confidence: 99%

Integration of a Sedimentation Module to a Hydrologic Model and its Application to a Mercury TMDL Analysis

Marrero¹

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Development of a Mercury Speciation, Fate and Biotic Uptake (Biotranspec) Model: Application to Lahontan Reservoir, Nevada, Usa

Cited by 7 publications

References 0 publications

Critical load analysis in hazard assessment of metals using a Unit World Model

Critical load analysis in hazard assessment of metals using a Unit World Model

Modeling the Highly Dynamic Loading of Mercury Species in the Carson River and Lahontan Reservoir System, Nevada

Integration of a Sedimentation Module to a Hydrologic Model and its Application to a Mercury TMDL Analysis

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