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  • 1.
    Arwidsson, Zandra
    et al.
    Örebro University, School of Science and Technology.
    Allard, Bert
    Örebro University, School of Science and Technology.
    Elgh-Dalgren, Kristin
    Örebro University, School of Science and Technology.
    van Hees, Patrick
    Örebro University, School of Science and Technology.
    Recycling of amino polycarboxylic acids in soil washing of heavy metal contaminated soilManuscript (preprint) (Other academic)
  • 2.
    Arwidsson, Zandra
    et al.
    SAKAB AB, Kumla, Sweden.
    Elgh-Dalgren, Kristin
    Örebro University, School of Science and Technology.
    Nehrenheim, Emma
    School of Sustainable Development of Society and Technology, Mälardalen University, Västerås, Sweden.
    Odlare, Monica
    School of Sustainable Development of Society and Technology, Mälardalen University, Västerås, Sweden.
    Ribé, Veronica
    School of Sustainable Development of Society and Technology, Mälardalen University, Västerås, Sweden.
    Sjöberg, Ragnar
    Solventic AB, Motala, Sweden.
    von Kronhelm, Tomas
    SAKAB AB, Kumla, Sweden.
    van Hees, Patrick
    Örebro University, School of Science and Technology.
    Allard, Bert
    Örebro University, School of Science and Technology.
    Remediation of soils and sludges containing organic contaminants as well as metals – soil-wash procedures combining biodegradation, chemical complexation and mechanical separation of particulate matter2009Conference paper (Refereed)
    Abstract [en]

    Soil contamination is an urgent issue world wide. More than 83,000 contaminated sites have been identified in Sweden alone, of which approximately some 4,000 require treatment in the near future. Most of the sites carry a mixture of contaminants, metals as well as persistent organics. Most soil remediation efforts are made ex situ, which means that the soil or sludge is dug up and transported to a facility for treatment, or simply for deposition. The aim of the present project is to design a strategy for ex situ treatment of soils with mixed contaminants. A variety of soils and sludges from different sites (around 10), essentially all with organic as well as inorganic (metallic) contaminants, have been selected for experimental studies in laboratory and pilot scale: Military sites (metals, explosives), wood preservation sites (PAHs, As, metals), industrial sites (metals, hydrocarbons, mercury, dioxins and others). Of particular importance in the present study are:

    Metals – Pb, Cu, Zn, Cr, Hg, as well as As Organics – PAHs, nitro aromatics, dioxins

    A number of processes are selected and applied: •Biodegradation - use of commercially available cultures, as well as bacteria cultivated from the contaminated site itself •Mobilisation of organics - use of surface active agents •Mobilisation of metals - use of (1) complexing microbial metabolites produced in the soil (by fungii in paricular), (2) complexing agents generated by degradation of natural organic products (polyhydroxy carboxylic acids), and (3) artificial complexing agents (polyamino carboxylic acids).

    Biodegradation is performed in batches (anaerobic in most cases), while release and mobilisation of contaminants from soil aggregates are achieved during soil-wash performed in a dynamic system where wash solution is forced through the soil under high pressure (the WTC-process). The efficiency of biodegradation and subsequent soil-wash under various conditions is evaluated from chemical analysis, but also by several ecotoxicological tests. Some results are given that illustrates suitable strategies for treatment of mixed contaminated soil from real sites (soil) as well as for treatment of residues from industrial production (sludges etc).

  • 3.
    Arwidsson, Zandra
    et al.
    Örebro University, School of Science and Technology. SAKAB AB, Kumla, Sweden.
    Elgh-Dalgren, Kristin
    Örebro University, School of Science and Technology.
    von Kronhelm, Thomas
    SAKAB AB, Kumla, Sweden.
    Sjoberg, Ragnar
    Solvent AB, Motala, Sweden.
    Allard, Bert
    Örebro University, School of Science and Technology.
    van Hees, Patrick A. W.
    Örebro University, School of Science and Technology.
    Remediation of heavy metal contaminated soil washing residues with amino polycarboxylic acids2010In: Journal of Hazardous Materials, ISSN 0304-3894, E-ISSN 1873-3336, Vol. 173, no 1-3, p. 697-704Article in journal (Refereed)
    Abstract [en]

    Removal of Cu, Pb, and Zn by the action of the two biodegradable chelating agents [S,S]-ethylenediaminedisuccinic acid (EDDS) and methylglycinediacetic acid (MGDA), as well as citric acid, was tested. Three soil samples, which had previously been treated by conventional soil washing (water), were utilized in the leaching tests. Experiments were performed in batches (0.3 kg-scale) and with a WTC-mixer system (Water Treatment Construction, 10 kg-scale). EDDS and MGDA were most often equally efficient in removing Cu, Pb, and Zn after 10-60 min. Nonetheless, after 10 d, there were occasionally significant differences in extraction efficiencies. Extraction with citric acid was generally less efficient, however equal for Zn (mainly) after 10 d. Metal removal was similar in batch and WTC-mixer systems, which indicates that a dynamic mixer system could be used in full-scale. Use of biodegradable amino polycarboxylic acids for metal removal, as a second step after soil washing, would release most remaining metals (Cu, Pb and Zn) from the present soils, however only after long leaching time. Thus, a full-scale procedure, based on enhanced metal leaching by amino polycarboxylic acids from soil of the present kind, Would require a pre-leaching step lasting several days in order to be efficient. (C) 2009 Elsevier B.V. All rights reserved.

  • 4.
    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.

  • 5.
    Elgh-Dalgren, Kristin
    et al.
    Örebro University, School of Science and Technology.
    Arwidsson, Zandra
    Sakab AB.
    Camdzija, Aida
    Sjöberg, Ragnar
    Ribé, Veronica
    Mälardalen University.
    Waara, Sylvia
    Mälardalen University.
    Allard, Bert
    Örebro University, School of Science and Technology.
    von Kronhelm, Thomas
    van Hees, Patrick A. W.
    Örebro University, School of Science and Technology.
    Laboratory and pilot scale soil washing of PAH and arsenic from a wood preservation site: Changes in concentration and toxicity2009In: Journal of Hazardous Materials, ISSN 0304-3894, E-ISSN 1873-3336, Vol. 172, no 2-3, p. 1033-1040Article in journal (Refereed)
    Abstract [en]

    Soil washing of a soil with a mixture of both polycyclic aromatic hydrocarbons (PAH) and As was evaluated in laboratory and pilot scale, utilizing both single and mixtures of different additives. The highest level of decontamination was achieved with a combination of 0.213 M of the chelating agent MGDA and 3.2xCMC* of a nonionic, alkyl glucoside surfactant at pH 12 (Ca(OH)2). This combination managed to reach Swedish threshold values within 10 min of treat­ment when performed at elevated temperature (50°C), with initial conta­minant concentrations of As = 105±4 mg/kg and US-EPA PAH16 = 46.0±2.3 mg/kg. The main mechanisms behind the removal were the pH-effect for As and a combina­tion of SOM-ionization as a result of high pH and micellar solu­bilization for PAHs. Implementation of the laboratory results utilizing a pilot scale equipment did not improve the performance, which may be due to the shorter contact time between the washing solution and the particles, or changes in physical characte­ristics of the leaching solution due to the elevated pressure utilized. The ecotox­icological evaluation, Microtox®, demonstrated that all soil washing treatments increased the toxicity of soil leachates, possibly due to in­creased availability of contaminants and toxicity of soil washing solutions to the test organism.

  • 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.
    Arwidsson, Zandra
    Örebro University, School of Science and Technology.
    Sjöberg, Ragnar
    Allard, Bert
    Örebro University, School of Science and Technology.
    von Kronhelm, Tomas
    van Hees, Patrick
    Örebro University, School of Science and Technology.
    Effect of chemical amendments on the distribution of arsenic and polycyclic aromatic hydrocarbons in a contaminated soil2009Conference paper (Refereed)
  • 8.
    Elgh-Dalgren, Kristin
    et al.
    Örebro University, School of Science and Technology.
    Düker, Anders
    Örebro University, School of Science and Technology.
    Allard, Bert
    Örebro University, School of Science and Technology.
    van Hees, Patrick
    Örebro University, School of Science and Technology.
    Simultaneous re­mediation of explosives and lead from contaminated soil by pH-adjust­mentManuscript (preprint) (Other academic)
    Abstract [en]

    Soil washing with pH-adjusted water was evaluated in two soils containing dif­ferent concentrations of heavy metals and explosives. Overall, the most efficient treatment was with water adjusted to pH 12 by NaOH. For explosives, pH 12 removed significantly higher amounts (P<0.05) of RDX and TNT compared to pH 4 (adjusted with HNO3) and distilled water in a moderately contaminated soil (230 mg HMX/kg, 1340 mg RDX/kg, 450 mg TNT/kg). In a more highly contaminated soil (6080 mg HMX/kg, 28740 mg RDX/kg, 3120 mg TNT/kg), the pH 12-treatment was the most efficient for removal of TNT and 2,4-DNT. Explosives removal increased with treatment time, probably due to the kineti­cally slow processes underlying the explosives degradation. Mobilization of heavy metals was strongly dependent on pH, with pH 12 mobilizing more than pH 3. In addition, the change in distribution coefficient (Kd) was more pro­nounced for local contaminants Pb and Cd in comparison with Cu and Zn, which were present in background concentrations.

  • 9.
    Elgh-Dalgren, Kristin
    et al.
    Örebro University, School of Science and Technology.
    Düker, Anders
    Örebro University, School of Science and Technology.
    Arwidsson, Zandra
    Örebro University, School of Science and Technology.
    von Kronhelm, Thomas
    van Hees, Patrick A. W.
    Örebro University, School of Science and Technology.
    Re-cycling of remediated soil: evaluation of leaching tests as tools for characterization2011In: Waste Management, ISSN 0956-053X, E-ISSN 1879-2456, Vol. 31, no 2, p. 215-224Article in journal (Refereed)
    Abstract [en]

    In Sweden, leaching tests with deionized water (D.W.) are frequently utilized in risk assessment, but implementation of these results to evaluate the risk of spreading in the environment is difficult. One problem is that most leaching procedures only consider heavy metals release, whereas organic pollutants are left out. The aim of the present study was to assess the possible pollutant miti­gation in four remediated soils, three with heavy metals and one with polycyclic aromatic hydrocarbons (PAH), utilizing three different leaching solutions: D.W., a weak ionic solution (0.001 M CaCl2) and an artificially made soil wa­ter (ASW). In general, batch leaching implied larger contaminant removal than column leaching, possibly due to the more rough treatment of the soil particles, and guidelines would at times be exceeded by batch leaching but not column leaching. Utilization of CaCl2 was found to release much less heavy metal than D.W., whereas the metals mobilized by ASW were removed from solution by the filtration of soil leachates. Low molecular weight PAH was most efficiently mobilized by CaCl2, while D.W. worked better for high molecular weight PAH. Despite very low initial PAH-concentrations, tap- and groundwater criteria were exceeded by all leaching solutions.

  • 10.
    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.

  • 11. Finlay, R.
    et al.
    Wallander, H.
    Smits, M.
    Holmstrom, S.
    van Hees, Patrick A. W.
    Örebro University, School of Science and Technology.
    Lian, B.
    Rosling, A.
    The role of fungi in biogenic weathering in boreal forest soils2009In: Fungal Biology Reviews, ISSN 1878-0253, Vol. 23, no 4, p. 101-106Article in journal (Refereed)
    Abstract [en]

    In this article we discuss the possible significance of biological processes, and of fungi in particular, in weathering of minerals. We consider biological activity to be a significant driver of mineral weathering in forest ecosystems. In these environments fungi play key roles in organic matter decomposition, uptake, transfer and cycling of organic and inorganic nutrients, biogenic mineral formation, as well as transformation and accumulation of metals. The ability of lichens, mutualistic symbioses between fungi and photobionts such as algae or cyanobacteria, to weather minerals is well documented. The role of mycorrhizal fungi forming symbioses with forest trees is less well understood, but the mineral horizons of boreal forests are intensively colonised by mycorrhizal mycelia which transfer protons and organic metabolites derived from plant photosynthates to mineral surfaces, resulting in mineral dissolution and mobilisation and redistribution of anionic nutrients and metal cations. The mycorrhizal mycelia, in turn provide efficient systems for the uptake and direct transport of mobilised essential nutrients to their host plants which are large sinks. Since almost all (99.99. %) non-suberised lateral plant roots involved in nutrient uptake are covered by ectomycorrhizal fungi, most of this exchange of metabolites must take place through the plant-fungus interface. This idea is still consistent with a linear relationship between soil mineral surface area and weathering rate since the mycelia that emanate from the tree roots will have a larger area of contact with minerals if the mineral surface area is higher. Although empirical models based on bulk soil solution chemistry may fit field data, we argue that biological processes make an important contribution to mineral weathering and that a more detailed mechanistic understanding of these must be developed in order to predict responses to environmental changes and anthropogenic impact. © 2010 The British Mycological Society.

  • 12.
    Fujii, Kazumichi
    et al.
    Grad Sch Agr, Sakyo Ku, Kyoto Univ, Kyoto, Japan.
    Hayakawa, Chie
    Grad Sch Agr, Sakyo Ku, Kyoto Univ, Kyoto, Japan.
    van Hees, Patrick A. W.
    Örebro University, School of Science and Technology.
    Funakawa, Shinya
    Grad Sch Agr, Sakyo Ku, Kyoto Univ, Kyoto, Japan.
    Kosaki, Takashi
    Grad Sch Agr, Sakyo Ku, Kyoto Univ, Kyoto, Japan.
    Biodegradation of low molecular weight organic compounds and their contribution to heterotrophic soil respiration in three Japanese forest soils2010In: Plant and Soil, ISSN 0032-079X, E-ISSN 1573-5036, Vol. 334, no 1-2, p. 475-489Article in journal (Refereed)
    Abstract [en]

    Low molecular weight (LMW) organic compounds in soil solution could be important substrates for heterotrophic soil respiration. The importance of LMW organic compound mineralization in heterotrophic soil respiration needs to be confirmed for different types of soils. The concentrations of LMW organic compounds in soil solution and mineralization kinetics of C-14-radiolabelled glucose, acetate, oxalate and citrate were studied in three Japanese forest soils (Andisol, Spodosol and Inceptisol) with varying adsorption capacities. Based on those results, the fluxes of LMW organic compound mineralization and their magnitude relative to heterotrophic soil respiration were quantified. Monosaccharides and organic acids comprised on average 5.9-11.2% and 0.9-1.4% of dissolved organic carbon in soil solution, respectively. Monosaccharide mineralization make up 49-74% of heterotrophic (basal) soil respiration at the soil-profile scale, while organic acid mineralization accounts for between 5% (Andisol) and 47-58% (Spodosol and Inceptisol) of heterotrophic soil respiration. The mineralization of LMW organic compounds is a substantial fraction of heterotrophic soil respiration regardless of soil type, owing to their rapid and continuous production and consumption. The specific contribution of organic acid mineralization to heterotrophic soil respiration varies depending on soil adsorption capacities, namely iron and aluminum oxides.

  • 13. Geibe, Christine E.
    et al.
    Danielsson, Rolf
    van Hees, Patrick A. W.
    Örebro University, Department of Natural Sciences.
    Lundstrom, Ulla S.
    Comparison of soil solution chemistry sampled by centrifugation, two types of suction lysimeters and zero-tension lysimeters2006In: Applied Geochemistry, ISSN 0883-2927, E-ISSN 1872-9134, Vol. 21, no 12, p. 2096-2111Article in journal (Refereed)
    Abstract [en]

    The choice of sampling method for soil solution is of great importance. In this paper soil solution chemistry sampled by centrifugation, two types of suction lysimeters and zero-tension lysimeters have been studied with the purpose of investigating systematic differences between them. The samples were taken at 4 depths from an acidified forest soil as well as from adjacent lime and ash treated soils. A centrifugation drainage method was compared with two types of suction lysimeters ('Rhizon' and 'Prenart') and zero-tension lysimeters. About half of the 27 variables measured showed a significant difference between the sampling methods used. Typically the centrifuged samples had lower pH (4.0 vs. 4.4), Ca (21 mu M vs. 30 mu M) and Mg (25 mu M vs. 34 mu M) concentrations and higher CI (330 mu M vs. 230 mu M) and DOC (4.4 mM vs. 3.2 mM) concentrations than the Rhizon lysimeters. Also the other lysimeters showed significant differences compared to the centrifuged samples for about half the number of analytes. Centrifuged samples had higher concentrations of all analytes except NO3 and PO4 compared to zero-tension lysimeters and also for all analytes except NO3 and Al compared to Prenart lysimeters. Among the environmental factors considered depth showed an influence to some extent, while sampling occasion had a great significant impact on the difference between the centrifugation method and the Rhizon lysimeters. Factors like individual pits or soil treatment did not show any influence on the difference between the methods. (c) 2006 Elsevier Ltd. All rights reserved.

  • 14. Hagedorn, Frank
    et al.
    van Hees, Patrick A. W.
    Örebro University, Department of Natural Sciences.
    Handa, I. Tanya
    Haettenschwiler, Stephan
    Elevated atmospheric CO(2) fuels leaching of old dissolved organic matter at the alpine treeline2008In: Global Biogeochemical Cycles, ISSN 0886-6236, E-ISSN 1944-9224, Vol. 22, no 2, p. GB2004-Article in journal (Refereed)
    Abstract [en]

    Dissolved organic matter (DOM), the mobile form of soil organic matter (SOM), plays an important role in soil C cycling and in nutrient transport. We investigated the effects of 5 years of CO(2) enrichment (370 versus 570 mu mol CO(2) mol(-1)) on DOM dynamics at the alpine treeline, including the analysis of fast-cycling components such as low molecular weight organic acids (LMWOAs), dissolved organic carbon (DOC) biodegradability, and the decomposition of (14)C-labeled oxalate. Concentrations of DOC in canopy throughfall were 20% higher at elevated CO(2), probably driven by higher carbohydrate concentrations in leaves. In the organic soil layer, 5 years of CO(2) enrichment increased water-extractable organic C by 17% and soil solution DOC at 5 cm depth by 20%. The (13)C tracing of recently assimilated CO(2) revealed that the input of recent plant-derived C (< 15% of total DOC) was smaller than the CO(2)-induced increase in DOC. This strongly suggests that CO(2) enrichment enhanced the mobilization of native DOC, which is supported by significant increases in dissolved organic nitrogen (DON). We mainly attribute these increases to a stimulated microbial activity as indicated by higher basal and soil respiration rates (+27%). The (14)C-labeled oxalate was more rapidly mineralized from high CO(2) soils. The concentrations of LMWOAs, but also those of "hydrophilic'' DOC and biodegradable DOC (6% of total DOC), were, however, not affected by elevated CO(2), suggesting that production and consumption of "labile'' DOC were in balance. In summary, our data suggest that 5 years of CO(2) enrichment speeded up the cycling of "labile'' DOM and SOM in a late successional treeline ecosystem and increased the mobilization of older DOM through a stimulated microbial activity. Such a "priming effect'' implies that elevated CO(2) can accelerate the turnover of native SOM, and thus, it may induce increasing losses of old C from thick organic layers.

  • 15.
    Holmstrom, S. J. M.
    et al.
    Mid Sweden Univ, Dept Nat Sci Engn & Math, S-85170 Sundsvall, Sweden.
    Rosling, A.
    Swedish Univ Agr Sci, Dept Forest Mycol & Pathol, S-75007 Uppsala, Sweden.
    Finlay, R. D.
    Swedish Univ Agr Sci, Dept Forest Mycol & Pathol, S-75007 Uppsala, Sweden.
    van Hees, Patrick A. W.
    Örebro University, School of Science and Technology.
    Lundstrom, U. S.
    Mid Sweden Univ, Dept Nat Sci Engn & Math, S-85170 Sundsvall, Sweden.
    Contribution of ectomycorrhizal fungi to biogeochemical processes during iron and calcium limitation2009In: Geochimica et Cosmochimica Acta, ISSN 0016-7037, E-ISSN 1872-9533, Vol. 73, no 13, p. A546-A546Article in journal (Other academic)
  • 16.
    Johansson, Emma M.
    et al.
    Örebro University, School of Science and Technology.
    Fransson, Petra M. A.
    Department of Forest Mycology and Pathology, Swedish University of Agricultural Sciences.
    Ekblad, Alf
    Örebro University, School of Science and Technology.
    van Hees, Patrick A. W.
    Örebro University, School of Science and Technology.
    Autotrophic and heterotrophic soil respiration: the effects of non-mycorrhizal and mycorrhizal seedlings under elevated CO2Manuscript (preprint) (Other academic)
  • 17.
    Johansson, Emma M.
    et al.
    Örebro University, School of Science and Technology.
    Fransson, Petra M. A.
    Department of Forest Mycology and Pathology, Swedish University of Agricultural Sciences.
    Finlay, Roger D.
    Department of Forest Mycology and Pathology, Swedish University of Agricultural Sciences.
    van Hees, Patrick A. W.
    Örebro University, School of Science and Technology.
    Quantitative analysis of exudates from soil-living basidiomycetes in pure culture as a response to lead, cadmium and arsenic stress2008In: Soil Biology and Biochemistry, ISSN 0038-0717, E-ISSN 1879-3428, Vol. 40, no 9, p. 2225-2236Article in journal (Refereed)
    Abstract [en]

    Six different ectomycorrhizal fungi (Hebeloma velutipes, Piloderma byssinum, Paxillus involutus, Rhizopogonroseolus, Suillus bovinus and Suillus variegatus) and two saprotrophic fungi (Hypholoma fasciculare andHypholoma capnoides) were exposed to metal stress induced by Pb, Cd and As. After pre-growth ina nutrient solution in Petri dishes, metal exposure was performed either in a nutrient rich solution or ina nutrient poor solution for seven days. The fungi were exposed to two different metal concentrations,low and high (Pb: 10 þ 100 mM; Cd: 1 þ 10 mM; As: 1 þ 10 mM). Exudation of low molecular weightorganic compounds (low molecular weight organic acids (LMWOA), amino acids and dissolved monosaccharides),as well as dissolved organic carbon was quantified as a potential response to the metalstress. The main LMWOA identified was oxalate. Oxalate exudation increased significantly in response toboth low and high Pb and Cd concentrations, as well as low As exposure, relative to nutrient controls.Exposure to As and mixtures of metals (Pb þ Cd, Pb þ As) did not result in any significant increase inoxalate production compared to controls. The presence of a carbon source (glucose) in this study islikely to have been important for exudation of organic compounds. For the nutrient rich (þ1mMglucose) metal treatments exposure to Pb and Cd mainly increased exudation of oxalate and total aminoacids. Production of dissolved monosaccharides, as well as DOC, did not increase significantly in responseto metal exposure, irrespective of nutrient conditions. This may be explained by re-absorption ofthe organic compounds by the mycelium or by the fact that metals had no effect on exudation of thesecompounds.

  • 18.
    Johansson, Emma M.
    et al.
    Örebro University, School of Science and Technology.
    Fransson, Petra M. A.
    Department of Forest Mycology and Pathology, Swedish University of Agricultural Sciences.
    Finlay, Roger D.
    Department of Forest Mycology and Pathology, Swedish University of Agricultural Sciences.
    van Hees, Patrick A. W.
    Örebro University, School of Science and Technology.
    Quantitative analysis of root and ectomycorrhizal exudates as a response to Pb, Cd and As stress2008In: Plant and Soil, ISSN 0032-079X, E-ISSN 1573-5036, Vol. 313, no 1-2, p. 39-54Article in journal (Refereed)
    Abstract [en]

    We examined exudation of low molecular weight (LMW) organic compounds of ectomycorrhizal (ECM) and non-mycorrhizal (NM) seedlings in relation to metals. Scots pine seedlings, either colonized by one of six different ECM fungi or NM, were grown in Petri dishes containing glass beads and liquid growth medium and exposed to elevated concentrations of Pb, Cd and As. Exudation of LMW organic compounds (LMW organic acids (LMWOAs), amino acids and dissolved monosaccharides) and dissolved organic carbon (DOC) was determined qualitatively and quantitatively and exudation rates were calculated. Metals had a significant impact on exudation, especially of oxalate. For Pb and Cd treatments, exudation of oxalate and total LMWOAs generally increased by 15–45% compared to nutrient controls. Production of amino acids, dissolved monosaccharides and DOC was not significantly stimulated by exposure to metals; however, there were non-significant trends towards increased exudation. Finally, exudation generally increased in the presence of mycorrhizal seedlings compared to NM seedlings. The results suggest that ECM fungi may reduce the toxicity of metals to plants through significant increases in the production of organic chelators. Axenic conditions are required to assess the full potential for production of these molecules but their overall significance in soil ecosystems needs to be determined using additional experiments under more ecologically realistic conditions.

  • 19.
    Johansson, Emma M.
    et al.
    Örebro University, School of Science and Technology.
    Fransson, Petra M. A.
    Department of Forest Mycology and Pathology, Swedish University of Agricultural Sciences.
    Finlay, Roger D.
    van Hees, Patrick A. W.
    Örebro University, School of Science and Technology.
    Quantitative analysis of soluble exudates produced by ectomycorrhizal roots as a response to ambient and elevated CO22009In: Soil Biology and Biochemistry, ISSN 0038-0717, E-ISSN 1879-3428, Vol. 41, no 6, p. 1111-1116Article in journal (Refereed)
    Abstract [en]

    Despite its potential impact on soil carbon flow, few studies have attempted to quantify the effects of elevated carbon dioxide (CO2) on production of exudates by mycorrhizal plants. In this study we quantified low molecular weight (LMW) organic compounds exuded by non-mycorrhizal (NM) and ectomycorrhizal (ECM) plants in relation to exposure to elevated CO2. Scots pine seedlings, either colonized by one of eight different ECM fungi or non-mycorrhizal (NM), were exposed to either ambient (350 ppm) or elevated (700 ppm) concentrations of CO2. Exudation of LMW organic acids (LMWOAs), amino acids, dissolved monosaccharides and total dissolved organic carbon (DOC) was determined and exudation rates were calculated per g root and fungal dry mass. CO2 had a significant impact on exudation. Under elevated CO2, exudation of total LMWOAs increased by 120–160%, amino acids by 250%, dissolved monosaccharides by 130–270% and DOC by 180–220% compared to ambient CO2 treatment. Net CO2 assimilation rates increased significantly by 41–47% for seedlings exposed to elevated CO2. Exuded C calculated as a percentage of assimilated CO2 increased by 41–88% in the elevated CO2 treatment compared to ambient CO2 treatment.

  • 20.
    Larsson, Maria
    et al.
    Örebro University, School of Science and Technology.
    Lam, Monika M.
    Örebro University, School of Science and Technology.
    van Hees, Patrick
    Örebro University, School of Science and Technology. Eurofins Environment Testing Sweden AB, Lidköping, Sweden.
    Giesy, John P.
    University of Saskatchewan, Saskatoon, Canada.
    Engwall, Magnus
    Örebro University, School of Science and Technology.
    Occurrence and leachability of polycyclic aromatic compounds in contaminated soils: Chemical and bioanalytical characterization2018In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 622-623, p. 1476-1484Article in journal (Refereed)
    Abstract [en]

    An important concern regarding sites contaminated with polycyclic aromatic compounds (PACs) is the risk of groundwater contamination by release of the compounds from soils. The goal of this study was to investigate the occurrence and leachability of 77 PACs including polycyclic aromatic hydrocarbons (PAHs) and heterocyclic aromatic compounds (NSO-PACs) among total aryl hydrocarbon receptor (AhR) agonists in soils from historical contaminated sites. A novel approach combining chemical and bioanalytical methods in combination with characterization of leachability by use of a column leaching test was used. Similar profiles of relative concentrations of PACs were observed in all soils, with parent PAHs accounting for 71 to 90% of total concentrations in soils. Contribution of oxy-PAHs, alkyl-PAHs and N-PACs ranged from 2 to 9%, 3 to 9% and 1 to 14%, respectively. Although the contributions of groups of PACs were small, some compounds were found in similar or greater concentrations than parent PAHs. Leachable fractions of 77 PACs from soils were small and ranged from 0.002 to 0.54%. Polar PACs were shown to be more leachable than parent PAHs. The contribution of analyzed PACS to overall AhR-mediated activities in soils and leachates suggests presence of other AhR agonists in soils, and a potential risk. Only a small fraction of AhR agonists was available in soils, indicating an overestimation of the risk if only total initial concentrations in soils would be considered in risk assessment. The results of the study strongly support that focus on 16US EPA PAHs may result in inadequate assessment of risk and hazard of PACs in complex environmental samples.

  • 21. Nambu, K.
    et al.
    van Hees, Patrick A. W.
    Jones, D. L.
    Örebro University, Department of Natural Sciences.
    Vinogradoff, S.
    Lundström, U. S.
    Composition of organic solutes and respiration in soils derived from alkaline and non-alkaline parent materials2008In: Geoderma, ISSN 0016-7061, E-ISSN 1872-6259, Vol. 144, no 3-4, p. 468-477Article in journal (Refereed)
    Abstract [en]

    Parent material greatly influences pedogenesis and soil nutrient availability and consequently we hypothesized that it would significantly affect the amount of organic solutes in soil, many of which have been implicated in rhizosphere processes linked to plant nutrient uptake. Consequently, we investigated the influence of two contrasting parent materials in which calcite was present or absent (alkaline and non-alkaline soils) on the concentrations of dissolved organic carbon (DOC), low-molecular weight organic acids (LMWOA) and glucose in soil solution. Both soils were under Norway spruce. The dynamics of LMWOAs in soil were also investigated using 14C-labelled citrate and oxalate. Some of the mineral horizons of the alkaline soils showed significantly higher concentrations of DOC, phenolics, and fumarate in soil solution and also a higher basal respiration. No major differences were seen in organic solute status in the organic horizons of the two soil types. LMWOAs were present at low concentrations in soil solution (< 1 to 25 ΌM). Their mineralization rate significantly decreased with soil depth, however, overall neither their concentration or half-life in soil was markedly affected by parent material. The alkaline soils had significantly higher CO2-to-soil organic C (SOC) ratios, and consequently SOC in the alkaline soils did not seem more chemically stable against mineralization. Considering possible DOC and CO2 efflux rates it was suggested that the equal or larger SOC stocks in alkaline mineral soils were most likely linked to a higher net primary productivity. In conclusion, our study found that parent material exerted only a small effect on the concentration and dynamics of organic solutes in soil solution. This suggests that in comparison to other factors (e.g. vegetation cover, climate etc) parent material may not be a major regulator of the organic solute pool in soil. © 2008 Elsevier B.V. All rights reserved.

  • 22. Olsson, Susanna
    et al.
    Van Schaik, Joris W. J.
    Gustafsson, Jon Petter
    Kleja, Dan Berggreb
    van Hees, Patrick A. W.
    Örebro University, Department of Natural Sciences.
    Copper(II) binding to dissolved organic matter fractions in municipal solid waste incinerator bottom ash leachate2007In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 41, no 12, p. 4286-4291Article in journal (Refereed)
    Abstract [en]

    Information on Cu speciation in municipal solid waste incineration (MSWI) bottom ash leachate is needed for Cu leaching predictions and toxicity estimates. The complexation of Cu with dissolved organic matter (DOM) in leachates from a stored MSWI bottom ash was studied potentiometrically using a Cu-ion selective electrode. More than 95% of the copper was bound to DOM in the hydrophilic fraction of the leachate, indicating that the hydrophilic acids contribute to Cu complex formation. The hydrophilic acids constituted 58% of the dissolved organic carbon in the ash leachate. Comparisons between experimental results and speciation calculations with the NICA-Donnan model and the Stockholm humic model indicated differences between the ash DOM and the natural DOM for which the models have been calibrated. The ratio of carboxylic binding sites to phenolic binding sites was 2 times larger in ash DOM, and the Cu-binding affinity of the former was stronger than accounted for by the generic Cu-binding parameters. The Cu-binding affinity of the phenolic sites, on the other hand, was weaker. When these parameters were adjusted, a good description of the experimental data was obtained.

  • 23. Rosling, A.
    et al.
    Suttle, K. B.
    Johansson, E.
    van Hees, Patrick A. W.
    Örebro University, Department of Natural Sciences.
    Banfield, J. F.
    Phosphorous availability influences the dissolution of apatite by soil fungi2007In: Geobiology, ISSN 1472-4677, E-ISSN 1472-4669, Vol. 5, no 3, p. 265-280Article in journal (Refereed)
    Abstract [en]

    Apatite (Ca-10(PO4)(6)(OH,F,Cl)(2)) is the primary inorganic source of phosphorus in the biosphere. Soil fungi are known to increase plant-available phosphorus by promoting dissolution of various phosphate minerals. Yet no apatite dissolution studies exist using fungi as weathering agents, and regulation of fungal weathering activity in response to different levels of phosphorus availability is largely unknown. Fungi were isolated from a grassland soil in northern California. Three pathways of tri-calcium phosphate (Ca-3(PO4)(2)) (TCP) dissolution in liquid culture were identified among biogeochemically active fungi: (1) acidification (pH 3.3 +/- 0.16), (2) moderate acidification (pH 4.9 +/- 0.11) and (3) no acidification. Isolates representing pathway 1 and 2 were Zygomycetes in the order of Mucorales. All non-acidifying isolates in pathway 3 were Ascomycetes and cleared the media by altering TCP into hydroxyapatite (Ca-10(PO4)(6)(OH)(2)) and sequestering it within mycelial spheres. One isolate representing each pathway was used in fluorapatite dissolution experiments either with the fungi present or under abiotic conditions using cell-free liquid media conditioned by fungal growth at different phosphorus and calcium availabilities. Both Mucorales isolates acidify their substrate when growing in the presence of phosphorus. Mucorales exudates were mainly oxalic acid, and conditioned cell-free media with phosphorus induced fluorapatite dissolution at a rate of 10(-0.9 +/- 0.14) and 10(-1.2 +/- 0.22) mu mol P m(-2) s(-1). The ascomycete isolate on the other hand, induced fluorapatite dissolution at a rate of 10(-1.1 +/- 0.05) mu mol P m(-2) s(-1) by lowering the pH of the media under phosphorus-limited conditions, without producing significant amounts of low molecular weight organic acids (LMWOAs). Oxalate strongly etches fluorapatite along channels parallel to [001], forming needle-like features, while exudates from the ascomycete-induced surface rounding. We conclude that while LMWOAs are well-studied weathering agents, these do not appear to be produced by fungi in response to phosphorus-limiting growth conditions.

  • 24.
    van Hees, Patrick A. W.
    et al.
    Örebro University, School of Science and Technology.
    Elgh-Dalgren, Kristin
    Örebro University, School of Science and Technology.
    Engwall, Magnus
    Örebro University, School of Science and Technology.
    von Kronhelm, Thomas
    Sakab AB.
    Re-cycling of Remediated Soil in Sweden: An Environmental Advantage?2008In: Resources, Conservation and Recycling, ISSN 0921-3449, E-ISSN 1879-0658, Vol. 52, no 12, p. 1349-1361Article in journal (Refereed)
    Abstract [en]

    The disposal of soil material after ex-situ treatment of contaminated soil is an issue of growing concern. The handling and use of this material are surrounded by numerous regulatory, economic, technical and societal aspects that complicate or hinder recycling. As a consequence, the lack of means of recovery can in the long term bias the whole remedial process. In addition, it can affect the competition between various treatment options such as ex-situ, and in-situ techniques and landfilling. At the same time the materials must not have any negative environmental impacts, and their usage must be compatible with existing risk assessment and management frameworks regarding contaminated land. Other concerns such as a possible distinction against “lightly” contaminated materials, waste status and public acceptance add to the complexity. This paper focuses on Swedish conditions, but does also provide an outlook concerning EU regulation. A summary of leaching and batch tests employed for re-use of soil and waste is presented as well as an overview of the eco-toxicological aspects of treated materials. The main conclusion is that re-cycling of treated soil is desirable from numerous aspects, but has to go along an adequate risk assessment.

  • 25.
    van Hees, Patrick A. W.
    et al.
    Örebro University, Department of Natural Sciences.
    Johansson, Emma M.
    Örebro University, Department of Natural Sciences.
    Jones, D. L.
    Dynamics of simple carbon compounds in two forest soils as revealed by soil solution concentrations and biodegradation kinetics2008In: Plant and Soil, ISSN 0032-079X, E-ISSN 1573-5036, Vol. 310, no 1-2, p. 11-23Article in journal (Refereed)
    Abstract [en]

    Simple compounds in soil such as organic acids, amino acids and monosaccharides are believed to be important in regulating many aspects of terrestrial ecosystem functioning (e.g. C cycling, nutrient acquisition). Understanding the fate and dynamics of these low molecular weight (MW) compounds is therefore essential for predicting ecosystem responses to disturbance. Our aim was to quantify the amounts of these compounds in two podzolic forest soil profiles (O, E, Bs and C horizons) and to quantify their contribution to total soil respiration. The total concentration of organic acids, amino acids and monosaccharides in soil solution comprised on average 15 +/- 10% of the total dissolved organic C (DOC), with declining concentrations in the deeper soil layers. Dissolved organic N (DON) was the dominant form of N in soil solution and free amino acids contributed to 34% of this pool. The mineralization behaviour of glucose and galactose was described by parabolic (Michaelis-Menten) type kinetics with V-max and K (M) values in the range of < 1-250 mu mol kg(-1) h(-1) and 15-1,100 mu M, respectively. Assuming that (1) microbially mediated substrate turnover follows Michaelis-Menten kinetics, and (2) steady state soil solution concentrations, we calculated the rate of CO2 efflux attributable to the mineralisation of the three classes of low MW compounds. Our results indicated that in the O horizon, the turnover of these substrates could comprise similar to 100% of the basal, heterotrophic, soil respiration. In contrast, in the deeper mineral soil < 20% of total soil respiration could be attributable to the mineralization of these compounds. Our compound-specific approach has identified the main substrates contributing to soil respiration in forest topsoils. However, our results also suggest that soil respiration in subsoils may be attributable to compounds other than organic acids, amino acids and monosaccharides.

  • 26.
    van Hees, Patrick A. W.
    et al.
    Örebro University, Department of Natural Sciences.
    Rosling, A.
    Lundstrom, U. S.
    Finlay, R. D.
    The biogeochemical impact of ectomycorrhizal conifers on major soil elements (Al, Fe, K and Si)2006In: Geoderma, ISSN 0016-7061, E-ISSN 1872-6259, Vol. 136, no 1-2, p. 364-377Article in journal (Refereed)
    Abstract [en]

    Mobilisation of nutrients and dissolution of minerals are of key importance for plant growth and soil formation, as well as long term ecosystem sustainability. The effects of Pinus sylvestris seedlings, ectomycorrhizal colonisation and potassium supply on the mobilisation of Al, Fe, K and Si were studied in a soil column experiment. Budgets were constructed considering amounts in drainage water, accumulation in plants and changes in the pools of exchangeable ions (BaCl2 extractions). Drainage was the most important sink under the experimental conditions imposed, but the other two pools were also of quantitative significance. Plants had a significant positive effect on the total quantities of all elements mobilized. Mycorrhizal colonisation had limited quantitative impact on the mobilization, probably because the chosen mycorrhizal fungi did not cause any growth promotion in this experiment. Despite this, a multivariate analysis (PCA) showed a clear separate grouping of mycorrhizal, non-mycorrhizal and no-plant treatments, and in particular Si and K mobilization was related to soil biological variables which in turn were affected by the presence of mycorrhiza. When K was omitted from the watering solution, plants were able to mobilise significantly more K, which was reflected in plant uptake and a potential replenishment of the exchangeable pool. Up-scaling of total Al, K and Si mobilization to field conditions resulted in rates between equal to and up to 10 times higher than the average historical weathering rate. (c) 2006 Elsevier B.V. All rights reserved.

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