Electricity-Induced Simultaneous in Situ Remediation of Arsenic and

Overview

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Key numbers

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• dissolved PAH16 concentrations decreased by 62−94% across wells, with no accumulation of oxygenated or nitrogen-containing
• PAH. Dissolved As concentrations declined by up to 88% at low PAH levels, but reductions were weaker (55−57%) and more
• (Table S1). Shallow groundwater at the site predominantly flows concentrated nitric acid prior to analysis of metal concentrations using
• used as electrodes. In total, 28 electrodes were placed 5 m apart in a grid with JCGM 100:2008,11 using a coverage factor of 2 (≈95% confidence
• recoveries generally required to fall within 70−130% and duplicate between samples, after normalization via scaled ranked subsampling
• Detection limits for each compound are provided in Table S2. taxa significantly enriched in samples of high As and PAH
• discriminate between sample means. μS cm−1), whereas all the other sampling points ranged between
• (v1.15.017), vegan (v2.5.718), and phyloseq (v1.26.019) for community depletion of ions in the treated area. However, the rather stable
• entire experimental period was 5.85 ± 0.34. This stability was immobilization of As in the same organic soil, a notable drop in
• Figure 3. Mean As and Fe concentrations in groundwater over the course of the experiment in comparison to the initial values measured at the start of
• Averaging the results over the course of the experiment, a Mean values over the two years for GW2−4 differed significantly
• across most sampling points compared to initial values (Figure dissolved As (by 88%), despite occasional peaks (Figures 4 and
• lowest As concentrations, remaining within the range observed decreased by 55% and 57%, respectively), and values fluctuated
• deviation of the means (Figure 3). Notably, both GW3 and formation of soluble organometallic complexes that increase As
• groundwater in GW2, meaning that decreasing PAH concen- three occasions during the second year of the experiment
• However, such a correlation was not significant in GW3 and species, with no detectable monomethylarsonate (MMA) and,
• in GW3, compared to GW2 (Figure 4). The peat-rich zones in arsenate, accounting for 96−100% of total As, except for one
• reducing their effective surface area and thereby limiting Fe−As of high soil organic matter content at varying depths (Table S1)
• values ranged between 2.4 and 5.6 mg L−1. The fluctuating
• the challenge of identifying soil remediation techniques capable S4).30 The mean PAH concentration during that period was
• for 55−84% of dissolved PAH present, followed by medium- at all in this sampling point.
• ting 0.4−13% of the total PAH. Although PAH-M compounds
• in groundwater than heavier PAH. (Table S2). Out of 13 measured compounds, four (acridine, 1-
• sampling points, reaching 85% in GW1, 84% in GW2, 62% in at creosote-contaminated sites,31 they were not detected in
• GW3, and 94% in GW4. The greatest average reduction was significant amounts in the groundwater at the studied site. This
• PAH-L at 74%. Since PAH-H concentrations were low initially, soluble than their parent PAH, underwent continuous
• the degradation of lighter PAH.26 (fluorene) by 550%. Although this appears to be an extreme
• and GW4 on average (Figure 6A). This general decline in alpha- patterns (Figure 6C), though fungi were only detectable in 9 out
• the prokaryotic communities (11−59%; Figure 7A), followed by conditions (LDA = 4.7, p = 0.019). Species within Rugosibacter
• Heatmap showing the relative abundance (%) of the top 50 most relatively abundant genera across samples. B: Heatmap showing key genera relative
• 0.02% at GW Ref1, and was significantly associated with both found in hydrocarbon-contaminated groundwater.46
• organic enrichment, including humic substances, leading to the potentials (Eh > 0 mV) and stable pH values around 6 favor both
• Fe(III) phases as suggested earlier. more than 95% of dissolved As in most samples, indicating
• were detectable only in 9 out of 15 samples. At the class level, and sorption capacity.61 Maintaining oxic conditions is therefore
• Leotiomycetes (8−96%; Figure 7B), a group that includes many critical, since Fe(III) reduction can dissolve Fe minerals and
• Dothideomycetes (0.6−28%), Sordariomycetes (3−21%), and health risk perspectives, this is particularly relevant, given the
• Tremellomycetes (0−40%) were widespread, with peak relative substantially lower toxicity and mobility of arsenate compared
• 26%) were most abundant at GW4 during September 2023, Importantly, the microbial community structure observed in
• Eurotiomycetes (0−18%) peaked at GW3, where both PAH and interactions. Along increasing As and PAH gradients, microbial
• As concentrations were high. Mucoromycetes (0−23%) communities showed clear selection for taxa tolerant of, and in
• (0−89%; class Leotiomycetes), was however present exclusively
• (Figure S8), Cladosporium (1−9%), with members capable of being more prevalent at less-contaminated sites. This divergence

Methods (brief)

• The aim of this study was to assess the efficiency of electricity- Groundwater PAH concentration data from this older well, collected
• in groundwater on a pilot scale at a former wood impregnation Groundwater samples were collected once a month during the first year
• to fully recover before the sample collection. Samples for PAH analyses
• groundwater, along with alterations of microbial community were collected into dark glass bottles and for metals into acid-washed
• phase layer, which limited the representativeness of the samples. For
• 2. EXPERIMENTAL SECTION those few samples that were collected, precautions were taken to
• prevent oil from entering the sampler, but creosote droplets were still
• 2.1. Pilot Site observed in these samples.
• on-site using creosote oil and Boliden salt (containing Cu/Zn, Cr, and 2024, day 679). Groundwater was collected in 1 L PE bottles. Prior to
• 33,000 m2. As a result, the site has been extensively contaminated with initial outflow was used to rinse the bottles. For the sample containing a
• groundwater, and ditch sediments. The plot for the current pilot study samples were transported to the laboratory in a cooling box. The
• construction activities, such as excavation for concrete footings, immediately upon arrival at the laboratory. All samples were filtered
• southward, although variations occur, and a hydraulic gradient toward ICP-OES (PerkinElmer Optima 8300). Arsenic speciation in ground-
• the north has also been observed. Both the hydraulic gradient and water was performed by HPLC-ICP-MS according to SOP-0601 at ALS
• soils at the pilot site were 35 800 mg kg−1 for PAH and 513 mg kg−1 for column, followed by ICP-MS detection. Detection limits for As(III),
• As (at 0.85−2 m depth). As(V), and DMA were 0.1 μg L−1, and for MMA they were 0.2 μg L−1.
• level). The provided reporting limits (LOR) were standard and specific between sample locations and dates were assessed by Kruskal−Wallis
• method blanks, laboratory control samples, laboratory duplicates, and with physiochemical factors. Beta-diversity analysis based on Bray−

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
• Chromium

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Update history

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