arsenic methylation in urban

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:

• other forums is permitted, provided the pattern. This decoupling, driven by differential rain-washing dynamics (24.5% As
• loss vs. 13.5% P loss), created unique selective pressure that drove co-enrich-
• 18%–27% of total arsenic in stormwater runoff provided direct evidence of active
• mechanisms, leading to the expectation that their distributions exposure: Industrial-High (IH, n = 3), Industrial-Low (IL, n = 3),
• should be positively correlated (Zhao et al., 2010). However, urban Traffic-High (TH, n = 3), Traffic-Low (TL, n = 3), Control-Campus
• interfaces present unique conditions where anthropogenic As (CC, n = 3), and Control-Gulangyu (CG, n = 3). All samples were col-
• arsenic transformation pathways have not been previously Supplementary Table S1.
• Cbefore × 100%, where Cbefore and Cafter represent total element concen- relation across the 18 urban interface samples (r = −0.76, p < 0.001;
• values are means across four rain events per site. (322 ± 71 mg kg−1), whereas control sites showed the opposite pat-
• DNA was extracted using the DNeasy PowerSoil Pro Kit (Qiagen). tern (CC: As = 7.0 ± 2.5 mg kg−1, p = 1,027 ± 154 mg kg−1; Table 1).
• are provided in Supplementary Table S4. transporter gene (pstS) showed parallel enrichment patterns across
• 2.3 Greenhouse gas production potential control sites (Figure 2a; Table 1). In contrast, the alkaline phosphatase
• Microcosm incubations were conducted following Angel et al. at P-rich control sites (Table 1). Notably, arsM and pstS abundances
• 120-mL serum bottles. Headspace was flushed with N2 (99.999%) for affinity phosphate uptake under dual As-P stress. The correlation
• 5 min and bottles were sealed with butyl rubber stoppers and alumi- matrix (Supplementary Table S3; Supplementary Figure S1) revealed
• Supplementary Section S4. arsenic (Figure 3; Table 2). Total As in runoff ranged from
• methylated arsenic species (MMA + DMA) comprised 18–27% of
• Statistical analyses were performed in R v4.3.1 (R Core Team, total runoff As across all groups (Figure 3b; Table 2), providing direct
• the shaded area indicating 95% confidence interval. (b) Box plots of As/P molar ratio across interface groups displayed on a logarithmic scale,
• demonstrating approximately 50-fold gradient from industrial-high to control sites. (c) Comparison of mean As (red bars) and P (blue bars, scaled ×10)
• Traffic-Low; CC, Control-Campus; CG, Control-Gulangyu. Statistical analysis of correlations is presented in Supplementary Table S3.
• TABLE 1 Physicochemical and microbial characteristics across urban interface types.
• Values are mean ± SD. Functional gene abundances are expressed as log10 copies g−1 dry weight.
• dynamics for As and P (Figure 4). Both elements decreased following PCA captured 77.3% of total variance in the first two axes
• rain events, but As showed consistently higher proportional losses (Figure 5; Supplementary Figure S1). PC1 (66.1%) clearly separated
• than P across all interface types (Figures 4a,b). At IH sites, mean As samples along the As-P gradient, with IH and IL sites clustering in the
• loss reached 24.5% compared to only 13.5% P loss (Figure 4c). This positive region associated with high As concentrations and elevated
• percentage in runoff. Data represent four rain events (n = 12 per group). Different lowercase letters indicate significant differences among groups (one-
• TABLE 2 Arsenic speciation and methylation potential in stormwater runoff.
• Values are mean ± SD from 4 rain events (n = 12 per group). MMA, monomethylarsonic acid; DMA, dimethylarsinic acid; Methylated As, MMA + DMA.
• Arsenic shows consistently higher loss rates than phosphorus, especially at industrial sites (IH: 24.5% vs. 13.5%), contributing to progressive As-P
• with arsC and arsM abundances slightly elevated during the wet was precluded by limited replication (n = 3). Leave-one-out analysis
• Supplementary Table S2). The pstS gene exhibited relatively stable r = 0.95. Although no formal multiple-testing correction was applied
• abundance (r = 0.98; Table 3). Interestingly, CO2 flux showed an
• nic transformation genes (Table 3). Both mcrA (r = 0.99, p < 0.001) gesting that high As levels may shift microbial carbon metabolism
• loadings. PC1 (66.1%) and PC2 (11.2%) together explain 77.3% of total variance. Red arrows indicate As-related variables (As, arsC, arsM, pstS); blue
• coefficients supporting this ordination are provided in Supplementary Table S3.
• Supplementary Table S3). Observed ASVs showed a similar pattern independently of phosphorus inputs derived mainly from biologi-
• pared to phosphorus during rain events (24.5% vs. 13.5% at industrial
• Top color bars indicate gene function category: As-related (red) or P-related (blue). Error bars represent standard error of the mean (n = 3 per group).
• Asterisks denote significant seasonal differences within each group (paired t-test; *p < 0.05, **p < 0.01, ns = not significant; n = 3). Seasonal data are
• TABLE 3 Anaerobic carbon metabolism potential and greenhouse gas-related gene abundances across urban interface types.

Methods (brief)

• cited, in accordance with accepted genes (r = 0.88, p < 0.001). Methylated arsenic species (MMA + DMA) comprising
• methylarsonic acid (MMA) and dimethylarsinic acid (DMA), thereby 2 Materials and methods
• Zhu et al., 2014). The arsM gene is widely distributed among bacteria 2.1 Study area, sampling design and sample
• interfaces present unique conditions where anthropogenic As (CC, n = 3), and Control-Gulangyu (CG, n = 3). All samples were col-
• explored. Surface biofilm samples were collected during the wet season
• 2006; Wang et al., 2015). Recent studies on paddy soils and con- collected within 24 h before and 24–48 h after the event from adjacent,
• iron/manganese can simultaneously suppress arsenic release and ing a disturbed surface. Stormwater runoff (500 mL) was collected
• reduce GHG emissions (Chen Y. et al., 2025; Chen et al., 2025a; Zhao from the base of sampled interfaces during each event. All samples
• et al., 1998). Whether urban interface biofilms harbor conditions Total As was determined by ICP-MS (Agilent 7,700x) after
• favorable for both arsenic methylation and anaerobic carbon metabo- HNO₃–HF-HClO₄ digestion (Huang et al., 2018). Total P was mea-
• in runoff (As(III), As(V), MMA, DMA) was determined by HPLC- the positive As-P correlation expected from shared geochemical
• ICP-MS (Gong et al., 2020). Phosphorus fractions (SRP, IP, OP) were behavior in natural systems. This decoupling is further reinforced
• Cbefore × 100%, where Cbefore and Cafter represent total element concen- relation across the 18 urban interface samples (r = −0.76, p < 0.001;
• trations (mg kg−1 dry weight) in biofilm samples collected from adja- Figure 1a; Supplementary Table S3). IH sites contained the highest
• was collected. Detailed incubation protocols are provided in Runoff samples revealed substantial microbial transformation of
• methylated arsenic species (MMA + DMA) comprised 18–27% of
• (As) and total phosphorus (P) concentrations across 18 urban interface samples. The solid line represents linear regression (r = −0.76, p < 0.001), with
• than P across all interface types (Figures 4a,b). At IH sites, mean As samples along the As-P gradient, with IH and IL sites clustering in the

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

• Fish — marine, non-predatory (sardines, anchovies, salmon, cod)
• Arsenic

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.