| 1. |
- Peltola, Pasi, et al.
(författare)
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Concentations and leachability of chemical elements in estuarine sulfur-rich sediments, W. Finland
- 2002
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Ingår i: Science of the Total Environment. - : Elsevier. - 0048-9697 .- 1879-1026. ; 284:1-3, s. 109-122
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Tidskriftsartikel (refereegranskat)abstract
- Concentrations, distributions and mobility of chemical elements were investigated in reduced sulfur-rich estuarine sediments located in western Finland. The main objective was to determine the possible extent of metal leaching when dredged masses of these sulfur-rich sediments are dumped on the land and thus exposed to air. When dredged, the reduced sulfur in the sediments oxidises resulting in a lowering of pH, which in turn is expected to leach metals. The study area is an artificial lake claimed from the Botnian sea in 1962. In this lake, several mass-kills of fish have occurred, believed partly to be due to dredging. Two sediment samples (0–50 and 50–100 cm) were taken from 39 sampling points in the lake. These samples were leached in aqua regia (2:2:2 HNO3/HCl/H2O) and analysed for Fe, Al, Mg, Ca, K, P, Na, Mn, Zn, Ba, V, Sr, Cr, Ni, Cu, Co, As, Pb, B, Mo and Cd with ICP-AES. Sulfur and organic carbon were analysed with Leco. In a controlled laboratory experiment, the sediments were allowed to oxidise for 1 year while moisturised with deionised water every month. The pH and conductivity were determined in the beginning of the experiment (reduced state) and in the end (oxidised state). In the supernatants in the oxidised states the amount of leached metals (Na, Al, Mn, Zn, Sr, Co, Ni, Cu, Cd, Cr, Pb, U, Li, Rb and As) were determined with ICP-MS. The sediments were found to contain low levels of toxic metals but, as expected, high concentrations of sulfur. In the experiment, pH was lowered (down to 3.0) and the conductivity increased in all samples due to oxidation and release of metal ions. The extent of leaching varied between 0.03% for As and 12.3% for Na. Critical pH values, at which high amounts of metals begin to leach, were obtained graphically. These values varied between 4.8 (Ni) and 3.3 (Cr). Not all elements were controlled by pH, e.g. Mn correlated well with its aqua regia leachable concentration. In a planned dredging operation in the area some 23 300 t (10 500 m3) (dry wt.) of sediments will be dredged. The amounts of metals likely to be leached, according to the results from this study, are as follows (kg): Al (1710), Mn (1230), Zn (59), Sr (39), Co (13), Ni (12), Cu (2) and less than 1 kg of Cd–Cr–As–Pb.
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| 2. |
- Barany, E, et al.
(författare)
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Trace element levels in whole blood and serum from Swedish adolescents
- 2002
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Ingår i: Science of the Total Environment. - 1879-1026 .- 0048-9697. ; 286:1-3, s. 129-141
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Tidskriftsartikel (refereegranskat)abstract
- Blood and serum samples from 372 15-year-old adolescents were collected in two cities in Sweden and analyzed by inductively coupled plasma mass spectrometry (ICP-MS). The objective was to (1) determine the levels of 13 elements in blood and serum from the teenagers; and (2) for each element, investigate the correlation between the concentrations in blood and serum. The concentrations in blood and serum were generally in line with that usually reported for the essential elements Co, Cu, Zn and Se, and generally low for the 'non-essential' elements Cd, Hg, Pb. The median concentrations were in blood and serum, respectively: of Co 031 and 0.48 mug/l, Cu 0.92 and 1.0 mg/l, Zn 6.1 and 0.99 mg/l, Se 110 and 100 mug/l, Rb 2.8 and 0.24 mg/l, Hg 1.1 and 0.44 mug/l, Pb 16 and 0.33 mug/l. The median concentration of W in blood was < 0.2 mug/l (below the detection limit) and in serum 0.087 mug/l. The median concentrations of Cd, Rh, Pd, Pt and TI were below the detection limits. Statistically significant correlations were found between the concentrations in blood and serum for Co, Cu, Zn, Se, Rb, W, Hg and Pb. The levels presented in this study constitute baseline levels or levels generally not exceeded in adolescents for 13 elements, including essential, ubiquitous toxic, and rare elements.
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| 3. |
- Bhattacharya, Prosun, et al.
(författare)
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Metal contamination at a wood preservation site : characterisation and experimental studies on remediation
- 2002
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Ingår i: Science of the Total Environment. - 0048-9697 .- 1879-1026. ; 290:03-jan, s. 165-180
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this investigation was to determine the occurrence of As, Cu, Cr and Zn in the soil at an abandoned wood preservation unit and to examine some possible extractants for the contaminants in the soil. The mean As content of the contaminated surface soils (0-10 cm) was 186 mg kg(-1), where as the mean concentrations of Cu, Cr and Zn in soils from the contaminated area were 26, 29 and 91 mg kg(-1), respectively. The elevated As content in the mineral soils is related to adsorption of inorganic As phases in the fine grained fractions, which are characterised by large surface area and high positive surface charge under the current acidic conditions. Cu and Cr were found to be rather mobile, which is reflected in their lower abundance in soils and significant accumulation in sediments in the drainage leaving the area. The fine fraction of the soil (<0.125 mm) has an average metal content increased by nearly 34% as compared to the <2-mm fraction conventionally used for the analysis and assessment of soil contamination. The <2-mm fraction constitutes approximately 65% of the total weight while the fine fraction (< 0.125 mm) constitutes approximately 10%. These facts, taken together, are essential for the choice of remediation measures. Oxalate solutions have been tested as extractants for soil remediation. Dark acid oxalate extraction dissolves the amorphous Al- and Fe-oxides and hydroxides and mobilises the adsorbed inorganic As species. Oxalate also acts as a ligand for the cationic heavy metals, releasing them from exchangeable sites. With a three-step sequential leaching, up to 98-99% of the metals could be removed. At lower concentrations and higher pH, the leaching decreased to approximately 70%.
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| 4. |
- Bozkurt, S., et al.
(författare)
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Long-term processes in waste deposits
- 2000
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Ingår i: Science of the Total Environment. - 0048-9697 .- 1879-1026. ; 250:03-jan, s. 101-121
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Tidskriftsartikel (refereegranskat)abstract
- A conceptual model, which is a unitary and continuous description of the overall processes in waste deposits, has been developed. In the model the most important processes governing the long-term fate of organic matter in landfills and the transport and retention of toxic metals are included. With the model as a base, a number of scenarios with different levels of complexity have been defined and studied in order to carry out long-term assessments of the chemical evolution in waste deposits for industrial and municipal solid waste containing much organic matter and the leaching of toxic metals. The focus of the modelling has been to quantify the important processes occurring after the methane production phase has ceased, i.e. during the humic phase. The scenarios include the main mechanisms based on various transport processes as well as different landfill constructions, e.g. binding capacities of sulfides and humic substances. They also include transport mechanisms by which the reactant oxygen can intrude into a deposit, sorption capacities of hydrous ferric oxides, and pH-buffering reactions, etc. Scoping calculations have shown that the binding capacity of humic substances is sufficient to bind all toxic metals (Cd, Cr, Pb, Zn and Hg). In addition, the humics could also bind a smaller part of Ca, Fe and Al, provided much of the organic waste remain as humic substances. Sulfides on the other hand can bind approximately twice the amount of all toxic metals. The binding capacity of hydrous ferric oxides, which can be formed by oxidation reactions during the humic phase, is estimated to be three times the total content of metals that can sorb on hydrous ferric oxides. In the studied landfill the pi-I-buffering capacity, primarily represented by calcite, is estimated to be 1 mol/kg dry waste. Quantifications indicate that the alkalinity of the wastes is high enough to buffer the acidity produced by the oxidation of sulfides and by the degradation of organic matter, as well as that added by acid precipitation. Therefore, the main conclusion is that higher remobilisation rates of heavy metals due to lowering of pH are not expected for many thousands of years.
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| 5. |
- Bozkurt, S., et al.
(författare)
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The long-term evolution of and transport processes in a self-sustained final cover on waste deposits
- 2001
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Ingår i: Science of the Total Environment. - 0048-9697 .- 1879-1026. ; 271:03-jan, s. 145-168
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Tidskriftsartikel (refereegranskat)abstract
- A new principle for confinement of waste based on a self-sustained seal is presented. The top cover is considered to consist of two main layers; an organic carbon rich surface layer that is able to support vegetation and an inorganic layer beneath it. The function of the cover is to mitigate oxidation and acidification of landfilled waste and hence the release of toxic metals. It is suggested that forest soil formation and soil development could prove to be valuable information sources for the study of the long-term behaviour of a final cover on waste deposits. Since the cover is expected to develop in northern temperate climate the focus is on Spodosol soil. A number of simulations of the long-term behaviour of the final self-sustained landfill cover are made, including the rates of influx of oxygen into the cover. A cover having a large portion of organic matter compared with a cover with no organics can considerably decrease the oxygen concentration and thus the influx of oxygen into a landfill. The calculated oxygen intrusion rate for the former case is of the order of 0.05 kg m(-2) year(-1). Degradation of the organics produces acids. Our simulations indicate that the pH-buffering capacity of the mineral layer, represented by calcite and primary rock minerals, will last for many thousands of years.
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| 6. |
- Bäckström, Mattias, 1974-, et al.
(författare)
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Effects of a fulvic acid on the adsorption of mercury and cadmium on goethite
- 2003
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Ingår i: Science of the Total Environment. - Amsterdam, Netherlands : Elsevier. - 0048-9697 .- 1879-1026. ; 304:1-3, s. 257-268
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Tidskriftsartikel (refereegranskat)abstract
- The effects of an aquatic fulvic acid on the pH-dependent adsorption of Hg(II) and Cd(II) to particulate goethite (a-FeOOH) were studied in batch systems. The ionic medium consisted of 0.01 M HClO and the total concentrations 4 of mercury and cadmium were maintained at 10y8 M with 203Hg and 109Cd as tracers. pH In the systems was varied in the range 3–10 by addition of HClO and NaOH.All commercial chemicals were of analytical grade or better. An 4 aquatic fulvic acid (20 ppm), previously isolated and characterised in detail, was used as a model for humic substances and its adsorption to goethite is included in this study. The adsorption of the fulvic acid (20 ppm) onto goethite decreased slowly from 90% at pH 3–7.5 to 10% at pH 10. In systems without fulvic acid the adsorption of mercury increased in a linear fashion from 10% at pH 3 to 70% at pH 10.In the presence of fulvic acid (20 ppm), the adsorption was almost quantitative in the intermediate pH range (pH 5–7), and exceeded 92% over the entire pH range. Thus, association between mercury and the fulvic acid enhanced adsorption in general although the largest impact was found at low pH.Adsorption of cadmium increased from nearly 0 to almost 100% at approximately pH 6. In the presence of fulvic acid, the adsorption increased below pH 7 and decreased above pH 7. The adsorption isotherm for mercury when the concentration was increased from 10y8 to 1.8=10y4 M showed a corresponding increase of K (lyg) up to a total concentration at 10y6 M.At higher mercury concentrations K was lowered. In the presence of fulvic acid the corresponding relationship of K was bi-modal, i.e. high values at low and intermediate concentrations of mercury. This behaviour suggests that in the absence of fulvic acid the adsorption follow the expected behaviour, i.e. adsorption sites with similar affinity for mercury. In the presence of fulvic acid, additional adsorption sites are available by the organic molecule (possibly sulfur groups) when it is associated to the goethite. The adsorption isotherm for cadmium indicates a lowering of K at 10y4 M. Cadmium had no competitive effect on mercury and vice versa. Zinc, however, affected the adsorption of cadmium but not the adsorption of mercury.
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| 7. |
- Carlsson, E., et al.
(författare)
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Sequential extraction of sulfide-rich tailings remediated by the application of till cover, Kristineberg mine, northern Sweden
- 2002
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Ingår i: Science of the Total Environment. - 0048-9697 .- 1879-1026. ; 299:1-3, s. 207-226
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Tidskriftsartikel (refereegranskat)abstract
- A sequential extraction has been carried out on sulfide-rich mine tailings. The purpose was to investigate how elements released by oxidation are secondarily retained in the tailings and the possible consequences of the remediation. After investigating the solid tailings, seven samples were chosen for sequential extractions. Two samples were oxidised, situated just above the oxidation front, two samples from just below the former oxidation front with increased concentrations of several elements, two unoxidised samples were from an intermediate depth, and the deepest sample was from the tailings-peat boundary at the bottom of the impoundment. Five phases were extracted: adsorbed/exchangeable/carbonate, labile organics, amorphous Fe-oxyhydroxides/Mn-oxides, crystalline Fe-oxides, and organics/sulfides. The addition from dried porewater to the extracted fractions has been calculated and considered as minor. In the oxidised tailings, the sulfide fraction still dominates for elements such as Fe, S, Cd, Co, Cu, Hg and Zn, although the concentrations are low compared to the unoxidised tailings. Generally, the second most important fraction is the adsorbed/exchangeable/carbonate fraction. Below the oxidation front, the sulfide content of the tailings sharply increases. In the secondary enrichment zone, the total element concentrations increase compared with the deeper unoxidised samples, mainly due to secondary retention. For some elements, secondary retention is greater than the total amount extracted for the deeper unoxidised samples. In the secondary enrichment zone the adsorbed/exchangeable/carbonate fraction represents approximately 20 wt.% or more for Cd, Co, Mn, Ni and Zn. The amorphous iron oxyhydroxide or the crystalline iron oxide fractions are less important at this level, although for As, Ba and Cu the amorphous iron oxyhydroxide fraction represents up to 20 wt.%. At the lower border of the enrichment zone, the total concentration for most metals is lower, but the importance of the adsorbed/exchangeable/carbonate fraction is further enhanced for Cd, Cu, Ni and Zn. These elements have 35-60 wt.% of the total amount from this fraction. For As, Cd, Cu, Ni and Pb, the secondary fractions extracted (extractions A-D) represent between 60 and 80 wt.% of the total content. At greater depth in the impoundment the relative importance of the adsorbed/exchangeable/carbonate fraction decreases, whilst the importance of amorphous iron oxyhydroxide and crystalline iron oxide fractions increases. The adsorbed/exchangeable/carbonate fraction is the most easily remobilised fraction. A raised groundwater table previously situated below the enrichment zone may result in the release of secondarily retained metals. © 2002 Elsevier Science B.V. All rights reserved.
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| 8. |
- Danilov, Roman, et al.
(författare)
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The use of epiphyton and epilithon data as a base for calculating ecological indices in monitoring of eutrophication in lakes in central Sweden
- 2000
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Ingår i: Science of the Total Environment. - 0048-9697 .- 1879-1026. ; 248, s. 63-70
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Tidskriftsartikel (refereegranskat)abstract
- Eutrophication was monitored with the aid of one similarity and seven diversity indices in the lakes of different trophic levels (eutrophic, mesotrophic and oligotrophic) in central Sweden. The ecological indices were applied separately to epiphyton and epilithon communities. Epiphyton turned out to be inappropriate for assessing eutrophication in the lakes studied. On the other hand, Hurlbert's, Simpson's and the similarity indices turned out to be promising environmental tools when applied to the data of epilithon.
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| 9. |
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| 10. |
- Engwall, Magnus, 1965-, et al.
(författare)
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Fate of Ah-receptor agonists in organic household waste during anaerobic degradation : estimation of levels using EROD induction in organ cultures of chick embryo livers
- 2002
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Ingår i: Science of the Total Environment. - 0048-9697 .- 1879-1026. ; 297:1-3, s. 105-108
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Tidskriftsartikel (refereegranskat)abstract
- The fate of 7-ethoxyresorufin O-deethylase (EROD)-inducing compounds in source-separated organic household waste subject to anaerobic degradation (i.e. mesophilic/thermophilic anaerobic treatment) was investigated using organ cultures of embryonic chicken livers from fertilised hen eggs. This bioassay reflects the combined effect of all EROD-inducing, possibly dioxin-like compounds in a sample, including chemicals that are seldom or never analysed. All samples tested induced EROD in the bioassay, indicating the presence of dioxin-like compounds. In the anaerobic processes, the amounts of acid-resistant EROD-inducing compounds coming out of the reactors were considerably higher than the incoming amounts, especially for the low-temperature (mesophilic) process. This apparent production of EROD-inducing compounds may be due to de novo synthesis or to an increase in the EROD-inducing potency of the compounds in the material.
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