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Chromium is a common soil contaminant and, although it has been studied widely, questions about its speciation and dissolutions kinetics remain unanswered. We combined information from an irrigation experiment performed with intact soil... more
Chromium is a common soil contaminant and, although it has been studied widely, questions about its speciation and dissolutions kinetics remain unanswered. We combined information from an irrigation experiment performed with intact soil columns with data from batch experiments to evaluate solubility and mobilization mechanisms of Cr(III) in a historically contaminated soil (>65 years). Particulate and colloidal Cr(III) forms dominated transport in this soil, but their concentrations were independent of irrigation intensity (2-20 mm h). Extended X-ray absorption fine structure (EXAFS) measurements indicated that Cr(III) associated with colloids and particles, and with the solid phase, mainly existed as dimeric hydrolyzed Cr(III) bound to natural organic matter. Dissolution kinetics of this species were fast (≤1 day) at low pH (<3) and slightly slower (≤5 days) at neutral pH. Furthermore, it proved possible to describe the solubility of the dimeric Cr(III) organic matter complex with a geochemical equilibrium model using only generic binding parameters, opening the way for use of geochemical models in risk assessments of Cr(III)-contaminated sites.
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Research Interests: Earth Sciences, Geochemistry, Forestry, Biogeochemistry, Hydrology, and 15 moreForest Ecology, Biological Sciences, Concentration, Environmental Sciences, Biogeosciences, Dissolved organic matter, Afforestation, Forest ecosystem, Aboveground biomass, Dissolved Organic Carbon, Dissolved Organic Nitrogen, Flux, Forest Floor, Arable Land, and hydrologic model
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This paper presents aluminium (Al)-solubility data for two acid forest soils (Inceptisol and Spodosol), obtained in connection with lysimeter measurements (tension-cup and zero-tension lysimeters) and batch equilibrium experiments. The... more
This paper presents aluminium (Al)-solubility data for two acid forest soils (Inceptisol and Spodosol), obtained in connection with lysimeter measurements (tension-cup and zero-tension lysimeters) and batch equilibrium experiments. The solubility of Al obtained in the batch experiments was used as a reference to test whether Al3+in soil solutions collected by the lysimeters was in equilibrium with secondary forms of solid-phase Al (Al(OH)3or organically bound Al). The relation between pH and Al3+activity found for the zero-tension lysimeter solutions collected from the Inceptisol agreed well with that obtained in the batch experiment. This suggests that Al3+in the lysimeter solutions were in, or close to, equilibrium with the solid phase, whether this was organically bound Al (A horizon) or an Al(OH)3phase (B horizon). For the tension-cup lysimeters, solutions obtained from the Inceptisol B and Spodosol Bs1 horizons were generally close to equilibrium with respect to secondary solid...
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... Concerning the time scale, it is interest-ing to note that N deposition at the Dalby Norway spruce site in southernmost Sweden (28.8 kg N ha"1 yr"1) was ... estimated for Sitka spruce plantations in Wales... more
... Concerning the time scale, it is interest-ing to note that N deposition at the Dalby Norway spruce site in southernmost Sweden (28.8 kg N ha"1 yr"1) was ... estimated for Sitka spruce plantations in Wales receiv-ing a deposition of 20-30 kg N ha"1 yr"1 (Emmett & Reynolds 1996). ...
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ABSTRACT Background and aims Increased soil temperature and nutrient availability enhance soil biological activity. We studied how these affect fine root growth and survival, i.e. below-ground litter production, in relation to... more
ABSTRACT Background and aims Increased soil temperature and nutrient availability enhance soil biological activity. We studied how these affect fine root growth and survival, i.e. below-ground litter production, in relation to above-ground foliage litter production of Norway spruce (Picea abies (L.) Karst.). Methods The treatments, irrigation (I), soil warming + irrigation (WI), fertilization + irrigation (FI) and soil warming + fertilization + irrigation (WFI) were started in 1987 (F, I) and in 1995 (W). The annual production of fine root litter was estimated from minirhizotrons (survival) and soil-cores (biomass) and the annual above-ground litter production from litter traps. Results and conclusions The number and elongation of fine roots tended to be higher in WI and I compared to the other treatments, which may indicate nutrient shortage. Fine roots in the WFI treatment had the lowest median longevity and from three to fourfold higher below-ground litter production compared to WI, FI or I - higher soil temperature increased the litter input particularly into the mineral soil. Only fertilization increased the above-ground litter production. As warmer and more nutrient-rich soil significantly shortened the fine root lifespan and increased the litter input, the storage of carbon in boreal forest soil may increase in the future.
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ABSTRACT In the present study we examine the effects of Al on the uptake of Ca2+ and H2PO-4 in beech (Fagus sylvatica L.) grown in inorganic nutrient solutions and nutrient solutions supplied with natural fulvic acids (FA). All the... more
ABSTRACT In the present study we examine the effects of Al on the uptake of Ca2+ and H2PO-4 in beech (Fagus sylvatica L.) grown in inorganic nutrient solutions and nutrient solutions supplied with natural fulvic acids (FA). All the solutions used were chemically well characterized. The uptake of Al by roots of intact plants exposed to solutions containing 0, 0.15 or 0.3 mM AlCl3 for 24 h, was significantly less if FA (300 mg l−1) were also present in the solutions. The Ca2+(45Ca2+) uptake was less affected by Al in solutions supplied with FA than in solutions without FA. There was a strong negative correlation between the Al and Ca2+ uptake (r2=0.98). When the Al and Ca2+ (45Ca2+) uptake were plotted as a function of the Al3+ activity (or concentration of inorganic mononuclear Al), almost the same response curves were obtained for the -FA and +FA treatments. We conclude that FA-complexed Al was not available for root uptake and therefore could not affect the Ca2+ uptake. The competitive effect of Al on the Ca2+ uptake was also shown in a 5-week cultivation experiment, where the Ca concentration in shoots decreased at an AlCl3 concentration of 0.3 mM. The effect of Al on H2PO−4 uptake was more complex. The P content in roots and shoots was not significantly affected, compared with the control, by cultivation for 5 weeks in a solution supplied with 0.3 mM AlCl3, despite a reduction of the H2PO−4 concentration in the nutrient solution to about one-tenth. At this concentration Al obviously had a positive effect on H2PO−4 uptake. The presence of FA decreased 32P-phosphate uptake by more than 60% during 24 h, and the addition of 0.15 or 0.3 mM AlCl3 to these solutions did not alter the uptake of 32P-phosphate.
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Cadmium solubility and sorption in an arable clay loam soil that had received sewage sludge for 41 years were compared to an unsludged control in batch studies. Soil pH dominated Cd sorption, explaining >92% of the... more
Cadmium solubility and sorption in an arable clay loam soil that had received sewage sludge for 41 years were compared to an unsludged control in batch studies. Soil pH dominated Cd sorption, explaining >92% of the variation in Kd values in both treatments. At any pH, Cd sorption was apparently slightly but significantly (p < 0.05) smaller in the sludge-amended soil compared to the control, even though the organic carbon content was 70% larger and the ammonium oxalate-extractable iron content was roughly doubled. Correction for dissolved organic carbon (DOC) complexation with the speciation model WHAM reduced the difference in sorption between treatments, but the sludged soil still had significantly smaller Kd values (p < 0.01). Batch equilibrations without addition of Cd showed that there was no significant difference in the solubility of "native" cadmium (defined as EDTA-extractable Cd) in sludged and control soils. The reason for the lack of increase in Cd sorption in the sludge-amended soil has not been established, but it may be due to competition for sorption sites on humic compounds with sludge-derived Fe and trace metals such as zinc. The fact that the pyrophosphate-extractable (i.e., organically associated) iron content was seven times larger in the sludged soil provides some supporting evidence for this hypothesis.
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ABSTRACT
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... Soil Sci. Soc. Am. J., 49: 256-261. Mortatti, J., Krug, FJ, Pessenda, LCR, Zagatto, EAG andStorgaard Jrrgensen, S., 1982. ... Can. J. Soil Sci., 61: 99-107. Ross, GJ, Ivarson, KC and Miles, NM, 1982. Microbial formation of basic... more
... Soil Sci. Soc. Am. J., 49: 256-261. Mortatti, J., Krug, FJ, Pessenda, LCR, Zagatto, EAG andStorgaard Jrrgensen, S., 1982. ... Can. J. Soil Sci., 61: 99-107. Ross, GJ, Ivarson, KC and Miles, NM, 1982. Microbial formation of basic ferric sulfates in laboratory systems and in soils. ...
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2. Abstract Long-term acidification has been shown to result in a considerable decrease in the amount of organically bound soil Al and in a gradual decrease in the solubility of Al. We examined the solubility of soil organic matter (SOM)... more
2. Abstract Long-term acidification has been shown to result in a considerable decrease in the amount of organically bound soil Al and in a gradual decrease in the solubility of Al. We examined the solubility of soil organic matter (SOM) and Al in four acid mineral soils (one ...
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ABSTRACT We examined the aluminium solubility in the upper B horizon of podzols and its relation to the solid phase of the soil in 60 samples covering a pH range from 3.8 to 5.1. Solid phases were characterized by extractions with acid... more
ABSTRACT We examined the aluminium solubility in the upper B horizon of podzols and its relation to the solid phase of the soil in 60 samples covering a pH range from 3.8 to 5.1. Solid phases were characterized by extractions with acid oxalate and pyrophosphate (pH 10). The solubility of Al was studied in a batch experiment in which samples were equilibrated with 1 mm NaCl at 8°C for 5 days. We also monitored the dissolution kinetics of Al and Si, in some samples. The oxalate and pyrophosphate extractions suggested that secondary Al was mainly organically bound in most soils, and imogolite-type materials seemed to constitute much of inorganic secondary Al. No single gibbsite or imogolite equilibrium could explain Al3+ activities. In all samples Al solubility, defined as log{Al3+} + 1.65pH, was closely related to the molar ratio of aluminium to carbon in the pyrophosphate extracts (Alp/Cp). Solubility increased with the Alp/Cp ratio until the latter reached ≈ 0.1. This indicated that solubility was controlled by organic complexation, at least when Alp/Cp was small. Silica dissolved slowly in most soils used in the kinetic experiments. We conclude that imogolite-type materials in the upper B horizon dissolved slowly because of coating with humic substances or ageing or both.
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The use of mechanistically based models to simulate the solution concentrations of heavy metals in soils is complicated by the presence of different sorbents that may bind metals. In this study, the binding of Zn, Pb, Cu, and Cd by 14... more
The use of mechanistically based models to simulate the solution concentrations of heavy metals in soils is complicated by the presence of different sorbents that may bind metals. In this study, the binding of Zn, Pb, Cu, and Cd by 14 different Swedish soil samples was investigated. For 10 of the soils, it was found that the Stockholm Humic Model (SHM) was able to describe the acid-base characteristics, when using the concentrations of "active" humic substances and Al as fitting parameters. Two additional soils could be modeled when ion exchange to clay was also considered, using a component additivity approach. For dissolved Zn, Cd, Ca, and Mg reasonable model fits were produced when the metal-humic complexation parameters were identical for the 12 soils modeled. However, poor fits were obtained for Pb and Cu in Aquept B horizons. In two of the soil suspensions, the Lund A and Romfartuna Bhs, the calculated speciation agreed well with results obtained by using cation-exchange membranes. The results suggest that organic matter is an important sorbent for metals in many surface horizons of soils in temperate and boreal climates, and the necessity of properly accounting for the competition from Al in simulations of dissolved metal concentrations is stressed.
Research Interests: Geochemistry, Soil, Modeling, Multidisciplinary, Environmental science and technology, and 15 moreAdsorption, Soil Pollution, Heavy metals, Lead, Humic Substances, Sorption, Solubility, Acid, Reaction Mechanism, Ferric Compounds, Natural Organic Matter, Organic Chemicals, Soil Pollutants, Entisols, and Inceptisol
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Within the Lustra program (1999-2006) three common field sites have been established for coordinated measurements of greenhouse-gas fluxes and abiotic conditions. The overall aim is to develop better understanding of the fluxes, their... more
Within the Lustra program (1999-2006) three common field sites have been established for coordinated measurements of greenhouse-gas fluxes and abiotic conditions. The overall aim is to develop better understanding of the fluxes, their relation to abiotic conditions and ...
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We investigated the fate of added N and its effect on N fluxes in a long-term nitrogen fertilisation experiment. Ammonium nitrate was added annually (30 years) at mean rates of 0 (N0), 35 (N1), 73 (N2) and 108 (N3) kg N ha-1 yr-1 to a... more
We investigated the fate of added N and its effect on N fluxes in a long-term nitrogen fertilisation experiment. Ammonium nitrate was added annually (30 years) at mean rates of 0 (N0), 35 (N1), 73 (N2) and 108 (N3) kg N ha-1 yr-1 to a spruce forest in Sweden, which initially showed signs of N deficiency. Net N mineralisation and
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In risk assessments for contaminated soils an important part is to understand and to describe the transport of metals in soils and groundwaters. This requires knowledge not only of the leaching patterns from the contamination source for... more
In risk assessments for contaminated soils an important part is to understand and to describe the transport of metals in soils and groundwaters. This requires knowledge not only of the leaching patterns from the contamination source for the metals under consideration, but also of hydrological, geological and geochemical factors that affect the transport to nearby water systems through dilution and retardation processes. Different types of transport models can be applied, depending on the nature of the contaminant, on the nature of the medium (soil, groundwater, surface water, sediment), on hydrogeological conditions, and not least on the question to be answered. The most simplified transport models in use today for contaminated areas (used for example for calculations of guidance values) do not consider sorption of contaminants to the solid phase and hence not to any retardation during the transport through the saturated zone. Instead only dilution processes with groundwater are con...
The aims of the study were to evaluate the influence of former N deposition and land-use on N status expressed as net N mineralisation and soil C/N ratio, and to evaluate the relationship between N leaching and N status, N deposition or a... more
The aims of the study were to evaluate the influence of former N deposition and land-use on N status expressed as net N mineralisation and soil C/N ratio, and to evaluate the relationship between N leaching and N status, N deposition or a combination of both. Net nitrogen (N) mineralisation and C/N ratio in the soil were measured at seven Swedish sites, all dominated by Norway spruce (Picea abies (L.) Karst). The atmospheric N deposition at the sites ranged from 3 to 24 kg N ha−1 per year. At three of the sites, fertilised plots (30–75 kg N ha−1 per year) were also included in the study. The rate of NO3− leaching ranged from 0 to 25 kg N ha−1 per year. Measured net N mineralisation rate ranged from 4 to 104 kg N ha−1 per year and was correlated with the soil C/N ratio, both depending on previous N inputs and former land-use. Nitrate leaching was poorly correlated with N input (atmospheric deposition+fertilisation), but more so with the net N mineralisation; i.e. enhanced NO3− leachi...
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... East and South Africa. One example is the work by Lisanework and Michelsen (1994), who studied decomposition and nutrient release in native forest and tree plantations using the litterbag technique. Detailed studies of leaf ...
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Oxygenated polycyclic aromatic hydrocarbons (oxy-PAHs) are a class of ubiquitously occurring pollutants of which little is known. They can be co-emitted with PAHs or formed from PAHs in the environment. The environmental fate and risk of... more
Oxygenated polycyclic aromatic hydrocarbons (oxy-PAHs) are a class of ubiquitously occurring pollutants of which little is known. They can be co-emitted with PAHs or formed from PAHs in the environment. The environmental fate and risk of oxy-PAHs are difficult to assess due to a lack of methods to quantify their pore water concentrations. One sampler that can be used to determine freely dissolved concentrations of organic contaminants is polyoxymethylene (POM). In this study, POM - water partition coefficients (KPOM) were determined for 11 oxy-PAHs. KPOM values of 8 PAHs with similar hydrophobicities as the oxy-PAHs were determined for comparison. Results showed that logKPOM values ranged from 2.64 to 4.82 for the PAHs (2-4 rings), similar to previously determined values. LogKPOM values for investigated oxy-PAHs ranged from 0.96 to 5.36. The addition of carbonylic oxygen on a parent PAH generally lowered KPOM by 0.5 to 1.0 log units, which is attributable to the presence of carbonylic oxygens increasing water solubility. The KPOM values presented here will facilitate simultaneous assessments of freely dissolved water concentrations of oxy-PAHs and PAHs in environmental media.
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Soil quality standards are based on partitioning and toxicity data for laboratory-spiked reference soils, instead of real world, historically contaminated soils, which would be more representative. Here 21 diverse historically... more
Soil quality standards are based on partitioning and toxicity data for laboratory-spiked reference soils, instead of real world, historically contaminated soils, which would be more representative. Here 21 diverse historically contaminated soils from Sweden, Belgium, and France were obtained, and the soil-porewater partitioning along with the bioaccumulation in exposed worms (Enchytraeus crypticus) of native polycyclic aromatic compounds (PACs) were quantified. The native PACs investigated were polycyclic aromatic hydrocarbons (PAHs) and, for the first time to be included in such a study, oxygenated-PAHs (oxy-PAHs) and nitrogen containing heterocyclic PACs (N-PACs). The passive sampler polyoxymethylene (POM) was used to measure the equilibrium freely dissolved porewater concentration, Cpw, of all PACs. The obtained organic carbon normalized partitioning coefficients, KTOC, show that sorption of these native PACs is much stronger than observed in laboratory-spiked soils (typically by factors 10 to 100), which has been reported previously for PAHs but here for the first time for oxy-PAHs and N-PACs. A recently developed KTOC model for historically contaminated sediments predicted the 597 unique, native KTOC values in this study within a factor 30 for 100% of the data and a factor 3 for 58% of the data, without calibration. This model assumes that TOC in pyrogenic-impacted areas sorbs similarly to coal tar, rather than octanol as typically assumed. Black carbon (BC) inclusive partitioning models exhibited substantially poorer performance. Regarding bioaccumulation, Cpw combined with liposome-water partition coefficients corresponded better with measured worm lipid concentrations, Clipid (within a factor 10 for 85% of all PACs and soils), than Cpw combined with octanol-water partition coefficients (within a factor 10 for 76% of all PACs and soils). E. crypticus mortality and reproducibility were also quantified. No enhanced mortality was observed in the 21 historically contaminated soils despite expectations from PAH spiked reference soils. Worm reproducibility weakly correlated to Clipid of PACs, though the contributing influence of metal concentrations and soil texture could not be taken into account. The good agreement of POM-derived Cpw with independent soil and lipid partitioning models further supports that soil risk assessments would improve by accounting for bioavailability. Strategies for including bioavailability in soil risk assessment are presented.