Water chemistry and fish community responses to episodic stream acidification in Pennsylvania, USA

Five streams were studied on the Northern Appalachian Plateau of Pennsylvania from October 1988 through June 1989 to determine chemical changes that occur during episodic storm run-off and the responses of fish to these events. These second-order streams flowed through undisturbed, wooded, sandstone bedrock catchments with surface areas ranging from 500 to 1000 hectares. Median pH of precipitations was about 4.2, and among streams it ranged from 5.0 to 6.2. During storm events, pH declined by as much as 1.2 units and peak concentrations of total monomeric Al ranged from < 0.01 to 0.75 mg litre(-1). Organically bound A1 was generally a minor component of total monomeric A1. Wild brook trout (Salvelinus fontinalis) were found in all streams, although only a remnant population existed in the most acidic stream. Sculpins (Cottus bairdi or C. cognatus) were collected only in the two streams with the least severe episodes. Mortality of brook trout and sculpins in in situ bioassays ranged from 0 to about 80% among streams during acidic episodes and was positively related to concentrations of total dissolved Al. Radio-tagged brook trout moved downstream during episodes when Al reached toxic concentrations. Some displaced trout were found near groundwater seeps, where pH was higher and dissolved Al was lower than in the main channel.     

Reproductive status, blood chemistry, gill histology and growth of perch (Perca fluviatilis) in three acidic lakes

Perch (Perca fluviatilis L.) were sampled soon after spawning in three small acidic lakes (pH 4.3-6.1, Al(lab) 5-106 microg litre(-1), Ca2+ 0.01-0.08 mmol litre(-1)) and in one circumneutral lake (pH 5.9-6.4, Al(lab) 4-12 microg litre(-1), Ca2+ 0.06-0.07 mmol litre(-1)) in southern Finland. Due to the delayed spawning of perch in the acidic lakes, sampling in those lakes was performed later than in the reference lake. In spite of that, the gonadosomatic index (GSI) of males in all the acidic lakes was significantly greater than in the reference lake. Of the two lakes with similar low water pH, the effects on reproduction were more prominent in the lake with higher water Al content. The plasma Ca2+ concentrations of females in the acidic lakes were significantly smaller than in the females of the reference lake. The low female:male plasma Ca2+ ratio (1.0-1.32) depicted delay of spawning. Stress in perch in acidic water was also seen in elevated blood haematocrit values, especially in females. On the other hand, a low plasma Cl- level, a common response to acidic water in salmonids, was not detected in perch in the most acidic lakes. The amount of Al accumulated in the gill epithelium was highest in the most acidified lake with high Al concentration, but was also pronounced in a lake with low pH and low Al concentration.     

Evaluation of modified clay coagulant for sewage treatment

The use of modified clays as coagulants for sewage treatment was investigated in this study. The raw clays were montmorillonites K10 and KSF, and were modified by polymeric Al or Fe and/or Al/Fe mixing polymeric species. The comparative performance of modified clays and aluminium sulphate and ferric sulphate were evaluated in terms of the removal of turbidity, suspended solids, UV(254)-abs, colour, and total and soluble CODs. The results demonstrated that after being modified with mixing polymeric Al/Fe species, two montmorillonite clays possess greater properties to remove the particles (as suspended solids) and organic pollutants (as COD and UV(254)-abs) from the sewage and to enhance the particle settling rate significantly.     

Influence of some additives to aluminium species distribution in aluminium coagulants

Aluminium ions hydrolyse and polymerise into different species in water. Main aluminium species in aluminium coagulant solutions are monomeric Al species (Al1) and polymeric Al species Al13O4(OH)24(7+) (Al13). The aluminium species distribution in coagulant solutions can be influenced by many parameters. This paper studies influences of concentrations of total aluminium species (Al(t)) and other species--OH-, polysilicic acid and ferric species, which were added in aluminium coagulant solutions, on the aluminium species distribution through 27Al nuclear magnetic resonance (NMR) analysis. Results show that only Al1 and no Al13 exist in coagulant solutions at higher Al(t) concentrations (over 1 mol l(-1)), while both species exist at lower Al(t) concentrations (0.1 mol l(-1)). The increase of OH/Al value (molar ratio) increases the concentration of Al13 in coagulant solutions, while the addition of polysilicic acid and ferric species decreases the concentration of Al13.     

Artificial acidification of a non-acidic and an acidic headwater stream in Maine, USA

Two headwater streams with low DOC and different pHs (4.5-4.8 and 5-6.5) were acidified with H2SO4 to pH 4.1 and 4.5, respectively, for 24-h periods. Neutralization of the added acid occurred by protonation of ANC (HCO3-dominated in the higher pH stream), desorption of Ca (< 15 microeq litre(-1)) and Mg (<6 microeq litre(-1)), and desorption and dissolution of AL (<250 microg litre(-1)) from the stream bed. The concentrations of dissolved organic carbon (DOC) remained constant within the experimental reaches. The concentrations of Na, K an H4SiO4 also remained constant, indicating no detectable increase in the rate of chemical weathering in the stream bed. After acid addition was stopped, concentrations of Ca, Mg and Al decreased to below background, indicating reversible ion exchange as the principal mechanism for the mobility of Ca and Mg and to a lesser extent for Al. Repeated acidifications indicated that significant regeneration of cations on the exchange surfaces of the stream substrate occurs rapidly.     

An investigation of the impact of afforestation on stream-water chemistry in the Loch Dee catchment, SW Scotland

The impact of conifer afforestation on stream-water chemistry was investigated in the acidified catchment of Loch Dee, SW Scotland. Long-term trends in stream-water chemistry were evaluated during a period of forest growth from age 6 to 17 years. A significant increase was observed for pH (0.2 units) and a significant decline for aluminium (0.05 mg litre(-1)), sulphate (1.2 mg litre(-1)) and nitrate (0.02 mg litre(-1)) concentrations. The long-term decrease in stream-water acidity was ascribed to the marked reductions in sulphur depositions during the 1970s and early 1980s. There was no evidence that this response had been attenuated by afforestation, the improvements in stream-water chemistry being of a similar magnitude to those recorded in nearby moorland lochs and exceeding that in an adjacent moorland-catchment stream. The lack of a clear forest acidification effect is consistent with deposition-model estimates which show the increased scavenging of occult and dry deposition by the growing forest to be small at this site (相似文献   

The effects of intermittent exposure to suspended solids and turbulence on three species of freshwater mussels

A laboratory experiment was performed to evaluate the effects of intermittent suspended solids exposure on the unionid clams Quadrula pustolosa, Fusconaia cerina and Pleurobema beadleanum. Intermittent impacts of this type are important effects of commercial navigation traffic in freshwater. Clams were cyclically exposed to turbulence alone or accompanied by 600-750 mg litre(-1) of suspended inorganic solids for 9 days. Clams exposed to suspended solids every 3 h reduced their metabolic rate but did not shift from the mainly protein based catabolism of controls. Feeding impairment was apparently compensated for by a reduction in metabolic demand. Conversely, clams exposed every 0.5 h to suspended solids shifted to virtually complete reliance on non-protein body stores as indicated by O:N values averaging 197.     

Trout farm effluents: characterization and impact on the receiving streams

Effluents from three rainbow trout (Oncorhynchus mykiss) farms located in Northern Portugal were characterized and their impact on the receiving streams was evaluated. Mean fish productions in the studied fish farms were 15, 55 and 500 t of trout per year, respectively. The feeding water was abstracted from Fornelo, Inha and Coura Rivers, at flow rates ranging from 1.2 (15 t year(-1) fish farm) to 4.8 litre s(-1) per ton annual fish production (500 t year(-1) fish farm). As the water flows through the farms, net variations in the chemical characteristics were observed: a mean reduction in the dissolved oxygen (DO) concentration between 0.7 and 2.4 mg litre(-1); mean increases between 1.9 and 3.2 mg CaCO3 litre(-1) for total alkalinity, between 0.9 and 14 mg litre(-1) for BOD5, between 0.27 and 1.46 mg litre(-1) for ammonia nitrogen (NH4-N), between 0.060 and 0.579 mg litre(-1) for soluble phosphorus (PO4-P) and less than 16 mg litre(-1) for suspended solids; variations in the pH value and nitrate nitrogen concentration were not statistically significant (p<0.05). At the 500 t year(-1) fish farm it was also possible to detect net increases of total hardness (3.2 mg CaCO3 litre(-1)), electric conductivity (19 mS cm(-1)) and permanganate value (3.6 mgO2 litre(-1)). At the other farms net variations in these parameters were not significant. Net mass flow variations reported to the annual fish production are presented. The DO mass flow decreased, on average, between 255 and 549 g t(-1) of fish per day. The mean daily BOD5 increase ranged from 353 to 1510 g t(-1) of fish. The corresponding ranges for the other parameters were 105-157 g t(-1) for NH4-N, 24-62 g t(-1) for PO4-P, 348-1035 g CaCO3 t(-1) for total alkalinity and 224 x 10(6)-506 x 10(6) t(-1) for mesophilic bacteria. Daily net variations of suspended solids, total hardness, electric conductivity and permanganate value were below 1753 g t(-1), 342 g CaCO3 t(-1), 2081 mS cm t(-1) and 392 gO2 t(-1), respectively. Longitudinal concentration profiles for the most relevant parameters show the impact of the effluent discharges on the physico-chemical and bacteriological river water quality downstream from the trout farms. Analyzing the situations from a purely chemical point of view, the polluted stretches were 3, 5 and 12 km long downstream from the effluent discharges, respectively. The microbiological contamination extended over longer distances.     

Characterization of polycyclic aromatic hydrocarbons in urban stormwater runoff flowing into the tidal Anacostia River, Washington, DC, USA

To investigate the sources, fate, and transport dynamics of PAHs (polycyclic aromatic hydrocarbons) in stormwater runoff that is a leading source of pollution in urban watersheds, storm and base flow samples were collected in six branches along the lower Anacostia River. PAHs in storm flow (1510-12,500 ng/L) were significantly enriched in the particle phase, which accounted for 68-97% of the total PAHs. It suggests that reducing particles in stormwater using post-treatment system would decrease PAHs considerably. The solid-water distribution coefficients (KD) of PAHs in the storm flow samples were up to 340 times higher than predicted values. A greater portion of high molecular weight PAHs and their distribution patterns indicate higher contribution of automobile originated pyrogenic PAHs. Total suspended solids in storm flow had a positive relationship with flow rates and exceeded benchmark level for the protection of aquatic biota in some samples.     

Assessment of the contribution of sewer deposits to suspended solids loads in combined sewer systems during rain events

Within the French observatories network SOERE “URBIS,” databases of continuous turbidity measurements accumulating hundreds of events and many dry weather days are available for two sites with different features (Clichy in Paris and Ecully in Lyon). These measurements, converted into total suspended solids (TSS) concentration using TSS–turbidity relationships and combined with a model of runoff event mean concentration, enable the assessment of the contribution of sewer deposits to wet weather TSS loads observed at the outlet of the two watersheds. Results show that the contribution of sewer deposits to wet weather suspended solid’s discharges is important but variable (between 20 and 80 % of the mass at the outlet depending on the event), including a site allegedly free of (coarse) sewer deposits. The uncertainties associated to these results are assessed too.     

The impact of aluminium on green algae isolated from two hydrochemically different headwater streams, Bavaria, Germany

Two strains of green algae (Scenedesmus sp. and Chlorella sp.) have been isolated from two headwater streams differing in stream chemistry (Eger river: acidic, low alkalinity; Püttlach river: slightly alkaline, high alkalinity). In this study the growth response of these indigenous algae to increased concentrations of aluminium (Al) is investigated. A semi-continuous culture technique was used for Al-toxicity studies. Algal response was determined by calculating growth rates from turbidity and cell counts. Those Al-species which are well known to be toxic were estimated by equilibrium calculations using the WATEQ computer program (Truesdall & Jones, 1973). The pH-value of the culture media was usually pH=5, except for one of the test series. Tested concentrations ranged from c=4 to 220 micromol litre(-1). The isolated strains of green algae were highly sensitive to increased Al-concentrations. The strain isolated from the Püttlach river was more sensitive than the Eger river algae. A total growth inhibition occurs at Al-concentrations of c=4 micromol litre(-1) if the whole Al was added at once. If Al was added gradually into the growth media the response of the algae was delayed. This is due to Al-enrichment in cells. In our long term toxicity studies, growth inhibition occurs even at nearly neutral pH-conditions (pH=6.5) although Al toxicity is expected at pH-values less than pH=5.5. This new result confirms the need of long-term studies in continuous cultures under simulated natural conditions. This might be the only way to achieve valid conclusions about the fate and the toxicity of environmental pollutants.     

Influence of soil hydrological pathways on stream aluminium chemistry at Llyn Brianne, mid-wales

Storm runoff in afforested catchments at Llyn Brianne is acidic and Al-bearing. At baseflows, stream water is well-buffered with low Al levels. This paper presents the results of a study into how hydrological pathways account for these variations in stream-water chemistry. The investigation was carried out in the LI1 catchment; a 0.4-ha subcatchment covered by stagnohumic gley soils was monitored between October 1988 and September 1989. An instrumented hill-slope was established to identify the hydrological pathways that control the hydrochemistry of storm runoff draining from the subcatchment. Perched watertables developed in the surface horizons of the soil during storm episodes and produced lateral flow above the impeding subsoil. This near-surface flow path was responsible for generating acid, Al-rich storm runoff. Some water drained vertically through the soil profile into the underlying slope drift; seepage from groundwater in the drift sustained baseflows. Buffering reactions in the groundwater zone reduced the acidity and Al levels of baseflows. These hydrochemical characteristics are likely to be representative of other areas of stagnohumic gley soils, which cover 19% of the LI1 catchment: these soils may therefore provide a substantial source of acid, Al-bearing storm runoff in LI1 and similar afforested catchments.     

Chemical and biological effects of acid, aluminium and lime additions to a Welsh Hill-stream

Chemical and biological responses to simultaneous additions of acid, aluminium and lime were investigated in contiguous 250m-reaches of a chronically acidic stream in Wales. Treatments were applied for 24 h, and from the upstream end were as follows: zone A-untreated, pH 5.0, 0.37 mg litre(-1) filterable Al; zone B-acidified to pH 4.5, 0.40 mg Al litre(-1) (47% of Al attributed to release from the stream bed due to acid additions); zone C-acidified to pH 4.5 and Al dosed to 0.67 mg litre(-1); zone D-dosed with limestone slurry, resulting in pH 7.2, 0.13 mg Al litre(-1). In all reaches, the chemistry of the interstitial water at depths of 0.15 and 0.3 m never fell below pH 5.5, with corresponding decreases in Al and increases in base cation concentrations. Brown trout, Salmo trutta, and crayfish, Austropotamobius pallipes, held in the stream showed decreases in plasma [Na(+)] and haemolymph [Na(+)], respectively, in all acidic zones (A, B, C): these responses were mitigated by liming (zone D). Thus both chronic and simulated episodic levels of pH and dissolved Al were sub-lethally toxic to test species of aquatic fauna. This experiment also demonstrates a stream bed source/sink of Al, and the availability of a possible refuge from acidic surface waters within the substratum.     

The influence of plantation forestry on the pH and aluminium concentration of upland welsh streams: a re-examination

Previous studies relating forest presence to stream acidity and aluminium concentration were based on small numbers of catchments, often precluding the elimination of confounding influences on stream chemistry, such as geology or soil type. Spatial patterns in aluminium and pH data from 113 Welsh catchments of contrasting land use were therefore analysed in three different ranges of acid sensitivity (< 10, 10-15, 15-25 mg CaCO(3) litre(-1) total hardness). In each range, pH declined and aluminium increased significantly with increasing percentage forest cover. There was no evidence that the relationships reflected a spurious effect of forest location. Where aluminium concentrations were elevated under forest in a sub-set of 13 streams, aluminium was present predominantly in the labile form, most toxic to fish. Regressions of pH and aluminium on percentage forest cover provide a useful method of assessing the amount of forest in Welsh catchments which might give rise to given chemical conditions (e.g. pH <6, Al > 80 microg litre(-1)), though some difficulties are likely in accurately specifying the conditions desirable for fish or other biota.     

Chemistry of soil solutions under different kinds of vegetation in the vicinity of a thermal power station

The influence of atmospheric deposition on the chemical characteristics of soil solutions in a small catchment area in NW Spain was studied. The soils, developed from slates, were sampled from seven sites supporting different forms of vegetation (deciduous and pine forest and heath). Soil solutions were extracted, by the column displacement method, from soil samples collected monthly from March 1992 until November 1993. The solutions were acidic with a low content of basic cations. The most common ions in all horizons were Cl(-) and Na(+), due to marine influence. In the surface horizons (0-10 cm), relatively high concentrations of SO(2-)4 (150-380 micromol litre(-1)) and Zn (approximately 2 micromol litre(-1)) were obtained, with good correlation between the two ions. These results, along with the prevalence of inorganic forms of Al (50-90% of total Al), were related to the effects of acidic deposition in the catchment area. The more rapid breakdown of litter in the soils under deciduous forest explains the greater ionic concentrations obtained in these solutions.     

Effects of aluminium ion on root growth, cell division, and nucleoli of garlic (Allium sativum L.)

The effects of different concentrations of aluminium chloride on root growth, cell division, chromosome morphology and nucleoli in root tip cells of garlic (Allium sativum L.) were studied. The concentrations of aluminium chloride (AlCl(3)) used were 10(-5), 10(-4), 10(-3), 10(-2) and 10(-1) m. Aluminium chloride inhibited root growth and caused mitotic irregularities, including c-mitosis, anaphase bridges, and chromosome stickiness. Nucleolar material was extruded from the nucleus into the cytoplasm. Extrusion was observed in inner root meristem and root cap cells. The poisoning by Al(3+) of the root tip cells of Allium sativum may result from the uptake and accumulation of Al and inhibition of Ca uptake, distribution of physiological activities of calmodulin (CaM) and the inhibition of some enzyme reactions.     

Phosphorus loads from different urban storm runoff sources in southern China: a case study in Wenzhou City

Storm runoff from six types of underlying surface area during five rainfall events in two urban study areas of Wenzhou City, China was investigated to measure phosphorus (P) concentrations and discharge rates. The average event mean concentrations (EMCs) of total phosphorus (TP), total dissolved phosphorus (TDP), and particulate phosphorus (PP) ranged from 0.02 to 2.5 mg?·?L^?1, 0.01 to 0.48 mg?·?L^?1, and 0.02 to 2.43 mg?·?L^?1, respectively. PP was generally the dominant component of TP in storm runoff, while the major form of P varied over time, especially in roof runoff, where TDP made up the largest portion in the latter stages of runoff events. Both TP and PP concentrations were positively correlated with pH, total suspended solids (TSS), and biochemical oxygen demand (BOD)/chemical oxygen demand (COD) concentrations (p?<?0.01), while TDP was positively correlated with BOD/COD only (p?<?0.01). In addition, the EMCs of TP and PP were negatively correlated with maximum rainfall intensity (p?<?0.05), while the EMCs of TDP positively correlated with the antecedent dry weather period (p?<?0.05). The annual TP emission fluxes from the two study areas were 367.33 and 237.85 kg, respectively. Underlying surface type determined the TP and PP loadings in storm runoff, but regional environmental conditions affected the export of TDP more significantly. Our results indicate that the removal of particles from storm runoff could be an effective measure to attenuate P loadings to receiving water bodies.     

Emission reduction of aluminium anodising industry by production of Mg2+-Al3+-SO4(2-) -hydrotalcite-type compound

The synthesis of Mg(2+)-Al(3+)-SO(4)(2-)-hydrotalcite-type compound from the acid wastewaters of the aluminium anodising industry has been studied as a possible way of reducing the emissions to the environment, recovering simultaneously resource materials as a valuable mineral. The process of synthesis was carried out using rinse wastewater solutions generated from the anodising treatment when a cascade rinsing system is employed. The method of co-precipitation at constant pH was employed for such a process, using MgO as a source of magnesium. The synthesis was studied as a function of precipitation pH (8-10) and flow rate of reagent mixture (5-30 ml min(-1)). High pH of precipitation and low flow rate of reagent mixture (5-15 ml min(-1)) were found optimal to improve the crystallinity of the synthesised product. The mineral characterisation was performed using X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric analysis and differential thermal analysis, all of which indicated characteristics typical of the desired compound. Almost 100% of the aluminium initially present in the acid wastewater solutions was recovered in the form of Mg(2+)-Al(3+)-SO(4)(2-)-hydrotalcite-type compound.     

Bioaccumulation of cadmium by the freshwater isopod Asellus aquaticus (L.) from aqueous and dietary sources

Experiments were conducted to determine the kinetics and relative importance of aqueous and dietary uptake of cadmium by the freshwater isopod Asellus aquaticus (L.). Test animals were exposed during 30 days to aqueous Cd in a continuous flow system (exposure levels: 0.2 - 10 microg litre(-1)) and kept on a diet of previously contaminated Elodea sp. (range of Cd concentrations: 2-350 microg g(-1), dry weight). Preceding semi-static experiments on dosage-control of the dietary factor revealed a rapid uptake of Cd by Elodea, with relatively high concentration factors (CF), which ranged from 4.8 to 5.5 (dry weight log (CF) after 16 days). For Asellus uptake from water appeared to be the predominant route. Highly significant bioconcentration of cadmium from water was observed in the animals, even at exposure levels below 1.0 microg litre(-1). In the various treatments, direct uptake from water accounted for 50-98% of the body burdens after 30 days exposure. The experimental results were described with a first order one-compartment bioaccumulation model. Model parameter estimates (mean +/- standard error) were obtained for rate constant of uptake (560 +/- 110 day(-1)), rate constant of elimination (0.032 +/- 0.017 day(-1)) and assimilation efficiency of Cd uptake from food (1.1 +/- 0.7%). The (dry weight) bioconcentration factor (BCF) and bioaccumulation factor (BAF) for extrapolated steady state conditions were estimated at 18 000 (BCF) and 0.08 (BAF). Experiments conducted at two different pH levels (5.9 versus 7.6) revealed no significant effects of pH on the uptake of aqueous Cd by the isopods. The results are discussed in relation to their potential significance to the field situation.     

Caesium selectivity and fixation by vermiculite in the presence of various competing cations

Caesium selectivity coefficients (k(G)) that were determined with respect to Na-, Mg-, Ca-, Sr- and Ba-ions, for Kent and Libby vermiculites,ranged from 4.8 to 11 (litres/mol) [Formula: see text], much higher than those with respect to K- and NH(4)-ions (0.01 to 0.06), indicating the high affinity of vermiculite for the weakly hydrated cations. Higher K(G) values were also found for low and extremely low Cs concentrations. Vermiculite samples were very effective in removing (137)Cs from solutions containing traces of (137)Cs (4 ng litre(-1)) and extremely higher quantities of K-, NH(4)-, Na-, Mg- and Ca-ions (500 mg litre(-1)). 0.5N chloride solutions of H, NH(4), K, Na, Mg and Ca were unable to remove Cs from Cs-saturated v vermiculite samples which had undergone heating at 110 degrees C. Significant quantities (50-65%) of fixed Cs were removed from these samples only after treatment with strong acids. The high preference and fixing ability of vermiculite for Cs suggests the use of this mineral as a radioactive Cs decontaminating agent.