Distribution and Homogenization of Multiple Mercury Species

Overview

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Key numbers

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one-way ANOVA analysis). In contrast, selective sequential extractions resulted in a homogeneous distribution, with >90% of each
surface exchange of gaseous and particulate Hg.10,13−15 For all wide range of rates in aggregation, deposition, methylation, and
credit system might implement a range of technologies and Hg2+, soluble 201Hg-humic acid complexes, nanoparticulate
components of a watershed in the Experimental Lakes region with locally sourced soil comprising 64, 28, and 13% sand, silt,
that have been observed in historically impacted and managed 30% v/v HNO3 (F4), and aqua regia (F5). F1 represents
watersheds.3 This dosing level was also selected to exceed the water-soluble Hg, F2 is meant to mimic human stomach fluid
dosing (17 ± 2 ng g−1, N = 9). In other wetland mesocosm species, F4 dissolves some solid-phase Hg species or elemental
of the experiment (sediment total Hg = 14 ± 4 ng g−1, N = 9). Approximately 0.7 g of wet-weight-homogenized sediment
samples (N = 4−6 per mesocosm box) were collected by hand resuspended and washed with 40 mL of the same extractant,
(10%) of BrCl was used for F3 to ensure acidification. The
After the collection of water, sediment samples (N = 3 per determine the wet−dry ratio for normalization of Hg
water column (N = 6) and placed face down in the surface and DGTs were analyzed by stannous chloride reduction,
sediment of the submerged aquatic zone (N = 6) for 7 days. amalgamation (BrooksRand T-MERX) connected in line with
80, and 360 days after dosing (N = 4 per mesocosm). Fish the extraction of MeHg with acidified potassium bromide and
dichloromethane.47 For MeHg quantitation in fish, samples ANOVA assessed the differences in these % contributions for
(>70% for all samples) was used to correct the MeHg the variance of % contribution within each endmember group.
were within 80−120% of the reported average reference values. distribution was defined as p < 0.05. Additionally, for water
mesocosms. The values correspond to the average flux for N = 5 or 6 DGTs deployed in each mesocosm box at three different sampling events: (A)
17 days; (B) 38 days; and (C) 360 days after the Hg endmember dosing. Error bars represent one standard error around the mean.
42 days, and (C,F) 360 days after the Hg isotope dosing to the mesocosm boxes. The values correspond to the average concentration for N = 3 at
Day 3 after dosing, 9.1−18.5% of THg from the Hg spikes was uptake flux to the samplers differed by endmember (Figure 2).
larger (36.8−53.7%). For all sample time points for filtered initially dissolved forms yielded the largest uptake fluxes (from
mesocosms. The values correspond to the average flux for N = 5 or 6 DGTs deployed in each mesocosm box at three different sampling events: (A)
7 days; (B) 42 days; and (C) 360 days after the Hg isotope dosing. Error bars represent one standard error around the mean.
12 to 20 ng day−1 cm−2), while the respective DGT flux values THg corresponded to 46−550 and 8−28%, respectively, of the
mesocosms (0−2 cm depth), wide ranges of THg concen- surface sediment were highly dependent on the initial Hg
then the measured THg contents at 7 days after dosing experimental duration, with % MeHg values ranging from 0.07
represented 12−257% of the Hg added at the start of the to 2.73% at Day 7, 0.13 to 2.31% at Day 42, and 0.39 to 2.75%
deployed in the sediments were typically between 50 and 300 the extracted THg (>90%) was measured in the F3 extraction
result would be expected if most of the added Hg accumulated (between 60 and 110% of the separately measured THg
represent 0.01−0.1% of the added Hg for each endmember. months. At one year after dosing, the DGT uptake fluxes of the
observed to decrease by 80, 35, and 66% in the lake water
mercury stable isotopes. Geochim. Cosmochim. Acta 2011, 75 (3), (22) Shabman, L.; Stephenson, K. Achieving nutrient water quality
(13) Gerson, J. R.; Szponar, N.; Zambrano, A. A.; Bergquist, B.; mercury in a boreal forest wetland: A stable mercury isotope
(46) Hintelmann, H.; Evans, R. Application of stable isotopes in holbrooki) from three experimental populations. Environ. Toxicol.
(49) VanderPlas, J.; Granger, B.; Heer, J.; Moritz, D.; S. Chronic Engineered Nanoparticle Additions Alter Insect

Methods (brief)

of aqueous Hg in a diffusive gradient in thin-film (DGT) passive samplers. We observed that the four isotope spikes were relatively
after spike addition. However, the uptake fluxes of Hg in DGT samplers, deployed in both the water column and surface sediment,
within weeks after addition, these input pools remain differentiated for more than one year in terms of reactivity for passive samplers,
KEYWORDS: mercury, freshwater wetland, partitioning, passive samplers, bioaccumulation, fate and transport
phosphorus, and sediment.21−23 If this approach were applied gradient in thin-film (DGT) passive samplers for predicting the
(e.g., aqueous-solid phase partitioning, oxidation/reduction surface sediments and by deploying DGT samplers in surface
amount that targeted 100 ng Hg g−1 soil per endmember. This procedure, sediment samples were sequentially exposed to five
Wetland Sample Collection and Processing. Surface was mixed with 40 mL of the extraction fluid. After mixing
water and sediment samples were collected from each wetland end-overend for an overnight period, the suspension was
samples (N = 4−6 per mesocosm box) were collected by hand resuspended and washed with 40 mL of the same extractant,
samples were filtered with a poly(ether)sulfone filter (0.2 μm
aqua regia step (F5) entailed overnight digestion of the sample
and filtered water samples were amended with BrCl (1% v/v)
concentrated HNO3. After digestion, the mixture was diluted
After the collection of water, sediment samples (N = 3 per determine the wet−dry ratio for normalization of Hg
(Environmental Express Clean Cup digestion vessel; diameter Chemical Analyses. In situ dissolved oxygen, pH, and
laboratory, aliquots of the sediments corresponding to the top the collection of water, sediment, and fish samples. For a
2 cm layer were extruded from the core, homogenized, and subset of filtered water samples corresponding to -1, 10, and

Implications

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Verification notes

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Update history

The five most recent substantive edits to this page, classified major (evidence or structure moved), correction (a published value or statement was wrong and has been fixed), or minor (narrative rewritten without changing the underlying evidence). Each description is derived from what the edit did to this page; the linked commit is the authoritative record, routine regeneration passes are excluded, and the full version history lives in git. When DOI minting comes online (see schema docs), each entry below will also link to a version-pinned DataCite DOI.

Commit	Date	Change	Description
b01ec52c	2026-08-04	major	2 sections added
d49e450f	2026-08-03	major	5 sections added; narrative text revised