Overview
This source page is a mechanical bulk-ingest record for a PDF in the methylmercury infant-formula research pull. 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:
- License: This work is licensed under a Creative Commons Attribution 4.0 International License.
- Version of Record: A version of this preprint was published at Plant and Soil on January 2nd, 2026. See
- As speciation and Fe mineralogy were characterized in an 28-day anoxic microcosm experiment using
- concentrations of 11.6–46.3% in pore water of paddy soils. Oxalic acid had the strongest promoting
- As, resulting in 4.6%-22.5% lower pore water As compared to exudate alone. Elevated sulfide fluxes
- sulfate reduction facilitated the formation of dimethylarsenic and dimethylmonothioarsenate by 52.6-
- South and Southeast Asia, where geogenic As-enriched groundwater is prevalent (Aftabtalab et al. 2022;
- Mukherjee et al. 2024). The irrigation of As-contaminated groundwater has elevated As accumulation in
- application (Hong et al. 2023; Qiao et al. 2023). Under periodic flooding conditions, As is mobilized into
- et al. 2008; Zhu et al. 2008). As a result, rice consumption has become a major exposure pathway to As
- for population dependent on a rice-based diet (Hussain et al. 2021). Thus, a comprehensive
- transformation of iron (Fe) oxy(hydro)xides (Burton et al. 2011; Nghiem et al. 2023). Under oxic
- (Chen et al. 2023; Hong et al. 2023). In contrast, during flooded conditions, As(V) can be released
- (Guo et al. 2013; Huang et al. 2012). As(III) exhibits lower sorption affinity to Fe oxy(hydro)xides and is
- more readily mobilized into pore waters (Xiang et al. 2025). Additionally, Fe(Ⅱ)-catalyzed phase
- water phases (Wang et al. 2021). The formation of secondary Fe-bearing minerals such as green rust,
- adsorption, thereby reducing its concentration in pore water (Perez et al. 2020; Wang et al. 2018).
- (Guo et al. 2016). Although the reductions of poorly-crystalline Fe oxy(hydr)oxides and As(V) are
- thermodynamically more favorable than sulfate (SO42-) reduction, increasing evidence indicates that
- reduction of Fe oxy(hydr)oxides, As(V), and SO42- can occur concurrently in anoxic environments
- (Nghiem et al. 2023; Wu et al. 2024). Sulfide produced from sulfate reduction can rapidly react with Fe(II)
- crystalline pyrite (FeS2), although the diagenetic pathways remain incompletely understood (Burton et al.
- 2013). While FeS has limited capacity to adsorb or incorporate As, pyrite exhibits a strong affinity for As,
- facilitating its immobilization (Qiu et al. 2017; Wang et al. 2020a). Concurrently, sulfide can abiotically
- reduce As-bearing Fe oxy(hydr)oxides, enhancing As mobilization into pore water (Guo et al. 2016; Kocar
- et al. 2010; Zheng et al. 2020). Thus, As mobility in paddy soils is governed by was complex interaction
- reactive Fe oxy(hydr)oxides (Burton et al. 2014; Planer-Friedrich 2023). The impact of sulfate reduction
- on pore water As concentrations remain inconsistent across studies (Burton et al. 2014; Wang et al.
- 2017; Xu et al. 2019; Zheng et al. 2020).
- monomethylarsenate (MMA) (Chen et al. 2019; Wang et al. 2020c). Increasing evidence also indicates
- such as monothioarsenate (MTA, AsS(OH)3), dithioarsenate (DTA, AsS2(OH)22-) and organic forms such
- as monomethylmonothioarsenate (MMMTA, (CH3)AsS(OH)2), dimethylmonothioarsenate (DMMTA,
- (CH3)2AsS(OH)). These thiolated species commonly co-exist with As(III) and As(V), adding complexity to
- arsenic speciation under reducing conditions (Besold et al. 2018; Wang et al. 2020c).
- carbon in soils (Haichar et al. 2008; Liu et al. 2022b). These compounds can stimulate microbial
- processes such as sulfate reduction and the reductive dissolution of Fe oxy(hydr)oxides (Jia et al. 2014;
- Liu et al. 2022a), thereby influencing coupled Fe-S redox dynamics and the associated and speciation of
- underlying microbial mechanisms (Jiang et al. 2023; Liu et al. 2022a; Zou et al. 2024), their specific
- conditions and root exudate amendments. We hypothesize that: 1) sulfate reduction critically amplifies
- Surface paddy soils (0–20 cm) were collected from an As-contaminated paddy field in Qingyuan city of
- Guangdong province, China (23°42′ N, 113°4′ E). Due to mining activities, the paddy soils are heavily
- contaminated with As at a concentration of ~ 51 mg kg-1 soil, which has far exceeded the regulatory for
Methods (brief)
- by sulfate-reducing bacteria, producing methylated As species, such as dimethylarsenate (DMA) and
- Surface paddy soils (0–20 cm) were collected from an As-contaminated paddy field in Qingyuan city of
- Chinese paddy soils (Regulation 2018). Following transport to the laboratory, soil samples were air-dried
- samples. Reagents were deoxygenated by purging with nitrogen (N2), to create an oxygen-free
- Pore water was sampled at specific intervals (0.5, 1, 3, 7, 14, 21, and 28d). Following by filtering through
- 1.0 mL of pore water samples were added to 10 mM DTPA (neutralized to pH 7.5) and preserved at -20°C
- pore water was measured using a hydride-generation flame atomic absorption spectrophotometer (TAS-
- (Dionex ICS-1100, Thermo Scientific, USA) coupled to an inductively coupled pharma-mass spectrometry
- (ICP-MS, NexION 350X, PerkinElmer, Inc., Shelton, CT USA). Briefly, As species were separated using an
- species were then directly introduced into the ICP-MS, equipped with a Type C0.5 Glass Nebulizer, for
- quantification. The As(III), As(V), DMA, MMA and DMMTA were separated during speciation analysis.
- The average recovery of total As across all measured samples was 109 ± 19%, indicating that
- Then samples were washed once using 50 mL ultrapure water and combined with the extraction
- The detectable As species in pore water mainly included As(III), As(V), DMA, and DMMTA. At the end of
- The organoarsenical species DMA and DMMTA were detected, with concentrations ranging from 1.4 to
- 41 μg L⁻¹ (Fig. 3i-p). Both DMA and DMTA concentrations were initially increased and then rapidly
- declined over time. Sulfate addition significantly enhanced their concentrations. In control, the DMA and
- DMMTA and DMA were increased by 93% and 111% without root exudate, by 27% and 87% with citric
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.
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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 -layoutwas 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.