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- Hogfors-Ronnholm, Eva, et al.
(författare)
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Biodegraded peat and ultrafine calcium carbonate result in retained metals and higher microbial diversities in boreal acid sulfate soil
- 2020
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Ingår i: Soil Ecology Letters. - : Springer Nature. - 2662-2289 .- 2662-2297. ; 2:2, s. 120-130
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Tidskriftsartikel (refereegranskat)abstract
- To efficiently mitigate bacterial mediated acid and metal discharge from acid sulfate soils, iron-and sulfur-oxidizing microorganisms that catalyze the iron sulfide dissolution should be inactivated. An organic carbon source could further be introduced into the soil to promote the growth of iron- and sulfur-reducing bacteria. In this study, acid sulfate soil was amended with a mobile form of ultrafine calcium carbonate alone or in combination with fractions of peat, sodium acetate, or sodium lactate. The introduction of ultrafine calcium carbonate resulted in a raised pH that appeared to inactivate the acidophiles, but did not reactivate iron- or sulfur-reducing bacteria. The addition of organic matter resulted in higher microbial diversities and retention of metals, although acid-tolerant and acidophilic microbes still dominated. A low abundance of an iron-reducing bacteria was identified in the all treatments with both peat fractions and pure organic carbon compounds. These results indicated that biodegraded peat could be used as an energy source for at least iron-reducing bacteria in the acid sulfate soil at the same time as it retains metals in the soil. These findings are of value for further developing mitigation methods for the sustainable use of acid sulfate soils.
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| 2. |
- Hogfors-Ronnholm, Eva, et al.
(författare)
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Gallionella and Sulfuricella populations are dominant during the transition of boreal potential to actual acid sulfate soils
- 2022
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Ingår i: Communications Earth & Environment. - : Springer Nature. - 2662-4435. ; 3:1
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Tidskriftsartikel (refereegranskat)abstract
- Acid sulfate soils release metal laden, acidic waters that affect the environment, buildings, and human health. In this study, 16S rRNA gene amplicons, metagenomes, and metatranscriptomes all demonstrated distinct microbial communities and activities in the unoxidized potential acid sulfate soil, the overlying transition zone, and uppermost oxidized actual acid sulfate soil. Assembled genomes and mRNA transcripts also suggested abundant oxidized acid sulfate soil populations that aligned within the Gammaproteobacteria and Terracidiphilus. In contrast, potentially acid tolerant or moderately acidophilic iron oxidizing Gallionella and sulfur metabolizing Sulfuricella dominated the transition zone during catalysis of metal sulfide oxidation to form acid sulfate soil. Finally, anaerobic oxidation of methane coupled to nitrate, sulfate, and ferric reduction were suggested to occur in the reduced parent sediments. In conclusion, despite comparable metal sulfide dissolution processes e.g., biomining, Gallionella and Sulfuricella dominated the community and activities during conversion of potential to actual acid sulfate soils.
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| 3. |
- Yu, Changxun, 1983-, et al.
(författare)
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Manganese cycling and transport in boreal estuaries impacted by acidic Mn-rich drainage
- 2024
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Ingår i: GEOCHIMICA ET COSMOCHIMICA ACTA. - : Elsevier. - 0016-7037 .- 1872-9533 .- 0046-564X. ; 365, s. 136-157
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Tidskriftsartikel (refereegranskat)abstract
- As critical transition zones between the land and the sea, estuaries are not only hotspots of hydrogeochemical and microbial processes/reactions, but also play a vital role in processing and transferring terrestrial fluxes of metals and nutrients to the sea. This study focused on three estuaries in the Gulf of Bothnia. All of them expe-rience frequent inputs of acidic and Mn/metal-rich creek waters due to flushing of acid sulfate soils that are widespread in the creeks catchments. Analyzing existing long-term water chemistry data revealed a strong sea-sonal variation of Mn loads, with the highest values in spring (after snow melt) and autumn (after heavy rains). We sampled surface waters, suspended particulate matter (SPM), and sediments from the estuarine mixing zones and determined the loads and solid-phase speciation of Mn as well as the composition and metabolic potentials of microbial communities. The results showed that the removal, cycling, and lateral transport of Mn were governed by similar phases and processes in the three estuaries. Manganese X-ray absorption spectroscopy data of the SPM suggested that the removal of Mn was regulated by silicates (e.g., biotite), organically complexed Mn(II), and MnOx (dominated by groutite and phyllomanganates). While the fractional amounts of silicate-bound Mn(II) were overall low and constant throughout the estuaries, MnOx was strongly correlated with the Mn loadings of the SPM and thus the main vector for the removal of Mn in the central and outer parts of the estuaries, along with organically complexed Mn(II). Down estuary, both the fractional amounts and average Mn oxidation state of the MnOx phases increased with (i) the total Mn loads on the SPM samples and (ii) the relative abundances of several potential Mn-oxidizing bacteria (Flavobacterium, Caulobacter, Mycobacterium, and Pedobacter) in the surface waters. These features collectively suggested that the oxidation of Mn, probably mediated by the potential Mn-oxidizing microorganisms, became more extensive and complete towards the central and outer parts of the es-tuaries. At two sites in the central parts of one estuary, abundant phyllomanganates occurred in the surface sediments, but were converted to surface-sorbed Mn(II) phases at deeper layers (>3-4 cm). The occurrence of phyllomanganates may have suppressed the reduction of sulfate in the surface sediments, pushing down the methane sulfate transition zone that is typically shallow in estuarine sediments. At the outermost site in the estuary, deposited MnOx were reduced immediately at the water-sediment interface and converted most likely to Mn carbonate. The mobile Mn species produced by the Mn reduction processes (e.g., aqueous Mn(II) and ligand complexed Mn(III)) could partly diffuse into the overlying waters and, together with the estuarine Mn loads carried by the surface waters, transfer large amounts of reactive Mn into open coastal areas and subsequently contribute to Mn shuttling and inter-linked biogeochemical processes over the seafloor. Given the widespread occurrence of acid sulfate soils and other sulfidic geological materials on many coastal plains worldwide, the identified Mn attenuation and transport mechanisms are relevant for many estuaries globally.
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