The consequences of liming a highly acidified catchment in central Scotland

Research during the mid 1980s identified acidified, forested catchments in central Scotland whose hydrochemistry was not capable of supporting native fish populations. Calcium concentrations were around 20 μeq l^?1, less than the suggested critical value of 50 μeq l^?1, with hydrogen concentrations around 70 μeq l^?1, greater than the critical value of about 30 μeq l^?1. Limestone was applied by aerial application to the source areas of selected streams in 1990 with around 5% (15 ha) of the total catchment area of 270 ha treated at 10 tonnes ha^?1. Stream monitoring, carried out over the period 1989–1995, showed an immediate response to liming followed by a progressive decline. Calcium values were elevated to >150 μeq l^?1 and hydrogen concentrations reduced to 20 μeq l^?1, reverting in time towards pre-liming values. Although salmonid survival was improved during low flow conditions in summer, only a few fry survived to the autumn as acid episodes increased, and these were subsequently lost from the system during the winter period. Budget calculations indicated losses of around 30% of the applied calcium during the first four years. Studies on the vegetation and soils revealed a greater than expected penetration of calcium to depth (10–20 cm) in the soil profile. Results suggest that source area liming at this rate has had minimal effects on the vegetation and by increasing the proportion of the catchment limed to 15% could have a much greater success in reducing the frequency of biologically damaging episodes.     

Operational liming of surface waters in Sweden

From 1977 to 1982, liming of acidified waters was performed for a trial period using governmental subsidies. Based on the experience gained, an operational liming program was started in 1982 by the National Environmental Protection Board of Sweden. All waters with pH of less than 6 and/or an alkalinity of less than 0.05 meq L^?1 have been eligible for subsidies. Individual water owners as well as organizations and federal agencies may apply for subsidies. Normally 85% of the costs are covered by government grants. Each county administration draws up a 5 yr liming plan and applies yearly for subsidies on a county basis. Since 1977, SEK (Swedish Kroner) 373 million have been spent on liming operations and SEK 33 million on administration and follow-up studies. A yearly budget of about SEK 110 to 130 million has been proposed for 1988 to 1991. The liming agent used has been powdered CaCO₃ with a particle size normally of 0 to 0.2 mm. At present, about 4,000 lakes have been treated. The results of the treatments are normally evaluated by analyzing water samples taken twice a year. These are analyzed for pH, alkalinity, conductivity, color, Ca and Mg. In addition, biological surveys are carried out in selected lakes and streams.     

Responses of phyto- and zooplankton to liming in a small acidified humic lake

Liming resulted in an immediate and transitory decrease of plankton biomass and phytoplankton primary production in the limed part of an acidified humic lake. In the longer term liming has changed species composition and dominance of phyto- and zooplankton. Due to increased transparency and improved oxygen conditions plankton biomass peaked deeper in the water column after liming. During the three years post-liming period phyto- and zooplankton communities have changed less than reported in several other studies. This is largely because liming was carried out well before the collapse of perch population, which has controlled zooplankton both in the pre- and post-treatment period.     

Effects of liming on water chemistry in shallow acidified pools in the netherlands: Enclosure experiments

Enclosure experiments have been carried out in two shallow acidified moorland pools in order to study the effects of liming on the water chemistry. The addition of buffering substances (sodium bicarbonate and calcium chloride or powdered marlstone) to enclosures in the Ven bij Schaijk, an oligotrophic acidified moorland pool with a mineral sediment, did not demonstrate internal eutrophication. After addition of NaHCO₃ and CaCl₂ the pH and alkalinity increased and all macronutrient concentrations, such as that of phosphate, remained low. After treatment with powdered marlstone, there was only a slight increase of pH and alkalinity, due to the slow weathering of marlstone. The alkalinity in this moorland pool remained more stable on a mineral sandy substrate than on an organic substrate, probably as a result of a higher acid release from the organic sediment. In enclosures in the Padvindersven, an eutrophied, acidified moorland pool with an organic gyttja-type of sediment, internal eutrophication took place after adding buffering substances. The phosphate concentration and turbidity of the water increased significantly after treatments with NaHCO₃ and CaCl₂ as well as with powdered marlstone. The acid release was even higher than from the organic sediment from the Ven bij Schaijk. It was concluded from these experiments that in case of the Ven bij Schaijk, liming with marlstone would be a sufficient way to restore the original water chemistry. In the Padvindersven, however, recovery of the non acidified poorly buffered conditions is only possible by liming in combination with the removal of the organic top layer of the sediment.     

Can forest-soil liming mitigate acidification of surface waters in Sweden?

Acidification of surface waters and forest soils is severe in large parts of southern Sweden. The shallow groundwaters are also affected. Large scale liming of surface waters and streams is in operation, often combined with wetland liming to limit the effects of acid episodes, e.g. at snow melt. Acid episodes are perhaps the most severe problem in limed surface waters and in many as yet well buffered waters, because of temperature-layered acid inflow, often superficial. As a result of some investigations, a large scale forest liming programme covering 6.500–10.000 km² was recently suggested. The main objectives of this forest liming programme are to retard cation depletion and to prevent nutrient imbalance and forest decline in acidified areas. This paper deals with the effects of forest soil liming on streams and surface waters. The response of water chemistry is very dependent on hydrological and soil properties. Although pH itself may be little affected by liming, the acidity (or negative ANC) decreases, inorganic Al-species decrease and the Al/BC-ratio increases in the runoff water. Especially interesting is that this is also true during acid episodes. This means that toxicity for acid sensitive biota decreases. These results indicate that large scale liming may have beneficial effects on surface water chemistry. Furthermore, as surface waters are expected to respond to smaller decreases in acid deposition than do forests soils, forest soil liming may allow less frequent liming of lakes. Consequently, forest soil liming in combination with the anticipated emission reductions may have very beneficial results on surface waters in certain areas of Sweden.     

Influence of wetland liming on water chemistry of acidified mountain streams in Lofsdalen,Central Sweden

Acidic precipitation has caused damage to the populations of fish and invertebrates in numerous streams in the southern part of the Swedish mountain range. In the middle of the 70's, the pH of precipitation decreased and has since then frequently been lower than 4.5. Many of the streamwaters were well buffered during most time of the year, but during periods with high discharge, the buffering capacity was completely exhausted, pH frequently decreased to around 4.5 and very high levels of Fe, Mn and Al occurred. In general, base cations (BC) and organic anions decreased during periods of high flow, while SO₄ increased or was relatively independent of flow. On an average, the ratio SO₄/BC was negatively correlated to pH, while organic anions/BC showed a weaker correlation to pH. In order to investigate if wetland liming could be used as a remedial measure in such areas, lime treatments were started in 1983 in the Lofsdalen area, province of Härjedalen. The liming stabilized the alkalinity and pH of the streams at circum-neutral levels, and reduced the leaching of Fe, Mn, and Al. The average levels of these elements decreased and the seasonal fluctuation decreased considerably.     

Changes of planktivore fauna and development of zooplankton after liming of the acidified Lake Gårdsjön

The quantitative dynamics of the zooplankton community was studied during a period of 13 years in the manipulated Lake Gårdsjön and an acidified reference lake. Lake Gårdsjön was acid during the first 3 years, limed and fishless the following 4 years and stocked with brown trout for a period of 6 years. During the final 2 years rainbow trout was added. Changes in water chemistry and phytoplankton standing stock are associated with the manipulations. Liming had a positive effect on the overall species richness and diversity among rotifers and cladocerans. Changes in the zooplankton community during the different phases of the lake restoration are discussed in relation to the development of the planktivorous fauna of the lake, phantom midge larvae, aquatic hemipterans and fish. It can be concluded that liming creates a potential for the restoration of the zooplankton diversity, but the actual structure of the zooplankton community in limed lakes is strongly influenced by predatory and competitive interactions.     

Factors controlling the removal of sulfate and acidity from the waters of an acidified lake

Although Lake Anna, an impoundment in Central Virginia, receives acid mine drainage (AMD) from Contrary Creek, the effects of the AMD pollution on the lake are less severe than expected. Previous work at Lake Anna has shown that bacterial sulfate reduction in the lake sediments plays an important role in the recovery of the lake from the AMD inputs. Sulfate removal rates were measured in sediment microcosms under a variety of experimental conditions to determine the factors controlling the rate of sulfate and acidity removal from the lake water. Sulfate removal rates were not significantly different over the short term (3 weeks) in summer sediment microcosms incubated at 6 vs 26 °C. Winter sediment microcosms showed no significant sulfate removal during the 18 day experiment when incubated at either 6 or 28 °C. Thus there is a strong seasonal temperature effect in Lake Anna sediments but no significant short term effect. Simulated AMD, with and without Fe, was added to sediment microcosms collected from an unpolluted part of the lake. The microcosms with Fe had significantly higher rates of sulfate removal indicating that Fe plays an important role in transporting sulfate to the sediment and/or in preventing oxidation of the reduced sulfide. After 27 days, from 54 to 96% of the added sulfate in the simulated AMD was recovered as FeS or S⁰ in the top 4 cm of sediment. In a separate experiment, ³⁵S-SO _inf4 ^sup2? was found to attach to precipitating Fe oxyhydroxides (1.5 to 4.7 mol SO _inf4 ^sup2? mol^?1 Fe precipitate) upon mixing Contrary Creek (AMD) and Lake Anna waters. Results of this study suggest that sulfate removal may be more rapid in metal rich AMD systems thans in metal poor systems characteristic of those which receive acidic deposition.     

The use of simulation models as resource management tools for restoring acidified waters

Several computer simulation models are available to resource managers for predicting the response of watersheds and adjacent surface waters to acidification and subsequent neutralization. Some of these models are useful in designing and implementing liming restoration programs. The simpler models emphasize in-lake biochemical processes involved in the dissolution of CaCO₃ and dilution hydrology; these are best suited for simulating straightforward direct applications to surface waters that have minimal hydrologic interaction with the terrestrial watershed. The more sophisticated models integrate various complex biogeochemical processes in land catchments in addition to in-lake and in-stream chemistry. These are best suited for rigorous, process-oriented research applications, for systems which have significant hydrologic interaction with the terrestrial catchment, and for simulating catchment liming applications. The approach and results from a recently published liming simulation study employing the modified Integrated Lake-Watershed Acidification (ILWAS) model are used to illustrate the methodology for using simulation models to complement field research and operational liming programs. Also, modifications to existing models are identified for increasing their suitability for more robust management applications under a wider variety of conditions in different regions.     

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.     

The effects of forest liming on fertilization on fine-root growth

Results are reported from the investigations of fine-root development in Norway spruce and Scots pine stands in South and Central Sweden, subjected to different liming and fertilization regimes. The growth responses of the fine roots to varying mineral nutrient regimes seem to be dependent on the tree species, the age of the tree population and soil conditions. Nitrogen fertilization in some of the investigated stands had negative effects on the development of fine roots, resulting in a reduction in the amount of fine roots to about 50% of that in the control. However, negative effects were not consistent in all stands, positive growth responses were also obtained. In these stands, the amount of fine roots was increased by 2 to 3 times. Liming in combination with fertilization resulted in a strong decrease in the amount of fine roots to about 30% of that in the control in some of the investigated stands. Liming in high doses is expected to produce a persistent increase in pH (H₂O and base saturation in the soil. However, results from the present study suggest that liming may have a negative effect on the development of tree fine roots, particularly in areas with a high N deposition. The application of crushed dolomite had less negative effects on fine root development than crushed calcitric lime and different types of residue products, such as wood and peat ashes.     

The effects of forest liming on fertilization on fine-root growth

Results are reported from the investigations of fine-root development in Norway spruce and Scots pine stands in South and Central Sweden, subjected to different liming and fertilization regimes. The growth responses of the fine roots to varying mineral nutrient regimes seem to be dependent on the tree species, the age of the tree population and soil conditions. Nitrogen fertilization in some of the investigated stands had negative effects on the development of fine roots, resulting in a reduction in the amount of fine roots to about 50% of that in the control. However, negative effects were not consistent in all stands, positive growth responses were also obtained. In these stands, the amount of fine roots was increased by 2 to 3 times. Liming in combination with fertilization resulted in a strong decrease in the amount of fine roots to about 30% of that in the control in some of the investigated stands. Liming in high doses is expected to produce a persistent increase in pH (H₂O) and base saturation in the soil. However, results from the present study suggest that liming may have a negative effect on the development of tree fine roots, particularly in areas with a high N deposition. The application of crushed dolomite had less negative effects on fine root development than crushed calcitric lime and different types of residue products, such as wood and peat ashes.     

Mobility of sulphate in experimentally acidified soils from Galicia (NW Spain)

Retention of S0₄ ^2? was investigated in Galician soils throughout an intense regime of acidification. Experiments consisted of the addition of an H2SO4 solution (pH 2.7) to columns of 6 soils of contrasting properties over 1, 2, or 5 months. Leachates were obtained continuously throughout the experiment for analysis, and analysis made of the solid fractions after 1, 2 or 5 months. The greatest capacities for retention of S0₄ ^2? were found in soil developed from serpentine and micaschist; the lowest in soils from granite, slate and sandy sediments. The surface horizons, especially those rich in organic matter, displayed low retention of 5042-. The amount of S0₄ ^2? adsorbed throughout the experiment depended on the content of crystalline forms of Fe and with the Fe and Al extracted with dithionite-citrate.The low retention of S0₄ ^2? in the organic horizons and the slightly negative relation with the organic matter suggest an inhibitory effect of the organic matter on the S0₄ ^2? retention process. Results of the study show, that under conditions of moderate acidity, SO₄ ^2? retention occurs in the form of adsorption; in strongly acidic conditions, the precipitation of aluminium-sulphate minerals may provide an additional retention mechanism.     

Vertical distribution of brown trout (Salmo Trutta) and perch (Perca Fluviatilis) in an acidified lake

Brown trout (Salmo trutta) and perch (Perca fluviatilis) had different vertical distributions throughout the year in the acidified lake Gjerstadvann. During summer, the brown trout lived in the 0 to 16 m depth interval, whereas the perch lived in the 0 to 8 m interval. In Gjerstadvann, the thermocline lies at 8 to 10 m depth. The epilimnion pH was usually > 5.6, and the thermocline pH was about 5.2. Brown trout and perch in Gjerstadvann, thus experienced different chemical environment during summer-stratification. Two rivers, one of them acidified, the other circum-neutral, were the most important spawning areas for the Gjerstadvann brown trout. Brown trout parr in the acidified river migrated to the lake and matured at younger ages than the brown trout spawning in the non-acidic river. The brown trout stocks were juvenilized because of low survival rate of adult fish (S = 0.15 to 0.19). The short life span was probably dus to low pH and elevated Al. The perch in Gjerstadvann showed fluctuating year class strength but the survival rate of adult perch (S = 0.57) did not seem to be affected by acidification during this investigation. This may due to its vertical distribution during summer.     

Population dynamics of brook trout (Salvelinus fontinalis) during maintenance liming of an acidic lake

Maintenance liming of an acidic lake in the Adirondack Mountains of New York state (Woods Lake) was conducted three times over a 5 yr period in an attempt to establish a self maintaining brook trout population. Various strains and age classes of marked brook trout were stocked annually and the population was inventoried semi annually to evaluate survival, growth, and reproductive success. The Woods Lake brook trout population was dominated by young, stocked fish throughout the maintenance liming period of 1985-89. Based on spring emergent fry trap catches and fall trap net catches of unmarked fish, only one naturally produced year class (1986) was successfully recruited to the Woods Lake brook trout population. Low annual survival rates (G 20%) of juvenile trout were observed throughout the study period. Although initial growth rates and condition of young trout were satisfactory, increased intraspecific competition for food resulted in declining growth rates and condition of older age classes. Fall standing crops of brook trout remained at relatively low levels of 6 to 10 kg ha^?1 and both production per unit biomass and growth efficiency decreased over the 5-yr. Repeated whole lake liming and limited spawning habitat improvement were not sufficient to sustain brook trout natural reproduction in Woods Lake. Low productivity, marginal spawning habitat quality, and low survival rates of stocked trout in Woods Lake resulted in the failure to establish a self maintaining, productive brook trout population in Woods Lake.     

Influence of liming on the epigeic spider (Araneae) community of the Krušné hory Mts. (Czech Republic)

We studied the influence of liming with the dolomitic limestone on the epigeic spider community in the birch stand of the Krušné hory Mts. in the Czech Republic. The treatment was carried out with the purpose of reducing the negative effect of anthropogenic air pollution and consequently to increase the ecological stability of the wood stand. Lime treatment in different amounts (6, 3, 1.5 and 0 t ha⁻¹) was applied in August 2003 and for the following three years the spider community was investigated. We compared occurrences of spiders on studied plots with different lime treatment and tested the influence of the environmental factors, altogether with liming, on the spider community. The most significant factor appeared to be the character of habitat and both, hierarchical cluster analysis and canonical correspondence analysis, did not confirm any significant feedback of liming to the spider community in birch stand of the Krušné hory Mts.     

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     

The sulphur-mercury(II) system in natural waters

Sulphur is an essential element for aquatic biosystems, the life processes of which lead to the formation of low molecular weight S compounds in the water. The results of our calculations indicate a pronounced tendency for Hg(II) to form HgS (or HgOHSH) and Hg(SR)₂ complexes in the presence of H₂S and thiols. Likewise, McHg will form CH₃HgSH and CH₃HgSR complexes, but in this case the chloride complex will dominate at low concentrations of H₂S and thiols. In acidic low salinity water, CH₃HgCl is the dominant McHg species at the lowest concentration of sulphide/thiols (0.1 nM), whereas a hundredfold increase of the sulphide/thiol concentration, or an increase of the pH to neutral or slightly alkaline conditions, will result in a total dominance for CH₃HgSH and CH₃HgSR.     

Responses of blacknose dace (Rhinichthys atratulus) and brook char (Salvelinus fontinatis) to acidified water in a laboratory stream

As part of the Shenandoah National Park: Fish in Sensitive Habitats (SNP: FISH) project, movements of blacknose dace (Rhinichthys atratulus) and brook char (Salvelinus fontinalis) were examined during exposure to artificial acidification in paired channels of a laboratory stream. The objective of this study was to determine the ability of the fish to avoid depressions in the ambient pH and recognize and use a neutral-pH microhabitat refuge during acute reductions. Fish preference for a particular channel was statistically predictable based on the delivery of food. We tested fish avoidance behavior by manipulating food and the delivery of a pulse of acidified water. Both blacknose dace and brook char avoided the acid pulse (ambient pH reduced from 7.2 to 5.1) by sheltering in the pH-neutral refuge. Extensive field sampling in refuge microhabitats before and during episodic acidification is needed to determine changes in the distributional patterns of these species associated with acid precipitation events.     

Fish kills of Atlantic salmon (Salmo salar) and brown trout (Salmo trutta) in an acidified river of SW Norway

This paper documents population responses of Atlantic salmon and brown trout to fish kills in River Vikedal, an acidified river in SW Norway. The angling statistics show that the adult population of Atlantic salmon in the river has decreased to low numbers during recent years, whereas catches of migrant brown trout have increased in the same period. A total of 659 dead salmon and trout were either collected or observed during spring snowmelt in the years 1982–1985. Parr suffered the highest mortality, and most large specimens. Only a few dead kelts were registered. In the springs of most unfavourable water quality and most severe episods of fish kills (1983 and 1984), salmon parr mortality were significantly higher than that of brown trout. Episodic death of parr in the spring is thought to be an important cause of the reduction in the adult stock of Atlantic salmon in the river during recent years.