Changes in the fish community of a limed lake near sudbury,Ontario: Effects of chemical neutralization or reduced atmospheric deposition of acids?

Nelson Lake, a moderately acidic (pH 5.7), metal-contaminated (Cu 22 μg L^?1; Zn 18 ug L^?1) lake, 28 km from the smelters at Sudbury, had a degraded fish community in the early 1970's, with lake trout (Salvelinus namaycush) scarce, smallmouth bass (Micropterus dolomieui) extinct, and the littoral zone dominated by the acid-tolerant yellow perch (Perca flavescens). Liming of the lake in 1975–76 increased pH to 6.4, and decreased metal concentrations. Chemical conditions have remained relatively stable in the 10 yr following base addition. Initially, it appeared that neutralization produced dramatic changes in the resident fish community. Yellow perch abundance declined rapidly after neutralization, lake trout abundance increased to the extent that 3.26 kg ha^?1 were caught in the winter of 1980, and reintroduced smallmouth bass reproduced and established a large population. However, these changes in the fish community can not be directly attributed to liming, as water quality and the sport fisheries of an unlimed nearby lake also improved. Reduced emissions from Sudbury smelters were responsible for improvements in the untreated lake. Recovery of the lake trout population in Nelson Lake appears to have begun prior to liming. Of the lake trout sampled during the 1980 winter fishery, 65.8% were present prior to the chemical treatment. Predation by lake trout was the likely cause of the perch decline. Our results suggest that chemical conditions producing population level responses in fish have abrupt thresholds and that neutralization of lakes above these thresholds may not produce distinguishable effects.     

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.     

Chemistry differences in two streams entering an acidic lake in the Adirondack Mountains,New York (U.S.A.)

Solution chemistry was measured in two major inlets, lake water column, lake outlet, and soils of the South Lake watershed in the Adirondack Mountains, New York. The east inlet had greater concentrations of H⁺, sulfate-S, and Al and smaller concentrations of base cations and silica than the west inlet (70, 116, 25, 90, 64 and 4, 99, 8, 228, 148 μeq L^?1 of H⁺ and sulfate-S, μmol L^?1 Al, μeq L^?1 total base cations and μmol L^?1 silica in east and west inlets, respectively). Concentrations of base cations in C horizon soil solutions (157 μeq L^?1 total base cations) were smaller and greater than west and east inlets, respectively. This suggests that water flowing into the west inlet contacted deeper mineral layers, whereas water reaching the east inlet did not. Lake and lake outlet concentrations were also intermediate between the two inlets, and the lake was acidic (pH 4.9 to 5.1) with relatively high total monomeric Al concentrations (8 to 9 μmol Al L^?1). The east inlet also had greater DOC concentrations than the west (0.38 and 0.24 μmol C L^?1, respectively), again indicating that soil solutions entering the east inlet passed through the forest floor but had more limited contact with deeper mineral layers in comparison with the west inlet. Differences between the streams are hypothesized to be related to contact of percolating solutions with mineral soil horizons and underlying glacial till, which provides neutralization of acidic solutions and releases base cations. This work indicates that processes controlling surface water acidification can be spatially quite variable over a small watershed.     

Extreme acidification of a lake in southern Norway caused by weathering of sulphide-containing bedrock

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 the late 1980's. During 1986–1989, a dramatic change in the water chemistry occurred because of blasting of and weathering of sulphidic gneisses in the watershed. The oxidation of sulphide to sulphate (sulphuric acid) caused an increase in the SO₄ concentration of the draining stream of up to ≈ 4800 μeq L^?1. Weathering and/or cation exchange of Ca and Mg neutralized approximately 52% of the protons from the sulphuric acid production, while about 46% were consumed by mobilization of aluminium and iron. Nevertheless, about 2% of the hydrogen ions from the sulfuric acid were still present, which resulted in a stream pH of 4.0. In the lake, the pH was 4.4, and the concentrations of all major cations and anions were significantly lower than in the heavily affected stream. Mixing of the stream water with lake water, formation of aluminium-sulphate complexes and coprecipitation of Ca may explain the resulting concentrations of major ions in the lake.     

Response to a smelter closure in Cascade mountain lakes

A statistically significant decrease in sulfate was observed in high elevation Cascade lakes during 1983 through 1988. The total decrease averaged 2.2 μeq L^?1 in two slow-flush lakes and 4.2 μeq L^?1 in three fast-flush lakes for 1983–1985 vs 1986–1988, respectively. Coincident with these changes in sulfate concentrations were a sharp decrease of SO₂ emissions from the ASARCO smelter (100 km SE of the lakes), from 87 to 70 kt yr^?1 during 1983–1984 to 12 in 1985, the year of its closure, and a gradual change in SO₂ emissions from Mt. St. Helens, from 39 to 27 during 1983–1984 to 5 in 1988. The sharpest decreases occurred in non-marine sulfate in fast-flush lakes from 1984 to 1985 (about 2 μeq L^?1) and in slow-flush lakes from 1985 to 1986 (1 μeq L^?1, which point to the ASARCO closure as the sole cause. However, some of the more gradual decline in non-marine sulfate observed during 1983 through the 1988 sampling periods may have been due to a slow washout of sulfate enriched ash from the 1980 Mt. St. Helens' eruption. Sulfate concentrations in precipitation also declined significantly by about 2 μeq L^?1, but changes in volume-weighted sulfate content were not significant. Lake alkalinity did not show a consistent increase in response to decreased sulfate. This was probably due to either watershed neutralization of acidic deposition or the greater variability in alkalinity measurements caused by small changes in acidic deposition making it difficult to detect changes.     

Dose-response relationships for the addition of limestone to lakes and ponds in the Northeastern United States

A titration based model (DeAcid) has been used to predict treatment dose and times for reacidification for CaCO₃-treated lakes in the Living Lakes, Inc. (LLI) aquatic liming program. Water quality constitutents (pH, ANC and Ca) were used to measure the effectiveness of the dosing model and reacidification rates. Data from 22 lakes or ponds in 5 northeast states have been collected since June 1986. With few exceptions, pH and ANC values ranged from 4.5 to 6.5 and ?30 to +65 ueq L^?1, respectively, in untreated sites and 6.5 to 7.8 and 120 to 300 ueq L^?1, respectively, in sites approximately 30 days after treatment. Changes in Ca concentration levels have been used to evaluate the utility of the dose model for treatment of both inland and coastal waters. For coastal, seepage lakes application of a single-box mass transfer model to observed post-liming changes in ANC and Ca adequately simulates lake response.     

Primary production in a eutrophic acid lake

Total P concentrations, chlorophyll concentrations, and phytoplankton production were investigated bi-weekly in Tibbs Run Lake, Monongalia County, West Virginia, from March 1977 to March 1978. Mean H⁺ concentration in the lake was 25.1 μeq 1^?1 (pH 4.6). The acidic condition of the lake is attributed to inputs of acid via precipitation (mean H⁺ concentration of the bulk precipitation was 79 μeq 1^?1, pH 4.1), and the low buffering capacity of the watershed (bedrock composition of sandstone). Effect of the watershed is shown by the net retention of imput of P (ca. 26%) and H⁺ (ca. 68%). Total P loading to the lake was 0.495 g P m^?2 yr^?1. The single inflow accounted for 95% of the total loading while bulk precipitation accounted for the remainder. Mean summer chlorophyll concentration was 22.2 mg m^?2. Phytoplankton production expressed volumetrically as aP-vol-x value was 9.78 mg C m^?3 h^?1. Regression analysis indicated that H⁺ do not affect chlorophyll concentrations or phytoplankton production but rather that P limits algal biomass. Trophic status of Tibbs Run Lake based on a P budget model, chlorophyll concentration, and volumetric production all indicate that the lake is meso-eutrophic.     

Acidity status of surface waters in Massachusetts

The Massachusetts Acid Rain Monitoring project surveyed 80.5% of the state's 5294 named water bodies between 1983 and 1985. PH and acid neutralizing capacity (ANC) were measured monthly the first 14 mo and semi-annually afterwards. Sample collection and analysis were performed by volunteers. The majority of surface waters in Massachusetts were found to be sensitive to possible long term acidification, with 63% exhibiting ANC less than 200 μeq L^?1 and 22% with ANC less than 40 μeq L^?1. Seasonal patterns in ANC were observed, the median ANC being 384 μeq L^?1 in summer/fall and 134 μeq L^?1 in winter/spring. Geographical differences were also found across the state: the streams and lakes with lowest pH and ANC were located in the southeastern and north-central parts of the state, while the most alkaline surface waters were found in the western-most part of the state, which is the only area of the state with significant limestone deposits.     

Recovery Pattern from Acidification of Headwater Lakes in Finland

Acid sensitive headwater lakes (n=163) throughout Finland have been monitored during autumn overturn between 1987–1998. Statistically significant decline in sulphate concentration is detected in 60 to 80 percent of the lakes, depending on the region. Median slope estimates are from ?1.1 µeq L^?1 in North Finland to ?3.3 µeq L^?1 in South Finland. The base cation (BC) concentrations are still declining especially in southern Finland (slope ?2.5 µeq L^?1), where every second lake exhibits a significant downward trend. The BC slope is steeper for lakes with less peatlands, more exposed bedrock, longer retention time and southerly location, but these factors are inter correlated. Gran alkalinity slope medians for the three regions range from 1.4 to 1.8 µeq L^?1 yr^?1. No significant negative alkalinity trends were detected. The similarity in the slopes of SO₄, BC and alkalinity in this data compared to seasonal sampling data from Nordic Countries can be regarded as indirect evidence that autumnal sampling is representative for long term monitoring for these ions. There are no indications of increased organic carbon in lakes, as found in some recent trend analyses of similar regional data sets. Although the processes behind the positive development in these lakes have to be revealed with site- specific intensive studies, this data suggests, that the initial recovery from lake acidification in Finland is a regional phenomenon.     

Low cost limestone treatment of acid sensitive trout streams in the appalachian mountains of Virginia

The method of single point, single application liming has been studied as a means of mitigating anthropogenic acid in trout streams in Virginia. Three critically acid sensitive streams were dosed with a total of five applications of limestone sand and monitored before, during and after the treatments to assess changes in water chemistry and biota. Limestone treatments of 8 to 50 tons (particle sizes 150–1000 μm), with the amounts based on sulfate deposition loading and existent stream water chemistry, were used to restore ‘lost’ acid neutralizing capacity (ANC). Contact time between the limestone bed in the stream bottom and the water was the limiting factor affecting the degree of treatment with bed length primarily controlled by the gradient of the stream at the dosing site. A single site application was able to restore approximately 2/3 of the ANC. Exponential fits of limestone consumption data were used to predict that treaments of similar streams would last from two five years before reliming was necessary. Both total and monomeric aluminum levels were reduced up to 50%, and aquatic biota increased below the treatment sites. Post-liming average values for the three streams were pH 6.66, 82.7 μeq L^?1 ANC and 2.63 mg L^?1 Ca. The average ANC improvement suggests that some 88% of the native trout streams in Virginia, which average 29 μeq L^?1 ANC reduction from acid deposition, could be temporarily restored using single application liming.     

Liming and reacidification reactions of a forest lake ecosystem,lake Lysevatten,in SW Sweden

Long-term monitoring, 1973 to 1987, of reactions to liming and reacidification of a forest lake ecosystem near the Swedish west coast is reported in this study. Treatment of Lake Lysevatten with a slag product of limestone in 1974 resulted in neutralization and a positive alkalinity. Prolonged dissolution proceeded for about 7 yr whereby 86% dissolved. During 1984–86 Lake Lysevatten approached maximum reacidification with high Al concentrations and an affected biota. Asellus aquaticus L. decreased and dominance within chironomid groups approached preliming conditions. However, the most obvious biological change was the development of the filamentous algal genus Mougeotia and increased growth of Sphagnum. Populations of both plants increased notably when pH declined to about 5. Our study suggests that extensive reacidification (pH < 6.0) of limed lakes should be avoided by successive treatments to prevent development of destabilized lake ecosystems.     

Acid precipitation and surface-water vulnerability on the western slope of the high colorado rockies

Precipitation and surface waters in a high-elevation watershed on the western slope of the Colorado Rockies were studied over a three-year period. The volume-weighted average pH for summer events was 4.61, for winter events was 5.11 and for the entire period was 4.91. Within the watershed, both low- and medium-alkalinity surface waters exist. Weekly alkalinity measurements ranged from 10 to 70 μeq L^?1 in the former and 100 to 900 μeq L^?1 in the latter.     

Formiate and acetate in wet deposition at Pallanza (NW Italy) in relation to major ion concentrations

Weekly samples of wet deposition were collected at Pallanza (NW Italy) from January 1987 to December 1988. Their chemistry is characterized by high mineral acidity, with a median pH value of 4.26; only in 2 out of 62 samples was pH higher than 6.0. Sulphate, nitrate and ammonium are the main ions. Formiate and acetate showed a volume weighted average of 7 and 4 μeq L^?1, respectively; the values for the dissociated forms are 5 and 1 μeq L^?1, respectively. The contribution of formiate and acetate (dissociated form) to the total ionic concentration is about 2%, while the contribution to free hydrogenion is about 13%, mainly deriving from formic acid. Seasonal variations in concentration and the relationships between organic acid and other ions indicate that the photolysis of isoprenoid compounds released into the atmosphere from vegetation is a significant source for formic acid. In the case of acetic acid there is a contribution from anthropogenic emissions, more marked during the winter period.     

Acid-base chemistry of high-elevation streams in the great smoky mountains

Longitudinal and temporal variations in water chemistry were measured in several low-order, high-elevation streams in the Great Smoky Mountains to evaluate the processes responsible for the acid-base chemistry. The streams ranged in average base flow ANC from ?30 to 28 μeq L^?1 and in pH from 4.54 to 6.40. Low-ANC streams had lower base cation concentrations and higher acid anion concentrations than did the high-ANC streams. NO₃ ^? and SO₄ ^2? were the dominant acid anions. NO₃ ^? was derived from a combination of high leaching of nitrogen from old-growth forests and from high rates of atmospheric deposition. Streamwater SO₄ ^2? was attributed to atmospheric deposition and an internal bedrock source of sulfur (pyrite). Although dissolved Al concentrations increased with decreasing pH in the study streams, the concentrations of inorganic monomeric Al did not follow the pattern expected from equilibrium with aluminum trihydroxide or aluminum silicate phases. During storm events, pH and ANC declined by as much as 0.5 units and 15 μeq L^?1, respectively, at the downstream sites. The causes of the episodic acidification were increases in SO₄ ^2? and DOC.     

HPLC fluorometric determination of natural phytoplankton phycocyanin and its usefulness as cyanobacterial biomass in highly eutrophic shallow lake

A method for HPLC determination of phycocyanin in phytoplankton samples using gelchromatography with a fluorescence detector was developed to examine the use of phycocyanin as an index of the appearance and progress of cyanobacterial blooms in highly eutrophic lake. At least two types of phycocyanin with different molecular weights, each spectroscopically different from phycoerythrin and allophycocyanin, were found in natural phytoplankton samples. Changes in phycocyanin concentrations were clearly coupled to changes in chlorophyll-a concentrations during June to October while cyanobacterial blooms were occurring. The chlorophyll-a to phycocyanin relationship was linear at chlorophyll-a concentrations of less than 250 μg L^?1. The relationship between cyanobacterial carbon and phycocyanin concentration was also linear, suggesting that phycocyanin content may be a useful index of cyanobacterial biomass in highly eutrophic lakes where large cyanobacterial blooms occur.     

Counteractions Against Acidification in Forests Ecosystems. Effects on stream water quality after dolomite application to forest soil in Gjerstad,Norway

The deposition of strong acids is one of many threats to forest ecosystems and viable forestry. Several counteractions against acidification have been launched, e.g. changes in forestry management and the introduction of chemicals. The inter-institutional programme “Counteractions Against Acidification in Forest Ecosystems” was established in 1993 to evaluate existing knowledge and run experimental and fullscale field experiments. A total of 240 metric tons of coarse dolomite powder was spread by helicopter in September 1994 on 84 ha forest catchment dominated by pine (Pinus sylvestris) and Norway spruce (Picea abies). Potential desirable and undesirable effects after this carbonate application may be less pronounced than recorded at other sites due to the relatively moderate dose (3 tons ha^?1). Pre-liming stream water quality (mean values for May 1993-September 1994) was as follows: pH 4.8; Ca 1.13 mg L^?1; reactive Al (RAl) 248 μg L^?1; inorganic monomeric Al (Al) 72 μg L^?1. The reference station was slightly higher in Ca and slightly lower in both RAl and Al. Dolomite application resulted in a significant increase in pH to 5.7 as mean value for the post-liming period (September 1994-April 1995). Both Ca and Mg increased significantly after liming, and both RAl and Al, declined significantly. The rapid detoxification of stream-water may be explained by dissolution of dolomite particles in both streams and catchment, a resulting pH increase and change in Al species composition. Retention of Al in the catchment probably explains the reduction in RAl. No increase in NO₃, total N, total P or TOC was recorded the first seven months.     

Chemical effects of spring and summer alum additions to a small,Northwestern Ontario Lake

Aluminum was added as aluminum sulfate (alum) to Lake 114, a small, shallow lake of the Experimental Lakes Area, northwestern Ontario, in spring and summer point-source additions. Aluminum and H⁺ gradients were established during the additions, with high Al and low pH (about 1000 μg L^?1 Al, pH 4.7) near the alum sources, and background conditions (< 50 μg L^?1 Al, pH 5.7) further from the sources. Approximately 80% of the added Al was lost from the water column in two weeks. Phosphorus concentrations remained unchanged during the additions, whereas lake alkalinity decreased and sulfate increased close to the sources. Dissolved organic carbon (DOC) concentrations decreased slightly (from 540 μM L^?1 to about 500 μM L^?1) near the alum source during the summer addition.