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  • 1.
    Arwidsson, Zandra
    et al.
    Örebro University, School of Science and Technology. SAKAB AB, Kumla, Sweden.
    Allard, Bert
    Örebro University, School of Science and Technology.
    Remediation of Metal-Contaminated Soil by Organic Metabolites from Fungi II-Metal Redistribution2010In: Water, Air and Soil Pollution, ISSN 0049-6979, E-ISSN 1573-2932, Vol. 207, no 1-4, p. 5-18Article in journal (Refereed)
    Abstract [en]

    Exudation of low molecular weight organic acids by fungi was studied in a project focusing on bioremediation of metal-contaminated soils. The production of acids (mainly oxalic and citric acid) as a response to nutrient variations and presence of metals has recently been reported (Arwidsson et al. 2009). A significant release of metals was observed and was related not only to the production of organic acids but also to the resulting pH decrease in the systems. The processes governing the release and redistribution of metals in the soil-water fungus system were the focus of the present continuation of the project, based on observations of Aspergillus niger, Penicillium bilaiae, and a Penicillium sp. The release of lead was 12% from the soil with the second highest initial load (1,600 mg kg(-1)), while the release of copper was 90% from the same soil (140 mg kg(-1)). The dominating mechanism behind the release and subsequent redistribution was the change in pH, going from near neutral to values in the range 2.1-5.9, reflecting the production of organic acids. For some of the systems, the formation of soluble complexes is indicated (copper, at intermediate pH) which favors the metal release. Iron is assumed to play a key role since the amount of secondary iron in the soils is higher than the total load of secondary heavy metals. It can be assumed that most of the heavy metals are initially associated with iron-rich phases through adsorption or coprecipitation. These phases can be dissolved, or associated metals can be desorbed, by a decrease in pH. It would be feasible to further develop a process in technical scale for remediation of metal-contaminated soil, based on microbial metabolite production leading to formation of soluble metal complexes, notably with copper.

  • 2.
    Arwidsson, Zandra
    et al.
    Örebro University, School of Science & Technology, Örebro, Sweden; SAKAB AB, Kumla, Sweden.
    Johansson, Emma M.
    Örebro University, School of Science and Technology.
    von Kronhelm, Thomas
    SAKAB AB, Kumla Sweden.
    Allard, Bert
    Örebro University, School of Science and Technology.
    van Hees, Patrick A. W.
    Örebro University, School of Science and Technology. Eurofins Environment Sweden AB, Lidköping, Sweden.
    Remediation of Metal Contaminated Soil by Organic Metabolites from Fungi I—Production of Organic Acids2008In: Water, Air and Soil Pollution, ISSN 0049-6979, E-ISSN 1573-2932, Vol. 205, no 1-4, p. 215-226Article in journal (Refereed)
    Abstract [en]

    Investigations were made on living strains offungi in a bioremediation process of three metal (lead)contaminated soils. Three saprotrophic fungi (Aspergillusniger, Penicillium bilaiae, and a Penicillium sp.) wereexposed to poor and rich nutrient conditions (no carbonavailability or 0.11 M D-glucose, respectively) andmetal stress (25 μM lead or contaminated soils) for5 days. Exudation of low molecular weight organicacids was investigated as a response to the metal andnutrient conditions. Main organic acids identified wereoxalic acid (A. niger) and citric acid (P. bilaiae).Exudation rates of oxalate decreased in response tolead exposure, while exudation rates of citrate were lessaffected. Total production under poor nutrient conditionswas low, except for A. niger, for which nosignificant difference was found between the poor andrich control. Maximum exudation rates were 20 μmoloxalic acid g^−1 biomass h^−1 (A. niger) and 20 μmolcitric acid g^−1 biomass h^−1 (P. bilaiae), in the presenceof the contaminated soil, but only 5 μmol organic acidsg^−1 biomass h^−1, in total, for the Penicillium sp. Therewas a significant mobilization of metals from the soilsin the carbon rich treatments and maximum release ofPb was 12% from the soils after 5 days. This was notsufficient to bring down the remaining concentration tothe target level 300 mg kg^−1 from initial levels of 3,800,1,600, and 370 mg kg^−1in the three soils. Target levelsfor Ni, Zn, and Cu, were 120, 500, and 200 mg kg^−1,respectively, and were prior to the bioremediationalready below these concentrations (except for Cu Soil1). However, maximum release of Ni, Zn, and Cu was28%, 35%, and 90%, respectively. The release of metalswas related to the production of chelating acids, but alsoto the pH-decrease. This illustrates the potential to usefungi exudates in bioremediation of contaminated soil.Nonetheless, the extent of the generation of organicacids is depending on several processes and mechanismsthat need to be further investigated.

  • 3.
    Bäckström, Mattias
    et al.
    Örebro University, Department of Natural Sciences.
    Bohlin, Hanna
    Karlsson, Stefan
    Örebro University, Department of Natural Sciences.
    Holm, Nils
    Element (Ag, Cd, Cu, Pb, Sb, Tl and Zn), element ratio and lead isotope profiles in a sediment affected by a mining operation episode during the late 19th century2006In: Water, Air and Soil Pollution, ISSN 0049-6979, E-ISSN 1573-2932, Vol. 177, no 1-4, p. 285-311Article in journal (Refereed)
    Abstract [en]

    Mining operations at Maarsaetter in 1877-81 resulted in increased metal loading to a small lake, notably as sulphidic tailings. The event is taken as an opportunity to study the present environmental impact of a historical single major metal release. Lake water and four sediment cores were sampled and analysed for principal and trace elements in solid and aqueous phases as well as general hydrochemical conditions. Chronologies were determined from super(206)Pb/ super(207)Pb ratios and historical records.Ordinary sedimentation after the event has lead to that the tailings are found as a distinct layer at a depth of 18-22 cm in the sediment. The layer is characterized by elevated metal concentrations in the solid and pore water phases, respectively, circum neutral pH and sulphate concentrations below detection. Geochemical modelling indicated a preference for carbonate equilibrium in the waste while sulphides prevailed above it. It is concluded that the growth of the ordinary sediment on top of the waste has lead to a physicochemical barrier that seals of the waste from the overlying sediment. Chemical or physical rupture of the barrier will release the metals to downstream regions.According to the chronologies at least three sources have contributed to the present elevated levels of metals, in additions to the release of tailings. Copper from a historical blast furnace prior to the event at Maarsaetter, transport from mineralized parts of the watershed and release of contaminated water from present mining operations maintain elevated levels of notably zinc, silver, cadmium and lead. At present less than 10% of the lead content at the sediment/water interface comes from atmospheric deposition. Increased levels of antimony and thallium were not observed prior to ca 1950.

  • 4.
    Bäckström, Mattias
    et al.
    Örebro University, Department of Natural Sciences.
    Nilsson, Ulrika
    Håkansson, Karsten
    Allard, Bert
    Örebro University, Department of Natural Sciences.
    Karlsson, Stefan
    Örebro University, Department of Natural Sciences.
    Speciation of heavy metals in road runoff and roadside total deposition2003In: Water, Air and Soil Pollution, ISSN 0049-6979, E-ISSN 1573-2932, Vol. 147, no 1-4, p. 343-366Article in journal (Refereed)
    Abstract [en]

    The concentrations of Cd, Co, Cu, Pb, W and Zn were measured in road runoff and total deposition at two Swedish field sites during one year. It was found that the concentrations of most elements increased significantly during the winter, up to one order of magnitude. For cobalt and tungsten, it was found that around 90% of the total mass transport occurred during the winter, whereas for Cu, Pb, Cd, Zn and Na, the corresponding figures were 70–90, 40–80, 60–90, 50–70 and >99% depending on site specific conditions. The deicing salts (rock salts) did not significantly contribute to the increase in trace element concentrations. Instead, the increased concentrations were due to more intense wearing of the pavement during the winter because of the use of studded tires in combination with the chemical effects caused by the use of deicing salts. New potential elemental markers for roads and traffic are suggested.

  • 5.
    Bäckström, Mattias
    et al.
    Örebro University, School of Science and Technology.
    Sartz, Lotta
    Örebro University, School of Science and Technology.
    Mixing of acid rock drainage with alkaline ash leachates: fate and immobilisation of trace elements2011In: Water, Air and Soil Pollution, ISSN 0049-6979, E-ISSN 1573-2932, Vol. 222, no 1-4, p. 377-389Article in journal (Refereed)
    Abstract [en]

    Acid rock drainage (ARD) from mine waste dumps often contains ferrous iron, sulphate and high concentrations of trace elements detrimental to the environment. Future costs will be enormous if the problem is not treated today. Simple, low maintenance, cost-effective methods for remediation of historical mine sites are therefore desired. In this study several mine waters were mixed with an alkaline ash leachtes in order to study the fate of the trace elements from both the mine waters (Cd, Cu, Pb, Zn, Ni and Co) and the ash leachates (Cr and Mo). It was found that the addition of ash water will precipitate hydrous ferric oxides (HFO) and hydrous aluminium oxides (HAO) and thereby inducing trace element sorption and co precipitation. It is also clear that the composition of the formed HFO/HAO mix determines the efficiency of the sorption for different trace elements. It is apparent that the amount of precipitating iron will determine the effectiveness of the removal of the trace elements. Sorption occurred much earlier (often one pH unit or more) in the system with high iron concentrations compared to the systems with lower iron concentrations. Removal of cadmium and zinc is difficult below pH 8 if the amount of precipitates is low. Using ash for generation of alkaline water may be a problem with regards to chromium and molybdenum. It is, however, possible to avoid problems with molybdenum by keeping the final pH around 7 and chromium(VI) from the ash water will be reduced into chromium(III) and precipitated as the hydroxide in the presence of iron(II) from the mine waters.

    The results imply that it is possible to also use fly ashes in alkaline leach beds in order to neutralize ARD followed by precipitation and sorption of trace elements.

  • 6.
    Elgh-Dalgren, Kristin
    et al.
    Örebro University, School of Science and Technology.
    Arwidsson, Zandra
    Ribé, Veronica
    Mälardalen University, Västerås, Sweden.
    Waara, Sylvia
    Mälardalen University, Västerås, Sweden.
    von Kronhelm, Thomas
    van Hees, Patrick A. W.
    Örebro University, School of Science and Technology.
    Bioremediation of a soil industrially contaminated by wood preservatives: degradation of polycyclic aromatic hydro­carbons and monitoring of coupled arsenic distribution2011In: Water, Air and Soil Pollution, ISSN 0049-6979, E-ISSN 1573-2932, Vol. 214, no 1-4, p. 275-285Article in journal (Refereed)
    Abstract [en]

    Two commercially available aerobic bioremediation methods (Daramend® and BioSan) were utilized to study the aerobic biodegradation of polycyclic aro­matic hydrocarbons (PAH) and the effect of the simultaneously present arsenic. The soil was collected at an old wood preservation site and the initial PAH16-concentration was 46 mg/kg, with mainly high molecular weight congeners. The As-concentration was105 mg/kg with low availability as assessed with se­quential extraction. To enahce the availability of PAH, the effect of a non-ionic surfactant was evaluated. Degradation of both low and high molecular weight PAH was observed, however after 30 weeks, the degradation was generally low and no treatment was significantly better than the others. The treatments had, on the other hand, an effect on As-distribution, with increased As-concentra­tion in the available fraction after treatment. This may be due to both the mi­crobial activity and the presence of anoxic micro sites in the soil. The overall efficiency of the biological treatment was further evaluated using the standar­dized ecotoxicity test utilizing Vibrio fischeri (Microtox®). The toxicity test demonstrated that the bioremediation led to an increase in toxicity, especially in treatments receiving surfactant. The surfactant implied an increase in conta­minant availability but also a decrease in surface tension, which might have contributed to the overall toxicity increase.

  • 7.
    Elgh-Dalgren, Kristin
    et al.
    Örebro University, School of Science and Technology.
    Waara, Sylvia
    Mälardalen University.
    Düker, Anders
    Örebro University, School of Science and Technology.
    von Kronhelm, Thomas
    SAKAB AB.
    van Hees, Patrick A. W.
    Örebro University, School of Science and Technology.
    Anaerobic bioremediation of a soil with mixed contaminants: Explosives degradation and influence on heavy metal distribution, monitored as changes in concentration and toxicity2009In: Water, Air and Soil Pollution, ISSN 0049-6979, E-ISSN 1573-2932, Vol. 202, no 1-4, p. 301-313Article in journal (Refereed)
    Abstract [en]

    Two soils with explosives and metals were evaluated for the degradation efficiency of explosives by native microorganisms under anaerobic conditions. The commercially available method Daramend®, amended with zero-valent iron (ZVI), was compared with a horse-manure amended compost and a treatment with ZVI alone. In a moderately contaminated soil, Daramend® and ZVI treatment gave significantly higher removal rates compared  to compost and control treatments (Tukey’s test, P<0.05). The largest overall decrease in ecotoxicity, measured with bioluminescent bacteria (Vibrio fischeri), was achieved with ZVI-treatment. In a more contaminated soil no degradation of contaminants and no decline in soil toxicity could be distinguished after the same time period. Problems with establishment of anaerobic conditions during parts of the remediation process and low microbial activity due to acute toxicity of contaminants are plausible explanations. Redistribution that could potentially lead to mobilization of the co-contaminant Pb was not observed in either of the soils during the biological treatments.

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