matter with inorganic mercury and

Overview

This source page is a mechanical bulk-ingest record for a PDF in the research-pulls corpus. It preserves source-level identity, routeable product/analyte scope, and exact extracted numeric lines for later human or fresh-context audit. It does not derive HMTc thresholds, percentiles, or brand-by-brand comparisons.

Key numbers

The worker extracted the full PDF text with layout preservation twice and compared extraction hashes before commit. The following lines are copied from numeric/table-bearing regions of the PDF and retain the source units and wording where legible:

• 34 abundance of nitrogen and sulfur containing DOM are most often positively correlated (mean ρ =
• 36 important, though with weaker correlations (mean ρ = 0.51). For MeHg, low-oxidized lignins
• 38 % of all DOM-MeHg correlations regardless of season. Further network analyses reveal that the
• 40 range of NOSC values, indicating that DOM involved with the transport of inorganic mercury
• 41 encompasses a wide range of polarities and thermodynamic stabilities. In contrast, DOM
• 43 values, implying the preferential transport of MeHg with more thermodynamically stable and
• 124 relationships vary both spatially across streams draining a range of central Canadian boreal
• 148 shallow soil regions with near surface and exposed bedrock (SN, DE, n = 7). Forest coverage
• 157 dominated (DW; n = 2), and near surface/exposed bedrock regions (DE and SN, n = 7).
• 170 Monthly mean runoff for each watershed was calculated by dividing stream discharge by the
• 181 samples were stored in a 125 mL PETG bottle and trace metal grade HCl was added to 0.5% by
• 193 at least every 10 samples (Table S1).
• 213 samples. QA/QC results for all Hg analyses are found in Table S1.
• 224 for DOM ranged from 63-85 % of the initial DOM concentrations. A 7 T Bruker Solarix XR FT-
• 229 1-200), 1-50), 0-2), and 0-2) ranges and with a mass tolerance of ± 0.5 ppm.
• 245 based on possible arrangements of carbon, oxygen, hydrogen, sulfur, nitrogen, and phosphorus
• 260 correlation was conducted based on molecules commonly found in at least 80% of all
• 266 Hg(II) and MeHg concentrations. These network analyses were arranged based on a subset of the
• 301 DOM pool in the late spring (34 % and 23 %; respectively) whereas low-oxidized lignins and
• 302 oxidized lignins were the main DOM compound classes in the fall (50 % and 21 %; respectively)
• 304 in the late-spring than fall (10 % vs 0.5 %; p < 0.05) whereas in the fall, low oxidized lignin
• 308 (orange; B). Compound classes are normalized to the 1321 and 872 molecules identified in all 13
• 317 positive correlations between Hg(II) concentrations and low-oxidized lignins represented 21 % of
• 318 all Hg(II)-DOM correlations with comparable correlations among hydrolysable tannins (21 %),
• 319 and aliphatic/N-saturated molecules (15 %) in the late spring (Figure 4 A; Figure S3 A). MeHg
• 321 and hydrolysable tannins regardless of season (Figure 4 C, D), collectively accounting for 52 %
• 322 and 83 % of all MeHg-DOM significant correlations in the late spring and fall, respectively
• 328 DOM molecules and Hg(II) concentrations in the late spring where 42 % of the Hg(II) correlated
• 359 polyphenolic lignins, that account for 20% of conifer needle dry weight (Dickinson and Pugh
• 364 thermodynamically stable, and highly resistant to microbial degradation (Dickinson and Pugh
• 386 seasonally (Figure 5 A, B). Approximately 17 % of Hg(II) significantly correlated DOM
• 389 given that N-saturated DOM only accounted for 10 % of the total DOM pool in the late spring
• 393 molecules compared to the fall (5% vs 1%, respectively), an indication of greater biologically
• 399 originating from sources within streams. Both Hg(II) concentrations and total %S in DOM did
• 401 alone is not the only variable controlling Hg(II) mobility. Approximately 60 % of all Hg(II)-
• 402 DOM correlations in the fall were with low-oxidized lignin molecules, likely due to the 16 %
• 408 compound class region that correlated with Hg(II) concentrations (Figure 5 B). Given that %S
• 422 Figure 5: CHO (grey), CHON (green), CHONS (orange), and CHOS (purple) containing DOM
• 429 thermodynamically stable interactions with Hg(II) (Haitzer et al., 2002; Liem-Nguyen et al.,
• 432 2019; Wang et al. 2021). Even though thiol concentrations normally range between 0.96-3.40
• 438 coupled to low %S in freshwater boreal stream environments may create conditions where
• 477 correlated DOM molecules, 14 % contained sulfur atoms, whereas 3 of the 5 shared molecules

Methods (brief)

• 26 concentrations. In this study, we use a high-resolution mass spectrometry approach, Fourier-
• 27 transform ion cyclotron resonance mass spectrometry, to characterize DOM compound classes,
• 49 Keywords: Mercury, Dissolved Organic Matter, High Resolution Mass Spectrometry, Boreal
• 113 The recent development of high resolution mass spectrometry techniques like Fourier
• 114 transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) provide a breadth of
• 137 Site Description and Sample Collection
• 142 spring (May/June) and fall (October) of 2019 (Figure 1). The sampled forests of northwestern
• 145 with no human activity or current development. The sampled streams covered a representative
• 155 Figure 1: Thirteen low order streams sampled in the boreal forests of northwestern Ontario.
• 156 Sampled streams were found in glaciolacustrine sandy plain (CF, n = 4) regions, peatland-
• 172 DOM samples were collected in 1L polycarbonate bottles that were triple rinsed with
• 174 bottles were submerged with care to not disturb sediments, where the collected water was
• 175 transported for filtration. Water samples for Hg and MeHg analyses were collected using clean
• 177 water samples were filtered through a Whatman 0.45 m nitrocellulose acetate filter that was
• 178 pre-ashed at 450 C for 4 hours. DOM water samples for high resolution mass spectrometry were
• 179 collected in a 20 mL amber glass scintillation vial and acidified to pH 2 using HCl whereas
• 180 samples for DOC analysis were collected in 50mL centrifuge tubes (Falcon). Filtered Hg water
• 181 samples were stored in a 125 mL PETG bottle and trace metal grade HCl was added to 0.5% by

Implications

This page makes the source discoverable for category-level evidence routing. Values remain source-native and should be used only with the stated matrix, species, basis, geography, and censoring context from the paper. The page does not convert total mercury to methylmercury or use total arsenic as inorganic arsenic.

Wiki pages this source may touch

• Seaweed/kelp foods (nori, wakame, kombu, dulse — as food products)
• Mercury
• Mercury

Verification notes

• Identity check: DOI, raw handle, candidate cite-key, and SHA-256 were compared against existing wiki/sources/ pages before creation.
• Full-PDF read: pdftotext -layout was run on the full PDF twice; extracted text hashes matched before the page was written.
• Numeric verification: numeric/table-bearing lines were selected mechanically from the verified extraction and preserved without unit conversion or rounding.
• Brand firewall: the worker skips PDFs when extracted numeric lines appear brand/manufacturer-sensitive; this page contains category-level or species-level evidence only.
• HMTc firewall: no threshold, percentile, pass/fail, clean/dirty, or certification math is stated.

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.