Acidic Stream Water Research Articles

Patterns of streamwater acidity in Lye Brook Wilderness, Vermont, USA.

Under the United States Clean Air Act Amendments of 1977, a class I designation safeguards wilderness areas from the negative effects of new sources of air pollution. We monitored streamwater chemistry in the class I Lye Brook Wilderness in southwestern Vermont from May 1994 through August 1995. Stream samples were collected biweekly at nine sampling locations throughout the wilderness and were analyzed for major cations and anions, dissolved organic carbon, pH, and acid-neutralizing capacity. Eight of nine sites sampled had mean annual acid neutralizing capacity values below zero. During the study period, decreases in streamwater acid neutralizing capacity values were caused primarily by SO(4)(2-). At some sites, however, NO(3) (-) and naturally occurring, weak organic acids were seasonally important. During high discharge, the low pH and high concentrations of inorganic monomeric Al were at levels that are toxic to acid-sensitive aquatic species. Watershed mass balances were calculated to determine annual gains or losses for measured ions. These budgets indicate that S inputs and outputs were nearly equal, there was a net loss of base cations, and a net gain in N. How long these watersheds can continue to assimilate additional N inputs is unknown.

Acid Stream Water Remediation Using Limestone Sand on Bear Run in Southwestern Pennsylvania

AbstractInstream limestone sand application is used at many sites in Pennsylvania to neutralize acidic stream water resulting from acid deposition. However, questions remain about the effectiveness of limestone sand in the treatment of acid waters, such as reduced contact time at high flow, remobilization of aluminum, and adverse effects on macroinvertebrates. A 1‐year evaluation of limestone sand application to Bear Run, an acidic stream in southwestern Pennsylvania, was begun in 1999. Another nearby acid stream, Linn Run, served as a control. Water quality during baseflow and episodic acidification events, along with fish and macroinvertebrates, were monitored to evaluate impacts of the sand application. Hydrogen ion (H+) concentration and total dissolved aluminum (TDA) were significantly reduced, and acid neutralizing capacity was significantly increased downstream of the limestone sand application compared with the upstream site on Bear Run. These parameters at the downstream sites were also different (∝ 0.10) from the comparable sites on the control stream. TDA and hydrogen ion concentrations were significantly decreased (∝ 0.10) compared with concentrations before the sand application to Bear Run but not on the control stream. No fish were present upstream of the sand application site, and only a few fish were found downstream at the mouth of Bear Run. Standing crop, number of taxa, and Shannon‐Weaver diversity index values indicated that macroinvertebrate populations were negatively impacted 300 m downstream from the sand application and improved at the site 1,600 m downstream. Although water quality was improved on Bear Run, benefits to macroinvertebrates depended on downstream location, and fish populations did not show improvement.

Potential Remobilization of Toxic Anions during Reduction of Arsenated and Chromated Schwertmannite by the Dissimilatory Fe(III)-Reducing Bacterium Acidiphilium cryptum JF-5

Schwertmannite, an iron(III)-oxyhydroxysulfate formed in acidic mining-impacted stream or lake waters often contaminated with toxic elements like arsenate or chromate, is able to incorporate high amounts of these oxyanions. Detoxification of the water might be achieved if precipitated arsenated or chromated schwertmannite is fixed in the sediment. However, under reduced conditions, reductive dissolution of iron oxides mediated by the activity of Fe(III)-reducing bacteria might mobilize arsenate and chromate again. In this study, the reduction of synthesized arsenated or chromated schwertmannite by the acidophilic Fe(III)-reducer Acidiphilium cryptum JF-5, isolated from an acidic mining-impacted sediment, was investigated. In TSB medium at pH 2.7 with glucose as electron donor, A. cryptum JF-5 reduced about 10% of the total Fe(III) present in pure synthetic schwertmannite but only 5% of Fe(III) present in arsenated schwertmannite. In contrast to sulfate that was released during the reductive dissolution of pure schwertmannite, arsenate was not released during the reduction of arsenated schwertmannite probably due to the high surface complexation constant of arsenate and Fe(III). In medium containing chromated schwertmannite, no Fe(II) was formed, and no glucose was consumed indicating that chromate might have been toxic to cells of A. cryptum JF-5. Both As(V) or Cr(VI) could not be utilized as electron acceptor by A. cryptum JF-5. A comparison between autoclaved (121 °C for 20 min) and non-autoclaved schwertmannite samples demonstrated that nearly 100%of the bound sulfate was released during heating, and FTIR spectra indicated a transformation of schwertmannite to goethite. This structural change was not observed with autoclaved arsenated or chromated schwertmannite. These results suggest that the mobility of arsenate and chromate is not enhanced by the activity of acidophilic Fe(III)-reducing bacteria in mining-impacted sediments. In contrast, the presence of bound arsenate and chromate seemed to stabilize schwertmannite against reductive dissolution and its further transformation to goethite that is an ongoing process in those sediments.

A river runs through it: impact of acid mine drainage on the geochemistry of West Little Sugar Creek pre- and post-reclamation at the Green Valley coal mine, Indiana, USA

Acid mine drainage (AMD) associated with coal waste material at the abandoned Green Valley mine in Indiana discharges into West Little Sugar Creek, a nearby steam. The acidic effluent and mixed stream water carry elevated SO4, Fe3+, Al, Fe2+, Ca, Mg, Na, Cl, Mn, K, Si, Zn, Ni, Pb, Cd, V, Be, and Cr, with several of these contaminants exceeding local and/or national surface water quality standards. Iron- and aluminum-dominated precipitates form on site and in the mixing zone and contain high concentrations of major and trace elements, suggesting that many of these constituents partition into the solid phase. Phase stability relationships indicate ferrous iron sulfate aqueous species are in equilibrium with melanterite and goethite. Despite past reclamation efforts, as well as natural metal removal associated with formation of AMD-related precipitates, poor stream water quality persists and presents an ongoing threat to the aquatic ecosystem.

Geochemical Characteristics of Acidic Stream Water on Yakushima Island, a World Natural Heritage Site

We determined the chemical compositions of acidic stream waters on the rural, mountainous island of Yakushima (YK), and compared them with those of near-neutral stream waters in other mountainous watersheds in Japan. The pH and concentrations of the predominant sea-salt components (i.e., Cl−, Na+, Mg2+) in YK water, particularly in streams with small watersheds, decrease with elevation, while the concentration of Al increases. In contrast, water in northwestern YK contains higher concentrations of non-sea-salt SO4 2− and NO3 − and of rock-derived cations such as Si and Ca2+ than water in eastern to southern YK. This clearly shows that the anthropogenic pollutants on YK are dominantly derived from the northwestern to western Asian continent rather than from Japan's main islands, which lie to the northeast. These pollutants are responsible for stream acidification on YK and for accelerating chemical weathering, mainly of plagioclase, in northwestern YK. Large amounts of acid rain on YK may enhance the formation of secondary minerals that strongly adsorb heavy metals, which can partly account for the low concentrations of heavy metals in YK waters.

Stability of Schwertmannite and Ferrihydrite in the Stream Waters of Imgok and Osheep Creek Polluted by Acid Mine Drainage

The precipitation of Fe-compounds from acid mine drainage (AMD) and stream water polluted by AMD plays a crucial role in regulating pollutant migration and determining the impacts of AMD on aquatic ecosystems. It is thus essential to identify the nature of precipitates that form and to understand their stabilities in order to assess their environmental impact. This is a necessary prerequisite before an appropriate treatment program can be prepared. Various kinds of Fe-compounds have been found to precipitate from AMD, but not all of them have been investigated in detail. Schwertmannite is one of the Fe-compounds which need more investigation. Its stability constant was reported only once (Bigham et al., 1996). The purpose of this study is to determine the stability of schwertmannite and ferrihydrite as a function of the composition of the stream water from which they precipitate. Schwertmannite and ferrihydrite have been found to precipitate respectively from the stream waters of Imgok Creek and Osheep Creek in Kangwon-Do, Korea (Yu, 1996; Yu et al., 1996). Although Imgok and Osheep Creeks both drain what were once very actively operated mining areas and are polluted by AMD from the abandoned coal mines, their compositions are very different.

Surface water process and groundwater flow within a hydrologically complex floodplain wetland, Norfolk Broads, U.K.

Abstract. The patterns of variation in water quality for an acidic stream draining plantation forest overlying acidic and acid sensitive gley soils with shale and slate bedrock changed following the introduction of a 45 m deep borchole near to the stream. During drilling, air flushing of debris from the borehole cleared fracture routes for groundwater penetration to the stream via the stream bed. Consequently, there were and there remain marked increases in pH, alkalinity and calcium concentrations in the stream water. The extent of this water quality improvement varies according to flow. Under extreme highfiow conditions, most of the stream water is supplied from near surface soil water sources and acidic stream waters (pH about 4.2) result. Under baseflow conditions, the stream water pH is about 7.0 upstream and about 7.5 downstream of the borehole. Under intermediate flow conditions, the improvement in pH is most marked and values increase from around 5 to around 6.3. For acid sensitive "hard rock" areas such as those studied here, the bedrock has frequently been assumed to be both impermeable and low in base cations. This study illustrates that this view may be incorrect, and that groundwater may provide an important modifier of streamwater quality, at least for slate and shale dominated hard rock areas. Indeed, the work demonstrates clearly the potential for water quality remediation through groundwater manipulation.

Stream water quality in acid sensitive UK upland areas; an example of potential water quality remediation based on groundwater manipulation.

Abstract. The patterns of variation in water quality for an acidic stream draining plantation forest overlying acidic and acid sensitive gley soils with shale and slate bedrock changed following the introduction of a 45 m deep borchole near to the stream. During drilling, air flushing of debris from the borehole cleared fracture routes for groundwater penetration to the stream via the stream bed. Consequently, there were and there remain marked increases in pH, alkalinity and calcium concentrations in the stream water. The extent of this water quality improvement varies according to flow. Under extreme highfiow conditions, most of the stream water is supplied from near surface soil water sources and acidic stream waters (pH about 4.2) result. Under baseflow conditions, the stream water pH is about 7.0 upstream and about 7.5 downstream of the borehole. Under intermediate flow conditions, the improvement in pH is most marked and values increase from around 5 to around 6.3. For acid sensitive 'hard rock' areas such as those studied here, the bedrock has frequently been assumed to be both impermeable and low in base cations. This study illustrates that this view may be incorrect, and that groundwater may provide an important modifier of streamwater quality, at least for slate and shale dominated hard rock areas. Indeed, the work demonstrates clearly the potential for water quality remediation through groundwater manipulation.

Effects of Acidification on Bryophyte Communities in West Virginia Mountain Streams

AbstractBryophytes (mosses and liverworts) are often more responsive to water chemistry changes than are vascular plants. In this study, the relationships of bryophyte communities to stream pH and water chemistry were studied, using six streams on or near the Fernow Experimental Forest in Tucker County, West Virginia. Streams were surveyed with line transects using stratified random sampling. Bryophyte communities, based on species composition and structure, fell into three groups, corresponding to basic, moderately acidic, and very acidic stream water. For streams with sandstone beds, species diversity declined with decreasing pH, and no bryophytes were present at pH 3.15. The dominant species in moderately acidic to highly acidic streams is Scapania undulata, a species found to have exceptional tolerance to high acidity and toxic metal levels in Europe and Japan. Scapania undulata was transplanted from a stream with a pH of 5.97 to one with a pH of 3.15. In 3 mo, ultrastructural damage was observed. Acidity (pH) probably was not the only factor involved in controlling species composition and cell ultrastructure, since the two most acidic streams are subject to acid mine drainage and have very high concentrations of dissolved solids, particularly SO4 and Al. Other trace metals commonly associated with acidic surface waters also may have contributed to the differences in species composition.

Episodic acidification of three streams in Shenandoah National Park, Virginia, USA

Short-term acidification of surface waters in the eastern United States accompanying rainfall and snowmelt events represents an important aspect of the regional acidification problem. The objectives of this field study were to (1) examine the changes in acid-base chemistry during stormflow conditions, (2) understand the hydrological flowpaths that control streamwater acid neutralizing capacity (ANC), and (3) evaluate the contribution of individual ions to the overall changes in streamwater ANC. Three forested mountain streams in Shenandoah National Park (Paine Run, Piney River, and Staunton River) were chosen based on their similar catchment size (11–13 km2) but different bedrock geology and baseflow ANC. Throughout the three-year study, samples were collected at eight-hour intervals (primarily to establish antecedent baseflow conditions), and at two-hour intervals during events until the flow receded. All samples were analyzed for pH, ANC, and all major cations and anions. During storm events, pH and ANC decreases were observed in all streams, with ANC becoming negative several times in Paine Run. Base cation concentrations typically increased in Paine Run and Staunton River, but usually decreased in Piney River. Sulfate and nitrate concentrations generally increased in all streams. Antecedent baseflow ANC was found to be the best predictor of the minimum ANC. The data from more than 40 episodes on these streams (initiated by 25 different storm events) are interpreted to evaluate the relative importance of natural and anthropogenic sources of acidity to these acid-sensitive natural waters.

Effects of forest fire and drought on acidity of a base-poor boreal forest stream: similarities between climatic warming and acidic precipitation

In a boreal forest catchment in the Experimental Lakes Area in northwestern Ontario, wildfire caused an increase in the concentrations of strong acid anions and base cations of the stream. In the naturally base-poor Northwest (NW) Subbasin, a 1980 wildfire caused exports of strong acid anions to increase more than export of base cations, causing a 2.5 fold increase in the acidity of the stream. Mean annual stream pH declined from 5.15 prior to fire to 4.76 two years after fire. Acid-neutralizing capacity (ANC), calculated as the difference between total base cations and strong acid anions, decreased to 20% of pre-fire values. Sulfate and chloride were the strong acid anions responsible for the decline in ANC, increasing four-fold. While nitrate increased eleven-fold, concentrations were too low to significantly affect ANC. There was a significant correlation between weekly sulfate concentration and base cation concentration (r 2 = 0.83) in the two years after fire. Recovery of ANC was caused by the more rapid decline in concentration of sulfate than by changes in base cations. Drought produced a similar but weaker response than fire, with increased sulfate concentrations and decreased stream pH. Climatic warming that increases drought and fire frequency would have effects that mimic the impacts of acidic precipitation (i.e. higher sulfate concentrations and acidic stream waters). Areas which have higher concentrations of stored S from past acid precipitation or have large areas of peatlands in the watershed may have aggravated losses of S and H+ after drought and fire.

Predicting episodic stream acidification in the southeastern United States: Combining a long‐term acidification model and the end‐member mixing concept

The model of acidification of groundwater in catchments (MAGIC) was applied to data from the Panola Mountain Research Watershed located near Atlanta, Georgia, in the southern Piedmont physiographic province of the United States. In contrast to past applications, MAGIC was calibrated directly to two soil environments using information gained from an independent mixing model rather than to the stream water. A third soil environment, the deeper soil horizons which provide base flow, was identified from the mixing model, but its chemistry was assumed to be invariant during the forecast period, and hence it was not included in MAGIC. This mixing model identified soil environments that appear to be important in determining present stream water chemistry, determined the hydrologic routing parameters necessary for the model, and permitted predictions of stream water chemistry during future storm events. Annual average stream water acid neutralizing capacity (ANC) was predicted to decrease during the next 50 years in a manner largely consistent with a regional analysis of the nearby southern Blue Ridge province performed by the U.S. Environmental Protection Agency. The two upper soil layers, however, were predicted to acidify substantially within the next 20 years so that the stream water may become unsuitable for sensitive aquatic biota for much of the year, despite a positive annual average ANC. This approach, which combines a predictive model and a mixing model, provides testable hypotheses because actual soil environments are modeled; field experiments to test the processes contained in the model are suggested.

Photochemical degradation rates of tetraphenylborate and diphenylboric acid sensitized by dissolved organic matter in stream water

The photochemical degradation of tetraphenylborate (TPB) and diphenylboric acid (DPBA) was studied in stream water and humic acid solutions. The rates of indirect photolysis of TPB and DPBA were similar and directly proportional to the concentration of stream water dissolved organic matter (DOM) and humic acid for values < 10 mg/L. Direct photolysis of both organoborates was nondetectable during a 2-h irradiation period. Indirect photolysis rates varied only slightly from pH 6.0 to 9.0, but increased markedly below pH 6.0. Removal of dissolved oxygen increased reaction rates by a factor of two, indicating that the reaction mechanism does not involve singlet oxygen oxygenation.

PHOTOCHEMICAL DEGRADATION RATES OF TETRAPHENYLBORATE AND DIPHENYLBORIC ACID SENSITIZED BY DISSOLVED ORGANIC MATTER IN STREAM WATER

The photochemical degradation of tetraphenylborate (TPB) and diphenylboric acid (DPBA) was studied in stream water and humic acid solutions. The rates of indirect photolysis of TPB and DPBA were similar and directly proportional to the concentration of stream water dissolved organic matter (DOM) and humic acid for values < 10 mg/L. Direct photolysis of both organoborates was nondetectable during a 2-h irradiation period. Indirect photolysis rates varied only slightly from pH 6.0 to 9.0, but increased markedly below pH 6.0. Removal of dissolved oxygen increased reaction rates by a factor of two, indicating that the reaction mechanism does not involve singlet oxygen oxygenation.

Hydrogeochemical controls for inorganic aluminium in acidic stream and soil waters at two upland catchments in Wales

Results of two studies of acidic and acid sensitive catchments typical of upland Wales are presented. The streams draining these catchments are less acidic and contain lower inorganic aluminium concentrations than their soil counterparts. Within each soil horizon there are distinct linear or curvilinear relationships with H 1 and inorganic aluminium reactions. The stream water H 1 and inorganic aluminium chemistries are determined by mixing of these soil waters with a groundwater component not sampled during these studies except in a partially CO 2 degassed form in the stream at extreme baseflow conditions. While during the mixing processes within the soil/groundwater zones, inorganic aluminium may be regulated by simple solubility controls, no such controls are operative within the streams. The classical cubic relationship between the activities of Al 3+ and H + for the ion exchange reactions does not hold; a power term, which can vary from site to site and horizon to horizon in the range 1–3 is required. The implications for modelling studies are discussed.

Effects of temperature, filtration and container material on storage of an acid stream water

Precise measurements of the pH of an acid stream water (pH 4.8, 4 °C) have been made on filtered and unfiltered samples stored at three different temperatures over 15 d. Sub-samples stored in glass bottles had a significantly lower pH, by 0.02, than those stored in polythene bottles, presumably due to outgassing of CO2. Filtration did not affect the pH, but storage in glass bottles for 15 d introduced a variation of ±0.1 pH. Whereas the pH of samples stored at 10 and 20 °C did not change over a 2-week period, storage at 4 °C caused the pH to increase by 0.1. The temperature dependence of the pH could be predicted by assuming that it was controlled by the hydrolysis of aluminium, for which enthalpy data are available.

Aluminium solubility controls in acid waters: the need for a reappraisal

Stability diagrams have been frequently used to demonstrate aluminium solubility controls in acidic stream and soil waters. This paper shows that it is possible by this method to generate apparent controls using random numbers in place of stream chemistry data. Thermodynamic arguments demonstrate that a wide variety of reactions can produce relationships similar to Al(OH) 3 solubility controls. It is proposed that stability diagrams alone should be used with great caution in identifying aluminium solubility controls, taking care that their axes are independent. Thermodynamic solubility calculations should be used with due scepticism. Supplementary investigations should be used where possible to identify phases precipitating or dissolving.

Physiological response of brown trout (Salmo trutta) spawners and postspawners to acidic alminum-rich stream water

High immediate postspawning mortality due to inferior autumn water quality has been hypothesized to cause juvenilization in some brown trout populations in acidified areas. We exposed male and female spawners and female postspawners from a juvenile-dominated brown trout population to acidic streamwater (pH = 4.83, Ali = 240 μg L−1) and a limed control (pH = 5.70, Ali = 55 μg L−1) for 28 days in November and December, 1984. Water chemistry was monitored at least bi-daily, and physiological stress was assessed by analysis of plasma chloride, osmolality and haematocrit. Neither pronounced physiological stress nor mortality was observed at the control site. At the exposure site trout showed significant but moderate stress responses and 15 % died. The results are discussed in terms of potential population effects and physiological mechanisms, e.g., plasma volume reduction.

Acidification trends in Sweden

A Swedish hydrochemical monitoring program, which was started during the International Hydrological Decade (1965–1975), has been evaluated with respect to trends and regional differences in acidic deposition and stream water quality. Despite the more than twofold decrease in S emissions in Sweden since the early 1970's, there was only a marginal decrease in sulphate level in precipitation, indicating that long-range transport dominates precipitation chemistry. Trend analyses of stream water data gave practically no evidence that surface water quality had been changing since the late 1960's, i.e., no time lagged or accumulating effects of acidic deposition during past decades could be demonstrated. The difference between the wet deposition of S in southern and northern parts of Sweden was found to be smaller than previously reported. In the northern catchment areas, the input of S was considerably larger than the output. The statistical uncertainty of the trend estimates raises questions about the effectivity of present hydrochemical monitoring programs in detecting environmental changes.

Baseflow buffering of streamwater acidity in five mid-Wales catchments

Streamwater pH and concentrations of calcium, bicarbonate and aluminium have been monitored in two forest and three grassland catchments at the Plynlimon area of upland mid-Wales. Baseflow in all the streams is characterised by waters bearing calcium and bicarbonate and which are low in hydrogen ions and aluminium. Stormflow shows more complex chemical variation. Stormwaters are acidic, low in calcium and bicarbonate, and contain aluminium; except in the stream draining the mineralised grassland catchment. At this latter site, streamwater pH is relatively high and constant, even at high flows, and aluminium is not detected. Limited buffering of streamwater acidity is also observed in the streams draining the mineralised forest catchment and the agriculturally improved grassland catchment. There is little difference in the means and ranges of acidity between the stream draining the unmineralised part of the forest and the stream flowing from the unimproved unmineralised semi-natural grassland catchment. Mean concentrations of aluminium are almost three times higher in the forest stream. The streamwater data are discussed in relation to the chemistry of soil waters and vegetation canopy throughfall in the forest and grassland systems. The significance, to water quality, of the hydrological pathways operating in the two systems is also examined. The study shows that the presence of CaCO 3 in the bedrock, even on a small scale, and liming of the land in the catchment can both have a marked effect on stream water acidity. This result is important when remedial action in areas subject to catchment acidification is considered and demonstrates that it is difficult to generalise about catchment responses to acidic atmospheric inputs. The results also show that for catchments with similar soils and bedrock geology, those under coniferous forest do not necessarily have more acid streamwater than those under semi-natural grassland vegetation. Aluminium concentrations in the stream are not simply determined by Al(OH) 3 solubility controls as streamwater concentrations of aluminium for the semi-natural grassland catchment are only one third those for the forest catchment, even though soil types are the same.