Distribution of trace elements in soils surrounding the El Teniente porphyry copper deposit,Chile: the influence of smelter emissions and a tailings deposit

In the area surrounding the El Teniente giant porphyry copper deposit, eight soil sites were sampled at three depth levels in the summer 2004. The sites were selected for their theoretical potential of being influenced by past SO₂ emissions from the smelter and/or seepage from a now idle tailings impoundment. The soil mineralogy, grain size distribution, total organic matter contents, major element composition, cation exchange capacity, and Cu, Mo, Pb, Zn, As and SO₄ ²⁻ concentrations were determined for all samples after nitric acid extraction and separate leaches by ammonium acetate (pH 7) and sodium acetate (pH 5). For water rinses, only Cu could be determined with the analytical set-up used. Cu and SO₄ ²⁻ enrichment in topsoils was found at six sites either downwind from the smelter or within the combined influence of the smelter and the tailings impoundment. Both elements were released partially by ammonium and sodium acetate extractions. Due to the scarce background trace element concentrations of soil and rock outside the immediate mine area, assessment of trace element mobility for Mo, Zn, Pb and As was difficult. Arsenic was found to be concentrated in soil horizons with high smectite and/or organic matter contents. Mo appears to be linked to the presence of windblown tailings sediment in the soils. Mobilization of Mo, Zn, and As for the acetate extractions was minimal or below the detection limits for the AAS technique used. The presence of windblown tailings is considered to be an additional impact on the soils in the foothills of the El Teniente compound, together with the potential of acidity surges and Cu mobilization in topsoils after rainfalls. Two sites located at the western limit of the former SO₂ saturated zone with strongly zeolitized soils and underlying rock did not show any Cu or SO₄ ²⁻ enrichment in the topsoils, and remaining total trace element concentrations were below the known regional background levels.     

Acidification and Trace Metals of Lakes in Taiwan

One hundred and eighty lakes, ponds and reservoirs in Taiwan, and the offshore islands have been investigated since 1985. Effects such as warming/cooling, mixing, photosynthesis and respiration on pH have been identified. These effects were found to be less profound than those resulting from the geology. Since there is little rain or lake water pH data available prior to 1970, it was necessary to use proxy data in order to ascertain the history of lake acidification. In this study, we present data based on diatoms in a sediment core collected from a lake in the remote subalpine region of southern Taiwan. The acidity of this lake water was found to have increased since 1900. We measured the concentrations of 55 chemical species in lake water samples. In addition, concentrations of 26 chemical species were obtained from sediments. Conductivity, alkalinity (HCO₃ ^?), most other major and minor chemical species, as well as the non sea-salt SO₄/Na ratio in lake water clearly decrease with elevation. Distribution of pH is similar, although the trend is less clear. Distribution of trace metals, however, shows a different trend as anthropogenic pollution, diagenetic reduction and lake acidification are at play.     

巴丹吉林沙漠及其东南边缘地区水化学和环境同位素特征及其水文学意义

通过对巴丹吉林沙漠东南部湖水和南缘地区地下水离子化学成分及其环境同位素分析,初步探讨了沙漠地区湖水和地下水之间补给的关系。沙漠湖水的离子化学特征显示沙漠东南部湖泊的演化趋势:微咸湖-咸水湖-盐水湖。显著不同的盐度、CO₃^2-和HCO₃^-含量以及地质资料都表明,沙漠北部较大的湖泊和东南部的湖泊被一地形上的褶皱隆起阻隔而形成了不同的地下水补给体系。环境同位素的分析结果表明,巴丹吉林沙漠东南部的湖泊和地下水与沙漠东南边缘地区的地下水有着相似的蒸发趋势,暗示南缘地区的地下水和沙漠东南部地区湖泊之间存在一定的联系。同其他干旱地区地下水的同位素结果进行对比显示,雅布赖地区和沙漠地区的地下水应该是埋深较浅的地下潜水。因本次研究结果不支持单一远源或者深层地下水补给的观点,故推断沙漠东南部地区以及南缘地区的地下水主要是当地雨量丰沛时期的降水及南缘低山降水下渗补给的。     

The onset of anthropogenic activity recorded in lake sediments in the vicinity of the Horne smelter in Quebec,Canada: Sulfur isotope evidence

Contents and δ³⁴S values of several S compounds, enumerations of S-reducing bacteria (SRB) and Fe-reducing bacteria (IRB), and Fe, Pb and In concentrations were determined for ²¹⁰Pb-dated sediment cores from two lakes in Quebec, Canada. Both lakes are located approximately 70 km downwind of the Horne smelter and refinery in Rouyn-Noranda. Increases in Fe, Pb and In concentrations and a decrease in the δ³⁴S values of total S in both lake sediment cores coincide with the start-up of the smelter in 1927. The shift towards more negative δ³⁴S values was primarily caused by an increase in the extent of S isotope fractionation during bacterial (dissimilatory) SO₄ reduction due to SO₄ loading of the lakes after smelting began. Consequently, an enhanced accumulation of ³²S-enriched reduced inorganic S compounds is evident in the sediments. δ³⁴S values of organic S in the sediments decreased only slightly due to the smelter emissions between 1930 and 1980. Hence, due to the sulfide depositing mechanisms, S isotope ratios constitute a useful tracer recording the onset of S pollution in sediments of the two previously SO₄-limited lakes investigated. In contrast, total S concentrations alone are not reliable indicators for anthropogenic S loading in lake sediment records.     

Influence of emission from copper–nickel smelters on the chemical composition of lake water: Acidification forecast

The influence of the emission of sulfur dioxide and solid substances from Pechenganickel and Severonickel copper–nickel combines (Murmansk oblast) on the chemical compositions of lake water and the development of acidification is analyzed. The temporal dynamics of ∼100 lakes, studied in 1990, 1995, 2000, 2005, 2009, and the response of the chemical composition of the lake water to the impact of acid-forming substances depending on the load level (the distance of combines), geologically controlled sensitivity of catchment areas of the lakes studied to acid deposition, and the lake areas is discussed. The likely further changes in sulfate concentration and pH value in the lake water under the scenarios of increase/decrease of sulfur dioxide emissions from smelter are estimated.

     

Hydrochemistry of Salt Lakes of the Qinghai-Tibet Plateau, China

The authors have carried out scientific investigations of salt lakes on the Qinghai-Tibet Plateau since 1956 and collected 550 hydrochemical data from various types of salt lakes. On that basis, combined with the tectonic characteristics of the plateau, the hydrochemical characteristics of the salt lakes of the plateau are discussed. The salinity of the lakes of the plateau is closely related to the natural environment of lake evolution, especially the climatic conditions. According to the available data and interpretation of satellite images, the salinity of the lakes of the plateau has a general trend of decreasing from north and northwest to south and southeast, broadly showing synchronous variations with the annual precipitation and aridity (annual evaporation/annual precipitation) of the modern plateau. The pH values of the plateau salt lakes are related to both hydrochemical types and salinities of the lake waters, i.e., the pH values tend to decrease from the carbonate type → sodium sulfate subtype → magnesium sulfate subtype → chloride type; on the other hand, a negative correlation is observed between the pH and salinities of the lakes. Geoscientists and biological limnologists generally use main ions in salt lakes as the basis for the hydrochemical classification of salt lakes. The common ions in salt lakes are Ca²⁺, Mg²⁺, Na⁺, K⁺, Cl^? SO₄ ^2?, CO₃ ^2?, and HCO₃ ^?. In this paper, the Kurnakov-Valyashko classification is used to divide the salt lakes into the chloride type, magnesium sulfate subtype, sodium sulfate subtype and carbonate type, and then according to different total alkalinities (K _C = Na₂CO₃ + NaHCO₃/total salt × 100%) and different saline mineral assemblages, the carbonate type is further divided into three subtypes, namely, strong carbonate subtype, moderate carbonate subtype and weak carbonate subtypes. According to the aforesaid hydrochemical classifications, a complete and meticulous hydrochemical classification of the salt lakes of the plateau has been made and then a clear understanding of the characteristics of N–S hydrochemical zoning and E-W hydrochemical differentiation has been obtained. The plateau is divided into four zones and one area. There is a genetic association between certain saline minerals and specific salt lake hydrochemical types: the representative mineral assemblages of the carbonate type of salt lake is borax (tincalconite) and borax-zabuyelite (L₂CO₃) and alkali carbonate-mirabilite; the representative mineral assemblages of the sodium sulfate subtype are mirabilite (thenardite)-halite and magnesium borate (kurnakovite, inderite etc.)-ulexite-mirabilite; the representative mineral assemblages of the magnesium sulfate subtype are magnesium sulfate (epsomite, bloedite)-halite, magnesium borate-mirabilite, and mirabilite-schoenite-halite, as well as large amount of gypsum; The representative mineral assemblages of the chloride type are carnallite-bischofite-halite and carnallite-halite, with antarcticite in a few individual salt lakes. The above-mentioned salt lake mineral assemblages of various types on the plateau have features of cold-phase assemblages. Mirabilite and its associated cold-phase saline minerals are important indicators for the study of paleoclimate changes of the plateau. A total of 59 elements have been detected in lake waters of the plateau now, of which the concentrations of Na, K, Mg, Ca, and Cl, and SO₄ ^2?, CO₃ ^2?, and HCO₃ ^? ions are highest, but, compared with the hydrochemical compositions of other salt lake regions, the plateau salt lakes, especially those in the southern Qiangtang carbonate type subzone (I₂), contain high concentrations of Li, B, K, Cs, and Rb, and there are also As, U, Th, Br, Sr, and Nd positive anomalies in some lakes. In the plateau lake waters, B is intimately associated with Li, Cs, K and Rb and its concentration shows a general positive correlation with increasing salinity of the lake waters. The highest positive anomalies of B, Li, Cs, and K center on the Ngangla Ringco Lake area in the western segment of the southern Qiangtang carbonate type subzone (I₂) and coincide with Miocene volcanic-sedimentary rocks and high-value areas of B, Li, and Cs of the plateau. This strongly demonstrates that special elements such as B, Li, and Cs on the plateau were related to deep sources. Based on recent voluminous geophysical study and geochemical study of volcanic rocks, their origin had close genetic relation to anatectic magmatism resulting from India–Eurasia continent–continent collision, and B–Li (-Ce) salt lakes in the Cordillera Plateau of South America just originated on active continental margins, both of which indicate that global specific tectonically active belts are the main cause for the high abundances of B, Li, and Cs (K and Rb) in natural water and mineralization of these elements.     

Water quality in pit lakes in disseminated gold deposits compared to two natural, terminal lakes in Nevada

 Within the next 10–15 years, over 35 mines in Nevada will have a lake in their open pit mines after dewatering and cessation of mining. Of the ten past or existing pit lakes at eight different gold mines for which temporal data are available, most had near neutral pH, yet most had at least one constituent (e.g., As, SO₄, TDS) that exceeded drinking water standards for at least one sampling event. Most samples from pit lakes had TDS exceeding drinking water standards, but lower than that in the natural Pyramid (TDS≈5,500 mg/l) and Walker (TDS≈14,000 mg/l) Lakes. In the past century, salinity increased in both natural, terminal lakes, in part due to irrigation withdrawals and evapoconcentration. The salinity in the pit lakes may also increase through time via evapoconcentration. However, water balance models indicate that up to 132% (Walker Lake) of the total yearly inflow evaporates from the terminal lakes, whereas steady-state may be reached in the pit lakes modelled, where evaporative losses account for only ≈6% of the total pit lake volume annually and ≈100% of the net inflow (groundwater inflow minus outflow, precipitation and runoff into the lake). The effects of evapoconcentration are expected to be less significant at most pit lakes than at the natural, terminal lakes because (1) evaporation rates are lower at many pit lakes because they are located at higher elevations than the terminal lakes, and (2) the surface area to depth ratio of the pit lakes is >1000 times smaller than that of the terminal lakes. Received: 1 March 1999 · Accepted: 13 April 1999     

Hydrogeochemical investigation of Küçük Menderes River coastal wetland,Selçuk–Izmir,Turkey

Küçük Menderes River forms a rich coastal wetland inside in the Selçuk plain. Three saline/brackish lakes, one swamp and Küçük Menderes River are these wetlands’ components. Alkaline-slightly alkaline type lakes are recharged from precipitation and karstic springs that discharge from marble-schist and marble-alluvium contacts in the northern and southern parts of the study area. Water types of the wetland are Na–Cl and Na–Ca–Mg–HCO₃–Cl in both rainy and dry seasons. Both seawater intrusion and evaporation, as being the sources of the ions, justify the presence of Na–Cl, Na–SO₄ and Cl–SO₄, in the wetland water. Environmental isotopes were used to identify the relationship between wetland and groundwater in the Selçuk plain. The δ¹⁸O and δD composition of wetland area samples have changed between ?6.42 to ?4.56‰, and ?36.40 to ?23.80‰, respectively. The lakes and rivers are plotted on the mixing line by slope of 5.2 and these data indicate that wetland is affected from seawater intrusion. The recharge area that was sampled in order to compare the wetland has Ca–HCO₃ water type with a neutral-slightly alkaline pH values and the main hydrogeochemical process is weathering the different types of silicates. Iron, manganese and selenium are the dominant minor ions due to the high biological activities and organic matters in the lakes. There are two contamination risks for this wetland: (1) waste disposal site and (2) water treatment plant where the purified waters are released into the river. EC, Al, As, Cd, Cu, Fe and Zn values exceed those of aquatic life standards. In the near future these sites will pose a danger for wetland wild life and surrounding irrigation water suppliers.     

Rare earth element fractionation during the precipitation and crystallisation of hydrous ferric oxides from anoxic lake water

An enrichment of light rare earth elements (LREE) is characteristic for most of the acidic, Fe- and SO₄-rich pit lakes and groundwaters in the lignite mining area of Lower Lusatia (Germany). One of these acidic lakes – the pit lake “RL 1223” – has a strong thermal and chemical stratification. The upper water layer (0–9 m) shows pH values of about 3 during all seasons. The monimolimnion (10–17 m) of the lake is anoxic and has pH values of about 7. The rare earth element (REE) patterns of the upper lake water show enriched LREE (La_N/Yb_N = 1.6) whereas the opposite patterns (depletion of LREE, La_N/Yb_N = 0.4) are found in the anoxic water of the monimolimnion. Experiments were conducted to observe the behaviour of REE during Fe oxidation in water from the monimolimnion (depth 14 m). The sampled monimolimnion water was placed in plastic bottles, and the changing water chemistry was observed for 40 weeks after sampling. Due to the initial anoxic conditions almost all Fe precipitated in the investigated water, and the pH value decreased from about 7 to 3 during the oxidation. The Fe precipitates are identified as ferrihydrite which is transformed into goethite within the oxidation process. Stable pH conditions (pH 3.0) were reached after about 10 weeks of oxidation.The original REE patterns of the investigated water are generally reflected in the Fe precipitates collected at the beginning of the experiment as well as after up to 40 weeks of oxidation. However, in the corresponding water LREE were temporally enriched with a maximum La_N/Yb_N ratio of 1.0 and a maximum La_N/Sm_N ratio of 2.3 after 6 weeks of oxidation time (pH 3.8–4.9). Although complex geochemical changes took place between the start and the end of the experiment REE patterns observed at these points in time are nearly identical. These differences of the REE pattern can be explained by the sampling procedure. The experimental findings can be transmitted to the mining dump aquifers of the study area where geochemical conditions comparable to the experimental oxidation time from 3 to 6 weeks are found and hydrous ferric oxides are precipitating. Groundwater passing through the mining dumps can preferentially desorb LREE from the Fe precipitates and display the typical LREE enrichment and carry it to the epilimnion of the acidic pit lakes in Lower Lusatia.     

Chemistry of snow and lake water in Antarctic region

Surface snow and lake water samples were collected at different locations around Indian station at Antarctica, Maitri, during December 2004–March 2005 and December 2006–March 2007. Samples were analyzed for major chemical ions. It is found that average pH value of snow is 6.1. Average pH value of lake water with low chemical content is 6.2 and of lake water with high chemical content is 6.5. The Na⁺ and Cl^? are the most abundantly occurring ions at Antarctica. Considerable amount of SO ₄ ^2? is also found in the surface snow and the lake water which is attributed to the oxidation of DMS produced by marine phytoplankton. Neutralization of acidic components of snow is mainly done by NH ₄ ⁺ and Mg²⁺. The Mg²⁺, Ca²⁺ and K⁺ are nearly equally effective in neutralizing the acidic components in lake water. The NH ₄ ⁺ and SO ₄ ^2? occur over the Antarctica region mostly in the form of (NH₄)₂SO₄.     

Stable isotope characterization of fluids from the Lake Chany complex,western Siberia,Russian Federation

The Lake Chany complex and nearby lakes in western Siberia (Russian Federation) were studied to constrain the S cycle in these terrestrial lake environments. Surface water chemistry was characterized by Na–SO₄–Cl composition, comparable to other inland basins in semi-arid climatic zones associated with marine evaporite-bearing formations at depth. Dissolved sulfates showed elevated δ³⁴S (up to +32.3‰). These values are quite distinct from those in similar saline lakes in northern Kazakhstan, the Aral Sea, Lake Barhashi, and a gypsum deposit in the Altai Mountains. The localized distribution of such a unique S isotopic signature in dissolved SO₄ negates both aeolian and catastrophic flooding hypotheses previously suggested for the genesis of the dissolved salts. The probable source of the dissolved SO₄ in Lake Chany basin is inherited from hidden saline groundwaters (whose location and origins remain unclear) from eastern Paleozoic ranges with Upper Devonian formations with heavy S isotope values. Post-depositional enrichment of heavy S in the dissolved SO₄ from saline sediments may be caused by local activity of SO₄-reducing bacteria under the ambient supply of electron donors (dissolved river load organic matter and decaying bacterial mats) in the lake complex. Such microbial processes can remove up to ca. 60% of SO₄ from the system. Extensive and intensive evaporation of lake fluids, ca. 40%, was indicated by the progressive enrichment of δ¹⁸O values in meteoric water samples collected along the river and lake system. This evaporation process compensates the microbial loss of SO₄ dissolved in the incoming river water.     

Hydrogeochemical methods for base metal exploration in the northern Canadian shield

The use of lake waters for base metal exploration has been studied in the northern part of the Slave Geological Province of the Canadian Shield. The area is north of the treeline, within the zone of continuous permafrost, and, like most other regions of the Shield, has a high density of small lakes.A regional sampling of 1218 lakes established that less than 2 ppb (μg/l) Zn or Cu is typical of waters from unmineralized terrane. These samples had a median pH of 6.8 and a median specific conductivity of 19.5 μmhos. Lake waters were also taken from the areas surrounding five massive sulphide occurrences: High Lake, Canoe Lake, Takiyuak Lake, Hackett River and Agricola Lake. In all cases there are unambiguous anomalies for Zn. Anomalies are also present for Cu, but are less intense and extensive. This difference between the two elements is related to the superior mobility of Zn in surface waters and its more consistent presence as a major constituent of massive sulphides.A water sampling apparatus has been developed and tested on a light turbine helicopter. Using this, thirty sites may be sampled each hour when sampling at a density of 1 site per 2.8 km². Measurement of pH, conductivity and water temperature are recorded in the helicopter during sampling.A number of factors have been investigated that may influence the utility of lake water sampling for base metal exploration:

1. (1) Seasonal variability, while present to moderate degree, is unlikely to hinder application of the method.

2. (2) For the size of lakes sampled (2 km² or less), elements are homogeneously distributed across the lake surface during the ice-free season. During the initial period of break-up there are marked variations in element content around the ice-free lake margin. Sampling during this period may help define the source of metals for anomalous lakes.

3. (3) Study of sample preservation suggests that mobile elements, such as Zn, that are stable in solution within lakes, are also relatively stable when untreated water is stored in plastic bottles.

4. (4) Care must be taken to avoid contamination of the samples, particularly from the bottle.

The areal extent of lake water base metal anomalies appears to be less than equivalent lake sediment anomalies. Thus for wide-interval, regional geochemical reconnaissance, lake sediment sampling is the method of choice. Lake waters are an appropriate medium for detailed exploration of areas of interest, such as volcanic belts. For this application, the principal attractions are rapid sampling rates, and hence low costs, high contrast anomalies, and a uniform sampling medium.     

Assessing variability of water quality in a groundwater-fed perennial lake of Kashmir Himalayas using linear geostatistics

This paper presents a study on Manasbal lake, which is one of the high altitude lakes in the Kashmir Valley, India. Eighteen water samples were analysed for major ions and trace elements to assess the variability of water quality of the lake for various purposes. Geostatistics, the theory of regionalized variables, was then used to enhance the dataset and estimate some missing spatial values. Results indicated that the concentration of major ions in the water samples in winter was higher than in summer. The scatter diagrams suggested the dominance of alkaline earths over the alkali elements. Three types of water were identified in the lake that are referred to as Ca–HCO₃, Mg–HCO₃ and hybrid types. The lake water was found to be controlled by rock–water interaction with carbonate lithology as a dominant source of the solutes. The major (Ca^2 +, Mg^2 +, Na⁺, K⁺, NO₃ and HCO₃^-{\rm{HCO}}_{3}^{-}, CO₃ and Cl) and trace elements of the lake water were within the World Health Organization standards, therefore the lake water was considered chemically safe for drinking purposes. Although NO₃ concentration (ranging from 1.72 to 2 mg/L), is within the permissible limit and not very alarming, the gradually increasing trend is not acceptable. It is however, important to guard its spatio-temporal variability as the water is used for domestic as well as agricultural purposes. This study is significant as hydrogeological information on such high altitude lakes in India is scanty.     

Experimental Modeling of Cyanobacterial Bloom in a Thermokarst Lake: Fate of Organic Carbon,Trace Metal,and Carbon Sequestration Potential

Thermokarst lakes, formed during permafrost thaw in Western Siberia Plain over past tens to hundreds years, cover overall territory close to million km² and may represent significant source of CO₂ and CH₄ to the atmosphere. These acidic (3 < pH < 6) and humic [10 < dissolved organic carbon (DOC) < 50 mg/L] lakes are essentially inhabited by heterotrophic bacterioplankton with rare phytoplankton bloom occurring during warm periods. In order to understand possible effects of phytoplankton bloom on thermokarst lake hydrochemistry under climate warming scenario, we cultured pure cyanobacterium (Gloeocapsa sp.) and native cyanobacterial associate separated from the natural lake water. As substrates, sterilized thermokarst lake water and peat leachate from western Siberia were used. In these laboratory microcosm experiments which lasted 10 days, we monitored daily pH, biomass, DOC, and 40 major and trace elements. Despite significant variation of pH (4 to ~10.5) and biomass (a factor of 3–5), very few dissolved elements responded to massive cyanobacterial growth. The DOC varied within a factor of 1.2–1.5, exhibiting slow increase due to exometabolite production in thermokarst lake water and an initial decrease due to photodegradation in peat leachate. Elements appreciably affected by photosynthesis in both lake water and peat leachate substrates were P, Zn, Mn, and, in a lesser degree, Cd, K, Rb, Sr, Ba, Cr, Al, and U. While P, K (Rb), Mn, and Zn removal from solution during cell growth could be linked to biological demand by cyanobacteria, the adsorption of Cd, Sr, Ba, Al, Cr, U on the cell surface in response to the pH rise is most likely. Many other trace elements did not exhibit any significant evolution of the concentration during 10-day experiment either due to their strong complexation with allochthonous organic matter and essentially organic/organo-mineral colloidal status (Fe, Ni, Co, Cu, Pb, REEs, Ti, Zr, Hf, Th) or due to the lack of element interaction with cyanobacterial cells, via both adsorption and intracellular uptake (B, Si, V, Mo, As, Sb, Cs). Therefore, possible intensification of cyanobacterial bloom in thermokarst lakes caused by leaching of thawing peat will likely affect only few macronutrients and micronutrients such as P, K, Mn, and Zn, while the majority of trace elements bound to allochthonous DOC in the form of organic and organo-mineral colloids will not be affected by cyanobacterial biomass production and pH rise due to photosynthesis. Cyanobacterial bloom in organic-rich (20 mg DOC/L) thermokarst lakes exhibited significant potential of carbon sequestration from the atmosphere, which is more than an order of magnitude higher than the CO₂ evasion due to heterotrophic plankton respiration of allochthonous DOC.     

Trace metal deposition and mobility in the sediments of two lakes near Sudbury,Ontario

The accumulation and mobility of Fe, Mn, Al, Cu, Ni and Pb in the sediments of two lakes (Clearwater, pH 4.5; and McFarlane, pH 7.5) near Sudbury, Ontario have been investigated. The Al, Cu and Ni concentrations are expectedly relatively high in the overlying waters of Clearwater Lake and much lower for Al and Cu in McFarlane Lake. The low trace metal concentrations found in the anoxic porewaters of Clearwater Lake could be explained by a sharp increase in porewater pH concomitant with SO₄² reduction and H₂S production within the first 1–2 cm of the sediments, which has conceivably led to the precipitation of mineral phases such as AL(OH)₃, NiS, and CuS. In both lakes, Fe concentrations in anoxic porewaters appear to be controlled by FeS and/or FeCO₃ formation. Solubility calculations also indicate MnCO₃ precipitation in McFarlane Lake. In Clearwater Lake, however, both porewater and total Mn were relatively low, a possible result of the continuous loss of Mn(II) through the acidic interface. It is suggested that upwardly decreasing total Mn profiles resulting from the removal of Mn from the top sediment layers under acidic conditions may constitute a reliable symptom of recent lake acidification.The downward diffusion of AI, Cu and Ni from the overlying water to the sediments has been estimated from their concentration gradients at the interface and compared to their total accumulation rates in the sediments. In both lakes the diffusion of Al is negligible compared to its accumulation rate. However, diffusion accounts for 24–52% of the accumulation of Cu in the sediments of Clearwater Lake, but appears negligible in McFarlane Lake. The downward diffusive flux of Ni is important and may explain 76–161% of the estimated Ni accumulation rate in Clearwater Lake, and 59% in McFarlane Lake. The porewater Cu and Ni profiles suggest that the subsurface sedimentary trace metal peaks observed in Clearwater Lake (as in other acid lakes) may not be caused by sediment leaching or by a recent reduction in sedimentation but may have a diagenetic origin instead. Diffusion to the sediments thus appears to be an important and previously overlooked trace metal deposition mechanism, particularly in acid lakes.     

Sulfur isotope studies to quantify sulfate components in water of flooded lignite open pits – Lake Goitsche,Germany

A system of connected lignite mining pits (part of the former Goitsche mining complex, Germany) was flooded with river water between 1999 and 2002. A considerable accumulation of acid associated with oxidized sulfides in sediments was seen as a critical point for the development of the lake water. To characterize the components contributing to the supply of dissolved lake water SO₄ hydro-chemical and isotope investigations with respect to groundwater, pore water in the sulfide bearing sediments, river water and lake water were performed. δ³⁴S of pore water SO₄ that was dominated by oxidized pyrites ranges around −25‰ VCDT and differs strongly from river water SO₄ with about +4.4‰. Thus, interactions between lake water and sediments were particularly pronounced during the first phase of flooding. For this period, a more quantitative estimation of the SO₄ components in the lake water was difficult because of the heterogeneous SO₄ distributions between the different sub-basins of the lake and according to the flooding process itself. Later, a component separation was attempted following mixing of the whole lake, which first occurred in spring 2002. A very heterogeneous groundwater environment with respect to highly variable SO₄ concentrations and δ³⁴S values and changing interaction with the forming lakes proved to be one of the most important limitations in the calculations of the mixing.     

Major ion chemistry,weathering processes and water quality assessment in upper catchment of Damodar River basin,India

The chemical characteristics of surface, groundwater and mine water of the upper catchment of the Damodar River basin were studied to evaluate the major ion chemistry, geochemical processes controlling water composition and suitability of water for domestic, industrial and irrigation uses. Water samples from ponds, lakes, rivers, reservoirs and groundwater were collected and analysed for pH, EC, TDS, F, Cl, HCO₃, SO₄, NO_3, Ca, Mg, Na and K. In general, Ca, Na, Mg, HCO₃ and Cl dominate, except in samples from mining areas which have higher concentration of SO₄. Water chemistry of the area reflects continental weathering, aided by mining and other anthropogenic impacts. Limiting groundwater use for domestic purposes are contents of TDS, F, Cl, SO₄, NO₃ and TH that exceed the desirable limits in water collected from mining and urban areas. The calculated values of SAR, RSC and %Na indicate good to permissible use of water for irrigation. High salinity, %Na, Mg-hazard and RSC values at some sites limit use for agricultural purposes.     

Geochemistry and stable isotope composition of the Berkeley pit lake and surrounding mine waters,Butte, Montana

Samples of mine water from Butte, Montana were collected for paired geochemical and stable isotopic analysis. The samples included two sets of depth profiles from the acidic Berkeley pit lake, deep groundwater from several mine shafts in the adjacent flooded underground mine workings, and the acidic Horseshoe Bend Spring. Beginning in July-2000, the spring was a major surface water input into the Berkeley pit lake. Vertical trends in major ions and heavy metals in the pit lake show major changes across a chemocline at 10–20 m depth. The chemocline most likely represents the boundary between pre-2000 and post-2000 lake water, with lower salinity, modified Horseshoe Bend Spring water on top of higher salinity lake water below. Based on stable isotope results, the deep pit lake has lost approximately 12% of its initial water to evaporation, while the shallow lake is up to 25% evaporated. The stable isotopic composition of SO₄ in the pit lake is similar to that of Horseshoe Bend Spring, but differs markedly from SO₄ in the surrounding flooded mine shafts. The latter is heavier in both δ³⁴S and δ¹⁸O, which may be due to dissolution of hypogene SO₄ minerals (anhydrite, gypsum, barite) in the ore deposit. The isotopic and geochemical evidence suggests that much of the SO₄ and dissolved heavy metals in the deep Berkeley pit lake were generated in situ, either by leaching of soluble salts from the weathered pit walls as the lake waters rose, or by subaqueous oxidation of pyrite on the submerged mine walls by dissolved Fe(III). Laboratory experiments were performed to contrast the isotopic composition of SO₄ formed by aerobic leaching of weathered wallrock vs. SO₄ from anaerobic pyrite oxidation. The results suggest that both processes were likely important in the evolution of the Berkeley pit lake.     

Hydrogeochemical investigation in an arid region of Iran (Tabas, Central Iran)

Groundwater is the most important source of water supply in Iran and understanding the geochemical evolution of groundwater is important for sustainable development of the water resources in Tabas area. A total of 29 samples of groundwater in Tabas area have been analyzed for ions and major elements. Groundwater of the study area is characterized by the dominance of Na–Cl water type. Groundwater was generally acidic to high alkaline with pH ranging from 5.42 to 10.75. The TDS as a function of mineralization characteristics of the groundwater ranged from 479 to 10,957 mg/l, with a mean value of 2,759 mg/l. The Ca²⁺, Mg²⁺, SO₄ ^2? and HCO₃ ^? were mainly derived from the dissolution of calcite, dolomite and gypsum. The Cu, Pb and Zn ions are not mobile in recent pH–Eh, but these conditions controlled dissolved Se, V and Mo in groundwater. The As is released in groundwater as a result of the weathering of sulfide minerals like arsenopyrite.     

Hydrogeochemical characterization and quality assessment of groundwater around Umrer coal mine area Nagpur District,Maharashtra, India

Quality assessment as well as hydrogeochemical characterization of 45 representative groundwater samples around Umrer coal mine area was undertaken. The pH of the water lies in the normal range i.e. from 7.5 to 8.5, the electrical conductivity varies from 826 to 1,741, the total hardness varies from 289 to 1,302 and the TDS values range from 528.6 to 1,114.2 mg/l which reflects variation in lithology and thus, the distinction in hydrogeological regime. The cation chemistry is dominated by Ca²⁺ and Mg²⁺ while anion chemistry is dominated by Cl^? and HCO₃ ^?. Out of total ten hydrochemical facies, the two dominant facies are Mg–Ca–HCO₃ (37.7 %) and Ca–Mg–SO₄–HCO₃ (17.7 %). The groundwater in the study area, in general, is useful for drinking and domestic use; however, it has marginal utility for irrigation purpose. Standard US Salinity Laboratory classification shows that water of the study area belongs to C2–S1 and C3–S1 classes. The concentration of 9 trace elements analysed from 18 samples did not exceed the desirable limit.