The effects of liming on juvenile stocks of Atlantic salmon (Salmo salar) and brown trout (Salmo trutta) in a Norwegian river

The effects of liming on juvenile stocks of Atlantic salmon (Salmo salar) and brown trout (Salmo trutta) in the river Vikedalselva in southwestern Norway were assessed. From 1987 to 1989, the river was limed only during the spring snow melt, and pH varied in the range between 5.5 and 7.0. In 1990 to 1993, the river was limed to pH 6.2 from 15 February to 1 June and to pH 5.7 during the rest of the year. Since 1994, the pH during late winter and spring was maintained above 6.5. Prior to liming fish kills were evident during spring snow melt, but these have not occurred since liming. Electrofishing in the autumn between 1981 and 1994 showed no significant change in densities of juvenile salmon and brown trout after liming, mean densities ranged between 19–50 and 9–32 individuals 100 m^–2 respectively. A significant linear correlation between production and biomass of both species was found, indicating that factors directly controlling density affect juvenile production and cause production to remain below carrying capacity. In spite of a clear increase in pH and a reduction in the concentration of labile aluminium after liming, the conditions still do not seem to be optimal for juvenile salmonids. We suggest that a complexity of different factors impose limitations on fish production in the river: inadequate egg deposition, environmental factors such as water temperature and flow, osmoregulatory failure in mixing zones between limed and acidic water and gill damage through deposition of aluminium and iron. However, there are several indications of a reduction in toxic effects after the pH was raised to 6.5 during spring snow melt.     

Flow and pH Modelling to Study the Effects of Liming in Regulated, Acid Salmon Rivers

In the regulated river Ekso, Western Norway, liming of the headwater has been introduced as a mitigating action to improve the water quality for Atlantic salmon (Salmo salar L.). Supply of lime from a dosing plant situated 5 km above the salmon producing part of the river, aims to raise pH from 5,0 to 6,5 during the smolt period for Atlantic salmon, and to 6,2 for the rest of the year. Hydrological modelling based on the relationship between CaCO₃ and pH is applied for the evaluation of the liming strategy, based on monitoring data from the spring 2000. The water quality demand was satisfied 80% of the time in the upper part of the salmon area, and 40% of the time in the lower part, influenced by power plant discharge. Flood forecasting and overdosing of lime ahead of floods will reduce the effects of acidified and unlimed tributaries. An additional lime doser is recommended to supply the power plant discharge.     

An acidic snowmelt event in a new jersey stream: Evidence of effects on an indigenous trout population

Van Campens Brook is a circumneutral stream in northwestern New Jersey that supports reproducing populations of brook trout (Salvelinus fontinalis), brown trout (Salmo trutta) and rainbow trout (Oncorhynchus mykiss). A short-term pH depression occurred in the stream following a snowmelt in the spring of 1984. A stream pH of 4.5 was recorded shortly after the onset of the snowmelt and the pH remained depressed (5.2) a week later. Stream pH did not fall below 6.2 following other rain and snowmelt events monitored during 1985–1987. An electrofishing survey conducted in 1985 revealed a near-total absence of 1984 year-class rainbow trout, spring spawners that are highly sensitive to acidity. Brook and brown trout spawning appeared to be unaffected. Rainbow trout reproductive success was good during 1985–87.     

Freshwater liming

Operational liming of surface waters is part of Sweden and Norway's strategy to counteract freshwater acidification caused by air pollutants. Smaller scale liming efforts are performed as research or experimental programs in other countries. Yearly, approx. 300,000 tons of fine-grained limestone (CaCO₃) is spread in lakes and streams and on wetlands to raise the pH in surface water at a cost of approximately 40–50 million $US. The chemical target is set by the biological goals and objectives. A total of over 11,000 lakes and streams are treated on a continuing basis. Dose calculations consider pH, inorganic monomeric Al, dissolved organic matter and the necessary buffering. Lake liming, limedosers at streams and terrestrial liming are used. A mix of different liming techniques is often preferred to get an optimal result. The vast majority of changes are desirable and expected Undesirable effects may appear and damaged wetlands are probably the most serious ones. Cost-benefit analysis show that liming may be profitable for the society. Recovery of the systems can take up to 10–20 years. Liming will in the long run restore the ecosystems but will not make them identical to what may be the original ones. In some cases, complementary measures, e.g. facilitation of recolonization, are necessary to enhance recovery. Reduced emissions of acidifying pollutants according to signed protocols will decrease the need for liming, but still liming is needed for several decades in large regions to preserve biodiversity.     

Identifying sources of snowmelt acidification with a watershed mixing model

We used ionic tracers to estimate the volume of old (soil and ground) water interacting with snowmelt in eleven Adirondack, NY watersheds. The contribution of old water varied from 66 to 90%, with no general relationship between old water % and soil depth to till. This approach also discriminated between watershed retention and release of particular ions to lake outlet water during snowmelt. Most watersheds released NO₃ ^? during snowmelt, in addition to the snowpack NO₃ ^?. Nitrification of snowpack NH₄ ⁺ explained part of the additional NO₃ ^? in lake out outlet water, but some NO₃ ^? was likely mineralized nitrogen from soil organic matter. All watersheds retained NH₄ ⁺ as well. Nitrogen release was greatest in the acidic watersheds in the southwestern Adirondacks, a region thought to be impacted by anthropogenic deposition. During snowmelt, Ca²⁺ and Mg²⁺ ions (presumably from soil exchange sites) were also released from most watersheds. In watersheds with acidic (minimum pH<4.6) lake outlet water, Al was also released during snowmelt. Thus, lake outlet water acidification during snowmelt was both buffered by cation release, and intensified by NO₃ ^? release. If the soil exchangeable cation pools were not replenished prior to snowmelt, or NO₃ ^? mobilization were increased, acidification during snowmelt would intensify.     

Mercury in fish muscle in acidified and limed lakes

The concentration of Hg in muscle was monitored during 10 to 12 years in different size and age groups of pike (Esox lucius) and perch (Perca fluviatilis). The study was performed in one reference and five lime treated lakes. Before liming, the highest levels of Hg in fish were measured in a lake with an annual mean pH just above 5.0. Lower levels were obtained both in lakes which were more acidified and in those which were less acidified. After the start of liming, the fastest and largest changes were obtained in the lakes which were moderately acid before liming (mean pH 5.4–5.8). In small perch, the Hg-concentration was markedly reduced in two years and showed an 80 % decrease in ten years. A slower response was registered in the lakes originally having about 0.5 units lower pH. In the most acidified lake (pH 4.9) the concentrations even increased the first years after liming, but decreased again later on. The possible mechanisms involved are discussed.     

Characterization of Five Chromium-Removing Bacteria Isolated from Chromium-Contaminated Soil

In the mid-20th century, similar to many lakes in the vicinity of Sudbury, Canada, Middle Lake was severely acidified due to nearby smelting operations. However, this lake is of particular interest because it was limed in 1973, and later fertilized as part of a restoration effort. Here, we use paleolimnological methods to track cladoceran assemblage responses to acidification, liming, and subsequent recovery in a ～250-year lake sediment record. Cladoceran assemblage changes, notably increases in Chydorus brevilabris, coincided with the late 1800s establishment of open-pit ore roasting in the region. As acidification progressed, the Daphnia pulex complex was replaced by the Daphnia longispina complex. At the height of acidification, and with similar timing to the liming, C. brevilabris increased abruptly in relative abundance in the sediment record, followed by a rapid decline. Invertebrate predation was investigated using Bosmina mucro length; however, no significant trends were evident. Our results suggest that complete biological recovery has not occurred. Specifically, species richness (rarefied) is ～64 % lower after the onset of acidification, and many rare species present prior to the onset of acidification have not yet returned to pre-impact levels despite dispersal events of these rare taxa being observed during contemporary zooplankton monitoring. Factors impeding the complete biological recovery of the cladocerans in Middle Lake may include biotic resistance, ongoing metal contamination, and a warming climate.     

Effects of liming on nutrient limitation of epilithic algae in an acid lake

The processes of lake acidification and lake restoration frequently involve major changes in DIC and DIN, both of which may potentially limit algal growth. We evaluate nutrient limitation of benthic algal biomass and species abundances during summers 1987 and 1989, before and after the liming of Lake Earnest (NE Pennsylvania) in November 1988. Limestone addition caused immediate increases in pH from 4.7 to 7.2. Alkalinity was ?34 μeq L^?1 in summer 1987, but rose to 620 μeq L^?1 in summer 1989, whereas DIN declined from 10.7 μmol L^?1 to 1.1 μmol L^?1 The algae were sampled after 45 to 46 d from clay flower pot substrates diffusing combinations of N, P and C. Algal biomass was strongly C-limited in 1987, but NP-limited in 1989. Mougeotia sp., which comprised >99% of total algal biovolume prior to liming, declined to < 1% of the community on control substrates, while Oedogonium sp. increased to 43% of total biovolume in 1989. The stimulation of chlorophyll-a accrual with C-enrichment during 1987 was consistent with the later increase in chlorophyll-a on control substrates following liming. Species enhanced by the diffused nutrients, however, generally differed from those which dominated the natural community.     

Effects of acidification and liming on carbon and nitrogen mineralization and soil organisms in mor humus

The aim was to determine if changes in C and N mineralization after acidification and liming could be explained by changes in the soil organism biomass. Intact soil cores from F/H layers in a Norway spruce (C:N=31) and a Scots pine (C:N=44) stand in central Sweden were treated in the laboratory for 55 days with deionized water (control), weak H₂SO₄ (successively applied as 72 mm of acid rain of pH 3.1), strong H₂SO₄ (applied as a single high dose of pH 1), and lime CaCO₃. Strong acidification reduced C mineralization and increased net N mineralization in both soils. Weak acidification resulted in similar but less pronounced effects. Liming initially stimulated C mineralization rate, but the rates declined, indicating that an easily available C source was successively used up by the microorganisms. Liming also increased net N mineralization in the C:N=31 humus, but not significantly in the C:N--44 humus. Strong acidification generally affected the amounts of FDA-active fungal hyphae, nematodes and enchytraeids more than the other treatments did. The increases in net N mineralization after acidification and liming could only partly be explained by the decreases in biomass N in soil organisms. Mineralization of biomass N from killed soil organisms could at the most explain up to about 30% of the increase in net N mineralization after strong acidification. Most of the effects on N mineralization seemed to depend on the fact that acidification reduced and liming increased the availability of C and N to the microorganisms. Furthermore, acidification seemed to reduce the incorporation of N from dead organisms into the soil organic matter and, thereby, make the N compounds more readily available to microbial decomposition and mineralization.     

Internal Distribution of Acid Materials within Snow Crystals

We found that river water is acidified not only in the first stage but also in the later stage of the snowmelt season in Japan, which differs from the so called acid shock occurring in the first stage of the snowmelt in the northern Europe. The acid shocks depend on the regional characteristics of the melt-refreeze processes forming the internal distribution of acid materials within snow crystals under the warm metamorphism. In a warm climatic region like the central Japan, there are possibilities to have the complicated distribution structure of acid materials within granular-snow crystals due to the repeated melt-refreeze processes even in midwinter. Consequently, the pH value of meltwater does not always increase as the snowmelt proceeds. Then, we showed the possibility by using the X-ray computed tomography that the domains with the acid materials exist in the inner parts of snow crystals. So, the acidification of the river water may occur even in the later stage of the snowmelt.     

Options for liming rivers to ameliorate acidity — A UK perspective

The options for large scale liming of river systems are reviewed with particular reference to the River Tywi in Wales, a major salmonid river with a reservoir in the upper catchment. For hydrological source area liming the cost of lime transport is high due to remoteness and inaccessibility. The concern of potential damage to wetland mires of conservation value is considered. Re-treatment intervals are expected to be 5–10 years, but results from sub-catchment experiments indicate that treatment longevity and the pattern of ecological recovery are uncertain. Flow-related dosing systems for rivers avoid impacts on wetlands but would treat only the main river. Reliability may be problematical though the reservoir provides a margin of safety against system failure. Reservoirs can be limed to treat the main river outflow. This avoids the problems of power supply. For the River Tywi, the financial costs of both direct treatment methods are lower than for catchment liming and comparable with estimates of the economic benefit to the fishery. The system currently operated on the Tywi is reservoir treatment. Results from the first 3 years demonstrate colonization of the main river by acid intolerant invertebrate taxa and clear increases in populations of juvenile Atlantic salmon, Salmo salar L. and sea/brown trout. Salmo trutta L.     

Effects of liming,fertilization and acidification on pH,soil moisture,and ATP content of soil from a spruce forest in Southern Germany

Short-term and medíum-term effects of liming (CaCO₃), fertilization [5Ca(NO)₃)₂·NH₄NO₃], and acidification on soil bioactivity were measured in a spruce stand in Southern Germany. The experiment was set up in a randomized block design. Acid precipitation lowered the pH, liming increased the pH, while fertilization caused only small alterations in pH values. Significant differences in soil moisture occurred only in the mineral horizons. The soil ATP content of the humus layers decreased in all plots (control included) up to day 100. On all sampling dates, a pronounced decrease in ATP content followed the acidification. Minor decreases in ATP were observed after fertilization, while liming produced no defined effects. Similar trends, but less pronounced, were observed in the mineral horizons. Only a few significant correlations were found between pH values and ATP or between moisture and ATP within a treatment and sampling date. Present address: Institut für Biologie II (Zoologie), RWTH Aachen, Kopernikusstrasse 16, D-52056 Aachen, Germany     

Effects of liming on survival and reproduction of two potentially invasive earthworm species in a northern forest Podzol

During the last several decades, colonization of soil by exotic earthworms and their effects on soil properties and biodiversity have been reported in forests of North America. In some northern hardwood stands, acid soils or harsh climate may have prevented earthworm colonization. However, climatic change and the increasing use of liming to restore the vigor of declining sugar maple (Acer saccharum Marsh.) stands, situated on base-poor soils in USA and Canada, could make many of these sites more suitable for earthworm colonization. We tested survival and reproduction of two exotic earthworm species (Lumbricus terrestris and Amynthas hawayanus) in unlimed and limed soils at the northern limit of the northern hardwood forest distribution in Canada. Improving soil parameters of base-poor, acidic soils by liming positively influenced activity, survivability and reproductive output of L. terrestris in this northern hardwood forest. In contrast, the high mortality and low vigor of L. terrestris observed in the unlimed plots show that soils in this area with a pH of 4.3 are not favorable to this species. Our results suggest that A. hawayanus was very active prior to winter at both soil pHs, but was not able to complete its life cycle during one year at this latitude. Both earthworm species significantly reduced organic C and total N, and increased the C/N ratio of the forest floor. Given that forest liming activities are increasing in proximity to human activities, there is high probability that some earthworm species, such as L. terrestris, will invade limed northern hardwood forests in the next decades, with possible consequences for soil organic matter turnover, nutrient cycling and forest biodiversity and dynamics.     

Improvements in Water Quality and Aquatic Ecosystems Due to Reduction in Sulphur Deposition in Norway

A program for monitoring acidification in Norway was developed in 1980. The program included water chemistry, fish and invertebrates. The monitoring have been performed in areas with strong as well as low acidification. Information about the status of the fauna is regularly obtained from sites covering both affected and unaffected areas. Tolerance limits for different species have been established and used for the evaluation of changes in acidification since the early eighties. A significant improvement in water chemistry was recorded in accordance with a 45 to 70 % reduction in sulphur deposition. The invertebrate monitoring shows recovery of sensitive species, and watersheds with earlier low damage have probably returned to an unaffected status. In the most acidified areas also significant improvements are noted, especially during the last ten years. However, acidic episodes connected with sea-salt deposition and spring snowmelt are found to confound the recovery process in these naturally low buffered systems.     

Side Effects of Liming - A Study of Four Dimictic Lakes in Southern Norway

Side effects related to liming have been studied in four dimictic lakes (553–642 m?a.s.l.; 59°57′N) in Finnemarka, a forested area in Southern Norway with poor catchment buffer capacity. Data series from lake profiles have been sampled two decades apart; 10 years prior to liming and after 10 years of liming. Water samples were collected during spring after ice breakup and during summer after the development of thermal stratification. Before liming, there were very low concentrations of bicarbonate (HCO ₃ ^– ; or alkalinity) in the lakes. After 10 years of liming, up to 90% of the ions in hypolimnion originate from lime products. Hence, liming strengthened the chemical stratification and increased the vertical stability. Differences in chemocline developments between lakes were explained by differences in physical properties, i.e. their depth/surface area ratio. The chemocline developments lead to increased concentrations of organic matter in the hypolimnion with a subsequent reduction in oxygen concentrations. Lime additions during late spring, as an alternative to early autumn, lead to pronounced anoxic conditions in the hypolimnion.     

Liming restores the benthic invertebrate community to “pristine” state

After liming of twelve acidified rivulets in central Sweden, the fauna increased its mean similarity to the fauna in unlimed non-acidified references. All species which were found after liming were also found in other waters north and south of the limed area. The species composition after liming should thus be considered as typical of the limed geographical area. Before liming, the fauna was characterized by the acid tolerant mayfly Leptophlebia spp. After liming the fauna was characterized by the acid sensitive mayfly genus Baetis, an important food organism for young brown trout. The restoration of the water quality by liming resulted in an apparently “pristine” benthic invertebrate community, enhancing the conditions for salmonid fish.     

Effects of liming and acid surface water on the mayfly Leptophlebia vespertina in Lake Hovvatn

The acidified Lake Hovvatn have been limed in 1981, 1987, 1989 and 1991. After the first liming the lake reacidified close to the prelimed condition. The reliming, which started in 1987, was planned to maintain the pH at a relatively high level for the lake. A detailed monitoring of pH and temperature was performed at depth 0.5, 1, 1,5 and 5 m since spring 1993. Quantitative samples of benthic invertebrates were taken in spring and fall in 1977 and regularly at the same seasons from 1981 at depth 0.5, 2, 5 and 10 m. A reference lake, Lille Hovvatn have been sampled with the same procedure since 1988. The acid tolerant mayfly Leptophlebia vespertina responded quickly to the first liming with a 20 times increase in density after a few months. However, the densities rapidly decreased during the first years of reacidification. The lime treatments in 1987 and 1989, resulted in a second peak in density in 1990. After this, the densities have been reduced in spite of generally good water quality in Hovvatn. During fall the density increase was significant at 0.5 m depth in 1990, at 2 m depth in 1989, 1990 and 1992 and at 5 m depth in 1988 to 1990. No significant increase was observed in the limed localities during spring. It is concluded that acid surface water, prior to ice break, affect the food resources to L. vespenina and reduce the population at all depths during spring and in the littoral zone in fall.     

Tillage and fertilizing effects on sandy soils. Review and selected results of long‐term experiments at Humboldt‐University Berlin

The Humboldt‐University of Berlin conducts several long‐term field trials designed to assess the effects of tillage methods, crop rotations, organic fertilization, mineral nitrogen, phosphorus, and potassium fertilizers, liming, irrigation, and weather conditions. On silty sand soils shallow ploughing resulted in a distinct accumulation of soil organic matter and phosphorus in the tilled soil layer while potassium and pH values were unaffected. On average shallow ploughing increased yields, with a tendency for higher yields in spring crops and lower yields in winter cereals. Different amounts of organic and mineral fertilizers applied over 30 years resulted in a great differentiation in soil organic matter content. In the following 32 years this variation stayed more or less unchanged, but with an overall reduction in the carbon content. In variants in which phosphate and potassic fertilizers were omitted, 16 kg ha^—1 P and 15 kg ha^—1 K per year were still being mobilized in the soil after 60 years. In treatments with mineral fertilization, the phosphorus is nearly balanced whilst only 60 % of the potassium is withdrawn from the soil. Additional organic fertilizers, given as farm yard manure, led to a nutrient surplus of 19 kg ha^—1 a^—1 P and 99 kg ha^—1 a^—1 K. Omitted liming caused an acidification of the soil to such an extent that crop production became impossible.     

Effects of artificial acidification and liming on the activity of digestive enzymes in Cognettia sphagnetorum (Vejdovsky´, 1878) (Annelida, Enchytraeidae)

The effects of simulated acid rain and acidification, combined with liming, on amylolytic, laminarinolytic and xylanolytic activity in whole body homogenates of enchytraeids Cognettia sphagnetorum were studied under field conditions. Simulated acid rain (pH 2.5) and simulated acid rain with subsequent liming (CaCO₃) were applied to experimental plots in a mixed forest soil. The pH of the soil was lowered by acid treatment (4.3), while the pH increased after liming (6.3) in comparison with the control (4.5). Acidification of soil caused a decrease in enchytraeid body mass and amylolytic activity. In acidified plots after liming, amylolytic activity and laminarinolytic activity increased, while live body mass decreased. The enzymatic activity of enchytraeids depended on season and also indirectly on individual mean mass. Received: 12 February 1996     

Temporal chemical variability in acid sensitive high elevation lakes

Chemical indicators suggest that slight, but discernable acidification occurs during smowmelt in some highly sensitive Cascade Mountain Lakes (mean alkalinity 20 ueq L^?1). Although some SO₄ in the lakes (mean 13 μeq L^?1 ) comes from local geologic sources, several considerations suggest that some also comes from atmospheric deposition and anthropogenic sources. If sampling is stratified, the relatively low lake-to-lake and year-to-year variability in chemical constituents demonstrates that these highly sensitive lakes represent excellent indicators of acidification. The contention that precipitation pH >4.6 is needed for protection of sensitive lakes is supported. However, the slight but temporary acidification effect currently detectable during snowmelt, suggests that for adequate protection of these highly sensitive lakes, precipitation pH should be >4.7 to 4.8.