Espen Lydersen - Academia.edu (original) (raw)

Papers by Espen Lydersen

Journal of Limnology, 2002

We have tested the influence of water ionic strength on the toxicity of aluminium in fish by comp... more We have tested the influence of water ionic strength on the toxicity of aluminium in fish by comparing the mortality of Atlantic salmon (Salmo salar) parr exposed to Al-rich water with additions of Ca 2+ or Na + . The fish were exposed in parallel to Al-rich water (Al 500 µg l -1 , pH 5.8) under non-steady state conditions, with and without the addition of one of the two base cations. The amount of Na + and Ca 2+ added to the water was calculated in order to obtain an identical increase in water ionic strength. Fish mortality was dependent on water residence time and whether or not base cations were added to the Al-rich water. In all Al-exposures, the highest mortality was always observed in fish exposed to water with the shortest residence time. Mortality decreased systematically with increasing water residence time through the exposure set-up. The addition of a base cation, Ca 2+ or Na + , to the Al-rich water reduced fish mortality significantly compared to the Al-only exposures. Furthermore, increasing ionic strength with Na + reduced mortality to a larger extent than the corresponding increase in ionic strength by the addition of Ca 2+ . The variation in mortality between the various aluminium and base cation treatments is discussed in terms of aluminium chemistry, specific mitigating effects of Ca 2+ and Na + , and the general importance of water ionic strength. This study clearly demonstrates that Ca 2+ does not play an unique role as an ameliorating cation for Al-toxicity in fish under non-steady state chemical conditions. Thus, ionic strength seems to be important, probably for the interaction between aluminium and the gill surface, reducing the possibility for positively charged aluminium species to bind to negatively charged sites.

Environment International, 1994

By linear regression analyses, flux, concentration, and net charge (NC in ~eq/mg C) of total orga... more By linear regression analyses, flux, concentration, and net charge (NC in ~eq/mg C) of total organic carbon (TOC) have been related to different physico-chemical parameters present in air/precipitation and streamwater at four long-term monitored catchments in Norway, during the period 1986-1992. The catchments vary a lot with respect to annual water input, acid rain, and the streamwater concentration of TOC. Thus, relationships between concentration/NC of TOC and chemical compounds in precipitation and streamwater were often catchment-specific. However, seasonal climatic changes, like air temperature and hydrology, were found to be important for the concentration variations of TOC. The correlation between concentration of nonmarine base cations (~-BC*) and concentration of TOC at the four sites was far more significant (r=0.$6) than the corresponding correlation between nonmarine sulphate (SO+*) and ~BC* (r=0.57). This indicates the important role of organic matter in weathering reactions in the catchment. Concerning weathering and cation leaching of aluminum, the correlation between concentration of total aluminum (RAL) and SO4" was far more significant (r=0.93) compared with the corresponding correlation between RAL and TOC (r=0.40). This should be expected, because a high concentration of SO4" means a low pH, which is needed to dissolve substantial amounts of Al from soils. The NC of TOC was found to be most affected by compounds in precipitation, primarily the inputs of sea salts. In the most acidified areas, the influence from strong acid inputs also affects the NC of TOC, but less significantly. The concentration of Na + in precipitation is much higher and the variations much larger compared with the concentration of H + in precipitation in the coastal areas, like Birkenes and especially Kaarvatn. Thus, it is reasonable that the variations in sea salt inputs (primarily NaCI) are more important for the temporary variation in NC of TOC compared with H ÷ ions at these sites. Only at Langtjern, the most TOC-influenced site, a significant and positive correlation was found between H ÷ and the concentration of TOC in streamwater. This indicates that at a certain TOC level, the weak organic acids may affect the streamwater pH. A comparison between measured and calculated concentrations of organic AI indicated that the dissociation constants (pK-values) of the organic acids present at Birkenes must be higher and/or the Al-complexing constants lower compared with the constants given by the programme. At the three other sites, it was the other way around. This may explain why a negative correlation between concentrations of TOC and labile AI was present at Birkenes, while the other sites exhibited a corresponding positive correlation with respect to labile AI or ~-AI °+. The comparison also documented larger differences in these constants between the sites, compared with monthly variations in the constants at one single site.

Lecture Notes in Earth Sciences, 1987

In natural waters trace elements may be present in different physico/chemical forms, varying in s... 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

Since early 1900 the brackish, land locked fjord Gunneklevfjorden in Norway has suffered from sig... 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 ...

Acid rain emerged as an important environmental problem in China in the late 1970s. Many years of... 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...

The Science of the total environment, 2014

Environmental drivers of total mercury (TotHg) concentrations, methylmercury (MeHg) concentration... 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...

Journal of Limnology, 2014

Seasonal variations of mercury (Hg) concentration in muscle tissue of northern pike -Esox lucius ... more Seasonal variations of mercury (Hg) concentration in muscle tissue of northern pike -Esox lucius L, European whitefish -Coregonus lavaretus L and European perch -Perca fluviatilis L have been investigated in Lake Heddalsvatn, southern Norway. Our data confirmed seasonal differences in the Hg concentrations in fish, but the causes for that may vary depending on fish species. Length (pike and perch) and age (perch and whitefish) were the strongest explanatory factors for the Hg fluctuations. Fish caught in December (pike and whitefish) had the highest Hg concentrations, while the concentrations in May were higher than in September for all 3 species, statistically significant for perch (P<0.0001) and close to significant for pike (P=0.07).

In 1986 Lake Langedalstjenn in southern Norway was a weakly acidified lake with a pH of 5.2–5.6, ... 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

A humic lake of pH 5.6 was acidified with H2SO4 to pH 4.1. Measurements of total and hollow-fiber... more A humic lake of pH 5.6 was acidified with H2SO4 to pH 4.1. Measurements of total and hollow-fiber ultrafiltered samples were made after three different times of storage, before and after the acid treatment. The nominal molecular weight cutoff of the hollow-fiber membrane was 10 kDalton. Assuming a linear molecular weight distribution of the organic complexes present in solution, the average organic molecule had an average molecular weight of 12.8 _+ 08 kDalton (n=6). Not only Ca a+ and Mg 2+, but also detectable amounts of Na + and K + was found to be present on high molecular weight forms. No significant change in the molecular weight distribution of these elements were observed after the pH decrease. Changes in the molecular weight distribution after the acid treatment were only observed for Fe and A1. Significant amounts of SO42-were present on high molecular weight forms. A small, but significant increase in the relative amounts of SO42-present on high molecular weight forms was observed after the pH lowering. Kinetic constraints were demonstrated for dissolution of A1 and Fe. To some extent, kinetic constraints in the equilibrium distribution of cation/anion exchange reactions of A1, Fe, and 8042-were also observed. After the acid treatment, the cation exchange capacity (CEC) of the organic pool present was estimated to be at least 18.2 _+ 1.4 (n=3) txeq of positive charges per mg C, probably because the negative sites on the organic pool are either not totally protonated or occupied by other cations at pH 4.09. This CEC is of the same order as industrially made cation exchange resins.

By using three water flow proportional river dosing units, 21 small water flow proportional dosin... 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...

Environmental Monitoring and Assessment, 2002

The goal of this work was to assess risk of chemical and biological effects of metals in reacidif... more The goal of this work was to assess risk of chemical and biological effects of metals in reacidified, limed water bodies in Norway and Sweden. The risk assessment is based on a literature review and evaluations of water chemical data from the 1995 Nordic Lake Survey. Compared to the pre-liming period, it us unlikely that enhanced remobilization of inorganic aluminium (Al) or other toxic metals (metal bomb hypothesis) from the catchment, the lake sediment and/or the streambed will occur when limed waters reacidify. Rather, the concentrations in surface waters are expected to be lower than before liming started, because of reduced atmospheric inputs of both strong acids and metals as Cd, Hg, Pb, and Zn during the last 10-20 yr. The concentrations in lakes relative to the biological effect levels, as well as the chemical properties of the different metals suggest that the potential biological risks associated to reacidification of limed lakes decrease in the order Al >> Cd > Pb. The risks associated with Cr, Cu, Fe, Mn, Ni and Zn are very low and do not have to be considered except in waters with known concentrations larger than the lowest biological risk level. Such waters are very rare (<2%). Aluminium is the metal that should be used to set the limit for judging the risk of biological damage due to reacidification of limed surface waters.

Acta hydrochimica et hydrobiologica, 1998

Water Air and Soil Pollution, 1990

Temperature affects the solubility of Al(OH)3(s), the solubility product formed, the hydrolysis a... 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

Water, Air, & Soil Pollution, 1995

Mixing of acid river water containing aluminium (pH 5.1, AI 345 btg.1 "I) with neutral water of a... more Mixing of acid river water containing aluminium (pH 5.1, AI 345 btg.1 "I) with neutral water of a lake (pH 7.0, A173 p.g.1 "~) resulted in water (pH 6.4, A1 245 p.g.l "x) with a pH (6.4) and A1 concentration (245 p.g.1 "l) expected to have low toxicity to fish on the basis of current AI toxicity models. However, under semi-field conditions the freshly mixed water (a few sec. after mixing) proved to be highly toxic to brown trout. The fish were exposed to the water at different places along a 30 m channel. At the beginning of the channel acid and neutral water were continuously mixed; the mixed water left the channel atter 340 sec. The cells of the gills showed a highly increased rate of cell death by apoptosis and necrosis. Intercellular spaces were enlarged, and many leucocytes penetrated in these spaces. Mucus release was stimulated to depletion. Plasma chloride levels were hardly affected. There was a clear gradient in the deleterious effects on the fish along the channel. The fish at the beginning of the channel (about 12 sec. after mixing of the water), were severely affected, whereas the fish kept at the end of the channel (340 sec. after mixing) were only mildly affected. In the natural situation fish will relatively quickly pass through a mixing zone. In our study we therefore focused on the effects on fish after a 60 min exposure to a mixing zone (5 sec after mixing), with subsequent recovery in a region downstream of the confluence and in neutral water with low AI. The recovery in the downstream area (at the end of the channel, i.e. 5 min after mixing) was clearly hampered when compared to the recovery in neutral water with low aluminium. Thus, a short exposure to the toxic mixing zone followed by a stay in water downstream of this zone, as may occur in nature, is detrimental to migrating trout. We conclude that freshly mixed acid and neutral water contain toxic components during the first seconds to minutes after mixing, that can not be explained by current models on aluminium toxicity.