Abstract Details
(2020) Characterization and Validation of a Novel Equilibrium Passive Sampler for Prediction of Porewater Methylmercury
Washburn S, Ghosh U, Damond J & Gilmour C
https://doi.org/10.46427/gold2020.2815
The author has not provided any additional details.
13h: Room 4, Wednesday 24th June 22:15 - 22:18
Spencer Washburn
View abstracts at 2 conferences in series
Upal Ghosh
Jada Damond
Cynthia Gilmour View all 3 abstracts at Goldschmidt2020 View abstracts at 5 conferences in series
Upal Ghosh
Jada Damond
Cynthia Gilmour View all 3 abstracts at Goldschmidt2020 View abstracts at 5 conferences in series
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Submitted by Natalie Szponar on Tuesday 16th June 22:00
Nice work! I was wondering if you could elaborate on the robustness of your estimates? How robust? how do your numbers compare? is there a field study that you can do to validate your numbers?
Hi Natalie, Thank you, and thanks for the question! The estimates we have made of MeHg concentrations in porewater and surface waters have been relatively robust (typically within a factor of between 2-3 from measured concentrations). This error in the estimate of actual porewater MeHg has held across deployments in a handful of "near-field" settings (sediment microcosms and outdoor macrocosms), and across some common geochemical conditions (e.g. saline vs. freshwater). However, the prediction of the porewater MeHg concentration is dependent on the choice of which partitioning coefficient to use (Kps) for the dominant MeHg species. As such, we have conducted a number of experiments to determine the range in partitioning coefficients for this materials, and what binding ligand characteristics, particularly for dissolved organic matter, influence variation in the partitioning of MeHg to the agarose+AC material. As for the replicability between samplers deployed in the same setting, deployment of samplers in large outdoor aquatic macrocosms led to inter-variability of predicted MeHg concs. that was typically low (on the order of 10% to 15% relative standard deviation). We had hoped to conduct some field deployments this summer, but were disrupted due to safety concerns. We are still hopeful to conduct some small-scale field deployments of the passive samplers this fall, as well as testing with a number of additional sediment sources in laboratory microcosm studies. -Spencer
Nice work! I was wondering if you could elaborate on the robustness of your estimates? How robust? how do your numbers compare? is there a field study that you can do to validate your numbers?
Hi Natalie, Thank you, and thanks for the question! The estimates we have made of MeHg concentrations in porewater and surface waters have been relatively robust (typically within a factor of between 2-3 from measured concentrations). This error in the estimate of actual porewater MeHg has held across deployments in a handful of "near-field" settings (sediment microcosms and outdoor macrocosms), and across some common geochemical conditions (e.g. saline vs. freshwater). However, the prediction of the porewater MeHg concentration is dependent on the choice of which partitioning coefficient to use (Kps) for the dominant MeHg species. As such, we have conducted a number of experiments to determine the range in partitioning coefficients for this materials, and what binding ligand characteristics, particularly for dissolved organic matter, influence variation in the partitioning of MeHg to the agarose+AC material. As for the replicability between samplers deployed in the same setting, deployment of samplers in large outdoor aquatic macrocosms led to inter-variability of predicted MeHg concs. that was typically low (on the order of 10% to 15% relative standard deviation). We had hoped to conduct some field deployments this summer, but were disrupted due to safety concerns. We are still hopeful to conduct some small-scale field deployments of the passive samplers this fall, as well as testing with a number of additional sediment sources in laboratory microcosm studies. -Spencer
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