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In natural waters trace elements may be present in different physico/chemical forms, varying in size, charge and density. In order to obtain information on the size distribution pattern, hollow-fiber ultrafiltration technique is a useful... more
In natural waters trace elements may be present in different physico/chemical forms, varying in size, charge and density. In order to obtain information on the size distribution pattern, hollow-fiber ultrafiltration technique is a useful tool. The membranes are made of inert polymers with different nominal molecular weight cut-off levels. Compared with traditional disc filtering techniques, the main advantages with hollow-fibers
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Since early 1900 the brackish, land locked fjord Gunneklevfjorden in Norway has suffered from significant contamination due to industrial discharges and run-off. Between 1947 and 1988 approximately 80 tonnes of mercury were discharged... more
Since early 1900 the brackish, land locked fjord Gunneklevfjorden in Norway has suffered from significant contamination due to industrial discharges and run-off. Between 1947 and 1988 approximately 80 tonnes of mercury were discharged into the fjord from a chloralkali plant. Plans for remediation of the fjord is under development. The history of mercury discharges are reflected in the sediment profile, formed by continuous sedimentation of contaminated material. Contamination peaks at 15 cm sediment depth with mercury concentrations of approximately 490 mg TotHg kg-1 (ppm). Termination of regular discharges of mercury has led to lower mercury concentrations in sedimenting material and our recent investigations have revealed 1.9 - 7.7 mg TotHg kg-1(ppm) in surface sediments. Mercury in surface sediments is bioavailable to bottom dwelling and bioturbating organisms mainly in the organic form methyl mercury. Methyl mercury is known to bioaccumulate in aquatic food webs. Methyl mercury ...
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Acid rain emerged as an important environmental problem in China in the late 1970s. Many years of record economic growth have been accompanied by increased energy demand, greater coal combustion, and larger emissions of pollutants. As a... more
Acid rain emerged as an important environmental problem in China in the late 1970s. Many years of record economic growth have been accompanied by increased energy demand, greater coal combustion, and larger emissions of pollutants. As a result of significant emissions and subsequent deposition of sulfur, widespread acid rain is observed in southern and southwestern China. In fact, the deposition of sulfur is in some places higher than what was reported from the 'black triangle' in central Europe in the early 1980s. In addition, nitrogen is emitted from agriculture, power production, and a rapidly increasing number of cars. As a result, considerable deposition of pollutants occurs in forested areas previously thought to be pristine. Little is known about the effects of acid deposition on terrestrial and aquatic ecosystems in China. This article presents the current situation and what to expect in the future, largely on the basis of results from a five-year Chinese-Norwegian c...
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Environmental drivers of total mercury (TotHg) concentrations, methylmercury (MeHg) concentrations, and MeHg fractions (a proxy for methylation potential, expressed as %MeHg) were assessed in a synoptic study of 51 lakes in southeast... more
Environmental drivers of total mercury (TotHg) concentrations, methylmercury (MeHg) concentrations, and MeHg fractions (a proxy for methylation potential, expressed as %MeHg) were assessed in a synoptic study of 51 lakes in southeast (Boreal) and northeast (Subarctic) Norway. Concentrations of TotHg and MeHg ranged between 0.5-6.6 ng/L and <0.02-0.70 ng/L, respectively. The lakes span wide ranges of explanatory environmental variables, including water chemistry, catchment characteristics, climate conditions, and atmospheric deposition of Hg, sulphur and nitrogen (N). Dissolved organic matter (DOM), measured as total organic carbon (TOC), was the variable most strongly correlated with TotHg (r(2)=0.76) and MeHg (r(2)=0.64) concentrations. Lakes in the Subarctic region had significantly lower TotHg and MeHg concentrations, and %MeHg than lakes in the Boreal region (p<0.01), implying a lower aquatic food web exposure of aqueous Hg species in Subarctic Norway than in the Boreal la...
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In 1986 Lake Langedalstjenn in southern Norway was a weakly acidified lake with a pH of 5.2–5.6, and an average concentration of SO4 of 330 µeq L-1. The total Al concentration varied between 10 and 20 µeq L-1 (expressed as Al3+). The lake... more
In 1986 Lake Langedalstjenn in southern Norway was a weakly acidified lake with a pH of 5.2–5.6, and an average concentration of SO4 of 330 µeq L-1. The total Al concentration varied between 10 and 20 µeq L-1 (expressed as Al3+). The lake supported populations of brown trout and perch and had supplied about 100 people with drinking water until
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By using three water flow proportional river dosing units, 21 small water flow proportional dosing units, and approximately 30 dripping units, the River Batnfjordselva has through two treatment periods, spring and autumn 2004, been... more
By using three water flow proportional river dosing units, 21 small water flow proportional dosing units, and approximately 30 dripping units, the River Batnfjordselva has through two treatment periods, spring and autumn 2004, been treated with aluminium with the purpose to eliminate Gyrodactylus salaris from the watershed. Rotenon has been used in ponds and ditches with non-circulating water. The knowledge for the Al-dosing has been taken from dosing technology in other relations, and is based on known methods developed for liming of acidified waters. By further development of the dosing technology, it has probably succeeded to eliminate G. salaris from the River Batnfjordselva. The results from this project show that the Al-method most likely will be effective in the battle against G. salaris in every infected Norwegian river, irrespective of the water chemistry, size and complexity of the River system. The new method also opens for the possibility to reduce the spreading of G. sa...
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Temperature affects the solubility of Al(OH)3(s), the solubility product formed, the hydrolysis and molecular weight distribution of aqueous Al species as well as the pH of the solutions. In the present work, identical solutions of... more
Temperature affects the solubility of Al(OH)3(s), the solubility product formed, the hydrolysis and molecular weight distribution of aqueous Al species as well as the pH of the solutions. In the present work, identical solutions of inorganic Al (400, 600, and 800 µg Al L-1) were stored for 1 mo at either 2 or 25 °C. In the solutions stored at
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... This agree with the decrease in total Ali of 28 -4-4 #g L -1 and the increase in total Alo of 14 4-2 #g L -1 ... Lydersen, E., Bjcrnstad, HE, Salbu, B., and Pappas, AC: 1987, &amp;amp;amp;amp;amp;#x27;Trace Element Speciation in... more
... This agree with the decrease in total Ali of 28 -4-4 #g L -1 and the increase in total Alo of 14 4-2 #g L -1 ... Lydersen, E., Bjcrnstad, HE, Salbu, B., and Pappas, AC: 1987, &amp;amp;amp;amp;amp;#x27;Trace Element Speciation in Natural Waters Using Hallow-fiber Ultrafiltration&amp;amp;amp;amp;amp;#x27;, in L. Ladner (ed.), Lecture Notes ...
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In natural waters, aluminium occurs in different physico-chemical forms, depending on pH, temperature and the presence of inorganic and organic ligands. Conventional methods for fractionation of AI species do not fully succeed in... more
In natural waters, aluminium occurs in different physico-chemical forms, depending on pH, temperature and the presence of inorganic and organic ligands. Conventional methods for fractionation of AI species do not fully succeed in separating monomeric, i.e., low relative molecular mass (Mr) AI species, from polymeric colloidal AI species. In the present work, hollow-fibre ultrafiltration and acid digestion steps are introduced prior to the ordinary Barnes-Driscoll procedure. By this method, a colloidal AI fraction is separated from the particulate fraction, i.e., the fraction that is able to precipitate by the force of gravity. Both the monomeric and colloidal AI fractions are characterized according to Mr and the chemical properties such as hydroxyquinoline-isobutyl methyl ketone-extractability and Amberlite IR-120 cation exchangeability. Changes in pH and/or temperature were found to be critical for the analytical results of AI. By combining size and charge fractionation techniques, increased information concerning AI species in dilute freshwaters was obtained. One important investigation is the presence of high Mr AI species in the operationally defined monomeric AI fractions.
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ABSTRACT
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We conducted a 3-year artificial deepening of the thermocline in the dimictic Lake Breisjøen, southern Norway, by means of a large submerged propeller. An adjacent lake served as untreated reference. The manipulation increased thermocline... more
We conducted a 3-year artificial deepening of the thermocline in the dimictic Lake Breisjøen, southern Norway, by means of a large submerged propeller. An adjacent lake served as untreated reference. The manipulation increased thermocline depth from 6 to 20 m, caused a significant increase in the heat content, and delayed ice-on by about 20 days. There were only minor changes
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... Limnology, Blindem, N0316 Oslo, Norway Espen l.ydersen NIVA, Nelsas, N0411 Oslo, Norway El 9507381 M (Received 26 April 1996; accepted 28 April ... effects on national avocado yields in Israel J. Lomas*,&amp;#x27;, D. Zametb... more
... Limnology, Blindem, N0316 Oslo, Norway Espen l.ydersen NIVA, Nelsas, N0411 Oslo, Norway El 9507381 M (Received 26 April 1996; accepted 28 April ... effects on national avocado yields in Israel J. Lomas*,&amp;#x27;, D. Zametb aMeteorological Institute, PO Box 25, Bet Dagan, Israel b ...
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ABSTRACT In 1990, wetlands and blanket bogs, constituting 4.0% of the catchment of Lake Roynelandsvatn in southern Norway, were limed by helicopter with 20 t . ha(-1) of fine-powdered limestone. Liming caused a rapid increase in stream pH... more
ABSTRACT In 1990, wetlands and blanket bogs, constituting 4.0% of the catchment of Lake Roynelandsvatn in southern Norway, were limed by helicopter with 20 t . ha(-1) of fine-powdered limestone. Liming caused a rapid increase in stream pH and calcium (Ca) and a decrease in reactive and inorganic monomeric aluminium (Al). Three years later the reactive Al concentration was still 50% lower and the Ca concentration twice as high as preliming values. Mean and minimum acid neutralizing capacity of the outlet stream were 23 and 8 mu equiv.. L(-1), respectively, and although pH had decreased to 5.2-5.3 the water quality was acceptable for the survival of brown trout (Salmo trutta). No significant increase in stream nitrate, organic nitrogen, or total organic carbon was measured after liming. Terrestrial liming may be a useful approach to neutralize acidic runoff because of the retention of inorganic monomeric Al in the catchment, the long-lasting increase in Ca concentration, and the inherent deacidification capacity during stormflows and snowmelt. Liming of strategic discharge areas in the catchment may limit the extent of undesirable effects, such as the death of Sphagnum mosses, on the terrestrial ecosystem.
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ABSTRACT The present study is mainly focusing on the effect of temperature on Al-chemistry and the resulting toxicity to fish. Atlantic salmon (Salmo salar L.) fingerlings were exposed to water at defined combinations of temperature, pH... more
ABSTRACT The present study is mainly focusing on the effect of temperature on Al-chemistry and the resulting toxicity to fish. Atlantic salmon (Salmo salar L.) fingerlings were exposed to water at defined combinations of temperature, pH and Al-concentration, and mortality was recorded. Mortality was correlated to the concentration of inorganic aluminium, and increased systematically with increasing temperature. The degree of ongoing Al-polymerization is thought to be the most important factor for the temperature dependent Al-toxicity observed.