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.     

Fish species distribution and water chemistry in Nova Scotia lakes

During the summers of 1981-1984, 19,714 fish (23 species) were netted in 234 Nova Scotian lakes. Surface and mid-depth water samples were also analyzed for major ions, metals, and DOC. Lakewater pH varied from 4.4 to 7.7, including eight lakes which produced no fish in standard 23-hr net sets. Fish data were partitioned into 6 pH groupings for analysis. Stepwise multiple regressions of fish species vs. H+, S0₄,A1, Fe, and Mn showed little predictive power. Productive lakes ranged up to 530 μg L^?1 Al, 1680 pg L^?1 Fe, and 836 μg L^?1 Mn. Apart from pH, fish distribution and abundance showed no significant relationships with water chemistry data. We note, however, that the more acidic lakes had fewer species of fish.     

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.     

Chronic effects of low ph and elevated aluminum on survival,maturation, spawning and embryo-larval development of the fathead minnow in soft water

Fathead minnows (Pimephales promelas) were exposed to a range of pH and A1 concentrations in soft water (8 mg Ca L^?1) to determine effect levels at various life stages. The tested pH levels ranged from 8.0 through 5.2 and inorganic monomeric Al from 15 through 60 μg L^?1. Reproductive processes including spawning, embryogenesis and early larval survival were more sensitive to acid stress than were juvenile growth and survival. Juvenile survival was significantly reduced at pH 5.2 + 60 μg Al L^?1 (P <0.05). Spawning success was reduced at pH 6.0 and 5.5 (P <0.10) and failed completely at pH 5.2, regardless of Al concentration. An apparant beneficial effect of added Al was observed during spawning at pH 7.5 + 35 μg Al L^?1, but this effect was not significantly greater than at pH 7.5 + 15 μg Al L^?1. A significant (P <0.05) decrease in larval survival occurred at pH 6.0 + 15 μg Al L^?1 and lower compared to the survival at pH 7.5 + 15 μg Al L^?1. Aluminum at 30 μg L^?1 provided protection resulting in short term increased embryo-larval survival at pH 5.5. The effect of parental exposure on progeny survival was assessed by an interchange of embryos from the spawning treatment to all tested exposure conditions. When reared at pH 8.0 + 15 μg Al L^?1 through 6.0 + 15 μg Al L^?1 or at pH 5.5 + 30 μg Al L^?1, parental exposure did not significantly influence progeny survival. However, survival was significantly reduced among progeny from brood fish reared at pH 5.5 + 15 μg Al L^?1 as compared to those spawned at pH 6.0 + 15 μg Al L^?1 and above, or at pH 5.5 + 30 μg Al L^?1 (P <0.05). Juvenile or 14 d larval growth effects were not detected under any exposure condition (P >0.05). Ultimately, fathead minnow young-of-the-year recruitment and production potential can be expected to diminish when environmental pH falls to 6.0, and to fail completely at 5.5 and lower.     

Airborne transport of sulphur: Impacts on chemical composition of rivers on north shore of the St. Lawrence River (Québec)

The St. Lawrence North Shore region (Québec) is subject to acid precipitation entailing sulphate deposition (17 to 22 kg SO₄ ^2? ha^?1 yr^?1) which poses a threat to sensitive aquatic ecosystems. Physicochemical surveys conducted in 1982–1983 revealed the extreme sensitivity of the region owing to weak mineralization of the waters (mean alkalinity of 55 μeq L^?1 and conductivity of 17 μS cm^?1). Calculation of the annual loads of S discharged from 21 rivers throughout the region shows atmospheric deposition as the principal source of sulphate. A decreasing west-east gradient in the concentration is interpreted in terms of the impact of long-range airborne transport, although certain local sources of S emission are not to be overlooked. Analysis of the seasonal variation in the sulphate load balance, conducted in a small drainage basin (40 km²), revealed that the sulphate anion plays a part in lowering the water pH in spring. The spring pH depression is apparently intensified by an additional input of sulphate stemming from the release of this element subsequent to accumulation in the drainage basin during summer and fall. Organic acids play a measurable role in the chemical equilibrium of surface waters in the region, particularly in the eastern sector where there is less S fallout. Low pH levels in this sector (5.5 to 6.0) point to some degree of organic acidification.     

The effects of low pH,low calcium concentrations and elevated aluminium concentrations on sodium fluxes in brown trout,Salmo Trutta L.

The effects of pH (c. 7.0, 5.4, 4.5 and 4.0), nominal Al levels (0 and 8 μmol L^?1) and Ca levels (10 and 50 μmol L^?1) on Na influx, efflux and netflux of brown trout have been investigated using artificial lake water of known composition. Low pH had little effect on influx, but tended to increase efflux, particularly in the low Ca treatments. A nominal addition of 8 μmol Al L^?1 at pH 4.5 and 4.0 reduced influx significantly. Efflux was unaffected. Aluminium addition at pH c. 7.0 and 5.4 had no such effect. The measured Al concentrations at the end of the static 8 hr flux measuring experiments were markedly lower than the nominal amount of A1 added to the start.     

铝和镉胁迫对两个大麦品种矿质营养和根系分泌物的影响

A hydroponic experiment was carried out to study the effect of aluminum （Al） and cadmium （Cd） on Al and mineral nutrient contents in plants and Al-induced organic acid exudation in two barley varieties with different Al tolerance. Al- sensitive cv. Shang 70-119 had significantly higher Al content and accumulation in plants than Al-tolerant cv. Gebeina, especially in roots, when subjected to low pH （4.0） and Al treatments （100 μmol L^-1 Al and 100 μmol L^-1 Al ＋1.0 μmol L^-1 Cd）. Cd addition increased Al content in plants exposed to Al stress. Both low pH and Al treatments caused marked reduction in Ca and Mg contents in all plant parts, P and K contents in the shoots and leaves, Fe, Zn and Mo contents in the leaves, Zn and B contents in the shoots, and Mn contents both in the roots and leaves. Moreover, changes in nutrient concentrations were greater in the plants exposed to both Al and Cd than in those exposed only to Al treatment. A dramatic enhancement of malate, citrate, and succinate was found in the plants exposed to 100 μmol L^-1 Al relative to the control, and the Al-tolerant cultivar had a considerable higher exudation of these organic acids than the Al-sensitive one, indicating that Al-induced enhancement of these organic acids is very likely to be associated with Al tolerance.     

Aluminum retention in a man-made Sphagnum wetland

Runoff from a highway interchange in western Maryland had Al concentrations averaging about 50 mg L^?1, with a maximum of 206 mg L^?1. As an alternative to expensive chemical treatment of this Al-rich water, in August 1984, the drainage was diverted through a 500 m² man-made wetland, constructed from organic peat. For a 10 week period, Al concentrations in water leaving the wetland averaged 1.5 mg L^?1. as compared to Al concentrations at the two major inflows to the wetland of 35.3 and 6.6 mg L^?1. However, effective treatment of the drainage by the wetland was not observed over the entire 27 mo sampling period. Peat chemical analysis indicated that over the 27 mo, total Al concentration in the peat increased from 2375 μg g^?1 to 13 634 μg g^?1. Of this increase 5.5 % was contributed by exchangeable Al, 4.3% by adsorbed Al, 39.8% by organically bound Al, 33.1% by oxide bound Al, and 17.2% by precipitated and residual Al. Changes in Fe, Mn, Ca, Mg, K, and Na chemistry in the peat associated with Al retention are discussed.     

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.     

Natural and anthropogenic acidity sources for Finnish Lakes

The headwater lakes in peat-rich areas in Finland commonly have high organic matter concentrations and are surrounded by soils and bedrock poor in bases. As a result the organic acid load on the watercourses is generally high. The significance of the organic vs anthropogenic acidity in 78 moderately acid lakes (pH range 4.3 to 7.1, TOC range 0.6 to 33.9 mg L^?1) was evaluated in areas receiving different levels of acid deposition. The lakes were sampled during autumn overturn, and their water quality (mean TOC = 10.9 mg L^?1, mean pH = 5.9) represents rather well the average water quality in small lakes in Finland. According to the correlation and regression analyses, TOC is a better predictor of pH than non-marine sulfate. Base cation concentrations are important in determining the sensitivity of the lakes to organic and anthropogenic acidity. The highest minerogenic acid contribution is found in high-deposition areas, while the percent organic acid contribution is greater in low deposition areas although TOC levels are comparable in both areas. It would appear that the pH of humic lakes is determined to a greater extent by individual watershed characteristics than by their geographical location at the present atmospheric loadings received in Finland.     

Avoidance of low pH and elevated Al concentrations by Brook Charr (Salvelinus fontinalis) Alevins in laboratory tests

Laboratory studies were conducted to test the ability of brook charr (Salvelinus fontinalis) alevins, the earliest free-swimming life stage of the species, to detect and avoid toxic levels of H⁺ and inorganic Al. Alevins were tested in steep gradient choice tanks using a range of H⁺ (pH 4.0 to 5.5) and Al (0 to 500 μg L^?1) concentrations in low Ca (2.0 mg L^?1) water. The young brook charr actively avoided acidic water with a pH < 5.0. Aluminum additions of 500 μg L^?l increased the avoidance response. The observed behavioral response of alevins to low pH and elevated levels of Al, may be of significant adaptive advantage in systems undergoing acidification.     

Can Phosphate Help Acidified Lakes to Recover?

Experimental addition of phosphate to enclosures in an acidified lake in Southern Norway was performed to study the effect on nitrate, pH and labile aluminium along a gradient of phosphate from 4–19 µg P L^?1. Nitrate decreased from 180 µg L^?1 to below detection limit after three weeks at P-concentrations > 17 µg L^?1, due to phytoplankton uptake. pH increased from 4.9 to 5.2, corresponding to a 50% decrease of H⁺-equivalents from 12 to 6 µg P L^?1 due to algal uptake of H⁺-ions when assimilating NO₃ ^?-ions. Due to the increased pH and probably also precipitation with phosphate, concentrations of labile aluminium decreased from 150 to 100 µg L^?1 within the P-interval 4–19 µg L^?1. Algal biomass increased from 0.5 to 6 µg chlorophyll a L^?1 along the same P-gradient. The results suggest that moderate P-addition (< 15 µg P L^?1 to avoid eutrophication problems) can improve water quality in moderately acidified lakes, and also increase nitrate retention in strongly acidified lakes. In humic lakes, the treatment will be less efficient due to light limitation of primary production and the presence of organic acids.     

Finnish lake survey: the role of organic and anthropogenic acidity

A lake survey consisting of 987 randomly selected lakes was conducted in Finland in autumn 1987. The survey covered the whole country, and the water quality of the lakes can be considered as representative of the approximately 56 000 lakes larger than 0.01 km² in Finland. The median TOC concentration is 12 mg L^-1 and the median pH 6.3. The proportion of lakes with TOC concentrations > 5 mg L^-1 in the whole country is 91 %. Organic anion is the main anion in the full data set (median 89 μeq L^-1). The high organic matter concentrations in Finnish lakes are associated with catchment areas containing large proportions of peatlands and acid organic soils under coniferous forest. The survey demonstrated that organic matter strongly affects the acidity of lakes in Finland. The decreasing effect of organic matter on the pH values was demonstrated by both regression analysis and ion balances. At current deposition levels of ^*SO₄ the pH of humic lakes in Finland is determined to a greater extent by high TOC concentrations than by ^*SO₄ in most areas. In lakes with pH values lower than 5.5 the average organic anion contribution is 56 % and non-marine sulfate contribution 39 %. However, in the southern parts of the country, where the acidic deposition is highest, the minerogenic acidity commonly exceeds the catchment derived organic acidity.     

Physiological responses of rainbow trout Salmo gairdneri exposed to plastic lake inlet and outlet stream waters

In Plastic Lake, Ontario, stocked rainbow trout (Salmo gairdneri) have failed to survive, one endemic fish species has become extinct and annual fish kills included up to five species, but especially pumpkinseeds (Lepomis gibbosus). The potential toxicity of Plastic Lake water was assessed by holding (hatchery) rainbow trout in the major inlet stream, the outlet, and in a portion of the outlet stream acidified to the pH of inlet No. 1. Stress on rainbow trout was assessed by measuring plasma and muscle concentrations of Na ⁺ Cl^?, and K⁺, plus gill A1 concentration. Trout held in Plastic Lake inlet No. 1 showed a rapid loss of plasma Na⁺ from 138 to 85 meq.L^?1and Cl^? from 120 to 75 meq.L^?1 within 24 hr. Gill A1 concentration increased from 20 to 105 μg.g^?1 dry weight. Trout held in the outlet steam showed only slight loss of plasma Na⁺ and Cl^? and no accumulation of Al on the gills. Trout held in the acidified outlet showed a significant loss of ions with plasma Na⁺ depressed from 140 to 115 meq.L^?1 and plasma Cl^? from 125 to 95 meq.L^?1over 24 hr. Gill Al concentration increased from 18 to 30 μg.g^?1 dry weight. The differences in stress response of rainbow trout held in the inlet and acidified outlet are likely due primarily to the difference in Al species concentrations in the two waters.     

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.     

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.     

Speciation and behavior of arsenic in the Nile delta lakes

Dissolved and particulate As species were measured in three River Nile coastal lakes in Egypt. Apart from input sources, As levels lie within the range 1.2 to 18.2 μg L^?1 (dissolved) and between 1.2 and 8.7 μg g^?1 (particulate). As(V) is the predominant dissolved As species constituting between 85 and 95% of total dissolved As(TDAs). Opposite to local sewage discharge points As(III) appeared constituting between 14 and 33% (of TDAs) at low and high water discharge periods. Dimethylarsenic is the dominant organic As form reaching 22% of total dissolved As while the maximum concentration of mono methylarsenic (1.0 μg L^?1) constituted about 8% of TDAs. Particulate As is mostly partitioned among reducible and detrital phases while the organic phase appeared dominant in eutrophic areas (> 30% of particulate As). About 413 t yr^?1 As entered the northern delta lakes via agricultural drains and waste water discharge. Phosphate fertilizers, detergents, herbicides, loamy Nile deposits are the main As sources to the drainage system. 52% of the total As derived to the Nile delta lakes is transported to the Mediterranean coastal seawater through the lakes' inlets.     

On the prediction of acid precipitation events and their effects on fishes

It is possible to predict acid rain events and melts of acid snow some 12 to 24 hr in advance, including estimation of the magnitude and duration of such events. This is sufficient notice to permit monitoring of stream chemistry and fish plasma and muscle ions before acid stress, and to continue this monitoring throughout and after specific events. Such a program has been in place for 2 yr in waters tributary to the Milford Bay Trout Hatchery, Ontario. During one snow melt in February 1984 surface waters showed a decline to pH 4 and associated negative ANC. Rainbow trout held in such water lost plasma Na and Cl rapidly and died within 28 hr. The hatchery water supply, consisting of a mixture of spring and surface water, showed a decline in alkalinity from 300 to 30 μeq.L^?1, and a pH change from 6.6 to 5.4, during snow melt. Total A1 concentration increased from 42 to 222 μg.L^?1 during snow melt with the “reactive” component increasing from 17 to 112 μg.L^?1. Rainbow trout held in this water did not show physiological stress. More rapid run-off of melt water could be expected to exhaust all of the alkalinity in the hatchery water supply permitting the pH to decline and A1 concentration to rise to levels lethal to the hatchery stock of rainbow trout.     

Recent trends in the acid-base status of surface waters in Maine,USA

Data from the EPA Long Term Monitoring Program lakes at the Tunk Mountain Watershed, Maine, indicate that decreases of ≤1 Μeq L^?1 yr^?1 in SO₄, and increases of ≤2 Μeq L^?1 yr^?1 in ANC occurred in the 1980s. The sum of base cations also increased. These changes in aquatic chemistry were coincident with decreased concentrations of all solutes in precipitation during the 1980s. Other data on lakes and streams in Maine collected between the 1930s and 1990 generally confirm these trends and further indicate that larger increases in ANC may have occurred in some lowland lakes since 1940. Paleolimnologic studies indicate that decreases of 0.1 to 0.5 pH units occurred in a few small mountain lakes during the past 20 to 70 yr. However, ongoing acidification of lakes is indicated based on available data. Only lakes that were already at least marginally acidic (pH ≤5.8, ANC approximately 0) appear to have acidified.