Terrestrial liming as a tool to mitigate acidification of Woods Lake,NY

The Soil Liming Model (SLiM) has been used to simulate lake and stream water quality response to different strategies for the application of limestone to subcatchment soils in the Woods Lake, NY watershed. Simulations using doses of 3, 10, or 30 t ha^–1 forecast that a dose in excess of 10 t ha^–1 must be applied to discharge areas in order to sufficiently improve water quality in the lake. At 3 t ha^–1 inlet stream water quality could support fish populations. As expected, treatment effectiveness is strongly influenced by subcatchment hydrologic flow paths. Where shallow flow predominates, soil liming provides a more effective tool for lake water quality improvement. In subcatchments drained primarily by ground water, the effect of liming on water quality is less pronounced albeit of longer duration. Based upon the results of these model simulations, the authors compare results of conventional lake liming to simulated watershed treatment predictions.     

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.     

Gårdsjön Project: lake acidification,chemistry in catchment runoff,lake liming and microcatchment manipulations

The Gårdsjön Project is an ecosystem approach in studying acid deposition and its effects on terrestrial parts and lakes within a catchment. The study is an attempt to quantify the processes causing the acidification as well as an analyses of the chemical and biological conditions before liming of the lake and manipulations in microcatchments. This paper gives a brief overview of some studies already performed and recently started experiments within the project, such as lake liming, lime application on land, forest fertilization, clearcutting and applications of acid and neutral sulphate on land.     

Fertilization as a tool to mitigate forest decline associated with nutrient deficiencies

Needle investigations carried out in autumn/winter 1983/1984 in southwestern West-Germany were compared with samples taken from comparable stands/sites over two decades ago. Results from these comparisons show dramatic changes indicating acute nutrient deficiencies. Based on these findings, a comprehensive program of `diagnostic fertilization trials' was initiated. Based on needle and soil analyses, appropriate fertilizers were selected and applied. Results from these experiments show a substantial visible and chemical improvement over a single vegetative period. Overall, the `new type' of forest decline when associated with nutrient deficiencies can be alleviated through the careful selection and application of fertilizers. However, once a critical degree of damage is reached, no revitilization is possible.     

Diatoms as indicators of the rate of lake acidification

Autecological studies of diatoms as pH indicators have opened the way to estimating a lake's past pH on the basis of its diatom species composition and relative abundance. Estimating the rate of lake acidification from its sediment subfossil diatoms is possible when these subfossils can be identified and accurately enumerated in the surface sediments of 20 to 30 lakes. Once this is done the diatoms down the length of the sediment core of one or more of these lakes can be enumerated and the pH inferred at each depth. This technique holds considerable promise in assessing the temporal impact of acid precipitation for acid-sensitive lakes. When loga values were regressed against observed pH for 28 lakes located north of Lake Superior, a significant (P < 0.01) correlation (r = 0.89) resulted. Downcore diatom stratigraphy for one of these lakes indicated that its pH had dropped from 6.2 to 5.2 over the last 20 yr while a second lake had dropped from a pH of 7.1 to 5.2 over the last 30 yr.     

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.     

Biological indicators of lake acidification

Indicator taxa are identified, based on both synoptic surveys and whole lake acidification experiments, for lake acidification in the pH 6.0 to 5.0 range. Acidobiontic diatoms (e.g Asterionella ralfsii, Fragillaria acidobiontica, etc.), periphyton (Mougeotia and related species), macroinvertebrates (e.g. Hyalella azteca, Orconectes sp., etc.), leeches, and cyprinid fishes (e.g. Pimephales promelas, Notropis cornutus, etc.) are identified as target organisms during early phases of lake acidification.     

Sulfur constituents of sediments and their relationship to lake acidification

Sulfate is a major component of acid precipitation in the Northeastern United States. Transformations and fluxes of S may be important indices of the effect of acidification on limnetic systems. Sulfur constiuents and respiration rates were compared in sediments among Oneida, Deer and South Lakes in New York which exhibit a range of buffering capacity and pH from high to low, respectively. Total S in Deer and South was higher near their major inlets. Sulfide was highest in Oneida sediment, which had a lower redox potential (Eh). Ester sulfate was a major portion of the S in the three lakes. Oxygen consumption was highest in Oneida and lowest in South sediments. The low ester sulfate and an elevated C/N ratio of South sediment may indicate that acidification inhibits decomposition     

Liming to mitigate acidification in freshwater ecosystems: A review of the biological consequences

The use of lime to mitigate the biological effects of surface water acidification, has recently become a widespread practice. Following a background section on liming strategies and physico-chemical effects, the observed effects of this treatment on the decomposition process and major biological components of freshwater ecosystems are reviewed. Available studies, which cover up to about 6 to 8 yr post-treatment, describe many positive biological responses to liming. These include population expansion of acid-sensitive plant and animal species, and restoration of fisheries. However, no ecosystems have so far been returned to pre-acidification status, and possible reasons for this are discussed. The frequent persistence of acid episodes in limed waters may adversely affect some species. Reductions in available P and dissolved organic C may also be limiting factors, whilst precipitated metal hydroxides are potentially toxic. When physicochemical conditions are favorable, biological recovery may be restricted by other factors, including colonization rates and the reduced genetic diversity of small residual or founding populations. If the long-term ecological consequences of liming are to be predicted, further understanding of these limitations and the stability properties of aquatic communities is necessary.     

The use of zooplankton in a biomonitoring program to detect lake acidification and recovery

A detailed review of the zooplankton literature found strong evidence that lake acidification consistently causes declines in crustacean and rotifer species richness, the relative abundance of cyclopoids and daphnids, and the relative abundance of 16 particular zooplankton species. Five species were found to consistently increase as lake pH declines. Inconsistent effects were observed on crustacean biomass and mean organism size. Biomonitoring response variables recommended to detect incipient community changes include the relative abundance of pH sensitive species, overall crustacean and rotifer community composition plotted in abundance ordination space, crustacean and rotifer species richness, and the relative abundance of acid tolerant species. If acidification effects have been detected using the above response variables, then more detailed monitoring to understand the functional characteristics of affected systems (e.g. crustacean biomass, rotifer biomass and/or overall community size spectra) is appropriate. A lake selection procedure is recommended to maximize the number of systems containing sensitive species, and ensure a set of reference systems whose acidity is unlikely to change significantly.     

Regional monitoring of lake acidification in Finland

The primary objective of this monitoring is to detect long-term Long-Range Transboundary Air Pollution (LRTAP) induced changes in the water quality of small lakes, throughout Finland, with low conductivity. The monitored lakes (n=171, sampled every autumn since 1990 and in 1987) have a smaller watershed (usually headwater or seepage lakes), a larger lake/catchment ratio, and lower base cation concentrations, alkalinity and pH than Finnish lakes on average. The monitoring network provides background data for air pollution dose/response studies, critical load calculations and for the modelling of acidification scenarios. The declining sulphate deposition seems to be reflected in small headwater lakes all over southern and central Finland as a lowering of the sulphate concentration in the waters. Nitrate concentrations in these lakes have been typically low in the autumn. The base cation concentration is not generally declining, as it is in deposition in many areas. The sulphate concentration in lakes has declined more than base cations. Hydrologically, the recent years have been quite variable because of varying annual precipitation. The variation in alkalinity and pH in typical Finnish lakes is dependent on the content of humic material derived from catchments. The monitoring period is too short to reveal consistent trends in major ion chemistry. However, signs of improvement in recent years can be seen; in comparing 1993 to 1987, years with similar organic acidity and base cations, it seems that the sulphate decline in lakes monitored is compensated by a significant rise in both alkalinity and pH.     

Simulated mobilization of metals from sediments in response to lake acidification

The regeneratable forms of pollutant metals in lake sediments were estimated using different chemical extractants and the effects of lake acidification on the mobilization of such metal fractions studied in laboratory microcosm. The release of each metal was found to increase exponentially below a threshold pH value, which was about 4.0 for Cu, Ni, Zn, Cd and Fe. The data suggest that a large percentage of pollutant metals are mobile as determined by chemical extraction techniques and long-term release experiments.     

Soil acidification and the importance of liming agricultural soils with particular reference to the United Kingdom

Soil acidification is caused by a number of factors including acidic precipitation and the deposition from the atmosphere of acidifying gases or particles, such as sulphur dioxide, ammonia and nitric acid. The most important causes of soil acidification on agricultural land, however, are the application of ammonium‐based fertilizers and urea, elemental S fertilizer and the growth of legumes. Acidification causes the loss of base cations, an increase in aluminium saturation and a decline in crop yields; severe acidification can cause nonreversible clay mineral dissolution and a reduction in cation exchange capacity, accompanied by structural deterioration. Soil acidity is ameliorated by applying lime or other acid‐neutralizing materials. ‘Liming’ also reduces N₂O emissions, but this is more than offset by CO₂ emissions from the lime as it neutralizes acidity. Because crop plants vary in their tolerance to acidity and plant nutrients have different optimal pH ranges, target soil pH values in the UK are set at 6.5 (5.8 in peaty soils) for cropped land and 6.0 (5.3 in peaty soils) for grassland. Agricultural lime products can be sold as ‘EC Fertiliser Liming Materials’ but, although vital for soil quality and agricultural production, liming tends to be strongly influenced by the economics of farming. Consequently, much less lime is being applied in the UK than required, and many arable and grassland soils are below optimum pH.     

Bioelement content and biomass in scots pine: Effect of acidification and liming

Dry weights and bioelement contents in biomass of Scots pine (aboveground) were estimated on some differently treated plots from one acidification experiment in North Sweden. Dry weight estimates of Scots pine biomass showed relatively small differences between treatments. The content of N, P, K, Ca, Mg, Mn, and S showed significant differences in a number of cases. The amount of N in different crown components increased; fertilizer-N recovered in the biomass was up to 10% of that added (in total, the NPK-plots received 1260 kg N ha^?1). The concentration of other elements (P, K, Ca, Mg, Mn and S) showed some effect of the treatments, but was not as marked as that of N. Especially interesting is a decrease in the level of Mg in needles and shoots on the NPK-treated plots. The concentration of S was influenced by application of acid, but much more by NPK-fertilization throughout the period.     

recent lake acidification and recovery trends in southern quebec,canada

A total of 51 lakes in southern Quebec, Canada, were sampled between 1985 and 1993 to study changes in water chemistry following reductions in SO₂ emissions (main precursor of acid precipitation). Time series analysis of precipitation chemistry revealed significant reductions in concentrations and deposition of SO₄ ^2- from 1981 to 1992 in southern Quebec as well as reductions in concentrations and deposition of base cations (Ca²⁺, Mg²⁺), NO₃ ^- and H⁺ in the western section of the study area. Reductions in atmospheric inputs of SO₄ ^2- have resulted in decreased lakewater SO₄ ^2- concentrations in the majority of the lakes in our study, although only a small fraction (9 of 37 lakes used in the temporal analysis) have improved significantly in terms of acidity status (pH, acid neutralizing capacity – ANC). The main response of the lakes to decreased SO₄ ^2- is a decrease in base cations (Ca²⁺+Mg²⁺), which was observed in 17 of 37 lakes. Seventeen lakes also showed significant increases in dissolved organic carbon (DOC) over the period of study. The resulting increases in organic acidity as well as the decrease in base cations could both play a role in delaying the recovery of our lakes.     

Bioelement content and biomass in scots pine: Effect of acidification and liming

Dry weights and bioelement contents in biomass of Scots pine (aboveground) were estimated on some differently treated plots from one acidification experiment in North Sweden. Dry weight estimates of Scots pine biomass showed relatively small differences between treatments. The content of N, P, K, Ca, Mg, Mn, and S showed significant differences in a number of cases. The amount of N in different crown components increased; fertilizer-N recovered in the biomass was up to 10% of that added (in total, the NPK-plots received 1260 kg N ha^?1). The concentration of other elements (P, K, Ca, Mg, Mn and S) showed some effect of the treatments, but was not as marked as that of N. Especially interesting is a decrease in the level of Mg in needles and shoots on the NPK-treated plots. The concentration of S was influenced by application of acid, but much more by NPK-fertilization throughout the period.     

Effects of lake liming on phytoplankton production in acidic Adirondack lakes

Phytoplankton community characteristics were monitored prior to and following CaCO₃ addition to two small, highly acidic lakes (Cranberry Pond and Woods Lake) and one larger, less acidic lake (L. Simon Pond). Data were also collected from a control site (Dart's Lake) exhibiting chemical characteristics similar to the pretreatment conditions observed at the experimental sites. In the two small, most acidic lakes, base addition was associated with higher chlorophyll levels during the first summer following treatment. Woods Lake was maintained at a circumneutral pH for 3 yr and exhibited increased phytoplankton abundance throughout the posttreatment period. In contrast, Cranberry Pond reacidified within 1 yr following based addition. Reacidification was accomplished by a decrease in lake chlorophyll levels to pre-treatment levels. At the larger, less acidic lake (L. Simon Pond), liming was associated with lower chlorophyll levels during the first summer after treatment. Reductions in chlorophyll levels at L. Simon Pond reflect the absence of the spring phytoplankton peak and a decrease in phytoplankton growth below the depth of the thermocline. At Cranberry Pond, annual differences in phytoplankton production did not correspond to changes in lake acidity and phytoplankton abundance. Productivity in Woods Lake exhibited an increasing trend during the 3 yr following treatment. Interpretation of treatment effects on productivity was confounded by high between-year variability at the control site.     

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 acidification and liming on feeding groups of nematodes in coniferous forest soils

Summary Nematodes were sampled in untreated, acidified, and limed plots in a Norway spruce (Fexboda) and a Scots pine (Norrliden) stand. At Fexboda, the total number of nematodes was significantly reduced after the acidification. This reduction was probably due to a shock effect, because the samples were taken only 5 months after an application of 200 kg H₂SO₄ ha^-1 to the forest floor. However, the root/fungal-feeding Aphelenchoides was not reduced, probably because it is more tolerant of high acid concentrations than most other nematodes. At Norrliden, where the samples were taken 7 years after the last application of H₂SO₄, no significant differences were found between the acidified and untreated plots. If the treatment with H₂SO₄ caused similar effects as at Fexboda, the results indicate a recovery of the nematode populations. Decreased predation from lumbricids rather than a recovery of microfloral populations probably allowed this recovery. No marked effect of lime, spread 2 (Fexboda) and 12 years (Norrliden) before the sampling on the numbers of any of the nematode feeding groups was found. This correlated with almost no change in bacterial biomass after liming, while the active fraction of fungal hyphae was unaffected by liming at Fexboda and reduced by liming at Norrliden. A tendency for decreasing numbers of all nematode feeding groups in the limed plots at Norrliden coincided with increasing numbers of lumbricids.