Acidic Mining Lakes Research Articles

Comammox Nitrospira and Ammonia-Oxidizing Archaea Are Dominant Ammonia Oxidizers in Sediments of an Acid Mine Lake Containing High Ammonium Concentrations.

Exploring nitrifiers in extreme environments is vital to expanding our understanding of nitrogen cycle and microbial diversity. This study presents that complete ammonia oxidation (comammox) Nitrospira, together with acidophilic ammonia-oxidizing archaea (AOA), dominate in the nitrifying guild in sediments of an acid mine lake (AML). The lake water was characterized by acidic pH below 5 with a high ammonium concentration of 175 mg-N/liter, which is rare on the earth. Nitrification was active in sediments with a maximum nitrate production potential of 70.5 μg-N/(g-dry weight [dw] day) for mixed sediments. Quantitative PCR assays determined that in AML sediments, comammox Nitrospira and AOA amoA genes had relative abundances of 52% and 41%, respectively, among the total amoA genes. Further assays with 16S rRNA and amoA gene amplicon sequencing and metagenomics confirmed their dominance and revealed that the comammox Nitrospira found in sediments belonged to comammox Nitrospira clade A.2. Metagenomic binning retrieved a metagenome-assembled genome (MAG) of the comammox Nitrospira from sediments (completeness = 96.76%), and phylogenomic analysis suggested that it was a novel comammox Nitrospira. Comparative genomic investigation revealed that this comammox Nitrospira contained diverse metal resistance genes and an acidophile-affiliated F-type ATPase. Moreover, it had a more diverse genomic characteristic on nitrogen metabolism than the AOA in sediments and canonical AOB did. The results suggest that comammox Nitrospira is a versatile nitrifier that can adapt to acidic environments even with high ammonium concentrations. IMPORTANCE Ammonia-oxidizing archaea (AOA) was previously considered the sole dominant ammonia oxidizer in acidic environments. This study, however, found that complete ammonia oxidation (comammox) Nitrospira was also a dominant ammonia oxidizer in the sediments of an acidic mine lake, which had an acidic pH < 5 and a high ammonium concentration of 175 mg-N/liter. In combination with average nucleotide identity analysis, phylogenomic analysis suggested it is a novel strain of comammox Nitrospira. Moreover, the adaption of comammox Nitrospira to the acidic lake had been comprehensively investigated based on genome-centric metagenomic approaches. The outcomes of this study significantly expand our understanding of the diversity and adaptability of ammonia oxidizers in the acidic environments.

From extremely acidic to alkaline: Aquatic invertebrates in forest mining lakes under the pressure of acidification

AbstractHuman activities, including the mining industry, have considerably degraded water habitats worldwide. Acidification has severely affected aquatic environments and biodiversity by altering food webs and reducing species richness. The study area in southern Poland is unique in addressing the effects of mining‐related acidification on biodiversity in freshwater ecosystems along a broad pH gradient (2.4–9.6) in mining lakes. Study was designed to test for effect of human induced acidification. Using multivariate ordination techniques, we analyzed how variations in invertebrate composition are related to environmental factors. The results indicated that pH, hardness, total dissolved solids, and the content of ammonia and calcium were significantly associated with the distribution of invertebrates in the studied mining lakes. The highest iron content, relatively high values of conductivity, and chlorides were found in the extremely acidic mining lakes. A clear trend in decreasing density with decreasing pH was observed for taxa such as Oligochaeta, Chironomidae, Glossiphonidae, and certain taxa of snails. However, the density of other taxa such as Lestidae, Libellulidae, Caenidae, Sialidae, Helodidae, Hydrophilidae, and Polycentropodidae increased with decreasing pH. Specific communities were found with increasing acidity. Therefore, a further increase in acidity will probably cause a stronger decline in most of taxa and their density, and on water chemistry (e.g., calcium concentration, nitrites, and hardness). The data yielded offer an opportunity to fill knowledge gaps on acidic stress concerning less‐studied environments such as mining lakes and link environmental pollution with communities, which is especially important, because aquatic forest habitats are especially exposed to different climatic factors and threats.

Living on the edge: reproduction, dispersal potential, maternal effects and local adaptation in aquatic, extremophilic invertebrates

Isolated extreme habitats are ideally suited to investigate pivotal ecological processes such as niche use, local adaptation and dispersal. Extremophilic animals living in isolated habitats face the problem that dispersal is limited through the absence of suitable dispersal corridors, which in turn facilitates local adaptation. We used five rotifer isolates from extremely acidic mining lakes with a pH of below 3 as model organisms to test whether these isolates are acidotolerant or acidophilic, whether they survive and reproduce at their niche edges (here pH 2 and circum-neutral pH) and whether local adaptation has evolved. To evaluate potential dispersal limitation, we tested whether animals and their parthenogenetic eggs survive and remain reproductive or viable at unfavourable pH-conditions. All five isolates were acidophilic with a pH-optimum in the range of 4–6, which is well above the pH (< 3) of their lakes of origin. At unfavourable high pH, in four out of the five isolates parthenogenetic females produced a high number of non-viable eggs. Females and eggs produced at favourable pH (4) remained vital at an otherwise unfavourable pH of 7, indicating that for dispersal no acidic dispersal corridors are necessary. Common garden experiments revealed no clear evidence for local adaptation in any of the five isolates. Despite their acidophilic nature, all five isolates can potentially disperse via circum-neutral water bodies as long as their residence time is short, suggesting a broader “dispersal niche” than their realized niche. Local adaptation might have been hampered by the low population sizes of the rotifers in their isolated habitat and the short time span the mining lakes have existed.

Removal of metals and metalloids from acidic mining lake (AML) using olive oil solid waste (OSW)

The acidic mining lakes have low pH values and high metal and metalloid concentrations. In this study, the ability of low-cost olive oil solid waste (OSW) to remove Al, As, Cd, Fe, B and Ti ions from aqueous solutions in short term has been evaluated. Adsorption capacities (mg g−1) of OSW (1:5–1:10 w/v) were 764.06–411.75 for Al, 0.26 for As, 0.07–0.14 for Cd, 2181.5–2406.5 for Fe, 23.70–82.50 for B and 0.12–0.0.34 for Ti. OSW addition increased acidic mine water (AMW) pH from 2.41 to 3.2 with 1:5 and from 2.41 to 2.7 to 1:10 mixing ratio, respectively, after 10 min. The best gradual decrease has been observed with different ratio of OSW applications on B and Ti concentrations. OSW adsorbs 32.41% and 62.68% of B at the ratio of 1:5 and 1:10 and 55.29% and 83.04% of Ti at the ratio of 1:5 and 1:10 (OSW:AMW) mixtures, respectively. The results show that OSW has great potential for metal removal from acidic mine water.

Contrasting patterns of freshwater microbial metabolic potentials and functional gene interactions between an acidic mining lake and a weakly alkaline lake

AbstractAcidic coal mining lakes (AMLs) are characterized by low pH, low biodiversity, and high concentrations of sulfate and metals. However, to date, knowledge is inadequate on the involvement of the aquatic microbial functions in biogeochemical processes of an AML. Here, we use a natural weakly alkaline lake (WAL) as a reference to investigate the functional gene structure of microbial communities in the aerobic surface waters of an AML by using a metagenomic approach with GeoChip‐based functional gene arrays (GeoChip 5.0). We found significant differences in the compositions of the microbial functional genes between the two lake types. The AML had significantly lower gene diversity than the WAL, and the functional genes detected in the AML were almost a subset of those in the WAL. We also found significant differences in the microbial metabolic potentials between the two lake types. In the AML, the microbial communities had higher functional capacities in phosphorus‐utilization, sulfur oxidation, and metal‐detoxification and had lower metabolic potentials of carbon and nitrogen fixation, and the degradation of starch, hemicellulose, cellulose, chitin, and lignin than those in the WAL. By performing null model and network analyses, we observed stronger deterministic effects of the functional gene assemblages and greater clustering among the co‐occurring functional genes in the AML than those in the WAL. Altogether, we demonstrated contrasting patterns of freshwater microbial metabolic potentials and functional gene interactions between an AML and a WAL, which may advance the understanding of microbial functional response to acidification in freshwater lakes.

High field FT-ICR mass spectrometry data sets enlighten qualitative DOM alteration in lake sediment porewater profiles

This study investigates how changes in dissolved organic matter (DOM) quality can be evaluated considering all existing principal data pools from high field Fourier transform ion cyclotron mass spectrometry (FT-ICR-MS). We recommend five steps, including suggestions on underlying processes. Two different sediment profiles from a highly acidic mining lake in Germany with different mixis of the overlying lake water (dimictic vs. meromictic) were selected as a model for the analysis of sediment porewater sample to a depth of 30cm. FT-ICR-MS datasets of elemental composition were evaluated for the presence of specific CHO molecular series. In six (seven) porewater depth groups of 63 (127) different data pools were identified. In the first step, the data pools were evaluated with components present in all six (seven) samples (total common presence). This group of components was analysed via a statistical rank analysis of the mass peak intensities (inter sample rankings analysis). The second step comprised the allocation of components which were not present in all samples to specific data pools (partial common presence and different presence pools). Of these pools the largest (containing most components) were selected in the third step for visualization of DOM quality change using van Krevelen diagrams. Underlying DOM transformations were discussed in the fourth step. The fifth step comprised the parallel allocation of changes in DOM quality and in concentrations of inorganic compounds. We identified the principal changes in both depth profiles and thereby demonstrated the potential of DOM data pool evaluation for elucidating biogeochemical processes.

Effect of Geogenic Factors on Water Quality and Its Relation to Human Health around Mount Ida, Turkey

Water–rock interactions strongly influence water quality. Waters originating from highly altered zones affect human health. Mount Ida region in western Anatolia is an example for such geogenic interactions and additional anthropogenic impacts. A water quality monitoring study was held and a total of 189 samples were collected from 63 monitoring stations to characterize the quality of water resources and its relation with human health. The results indicated that waters originating from altered volcanic rocks that are mainly used for drinking purposes have low pH, high conductivity and elevated trace element levels. In addition, a number of acidic mining lakes were formed in the open pits of abandoned mine sites in the study area and pyrite oxidation in altered volcanic rocks resulted in extremely acidic, high mineral content and toxic waters that demonstrate an eminent threat for the environmental health in the area. Overall, the water quality constituents in Mount Ida region had a spatially variable pattern and were locally found to exceed the national and international standards, mainly due to geogenic alteration zones and anthropogenic intervention.

Iron mineralogy across the oxycline of a lignite mine lake

Iron-rich pelagic aggregates of microbial origin named “iron snow” are formed in the water column of some acidic lignite mine lakes. We investigated the evolution of Fe mineralogy across the oxycline of the Lusatian lake 77, Germany at two sampling sites differing by their pH and mixing profiles. The central basin (CB) of this lake shows a dimictic water regime with a non-permanent anoxic deep layer and a homogeneous acidic pH all over the water column (pH3). In contrast, the northern basin (NB) is meromictic with a permanently anoxic bottom layer and a pH increase from pH3 in the mixolimnion (superficial part of the lake) to pH5.5 in the monimolimnion (anoxic bottom layer). Fe minerals above and below the oxycline were identified using X-ray Absorption Spectroscopy (XAS) at the Fe K-edge and further characterized down to the atomic scale by High Resolution Transmission Electron Microscopy (HRTEM) and Scanning Transmission Electron Microscopy (STEM) coupled to Energy Dispersive X-ray Spectroscopy (EDXS). We explored local Fe redox state and C speciation using Scanning Transmission X-ray Microscopy (STXM) at the Fe L2,3-edges and C K-edge. Schwertmannite [Fe8O8(OH)8-2x(SO4)x] identified as the sole Fe mineral in CB, was polycrystalline, consisting in the aggregation of nanodomains of 2–3nm each one exhibiting the crystal structure of schwertmannite. In contrast, schwertmannite was partly (40%) converted to aluminous ferrihydrite when reaching the oxycline in NB. This mineralogical transformation was most probably due to a combination of abiotic and microbial anaerobic processes promoting pH increase and release of Fe(II) (e.g. via heterotrophic Fe(III) reduction) that induce the catalytic hydrolysis of schwertmannite to ferrihydrite. Mineral products were stabilized in the monimolimnion by the adsorption of aluminum, silicate and organic matter. Noteworthy, local Fe redox state heterogeneities were observed, with a few areas enriched in Fe(II) as evidenced by STXM analyses at the Fe L2,3-edges. These local redox heterogeneities could arise from microbial activity (e.g. Fe(III) and/or sulfate reduction). All these results provide an in-depth mineralogical overview of iron phases forming in lake 77 as a basis for future investigations of microbial vs. abiotic parameters controlling their stability and transformation.

Generation of Acid Mine Lakes Associated with Abandoned Coal Mines in Northwest Turkey.

A total of five acid mine lakes (AMLs) located in northwest Turkey were investigated using combined isotope, molecular, and geochemical techniques to identify geochemical processes controlling and promoting acid formation. All of the investigated lakes showed typical characteristics of an AML with low pH (2.59-3.79) and high electrical conductivity values (1040-6430μS/cm), in addition to high sulfate (594-5370mg/l) and metal (aluminum [Al], iron [Fe], manganese [Mn], nickel [Ni], and zinc [Zn]) concentrations. Geochemical and isotope results showed that the acid-generation mechanism and source of sulfate in the lakes can change and depends on the age of the lakes. In the relatively older lakes (AMLs 1 through 3), biogeochemical Fe cycles seem to be the dominant process controlling metal concentration and pH of the water unlike in the younger lakes (AMLs 4 and 5). Bacterial species determined in an older lake (AML 2) indicate that biological oxidation and reduction of Fe and S are the dominant processes in the lakes. Furthermore, O and S isotopes of sulfate indicate that sulfate in the older mine lakes may be a product of much more complex oxidation/dissolution reactions. However, the major source of sulfate in the younger mine lakes is in situ pyrite oxidation catalyzed by Fe(III) produced by way of oxidation of Fe(II). Consistent with this, insignificant fractionation between δ(34) [Formula: see text] and δ(34) [Formula: see text] values indicated that the oxidation of pyrite, along with dissolution and precipitation reactions of Fe(III) minerals, is the main reason for acid formation in the region. Overall, the results showed that acid generation during early stage formation of an AML associated with pyrite-rich mine waste is primarily controlled by the oxidation of pyrite with Fe cycles becoming the dominant processes regulating pH and metal cycles in the later stages of mine lake development.

Organic matter in sediment layers of an acidic mining lake as assessed by lipid analysis. Part II: Neutral lipids

Natural neutralization of acidic mining lakes is often limited by organic matter. The knowledge of the sources and degradability of organic matter is crucial for understanding alkalinity generation in these lakes. Sediments collected at different depths (surface sediment layer from 0 to 1 cm and deep sediment layer from 4 to 5cm) from an acidic mining lake were studied in order to characterize sedimentary organic matter based on neutral signature markers. Samples were exhaustively extracted, subjected to pre-chromatographic derivatizations and analyzed by GC/MS. Herein, molecular distributions of diagnostic alkanes/alkenes, terpenes/terpenoids, polycyclic aromatic hydrocarbons, aliphatic alcohols and ketones, sterols, and hopanes/hopanoids were addressed. Characterization of the contribution of natural vs. anthropogenic sources to the sedimentary organic matter in these extreme environments was then possible based on these distributions.With the exception of polycyclic aromatic hydrocarbons, combined concentrations across all marker classes proved higher in the surface sediment layer as compared to those in the deep sediment layer. Alkane and aliphatic alcohol distributions pointed to predominantly allochthonous over autochthonous contribution to sedimentary organic matter. Sterol patterns were dominated by phytosterols of terrestrial plants including stigmasterol and β-sitosterol. Hopanoid markers with the ββ-biohopanoid “biological” configuration were more abundant in the surface sediment layer, which pointed to higher bacterial activity. The pattern of polycyclic aromatic hydrocarbons pointed to prevailing anthropogenic input. Pyrolytic makers were likely to due to atmospheric deposition from a nearby former coal combustion facility. The combined analysis of the array of biomarkers provided new insights into the sources and transformations of organic matter in lake sediments.

Schwertmannite formation at cell junctions by a new filament-forming Fe(II)-oxidizing isolate affiliated with the novel genus Acidithrix.

A new acidophilic iron-oxidizing strain (C25) belonging to the novel genus Acidithrix was isolated from pelagic iron-rich aggregates ('iron snow') collected below the redoxcline of an acidic lignite mine lake. Strain C25 catalysed the oxidation of ferrous iron [Fe(II)] under oxic conditions at 25 °C at a rate of 3.8 mM Fe(II) day(-1) in synthetic medium and 3.0 mM Fe(II) day(-1) in sterilized lake water in the presence of yeast extract, producing the rust-coloured, poorly crystalline mineral schwertmannite [Fe(III) oxyhydroxylsulfate]. During growth, rod-shaped cells of strain C25 formed long filaments, and then aggregated and degraded into shorter fragments, building large cell-mineral aggregates in the late stationary phase. Scanning electron microscopy analysis of cells during the early growth phase revealed that Fe(III)-minerals were formed as single needles on the cell surface, whereas the typical pincushion-like schwertmannite was observed during later growth phases at junctions between the cells, leaving major parts of the cell not encrusted. This directed mechanism of biomineralization at specific locations on the cell surface has not been reported from other acidophilic iron-oxidizing bacteria. Strain C25 was also capable of reducing Fe(III) under micro-oxic conditions which led to a dissolution of the Fe(III)-minerals. Thus, strain C25 appeared to have ecological relevance for both the formation and transformation of the pelagic iron-rich aggregates at oxic/anoxic transition zones in the acidic lignite mine lake.

Change detection and visualization of acid mine lakes using time series satellite image data in geographic information systems (GIS): Can (Canakkale) County, NW Turkey

Can, a county in the province of Canakkale, is one of the most prominent coal mining districts in Turkey. Many mining companies have been operating coal deposits for power generation and district heating in this region since 1980. Generally, small and medium-scale mining companies operate for short periods and abandon the operational land without providing any rehabilitation. Human intervention in the natural structure and topography of the earth surface causes large holes and deterioration in these areas. Artificial lakes occur because of surface discharge and underground leakage into abandoned open pit mines with high lignite sulfur content (0.21–14.36 wt %). Furthermore, these lakes gain acidic character due to acid generation from pyrite oxidation. Acid mine lakes are highly acidic (pH < 3.05) and have elevated concentrations of \({\text{SO}}_{4}^{2 - }\), Fe and some metals. The main objective of this study is to evaluate the environmental conditions and demonstrate the development of a monitoring system for their possible changes in the acid mine lakes of the open cast lignite mining area on a regional scale. For this purpose, the data received from remote sensing satellites were used. Areal change detection and perimeter changes of nine acid mine lakes caused by coal mining companies in Can from 1977 to 2011, were determined using Landsat, Quickbird and Worldview satellite images. As a case study, an area of 9 km2 was chosen for the variety of acid mine lakes. Using GIS software, satellite images were analyzed in time series, borders of acid mine lakes were digitized and converted into vector data format. At this stage, prior to the digitization, in order to create contrast on the satellite images, “stretch type” and “stretch values” were changed. The areal and perimeter changes were computed and presented via tables and graphics. In addition, thematic maps of the acid mine lakes were created and visualized. The results show that the number of acid mine lakes increased and these caused environmental risks due to their hydrochemical properties and areal increments.

Quantification of the inorganic phase of the pelagic aggregates from an iron contaminated lake by means of Raman spectroscopy

A semi-quantitative investigation of the inorganic phase of pelagic, iron-rich aggregates (iron snow, IS) formed in an iron polluted aquatic environment was performed by means of Raman spectroscopy. IS samples were collected from two basins of an acidic lignite mine lake and at two different water depths. Although the water chemistry differed at all four sites with respect to oxygen, pH, and, Fe(II) concentrations, the Raman analyses showed that the main mineral formed was schwertmannite (ideal formula: Fe8O8(OH)6SO4) with concentrations of more than 88% in all IS samples. To determine potential differences in the microbial communities of the IS samples we used denaturing gradient gel electrophoresis. Microbial communities differed between two basins, but showed similarities between redoxcline and deeper water layers of IS samples from the same basin. Surprisingly, these microbiological differences did not lead to strikingly qualitative similarities in the mineral composition, although the initial step in mineral formation, the oxidation of Fe(II) to Fe(III), is a pure microbial process at low pH. Thus, a semi-quantitative method was necessary to elucidate differences in the consecutive mineralization process which is apparently more controlled by water geochemical conditions.

Hydrochemical Status of an Acidic Mining Lakein Çan‐Çanakkale, Turkey

An acidic mining lake located in Can, Turkey was investigated to assess its water quality status and potential risk for environment. Morphological studies and water quality sampling were conducted to determine vertical and areal distributions of numerous water quality criteria and to assess the general status of the lake. The results revealed that the lake had an average pH of 2.28 and an average electrical conductivity value of 5925 microS/cm. The dissolved oxygen ranged between 0.83 and 6.45 mg/L and demonstrated a significant vertical profile. Sulfate was found to be the dominant anion with an average level of 5912.5 mg/L depicting the extent of pyrite oxidation. Similarly, aluminum, iron and manganese levels were extremely high with averages of 290155, 172344 and 91342 microg/L, respectively. With these levels, the lake is classified to be a Class 4 water resource according to pertinent regulations and is in need of immediate action for rehabilitation.

Book Review: Acidic Pit Lakes: The Legacy of Coal and Metal Surface Mines

Acidic Pit Lakes: The Legacy of Coal and Metal Surface Mines, edited by Walter Geller, Martin Schultze, Bob Kleinmann, and Christian Wolkersdorfer, was recently published by Springer-Verlag (525 pp., 212 fig., 66 tab., ISBN 978-3-642-29383-2). This book can be viewed as an excellent update of the 1998 book, Acidic Mining Lakes: Acid Mine Drainage, Limnology and Reclamation, which was edited by Walter Geller, H. Klapper, and W. Salomons. This earlier book set the scene on what was then an emerging but fascinating field and synthesized a large amount of research conducted in the decommissioned lignite mines of former East Germany, as the legacy pits filled with water. Until that book was published, these acidic lake environments were rarely described in limnology textbooks or journal papers. Since the earlier book, an increasing numbers of acidic pit lakes have come into existence as legacy pits are filled with water; many of these pit have been subject to intensive studies, before, during and after filling. While much of this data continues to remain in the private sector, more and more data is being analyzed and released through journal publications. In the 2013 book, Chief Editor Walter Geller is assisted by 43 co-authors and international experts predominantly from Germany, but also from the USA, Spain, Canada, Australia, and Poland. An international network of acidic pit lake experts has been developing over the past decade, and many are indeed co-authors for this book, which succinctly outlines recent advances in our understanding of these complex systems. This new book provides a comprehensive overview of the origins, geochemistry, and limnology of pit lakes and possible remediation options. The book outlines all aspects of pit lake function— physical, chemical and biological limnology. The section on physical limnology includes descriptions of stratification and circulation, waves and currents, mixing and vertical transport in pit lakes. The section on chemical limnology includes detailed descriptions of sediment–water interactions, and iron and phosphorus cycling. Personally, I would have liked to have seen an overview of nitrogen cycling in these acidic systems also included in this section. The final section in the limnology chapter covers lake ecology, including phytoplankton, zooplankton, microbial and fungi dynamics, macrophytes, and benthic primary production. This chapter on limnology provides an excellent overview of current knowledge of pit lake processes and is very rich in data from existing pit lakes. This chapter in itself could have been the basis of a very useful book. The following two chapters outline remediation and management options and then a series of case studies from Germany, Australia, Canada, the USA, and Spain. The majority of research into pit lakes over the last decade has come from Germany, many of the authors are from Germany, and thus it is reasonable that the latter chapter is dominated by case studies from Germany, including the famous Mining Lake 111 with its plethora of superb data. The case study chapter is dominated by case studies from temperate climate regions—a shortfall that is of concern given a significant proportion of mining operations in the world are in tropical, semi-arid and arid regions. Mine water and lake management in these climate zones is particularly challenging and thus I hope that the next update from these authors includes many case studies from other climatic regions. One of the most interesting and valuable parts of this book is the chapter titled ‘‘Lessons learned, open questions and concluding remarks’’. This chapter is a very rare C. Oldham (&) School of Environmental Systems Engineering, The University of Western Australia, Crawley, WA, Australia e-mail: carolyn.oldham@uwa.edu.au

Multiple environmental stressors confine the ecological niche of the rotifer Cephalodella acidophila

The planktonic food web in extremely acidic mining lakes is restricted to a few species that are either acidophilic or acidotolerant. Common metazoans inhabiting acidic mining lakes with a pH below 3 include rotifers in the genera Cephalodella and Elosa.The life history response of Cephalodella acidophila to three environmental key factors, pH (2, 3.5, 5.0 and 7.0), temperature (10, 17.5 and 25 °C) and food concentration (10 000, 35 000 and 50 000 algal cells per mL), was investigated in a full factorial design using life-table experiments.The effect of each of the three environmental variables investigated on the rotifer life cycle parameters (life span, fecundity and population growth rate) differed. C. acidophila is a stenoecious species with a pH optimum in the range 3–4 and a comparably high food threshold. Combining the laboratory results with field data, we conclude that C. acidophila is severely growth limited in its natural habitat. However, low pH alone is not harmful as long as temperatures are moderate to warm and food is abundant.The population of C. acidophila in the field is maintained mainly due to release from competitors and predators.

Geochemical Characterization of Acid Mine Lakes in Northwest Turkey and Their Effect on the Environment

Mining activity generates a large quantity of mine waste. The potential hazard of mine waste depends on the host mineral. The tendency of mine waste to produce acid mine drainage (AMD) containing potentially toxic metals depends on the amounts of sulfide, carbonate minerals, and trace-element concentrations found in ore deposits. The acid mine process is one of the most significant environmental challenges and a major source of water pollution worldwide. AMD and its effects were studied in northwest Turkey where there are several sedimentary and hydrothermal mineral deposits that have been economically extracted. The study area is located in Can county of Canakkale province. Canakkale contains marine, lagoon, and lake sediments precipitated with volcanoclastics that occurred as a result of volcanism, which was active during various periods from the Upper Eocene to Plio-Quaternary. Can county is rich in coal with a total lignite reserve >100 million tons and contains numerous mines that were operated by private companies and later abandoned without any remediation. As a result, human intervention in the natural structure and topography has resulted in large open pits and deterioration in these areas. Abandoned open pit mines typically fill with water from runoff and groundwater discharge, producing artificial lakes. Acid drainage waters from these mines have resulted in the degradation of surface-water quality around Can County. The average pH and electrical conductivity of acid mine lakes (AMLs) in this study were found to be 3.03 and 3831.33 μS cm(-1), respectively. Total iron (Fe) and aluminum (Al) levels were also found to be high (329.77 and 360.67 mg L(-1), respectively). The results show that the concentration of most elements, such as Fe and Al in particular, exceed national and international water-quality standards.

Systematics and species-specific response to pH of Oxytricha acidotolerans sp. nov. and Urosomoida sp. (Ciliophora, Hypotricha) from acid mining lakes

We investigated the morphology, phylogeny of the 18S rDNA, and pH response of Oxytricha acidotolerans sp. nov. and Urosomoida sp. (Ciliophora, Hypotricha) isolated from two chemically similar acid mining lakes (pH∼2.6) located at Langau, Austria, and in Lusatia, Germany. Oxytricha acidotolerans sp. nov. from Langau has 18 frontal-ventral-transverse cirri but a very indistinct kinety 3 fragmentation so that the assignment to Oxytricha is uncertain. The somewhat smaller species from Lusatia has a highly variable cirral pattern and the dorsal kineties arranged in the Urosomoida pattern and is, therefore, preliminary designated as Urosomoida sp. The pH response was measured as ciliate growth rates in laboratory experiments at pH ranging from 2.5 to 7.0. Our hypothesis was that the shape of the pH reaction norm would not differ between these closely related (3% difference in their SSU rDNA) species. Results revealed a broad pH niche for O. acidotolerans, with growth rates peaking at moderately acidic conditions (pH 5.2). Cyst formation was positively and linearly related to pH. Urosomoida sp. was more sensitive to pH and did not survive at circumneutral pH. Accordingly, we reject our hypothesis that similar habitats would harbour ciliate species with virtually identical pH reaction norm.

Significant habitat effects influence protist fitness: evidence for local adaptation from acidic mining lakes

It is currently controversially discussed if the same freshwater microorganisms occur worldwide wherever their required habitats are realized, i.e., without any adaptation to local conditions below the species level. We performed laboratory experiments with flagellates and ciliates from three acidic mining lakes (AML, pH ∼2.7) to investigate if similar habitats may affect similar organisms differently. Such man-made lakes provide suitable ecosystem models to test for the significance of strong habitat selection. To this end, we analyzed the growth response of three protist taxa (three strains of the phytoflagellate Chlamydomonas acidophila, two isolates of the phytoflagellate Ochromonas and two species of the ciliate genus Oxytricha) by exposing them to lake water of their origin and from the two other AML in a cross-factorial design. Population growth rates were measured as a proxy for their fitness. Results revealed significant effects of strain, lake (=habitat), and strain × habitat interaction. In the environmentally most adverse AML, all three protist taxa were locally adapted. In conclusion, our study demonstrates that (1) the same habitat may affect strains of the same species differently and that (2) similar habitats may harbor ecophysiologically different strains or species. These results contradict the ‘everything is everywhere' paradigm.

Organic matter in sediments of an acidic mining lake as assessed by lipid analysis. Part I: Fatty acids

Fatty acid (FA) patterns of sediments collected from the bottom of an acidic mine pit lake (AML) at different depths (surface sediment: 0 to 1cm; deep sediment: 4 to 5cm) were studied to characterize microbial communities and the sources of sedimentary organic matter (SOM). Studies were performed on the molecular level utilizing source-specific, diagnostic FA biomarkers. The biomarker-based approach has been used widely in marine sediment studies, but has not been applied for sediments from AMLs so far.Combined FA concentrations in the surface sediment were higher compared to those in the deep sediment (497 vs. 127μgg−1d.w., respectively). This was related to deposition of autochthonous biomass and higher terrestrial plants onto the surface sediment, as well as – to lesser extent – with higher bacterial activity on the sediment-water interface. The FA distribution in both sediments was characterized by a strong even-over-odd preference and was bimodal in nature: there was a cluster at nC14–nC18 characteristic of chiefly autochthonous (algal and bacterial) SOM production, and another cluster at nC22–28 related to input from higher plants. The FA distribution in the surface sediment pointed to higher terrestrial input compared to autochthonous contribution to SOM (67%:33%) as an estimate. Fingerprinting of viable bacteria was accomplished through signature FA markers including branched C15 and C17 surrogates, cyclopropanoic acids, 3-hydroxy (OH) acids and monounsaturated surrogates with unusual double bond localization. The abundance of Gram-negative bacteria was higher in the surface sediment as evidenced by total diagnostic 3-OH-fatty acids (37μgg−1 versus 25μgg−1). Potential source taxa in both sediment layers included acidophilic iron- and sulfur-oxidizing bacteria including Acidithiobacillus ferrooxidans. High abundances of terminally branched C15 and C17 surrogates in both sediments pointed to sulfate- and iron-reducing bacteria. Signature FAs characteristic of methanotrophs were virtually lacking in both sediments.