Walter Geller

Natural and Anthropogenic Sulfuric Acidification of Lakes

Since the early 1960s, acid rain has affected surface waters in regions with soils low in carbonates. The acidification of whole lake districts resulted from industrial emissions distributed through the atmosphere on a regional scale. A large body of literature exists about this acidification of surface waters by acid rain, its ecological consequences, and countermeasures to restore landscape and waters (e.g., Drablos and Tollan 1980; Fleischer 1993; Steinberg and Wright 1994; Stumm 1995). The hydrochemistry and the ecological consequences were extensively described (e.g., Dillon et al. 1984), leaving the impression that all acidic lakes are anthropogenic and artificial waters that principally need to be restored, for instance by liming measures (Henrikson and Brodin 1995).

First results on the water chemistry, algae and trophic status of an Andean acidic lake system of volcanic origin in Patagonia (Lake Caviahue)

The acidic caldera lake Caviahue (Patagonia, Argentina) and its main tributaries were studied on two dates during September 1998. The main results are: The acidity of the Lake Caviahue (pH: 2.56, acidity: >5 mmol H+ l−1) is controlled by the extremely acidic Upper Rio Agrio (pH: 1.78, acidity: >20 mmol H+ l−1). The high sulphate contents of both the river and the lake can be attributed to sulphuric acid generated by the uptake of sulphurous gases in the crater lake of Copahue Volcano at approximately 2800 m a.s.l. The high concentrations of both Fe and trace metals (e.g. Cr, Ni, Zn) in Lake Caviahue originate from sulphur–acid interactions with the predominantly volcanic geology of the catchment area. The P-rich andesitic geology influences both the Upper and Lower Rio Agrio and Lake Caviahue. Both were found to have high phosphorus concentrations (300–500 μg P l−1) indicative of a high potential for eutrophication. The plankton community consisted of bacterioplankton, phytoplankton and rotifers. The phytoplankton was dominated by one green alga, Keratococcus raphidioides (>90% of total abundance) followed by a green sphaerical and Chlamydomonas sp. The total phytoplankton density was about 15 000 cells ml−1 in the upper 10 m of the water column. Rotifers were represented by one bdelloid species and their abundance was highly variable (360–4040 ind l−1) in the water columm. In the Upper and Lower Rio Agrio, the epilithic community was dominated by one chloroccocal species and two species of Ulothricales. According to trophic categories based on phytoplankton density and TP concentration, Lake Caviahue can be classified as mesotrophic/eutrophic. However, chlorophyll a concentrations observed were not in agreement with this state.

Water quality management of mining lakes: a new field of applied hydrobiology

Underground and opencast mining generated many new lakes, some with dimensions comparable with natural glacier lakes. Research and water quality management on these lakes is multidisciplinary. A part of them is impaired by geogenic acidification with typical pH values between 2 and 3.5. Approaches are shown how to curb acidification during the mining process, the lake generation, and as a part of the water quality management by new eco-technologies using alkalinity producing microbial processes. An interesting field is the extreme acidic environment and the adaptations of organisms and functioning of the biocenosis.

Structure and function of the microbial community in an in situ reactor to treat an acidic mine pit lake

Sulfate-reducing bioreactors are a promising option for the treatment of acid mine drainage. We studied the structure and function of a biofilm in a methanol-fed fixed-bed in-lake reactor for the treatment of an acidic pit lake by a combination of laboratory incubations, chemical and molecular analyses and confocal laser scanning microscopy to determine whether competition by different groups of microorganisms as well as the precipitation of minerals affect reactor performance negatively. The biofilm growing on the surface of a synthetic carrier material consisted of dense microbial colonies covered by iron-sulfide precipitates. The microorganisms continuously had to overgrow this mineral coating, resulting in a high biomass turnover. About one third of the added methanol was used by sulfate reduction, and the rest by competing reactions. Sulfate-reducing bacteria as well as methanogens and acetogens were involved in methanol consumption. Six different groups of Deltaproteobacteria, dominated by the genera Desulfomonile, Desulfobacterium and a phylotype related to Geobacter, Gram-positive sulfate reducers of the genus Desulfosporosinus, acetogenic Acetobacteria, different fermenting bacteria as well as methylotrophic methanogens were identified. The versatility of the microbial food web is probably an important factor stabilizing the biofilm function under fluctuating and partly oxidizing conditions in the reactor.

The Acid Lakes of Lignite Mining District of the former German Democratic Republic

Large areas of central and eastern Europe have reserves of hard and brown coal. The map in Fig. 8.1 (following page) presents the according mining areas of Germany, Poland and the Czech Republic. The reserves of lignite in Germany with 56 x 109 tons of potential output correspond to 10% of the world reserves and 50% of the reserves of Europe (Mohlenbruch and Scholmerich 1992). There are two major lignite districts in the area of the former German Democratic Republic (G.D.R.): the central German district around the city of Leipzig and the Lusatian mining area in the surroundings of Cottbus, which both have been exploited since the 17th century. This exploitation culminated after World War II, when 90% of power generation in 1988 - the year of maximum output – was based on brown coal: globally the highest proportion of this kind of primary energy source (Couch 1992; Ei Bmann 1994). As a consequence, in the area of the former G.D.R., the per-capita emission of C02 from the total of primary energy sources was ranked second after the United States at 18.5 tons per year and per inhabitant (based on data from 1990); the respective per-capita emissions were 10.8 tons C02 for the area of the former West Germany (BMU 1994). The lignite output of 310 million tons was accompanied by 1353 million tons of overburden and by 1720 million m3 of groundwater which had to be removed in 1988 (Bilkenroth and Koziol 1990).

Limnology of sulphur-acidic lignite mining lakes. II. Chemical main constituents and buffering systems

Within the coal-mining districts of the Central European countries, Germany, Poland, Czechia and Slovakia, the two districts of the former GDR were the most intensively exploited European reserves of lignite (SCHRECK & GLAsSER 1998). After the unification o f Germany the close-down o f lignite mines was drastically accelerated (VON BISMARCK 1993). The number and size of the resulting mining lakes is remarkable: 118 new lake basins with a total water volume of 6.5 km are emerging. The largest of these new and of future mining lakes are compared in a ranking list covering the 45 largest lakes in Germany (Fig. 1). The list shows that, in the future, the mining lakes will make up one third of the largest lakes in Germany. Limnological research on these new emerging lakes is in its initial stage, and many of these are exotic habitats because of extreme chemical properties of the water.

Remediation and Management of Acidified Pit Lakes and Outflowing Waters

Pit lakes are a common feature in a mining-dominated landscape composed of active and closed mine sites, along with large dump areas and surface and groundwater that are adversely affected by acid drainage. The generally accepted goal is to have a landscape with a balanced and healthy system of lakes, rivers, and groundwater. The chapter presents a critical review of the currently known approaches for the abatement of acidification and its consequences, including hydrological management, chemical and biological in-lake treatment, treatment of in- and out-flows, and prevention.

Restoration of Acid Drainage

Acid drainage (AD) is the acidic water both from anthropogenic and from natural acid sources. Acid mine drainage (AMD) is one of the most serious worldwide historic environmental legacies of the mining industry. Contaminations coming from natural causes by weathering of pyrite or at active volcanoes are similar to those of acid mine drainage. There are active and passive technologies of water treatment to successfully remove contaminants and to neutralize the acidity. The restoration measures of AD-water aim to make the water neutral and to eliminate toxic metals, aluminum, and iron. The core processes for AD restoration are chemical treatment with alkaline substances and biological reduction of the metals and sulfate. Active treatment plants reach high efficiencies as needed for big volumes of strongly acidified water. Passive treatment is the deliberate improvement of water quality with low-flow, low-maintenance processes. The passive systems are simple and cheap, but not readily controlled. Both levels of treatment may include chemical and different biological processes, often arranged in sequence. To remedy acidification and metal loadings of acid ground water and pit lakes, suitable in situ treatments are also necessary. The chemical treatment of acid pit lakes can be sustainable in meromictic lakes, which have a permanent, anoxic deep-water body.

Seasonal variability of the embryonic development time of three planktonic crustaceans: dependence on temperature, adult size, and egg weight

The seasonal variability of the temperature dependence of embryonic development in Daphnia galeata, D. hyalina and Eudiaptomus gracilis of Lake Constance was investigated. We found a significant correlation between the adult size and the variability of the temperature function in all three species, and only in case of D. hyalina a significant influence of egg weight on the temperature function. We could demonstrate no general trend in the influence of the thermal adaptation of parent animals on the temperature function, but some specifically different responses among the investigated species.

The acidic waters of Rio Agrio and Lago Caviahue at Volcan Copahue, Argentina

Many active volcanoes are sources of highly acidic waters that originate from volatile mineral acids. Several crater Iakes and volcanic acid brines were chemically characterized (VAREKAMP et al. 200 l), showing a broad spectrum of dissolved elements, many heavy metals, and high temperatures (for more information on crater lakes and constraints in their physical and chemical properties see PASTERNACK & VAREKAMP 1997, VAREKAMP et al. 2000; for volcanoes and activities see JENSEN 2002). eopahue Volcano in Argentina has a crater lake near the summit at 2 700 m a.s.l. Ri o Agri o i s an acidic river emerging from a geothermic source below the crater lake at the flank of eopahue volcano (DE MooR et al. 2003). The 13-km Upper Ri o Agri o flows in to a glacial finger-lake, Lake eaviahue (l 600 m a. s. l.), the outflow o f which is the Lower Ri o Agri o. The system o f river stretches an d lakes ( Fig. l) shows an acidity gradient from p H O to 7 (PEDROZO et al. 200 I). The extreme chemistry along this gradient o f acidity was studied with an additional focus on microbiology and planktonic and epilithic algae.