Limnological Features of Different Acidic Drinking Water Reservoirs in the Erzgebirge (Germany)

The biological and chemical investigations of three drinking water reservoirs differing in their acidic and trophic conditions (neutral/meso-eutrophic; circumneutral/oligotrophic; acid/oligomesotrophic) and of some of their tributaries in the Erzgebirge (Germany) are presented. It is shown that the chemistry of acidic waters is very different from circumneutral ones, particularly with respect to hardness, acid neutralizing capacity, pH and aluminium. As acidity in running and stagnant waters increases, the filtrable aluminium concentration also rises. A consequence of the changed chemical and biological conditions and their direct and indirect effects on the organisms is an overall decrease in the number of species (despite the fact that also some species newly appear in the acidified waters). Furthermore, a loss of food web complexity is observed and the trophic structure changes, e.g. fish have disappeared and invertebrate predators have become more numerous. In the acidic reservoir, species well adapted to waters low in pH and hardness (e.g. Synura sphagnicola) are more abundant and commonly benthic animals (e.g. Chydorus sphaericus) are able to extend their habitat to the open waters.     

Some Physical and Chemical Properties of Water from an Undisturbed Tropical Catchment Area (Guma Dam,Sierra Leone)

The water had a very low content of total suspended solids (<1 mg l⁻¹), but its transparency was high (5–8 Hazen units). The concentration of Mg⁺⁺ and Ca⁺⁺ were below 1 mg l⁻¹, but that of SiO₂ was 5.3 mg l⁻¹. Free CO₂ was abundant (15.3 mg l⁻¹) and the pH was low (<6.5). These conditions were accompanied by low concentrations of PO₄-P, total iron and NO₃-N. The DO content of the water was always below 80 %, but the chloride concentration (8.4 mg l⁻¹) seems relatively high for this type of freshwaters. It is, however, much lower than that known for arid areas. It is concluded that the geology and vegetation dominate the chemistry of the water from the Guma Dam catchment area. The influence of man is acknowledged only in as far as he has protected the catchment area.     

Seasonal Variations in some Physical and Chemical Properties of Water from an Undisturbed African Tropical Catchment Area (Guma Valley,Sierra Leone)

Four perennial streams in a completely forested area were investigated. The water cooled and warmed up during both the rainy and dry seasons. The chloride content of the water varied according to rainfall. Dissolved solids were relatively high (20 mgl⁻¹) at the start of the rainy season due to leaching but they were diluted with increased volume of flow. Dissolved gases and BOD₅ varied according to discharge and total suspended solids content. All the other chemical species likewise were subject to seasonal variations.     

Influence of Arsenic from Anthropogenic Loaded Soils on the Mine Water Quality in the Tin District Ehrenfriedersdorf,Erzgebirge (Germany)

The central part of the tin ore deposit Ehrenfriedersdorf/Erzgebirge, which was exploited from the 13^th century to 1990, was flooded from 1994 to 1996. Since that time mine waters have flown through the gallery “Tiefer Sauberger Stolln” to the creek Wilisch in the Elbe river catchment area. The water at the mine portal shows high concentrations of arsenic and heavy metals. The average arsenic concentration is about 0.5 mg/L. Approximately two thirds of arsenic are transported dissolved. Where the mine water ascends from deeper levels, arsenic concentrations of about 0.4 mg/L were found. Here arsenic occurs predominantly particular. The mining gallery “Tiefer Sauberger Stolln” provides the unique opportunity of subsurface sampling for the identification of the arsenic sources under different hydrological conditions (normal and high water level). The sources of dissolved arsenic in the gallery part between the raise and the portal were determined and analyzed. Between these two monitoring points, many inflows of infiltration water were detected. The concentration of As in the infiltration water reaches up to 1.8 mg/L, which varies depending on the location in the gallery and the hydrological situation. The first part of the gallery was straightened, heightened and partly concreted with modern mining technique. The arsenic concentrations can decrease owing to high precipitation rates and snow melt events. The last part of the gallery was preserved due to low coverage. Here the arsenic concentrations in the infiltration waters increase with the surface water inflow. At a normal water level, 1 kg arsenic per day leaves the raise and 2.1 kg the gallery portal, which means that 50 % of the arsenic load comes from the infiltration water. At a high water level, 2.5 kg arsenic per day are transported through the raise and 8.2 kg per day through the gallery portal, which means that about 70 % of the arsenic load comes from infiltration water. The area of Ehrenfriedersdorf is characterized by a superposition of anthropogenic soil pollution over the geogenic inventory. There is a close connection between ancient soil contaminations by high amounts of water‐soluble arsenic compounds, e.g. arsenic trioxide formed by roasting the ores during ancient tin smelting, and high concentrations of dissolved arsenic in the infiltration water. The contamination of surface water and river sediments by arsenic is originating from an anthropogenic pollution of soils by ancient tailings via infiltration of water rich in arsenic into the mine gallery.     

Arsenic Concentrations in the Surface,Well, and Drinking Waters of the Hisarcik,Turkey, Area

Arsenic is one of the most important water pollutants because of its carcinogenicity. The association between arsenical poisoning and the development of internal malignancies and skin cancer is well known. The U.S. Environmental Protection Agency (USEPA) sets maximum contaminant level goals at zero for carcinogens. In this study are presented groundwater arsenic concentrations in the area of naturally rich boron sources of Turkey. Water samples were collected from the Hisarcik, Turkey, area, which has a large boron mine. An inductively coupled plasma/mass spectrometry method was used to analyze arsenic concentrations in water samples. The arsenic levels in water ranged from no detectable amounts to 3.00 mg As/L (mean: 0.46 ± 0.07SD). This mean As level exceeds by a factor of 10 the USEPA's current Maximum Contaminant Level of 0.05 mgAs/L. Some possible health problems associated with consumption of arsenic-contaminated water are discussed and public health interventions proposed.     

Effect of Increased Carbon Dioxide and Temperature on Runoff Chemistry at a Forested Catchment in Southern Norway (CLIMEX Project)

CLIMEX (Climate Change Experiment) is an integrated, whole-ecosystem research project that focuses on the response of forest ecosystems at the catchment scale to increased CO₂ and temperature. KIM catchment (860 m²) is completely enclosed by a transparent greenhouse, receives deacidifed “clean” rain, and has elevated CO₂ (560 ppmv) and elevated air temperature (3°–5°C above ambient). The uppermost 20% of the catchment is partitioned off, is not subject to changed CO₂ or temperature, and serves as an untreated control. Fluxes of nitrate and ammonium in runoff from KIM catchment increased from 2 mmol m^{− 2} y^{− 1} each in the 3 years before treatment to 6 and 3 mmol m^{− 2} y^{− 1}, respectively, in the 3 years after treatment (May 1994–April 1997), despite a 15 mmol m^{− 2} y^{− 1} decrease in N dry deposition due to the sealing of the walls to the enclosure. N flux in runoff from three reference catchments and the control section did not change. The net loss of inorganic N was thus about 20 mmol m^{− 2} treated soil y^{− 1}. There were no changes in organic N or total organic carbon in runoff. The ecosystem switched from a net sink to a net source of inorganic nitrogen (N). The increased loss of N may be due to accelerated decomposition of soil organic matter induced by higher temperature. Due to many decades of N deposition from long-range transported pollutants, the ecosystem prior to treatment was N saturated. If global change induces persistent losses of inorganic N on a regional scale, the result may be a significant increase in nitrate concentrations in fresh waters and N loading to coastal marine ecosystems. In regions with acid sensitive waters, such as southern Norway, the increased nitrate release caused by global change may offset improvements achieved by reduced sulfur and N deposition. Received 15 October 1997; accepted 18 November 1997.     

Seasonal and interannual dynamics of diatom assemblages in Sacrower See (NE Germany): a sediment trap study

Diatom assemblages from sediment trap samples collected during ten intervals between October 2003 and October 2005 in Sacrower See (NE Germany) were related to limnological and meteorological data. Sacrower See is a dimictic, 38 m deep, hypertrophic lowland lake (29.5 m a.s.l.). We identified distinct seasonal and interannual changes of diatom assemblages for the studied period. Diatoms showed a typical seasonal succession for temperate, dimictic, and eutrophic lakes. Stephanodiscus parvus, S. hantzschii, S. neoastraea, and S. alpinus had high accumulation rates during winter and spring, whereas species of the genera Stephanodiscus, Fragilaria, and Nitzschia were the predominant diatoms during summer and autumn. In a Canonical Correspondence Analysis, precipitation, air and water temperatures, epilimnetic calcium, pH, and total phosphorus concentrations together explained 70% of the variance of the diatom data. Interannual variability in the diatom assemblages during the two sampled years mainly seems to reflect changes in the total phosphorus concentration and temperature and secondarily the onset of the growing season and of stratification. Handling editor: J. Saros     

Ecological Restoration of Headwaters in a Rural Landscape (Normandy,France): A Passive Approach Taking Hedge Networks into Account for Riparian Tree Recruitment

The safeguard of riparian ecosystems is a major field of study in the understanding and maintenance of the ecological health of rivers. Vegetation communities found on these ecotones ensure essential functions such as limitation of river bank erosion and protection of rivers from pollutants. The aim of our study is to investigate the potential for natural regeneration of trees on river banks after passive restoration. We have also studied the influence of landscape on recolonization through the analysis of the influence of hedge networks. Our study takes place on headwaters in Normandy (France) on Vallée‐Aux‐Berges, a stream, which has been passively restored for the last 6 years. As passive restoration removes stresses (heavy trampling and grazing) caused by cattle on river banks, we expect it to help the growth of natural plant communities. The condition of this stream—from the start of restoration work to the present—is compared to another one in the same catchment considered to be ecologically healthy. Our results suggest that passive restoration leads to an increase in tree cover on river banks and contributes to the improvement of the banks' physical integrity. Landscape structure seems to be a major factor for this recolonization: the more the stream is surrounded by hedge networks, the more the recolonization by trees on banks is effective. These results indicate that the influence of landscape structure should be considered in future restoration management in similar headwaters.     

Nutrient concentrations and planktonic diatom-flagellate relations in the Oosterschelde (SW Netherlands) during and after the construction of a storm-surge barrier

Nutrients The inflow of Rhine water into the Oosterschelde was strongly reduced from 1987 onwards. This caused the winter concentrations of silicate and nitrate to decrease in the Eastern compartment, while those in the deeper Western compartment, more dependent on North Sea concentrations, hardly changed. The result was a levelling of the former East-West gradients for these nutrients. In East, summer concentrations of nitrate reached limiting levels in the post-barrier period and molar nitrate/ammonium ratios became < 1, indicating that any release of nitrogen must be important to stimulate phytoplankton growth in this area. Silicate summer concentrations in East, on the other hand, were higher in the new situation. In West, differences in summer nutrient concentrations between the old and new situation were smaller than in East, due to the still continuing exchange with the North Sea. Phytoplankton diatoms and flagellates In East during summer, N-depletion and longer residence times caused the phytoplankton to become strongly dependent on nutrient regeneration processes and increased zooplankton grazing. Average diatom biomass declined, but flagellate biomass rose during summer. Spring conditions for phytoplankton development in this area improved due to the increased water transparency, nutrients being present in excess, and this resulted in a higher new production of diatoms than before.In West, summer biomass of diatoms decreased, probably due to increased consumption by mussels under conditions of longer residence times; nutrients were not limiting, due to important benthic mineralization processes and exchange with the North Sea. The previously existing West-East biomass gradients disappeared, or sometimes reversed.Experimental (mesocosm studies) as well as field data, reported in the literature, give evidence for the given explanations.     

Responses of the Phytoplankton Community of a Tropical Reservoir (São Paulo,Brazil) to the Enrichment with Nitrate,Phosphate and EDTA

The effects of artificial enrichment with nitrate, phosphate and EDTA on the phytoplankton community were studied in the Lobo Reservoir (São Paulo, Brazil). After 14 days of in situ incubation, the amounts of suspended matter and chlorophyll a, the numbers of cells and the carotene/chlorophyll ratio were determined. The addition of nitrate and phosphate to water samples produced significant effects on the chlorophyll a and cell counts, while EDTA acted only on the cell production. Both nitrate and phosphate, when analysed individually, caused a decrease in the value of the carotene/chlorophyll ratio. A synergistic effect of the addition of EDTA and N on the suspended matter was observed.     

Contribution of Flooded Soils to Sediment and Nutrient Fluxes in a Hydropower Reservoir (Sarrans,Central France)

Ecosystems - When a water reservoir is created, the pre-existing soils and vegetation are flooded. Here, we took advantage of the complete emptying of the Sarrans Reservoir, which was flooded...     

Concentrations and distribution of Fe,Zn and Cu in tissues of the white sucker (Catostomus commersoni) in relation to elevated levels of metals and low pH

This study examines whether the process of lake acidification influences the accumulation of Fe, Zn and Cu in the tissues of the white sucker (Catostomus commersoni). Concentrations of Fe, Zn and Cu were measured in the liver, kidney and muscle of white sucker sampled from 4 acidic (pH range 4.8–5.3), 1 slightly acidic (pH = 5.8) and 3 circumneutral (pH = 6.3, 6.4) lakes located in south-central Ontario, Canada. Pearson product-moment correlation coefficients were used to determine relationships between average elemental concentrations in the 3 tissues and both sediment and water metal concentrations plus lake pH, DOC and alkalinity. Despite the 1000-fold difference in H+ concentration among the 8 study lakes, tissue concentrations of Fe, Zn and Cu did not correlate with lake pH. Average Fe, Zn and Cu tissue concentrations did not correlate with metal concentrations in lake water. Only Zn concentrations in the liver and muscle were correlated with Zn concentrations in the sediment (r = 0.83 and r = 0.88, P < 0.05). Iron and Cu were regulated by the white sucker over a wide range of lake pH and metal concentrations in both the water and sediment. In contrast, Zn tissue concentrations were correlated with sediment Zn concentrations, the latter are thought to result from Zn inputs of anthropogenic origin.     

Water column anammox and denitrification in a temperate permanently stratified lake (Lake Rassnitzer,Germany)

We studied microbial N₂ production via anammox and denitrification in the anoxic water column of a restored mining pit lake in Germany over an annual cycle. We obtained high-resolution hydrochemical profiles using a continuous pumping sampler. Lake Rassnitzer is permanently stratified at ca. 29 m depth, entraining anoxic water below a saline density gradient. Mixed-layer nitrate concentrations averaged ca. 200 μmol L⁻¹, but decreased to zero in the anoxic bottom waters. In contrast, ammonium was <5 μmol L⁻¹ in the mixed layer but increased in the anoxic waters to ca. 600 μmol L⁻¹ near the sediments. In January and October, ¹⁵N tracer measurements detected anammox activity (maximum 504 nmol N₂ L⁻¹ d⁻¹ in ¹⁵NH₄⁺-amended incubations), but no denitrification. In contrast, in May, N₂ production was dominated by denitrification (maximum 74 nmol N₂ L⁻¹ d⁻¹). Anammox activity in May was significantly lower than in October, as characterized by anammox rates (maximum 6 vs. 16 nmol N₂ L⁻¹ d⁻¹ in incubations with ¹⁵NO₃⁻), as well as relative and absolute anammox bacterial cell abundances (0.56% vs. 0.98% of all bacteria, and 2.7×10⁴ vs. 5.2×10⁴ anammox cells mL⁻¹, respectively) (quantified by catalyzed reporter deposition-fluorescence in situ hybridization (CARD-FISH) with anammox bacteria-specific probes). Anammox bacterial diversity was investigated with anammox bacteria-specific 16S rRNA gene clone libraries. The majority of anammox bacterial sequences were related to the widespread Candidatus Scalindua sorokinii/brodae cluster. However, we also found sequences related to Candidatus S. wagneri and Candidatus Brocadia fulgida, which suggests a high anammox bacterial diversity in this lake comparable with estuarine sediments.     

长江三峡库区诸葛菜属(十字花科)一新种

采于长江三峡库区一个植物新种,属于十字花科,与诸葛菜(Orychophragmus violaceus (L.) O.E.Schulz)相比较,其特点为柔弱草本,多分枝,茎生叶为间断羽状复叶或羽状复叶,种子为圆柱状长圆形,表面网状,命名为秭归诸葛菜(Orychophragmus ziguiensis Z．E．Zhao et J．Q．Wu)。     

长江三峡库区堇叶芥属（十字花科）一新种

采于长江三峡库区一个植物新种,属于十字花科堇叶芥属,与大花堇叶芥(Neomartinella grandifloraA l-schehbaz)相比较,其特点为常绿草本,叶两面密被糙伏毛,叶柄密被短柔毛,花序密被短柔毛,长角果略呈镰刀状,长0.9~1.2 cm,命名为兴山堇叶芥(Neomartinella xingshanensisZ.E.Zhao et Z.L.N ing)。     

Levels of Polychlorinated Dibenzo-P-Dioxins (PCDDs) and Polychlorinated Dibenzo-P-Furans (PCDFs) in the Atmosphere (PM10) of a Coastal Area of West Bengal,India

Particle-bound polychlorinated dibenzo-p-dioxins and dibenzo-p-furans (PCDDs/Fs) were analyzed in the coastal air of West Bengal, India. Total PCDD/Fs ranged from 4–2491 fg m^–3 with a mean of 355 fg m^–3 and their I-TEQ values ranged between 1 to 62.6 fg I-TEQ m^–3, with an average of 17.1 fg I-TEQ m^–3. The dominant congeners were OCDD (46%) OCDF (14%) 1,2,3,4,6,7,8-HpCDF (11%) and 1,2,3,4,6,7,8-HpCDD (10%) and accounted for >80% to the total PCDDs/Fs. TCDD (29%) > PeCDF (28%) > HxCDF (16%) > PeCDD (13%) were the dominant TEQ contributors. Rough estimates of tolerable daily intake (TDI) show a low health risk of exposure to PCDD/Fs measured in the ambient air of a rural coastal area of West Bengal, India.     

Small-scale distribution and diel vertical migration of zooplankton in a shallow lake (Lake Naardermeer,the Netherlands)

Groundwater is a major influence on the hydrological, chemical and thermal regime of chalk streams in the southern U.K. However, little is currently known about the nature of the sediment delivery system within these chalk stream systems, even though sediment-related problems have been increasingly cited as a cause of habitat degradation and of declining salmonid stocks. To address this knowledge gap, suspended sediment fluxes were monitored at 4 sites within the Hampshire Avon catchment between February 1999 and August 2000. Maximum suspended sediment concentrations ranged from nearly 45 mg l^–1 to 260 mg l^–1. Over the study period, annual suspended sediment loads ranged from 644 to 6215 t yr^–1 and annual specific sediment yields ranged from 1.4 to 12.5 t km^–2 yr^–1. The results show that, relative to other U.K. rivers, the study chalk streams are characterised by low suspended sediment concentrations and loads and less episodic behaviour.     

Consequences of the Ban of By-Products from Terrestrial Animals in Livestock Feeding in Germany and The European Union: Alternatives,Nutrient and Energy Cycles,Plant Production,and Economic Aspects

Consequences of the ban of meat and bone meal (MBM) and animal fat with regard to livestock feeding, cropping, ecology and economy where investigated with an inter-disciplinary approach for Germany and the European Union. Calculations were made for different production systems with pigs and poultry on the basis of statistical data for the production and for the feed markets as well as from requirement data for the respective species and production system. (1.) The ban of MBM from feeding caused a need for alternative protein sources. If all the amount of protein from MBM is to be replaced by soybean meal, in Germany and the EU about 0.30 and 2.30 · 10⁶t would be needed each year (supplementary amino acids not considered). Alternatively, doubling the grain legume acreage in Germany to about 420,000ha would supply a similar amount of protein. A wider application of phase feeding with adjusted dietary amino acid concentrations, however, would allow for saving protein to an extent which is similar to the amount of protein that was contributed by MBM in recent years. Thus, the ban is a minor problem in terms of ensuring amino acid supply. (2.) However, alternative plant ingredients cannot compensate for the gap in P supply that is caused by the ban. An additional demand for inorganic feed phosphates of about 14,000 and 110,000t per year is given in Germany and the EU, respectively. So far, this gap is filled almost completely by increased mining of rock phosphates. Alternatively, a general application of microbial phytase to all diets would largely fill this gap. Until the ban, MBM contributed to 57% of the supplementation of P that was needed for pigs and poultry. The ban of MBM makes large amounts of P irreversibly disappearing from the food chain. (3.) Energy from slaughter offal and cadavers can be utilized in different technologies, in the course of which the efficiency of energy utilisation depends on the technology applied. It is efficient in the cement work or rotation furnace if heat is the main energy required. In contrast, the energetic efficiency of fermentation is low. (4.) Incineration or co-incineration of MBM and other by-products causes pollution gas emissions amounting to about 1.4kg CO₂ and 0.2kg NO_x per kg. The CO₂ production as such is hardly disadvantageous, because heat and electrical energy can be generated by the combustion process. The prevention of dangerous gaseous emissions from MBM burning is current standard in the incineration plants in Germany and does not affect the environment inadmissibly. (5.) The effects of the MBM ban on the price for compound feed is not very significant. Obviously, substitution possibilities between different feed ingredients helped to exchange MBM without large price distortions. However, with each kg MBM not used in pig and poultry feeding economic losses of about 0.14¢ have to considered. In conclusion, the by far highest proportion of raw materials for MBM comes as by-products from the slaughter process. Coming this way, and assuring that further treatment is safe from the hygienic point of view, MBM and animal fat can be regarded as valuable sources of amino acids, minerals and energy in feeding pigs and poultry. Using them as feedstuffs could considerably contribute to the goal of keeping limited nutrients, phosphorus in particular, within the nutrient cycle and dealing responsible with limited resources.     

Restoration of a Stratified Lake (Feldberger Haussee,Germany) by a Combination of Nutrient Load Reduction and Long‐Term Biomanipulation

A long‐term biomanipulation has been performed in the stratified Feldberger Haussee since 1985. Prior to manipulation, nutrient load to the lake had declined due to waste water removal. Planktivorous fish were reduced by seining and by enhancement of piscivorous fish. Changes in transparency, nutrients, phytoplankton, zooplankton and fish were documented for both the premanipulation period (1978–1985) and the manipulation period (1986–1998). Transparency increased in response to the manipulation (+54%), but strong year‐to‐year fluctuations were observed. These fluctuations were correlated to chlorophyll a, primary production and the proportion of piscivores in the fish community. We conclude that the success of the restoration was predominantly attributed to bottom‐up forces as a result of the declining nutrient load and an intensified co‐precipitation of phosphorus with calcite. However, the increased predation impact by the piscivorous fish may have caused a reduced nutrient recycling by the planktivorous fish thus contributing also to the improvement in water quality.