Der Einfluß von Erdölkohlenwasserstoffen auf die Primärproduktion des Donauplanktons

Danube river water samples were saturated with mineral oil, and then the primary production (gross) was determined by means of the light-dark bottle method (oxygen) in situ at depths of 0.1… 1.5 m in comparison with untreated samples. Samples were exposed for half a solar day alternately during the first and second half-days. Investigations carried out between March and October for periods of 14 days showed a mean production of 2.56 g · m^?2d^?1 O₂, which was reduced by 36% due to 12.6 mg/l hydrocarbons. Production decreases with the water depth from 6.2 to 0.9 mg · l^?1d^?1 0₂, whereas the inhibition by hydrocarbons increases from 31 to 41%.     

Zur Rolle der Stickstoffixation im Stoffhaushalt eines geschichteten Sees

In the dimict lake Arend (5.1 km², 146 hm³, 49.5 m z_max), nitrogen is production-limiting with concentrations below the detection limit during the production period. Phytoplankton achieves biomasses of up to 18 mg/l fresh matter, essential contributions being made by Aphanizomenon with 2 mg/l and Anabaena with up to 10 mg/l. Nitrogen fixation was measured by the ethine reduction technique (acetylene reduction) during periods of the occurrence of heterocystforming Cyanophyceae and achieved peak values up to 6.59 μg N² · h^?1 · l^?1 or 14.87 m^?2 · h^?1 g N₂ · m^?2 · h^?1. The rates of fixation show a safe correlation with the biomass of heterocyst-containing Cyanophyceae (r = 0.88), their development beginning at values below the N : P-ratio of 2.66.     

Low boundary layer response and temperature dependence of nitrogen and phosphorus releases from oxic sediments of an oligotrophic lake

The effects of temperature, diffusive boundary-layer thickness, and sediment composition on fluxes of inorganic N and P were estimated for sediment cores with oxidized surfaces from nearshore waters (2?C10?m) of a montane oligotrophic lake. Fluxes of N and P were not affected by diffusive boundary-layer thickness but were strongly affected by temperature. Below 16?°C, sediments sequestered small amounts of P and released small amounts of N. Above 16?°C, the seasonal maximum water temperature, sediments were substantial sources of N (NH₄ ⁺?CN?=?2?C24?mg?m^?2 d^?1; NO₃ ^??+?NO₂ ^??CN?=?2?C5?mg?m^?2 d^?1) and P (0.1?C0.4?mg?m^?2 d^?1), indicating potential responsiveness of sediment?Cwater nutrient exchange, and of corresponding phytoplankton growth, to synoptic warming.     

Zur ökonomischen Bedeutung der biologischen Selbstreinigung

In twelve flowing water (Q 1.04… 30.4 m³/s, 0.5… 1.2 m/s) the self-purification efficiency in 110 river sections (L 1.3… 26.4 km) is determined as the load difference in kg · d^?1 COD-Mn as well as in g · m^?3 referred to the daily passage. In the economical comparison, the self-purification efficiency is valued as substitution for wastewater treatment plants of the same capacity. At a mean specific capacity of 8.6 g · m^?3, the self-purification efficiency of the investigated waters is equivalent to economical values of 124 · 10³… 534 · 10³ M km^?1 investment costs, 11 · 10³… 80 · 10³ M · a^?1km^?1 operating costs and 5… 81 MWh · a^?1 km^?1 expenditure of energy. The specific capacity in g · m^?3 COD-Mn shows an exponential regression to the degree of saprobity (L = 0.015 · exp (1.7358 · S)). From this empirical model the limits of the self-purification capacity of aerobic waters by oxygen input can be detected: in respective examples more than 50% of the required oxygen input are due to weirs.     

Hydrograph separation to improve understanding of Dissolved Organic Carbon Dynamics in Headwater catchments

Dissolved organic carbon (DOC) is a key component of the global carbon cycle, but, to date, large uncertainties still exist on its source and fate in first‐order streams. In a 23 ha rangeland and steep‐slope headwater of South Africa, our aim was to quantify the contribution of overland flow (OF), soil water (SW) and ground water (GW) to DOC fluxes (DOC_F), and to interpret the results in terms of DOC sources and fate. The average 2010–2011 DOC concentration (DOC_C) at the catchment outlet was 4.7 mg C l^?1 with a standard error of ±2.5 mg C l^?1, which was significantly lower than in SW (15.2 ± 1.6 mg C l^?1) and OF (11.9 ± 0.8 mg C l^?1), but higher than in GW (2.3 ± 0.6 mg C l^?1). Based on end‐member mixing using Si and Na concentration in the water compartments, the average SW contribution to DOC_F was 66.4%, followed by OF (30.0%) and GW (3.6%). The resulting estimated DOC_F at the catchment outlet was 8.05 g C m² y^?1. This was much higher than the observed value of 2.80 g C m² y^?1, meaning that 5.25 g C m² y^?1 or 65% of the DOC is lost during its downslope and/or downstream transport to the catchment outlet. Complementary investigations revealed that the DOC_C in SW dropped from 15.2 ± 1.6 to 2.6 ± 0.3 mg C l^?1 during its downslope transport to the river system, which corresponded to a net loss of 5.10 g C m² y^?1, or 97% of the catchment DOC losses. These results on DOC sources and potential fate in headwaters are expected to improve our understanding of the impact of hydrology on the global C‐cycle. Copyright © 2013 John Wiley & Sons, Ltd.     

Primary Productivity Studies on Freshwater Fish-Ponds of Bhagalpur,India

A one year study from October 1972 to September 1973 in four freshwater fishponds of Bhagalpur (87° 02' E long, and 25° 15'N lat.), India, has shown that a high phytoplankton primary production occurred twice during the annual cycle. There were seasonal variations in the production rate with a great fluctuation in the maximum and minimum values (3 … 4 times). Amongst the ponds studied, the highest daily production recorded was 6.93 g C/m²/day in Pond I and the minimum was 0.82 g C/m²/day in Pond II. The highest annual gross production was estimated to be 1611.98 g C/m²/y in Pond I, next in the order was 1543 g C/m²/y in Pond IV and then 1155.7.5 g C/m²/y in Pond I and the minimum was 641.75 C/m²/y in Pond II. It has also been observed that in certain months the net:gross ratio recorded was zero, while the community respiration as percentage of the gross production value reached 100% in few months. A comparison has been made in the annual production of temperate and tropical freshwater systems and this indicates that tropical waters are more productive than the temperate waters. Various physico-chemical factors such as rainfall, light, temperature and alkalinity may regulate or limit production.     

Grundwasserchemismus im Bezirk Neubrandenburg. Teil 3. Jodid im Grundwasser

The iodide contents in 389 ground-water-tapping plants of the county are compared with the geological character of the aquifer, the carbonate and non-carbonate hardness and the nitrate and chloride contents of the waters. 54% of the plants have I-concentrations of 3 … 7 μg/l. In the air-covered ground-water (hardness quotient<2.8) 2 … 50 μg/l I are found, whereas in the confined ground-water (hardness quotient >2.8) 2 … 50 μg/l I are contained. In general, the I-content increases with the carbonate hardness, a connection with till existing. Therefore, ground-waters of the Miocene have relatively low salt- and I-contents. Geogenic salt influences in the form of NaCl increase the I-contents to 50 … 100 μg/l. Anthropogenic influences in the residential area and due to waste increase the Cl^?- and I^?-concentrations. There were not detected any dependences between the I- and NO₃-contents.     

Groundwater Inflow Controls Acidity Fluxes in an Iron Rich and Acidic Lake

To ascertain the influence of hydrological boundary conditions on acidity fluxes in lakes influenced by acid mine drainage, acidity budgets were developed for two sediments in areas of differential groundwater inflow (approx. 1 L m^?2 d^?1 and 10 L m^?2 d^?1). In both sediments iron was deposited as schwertmannite leading to iron(III) enriched sediments (3.9…6.2 mmol g^?1, referred to dry weight). Compared to the surface water, the inflowing groundwater had higher pH (4.5 vs. 3), ferrous iron (6…20 mmol L^?1 vs. 0.8…2.0 mmol L^?1), and sulfate (5…60 mmol L^?1 vs. 8…13 mmol L^?1) concentrations. The inflow changed the sediment pore water chemistry and triggered a further increase in pH to above 5.5. In both sediments acidity generation in the surface water (10…30 mol m^?2 a^?1) strongly prevailed over acidity consumption in the sediments (> ?0.6 mol m^?2 a^?1). With advective groundwater inflow, however, more acidity was consumed due to TRIS formation (?0.12 mol m^?2 a^?1 vs. ?0.017 mol m^?2 a^?1), iron carbonate burial (upper estimate: ?0.14 mol m^?2 a^?1 vs. ?0.022 mol m^?2 a^?1), and unspecific ferrous iron retention (?0.39 mol m^?2 a^?1 vs. ?0.08 mol m^?2 a^?1). Also, less acidity was generated due to schwertmannite transformation (?2.4 mol m^?2 a^?1 vs. ?0.11 mol m^?2 a^?1). The acidity balance of internal processes in the sediment with groundwater inflow was negative, whereas it was positive in the other sediment. The study demonstrates that in acidic and iron rich lakes the hydrological boundary conditions strongly affect geochemical processes as subsumed in acidity fluxes.     

Petroleum hydrocarbons in zooplankton faecal pellets from the Sargasso Sea

Analysis of hexane-extractable hydrocarbons in zooplankton collected off Bermuda in August 1979, and their faecal pellets, gave an estimated removal rate of hydrocarbons from surface waters by ‘grazing’ of 16–46 μg m^?2 for a 4 h period. With a number of assumptions, this can be translated to 8–23 mg m^?2 yr^?1. When compared to the annual input due to petroleum discharge in the currents feeding the Sargasso Sea (18–70 mg m^?2 yr^?1 hexane-extractable hydrocarbons), this result implies that zooplankton are an important factor in the short-term removal of petroleum residues from open ocean surface waters.     

Water Quality,Phytoplankton Diversity and Production in G. B. Pant Sagar at Rihand Dam,Pipri

The man made reservoir, G. B. Pant Sagar at the dam site (24° 15′ N Lat) in the South Mirzapur district of eastern U. P. was investigated in terms of water quality, phytoplankton diversity and production at monthly intervals between January 1987 and December 1987. The reservoir water showed low to moderate dissolved oxygen (4.3 … 7.5 mg/l) and quite low nutrient contents (0.01-0.2 mg l^?1). Phytoplankton diversity narrowly fluctuated (3.17-3.74) and mean annual production (149.7 g/m³ · aC) showed a meso- to eutrophic condition. A significant positive correlation was obtained between gross production and phytoplankton density (r = 0.79; P < 0.001) Multiple regression equation (GPP = 11.292 + 0.043 BAC + 0.075 CHL + 0.073 CYN) indicates that Chlorophyta contributed more to gross production due to the presence of a higher number of individuals.     

Effect of Zinc,Copper and Mercury on Channa marulius (HAMILTON)

Static bioassay acute toxicity tests of Zinc, Copper and Mercury were conducted to determine the median lethal concentrations (LC₅₀s) of a freshwater teleost Channa marulius (HAM .) The 96 h LC₅₀ and 95% confidence limits for Zn²⁺ were 25.61 (24.13 … 27.12) mg/l; 0.90 (0.80 … 1.038) mg/l; for Cu²⁺ and 0.314 (0.257 … 0.371) mg/l for Hg²⁺. However, these values decreased at 240 h of exposure and were: 21.09 (18.29 … 24.60) mg Zn²⁺/l; 0.66 (0.568 … 0.841) mg Cu²⁺/l; and 0.131 (0.103 … 0.158) mg Hg²⁺/l. The relative potency ratio of Zn/Hg, Zn/Cu and Cu/Hg suggests that fish were most sensitive to Hg, followed by Cu and Zn ions. The acute toxicities of mixtures of Zn²⁺?Cu²⁺; Zn²⁺?Hg²⁺, Cu²⁺?Hg²⁺ and Zn²⁺?Cu²⁺?Hg²⁺ up to 48 h of exposure were also investigated. The additive index and ranges for Zn²⁺?Cu²⁺ were ?0.241 (-0.577 … 0.054); 0.056 (-0.269 … 0.475) for Zn-Hg; 0.285 (-0.043 … 0.718) for Cu-Hg; and -0.542 (-1.215 … 0.005) for Zn-Cu-Hg. All the mixtures tested showed a greater than additive toxicity because index ranges overlapped zero.     

Aerial flux of particulate hydrocarbons to the Chesapeake Bay Estuary

Bulk hydrocarbon deposition rates have been measured over a 15 month period at four stations in south-eastern Virginia surrounding the lower Chesapeake Bay. A nearly linear trend of atmospheric particulate deposition was recorded. Deposition rates at the urban station (195 μg m^?2 day^?1) were aproximately three times greater than those recorded for nonurban and coastal locations (mean value 69 μg m^?2 day^?1). The increased levels at the urban location were attributed to localized source inputs. Anthropogenic hydrocarbons accounted for approximately 50% of the total deposition at all stations. Significant biogenic inputs were indicated by the odd/even n-alkane distribution. A minimum flux to the water surface, based on mean nonurban deposition rates (24 mg yr^?1), indicated an annual particulate hydrocarbon flux of +275 metric tons. Little information is available for the comparison of additional source inputs; however, the data reported here indicate that the aerial deposition of hydrocarbons is of the same order of magnitude as the input from municipal wastewater facilities and accidental discharge and is a potentially significant source of hydrocarbon pollution to the Chesapeake Bay Estuary.     

Primary Productivity in Relation to the Abiotic Factors in a Temporary Freshwater Pond

The primary production in the small pond (3.5 m long, 1.5 m wide, 1.5 m deep) was measured in winter from November to April by means of the bright-dark-flask method at an exposure for 24 hours. The following results were obtained: gross production 0.9 … 11 g C/m³d, net production 0.8 … 7 g C/m³d, respiration 0.5 … 5.6 g C/m³d, P/R quotient 19.6 … 0.18. The results are discussed in connection with chemical and hydrographie parameters as well as with the hydrological situation.     

Estimate of the Eutrophication Process in the Gruža Reservoir (Serbia and Montenegro)

The Gru?a Reservoir (located at 238…269 m a. s. l., volume 64.6 · 10⁶ m³, surface 934 ha, drainage area 318 km², max. depth 31 m, mean theoretical retention time 22 months) was investigated during the years 1996 to 2001. The obtained values of trophic state parameters (9…200 μg L^?1 total phosphorus, 3…99 μg L^?1 chlorophyll‐a, and 0.5…2 m transparency) indicate that water of the Gru?a Reservoir is eutrophic according to three types of classification: Carlson, OECD, and Jones and Lee. It was noticed that values of average biomass abundance are large in the Gru?a Reservoir, and they could indicate a richer trophic state. When these indices are cited in connection with parameters of the trophic state, it is apparent that the Gru?a Reservoir can be classified as a eutrophic water on the basis of total phosphorus content of chlorophyll‐a and hypertrophic water with respect to transparency.     

Survivality and Impaired Growth in Arsenic Treated Fingerlings of Channa punctatus,a Fresh Water Murrel

The LC₅₀-values of As³⁺-compounds for Channa punctatus are determined for a 48-h exposure to 19.4 (18.02… 21.3) mg/1 and for a 96-h exposure to 14.3 (13.06… 16.80) mg/1. At a long-time exposure to 7.0 mg/1 As³⁺, during the first seven days there does not occur any change of growth, then the growth in length and the increase in weight decreased by 6.6 and 11.7%, respectively, till the 31st day. At the same time, the RNA content of the muscle decreased by 11.5% to 966.7 μg/g fresh weight and the protein content decreased by 12.5 % to 95.39 mg/g fresh weight.     

Modelluntersuchungen zur Denitrifikation im Grundwasser

Two subsurface reactors of 1 m³ volume, filled with fine gravel or coarse sand, are fed with a medium similar to groundwater having a nitrate concentration of 208 mg/l. The retention time of water in the reactor is 400 d. After 30 months the reactor effluent shows a stationary behaviour of the nitrate concentration. Then, the effluent concentration is 90 or 100 mg/l nitrate. The breakthrough curves of nitrate show four pronounced sections: up to the retention time, increase of nitrate to ca. 40 mg/l, a stationary intermediate phase, a further increase of nitrate to the final stationary phase. The stationary intermediate and final phases show 1st-order reaction constants of 0.0046 d^?1 and 0.0019 d^?1, respectively, or half-times of 150 and 330 … 400 d, respectively. The higher reaction constants of the intermediate phase are connected with the bituminous coating of the reactors by the relatively easily degradable organic substance of which reaction is accelerated. With respect to variance analysis the annual minima and maxima of the nitrate turnover show significant differences. This is demonstrated by the temperature dependence of denitrification.     

Ecophysiological Studies on Size-fractionated Phytoplankton Populations by Tracer Technique in Wadi el Majanin Dam,Libya

Wadi el Majanin, one of the largest hydraulic structures in Libya was studied for ecophysiological aspects in relation to ambient environment. The waterbody is alkaline (pH=7.2) and characteristic of hydrogen-carbonate (144.8 mg L^–1 CaCO₃) system. Vertical extinction coefficients (> 4.8) indicate very high (biogenic) turbidity. Conspicuous variations of a quantitative kind in algal development (e.g., Pediastrum bloom) together with abundant diatom populations (chlorococcales-diatom assemblage), apart from very common occurrence of cyanobacteria and euglenoids show eutrophic water condition. Winter-summer alternation induced pronounced seasonal variability in the rates of in situ planktonic algal photosynthetic activities (285.7...1305 mg m^–3 d^–1 C). Dark fixation activity, attributed largely to bacterial production, oscillated by order of 2-fold magnitude, characterized by summer maxima (47.6 mg m^–3 d^–1 C). Size-fractional analysis established that smaller forms (< 60 μm), broadly regarded nanno-phytoplankton, frequently dominated (c. 70%) overall algal productivity.     

Winter methane dynamics beneath ice and in snow in a temperate poor fen

The influence of winter on methane (CH₄) stored in pore water and emitted through snow was investigated in a temperate poor fen in New Hampshire over two winters. Methane accumulated beneath ice layers (1 cm) deposited by freezing rain, resulting in snow-pore air mixing ratios as high as 140 ppmv during the first winter and 600 ppmv during the second. An early winter snow crust of 300 kg m^?3 caused no discontinuity in a linear mixing ratio profile and therefore was not observed to retard snowpack emissions. Methane concentration-depth profiles in pore water steepened and concentrations increased by as much as 400 μM at the 10 and 20 cm depths as the ice cover formed. This suggests that the peat-ice cover plays an important part in CH₄ build-up in pore water by limiting the transport of gases between the peat and the atmosphere. Pore water concentrations gradually declined through late winter. The seasonality of dissolved CH₄ in pore water over two winters and one summer showed an average annual amplitude of 1.3 gCH₄m^?2 (25–75cm depth range), with a winter maximum of 4.7gCH₄m^?2. Emissions during the winter with average snowfall accounted for a larger percentage (9.2% in 1993–1994) of total annual emission than the winter with below-average snowfall and warmer air temperature (2% in 1994–1995). Emissions averaged 56 and 26mg m^?2 day^?1 during the first and second winter (December, January and February), respectively.     

Chlorination of Humic Acids and Chloroform Production

By diluting a boggy water there is produced water with a COD-Mn of 3.4 … 10.6 mg/l O₂ which is due only to humic substances. The water is mixed with 2.5 … 12.9 mg/l Cl₂ at pH-values of 5.2 … 8.5 and incubated for 24 h at 20°C. CHCl₃ concentrations of 38 … 480 μg/l were found by the subsequent gas-chromatographic determination. The production of chloroform can be calculated by means of a quadratic polynomial in dependence on COD-Mn, chlorine concentration and pH-value.