Showing papers in "Acta Hydrochimica Et Hydrobiologica in 2006"

The role and significance of extracellular polymers in activated sludge. Part I: Literature review

Abstract: In biological wastewater treatment, bacteria tend to aggregate by forming flocs, biofilms and even granules A large part of the floc structure in activated sludge is composed of extracellular polymers The extracellular polymeric substances (EPS) are mainly responsible for the structural and functional integrity of biofilms/flocs and they are considered to be important for the physico-chemical properties of activated sludge This review considers the composition of EPS and proportion between the constituents Moreover it includes the relationship between the EPS constituents and sludge properties such as sludge retention time, hydrophobicity and surface charge

Effects of nitrate on phosphorus release: comparison of two Berlin lakes

Abstract: After installation of phosphorus elimination plants at the inflows of the eutrophic Lake Tegel and Schlachtensee, phosphorus (P) loading declined by a factor of 40 and 100, respectively. This resulted in a pronounced reduction of phosphorus concentrations in the lake water, followed by a decline of chlorophyll-a concentrations. However, for many years P release from sediments due to mineralization and desorption of sedimentary P continued. In Schlachtensee, the presence of nitrate above the sediment suppresses P release, because the Fe/P ratio is sufficient to provide enough aerobic sorption capacity. In Lake Tegel, some P release occurs even under aerobic conditions because of the low aerobic P sorption capacity of the sediments. There, nitrate could moderate the P release peaks which occur when the Fe-P cycle at the sediment water interface is disturbed by precipitation of iron sulfide after reduction of sulfate during times of high mineralization intensity. The potentially mobile P pool in the sediments of both lakes is rather small, indicating that the P release could subside after sufficient reduction of the external P load in Lake Tegel and the disruption of the internal P cycle in Schlachtensee.

Spectroscopic investigation of humic substances in a tropical lake during a complete hydrological cycle

Abstract: Fluorescence and UV-VIS techniques were employed for the investigation of natural organic matter (NOM) of a tropical lake. The relationships of absorbance/dissolved organic carbon (A/DOC), fluorescence intensity/dissolved organic carbon (FI/DOC), fluorescence ratio (FR), and peak wavelength with the highest intensity (PW) were used to distinguish the pedogenic or aquagenic origin of NOM. The values of FR, PW and A285/DOC of high waters (HW) or flooded period samples and of low waters (LW) period samples of the dry season, except for September 2002, confirm the predominance of pedogenic material. The spectra of water were similar to the standard fulvic acid (FA), and the spectra of FA from the lake were similar to the nearby soils, indicative of pedogenic predominance. The results confirm that the dissolved NOM of Patos Lagoon – MS (Brazil), in all sampling periods, predominantly consisted of humic substances (FA) of pedogenic origin.

The effects of mining in Northern Romania on the heavy metal distribution in sediments of the rivers Szamos and Tisza (Hungary)

Abstract: The breach in the dam of a tailing pond in the processing plant of a gold mine in Baia Mare (NW Romania) in January 2000 lead to an ecological disaster in the rivers Szamos and Tisza. It was mainly caused by the released slurries containing cyanides and heavy metals. The investigation of surface sediment samples and depth profiles of the years 2000 and 2001 documented the pollution of the rivers Szamos and Tisza on Hungarian territory. In the Szamos and large areas of the Tisza floodplains a significant enrichment with the heavy metals Pb, Cd, Cu, and Zn is existent. The identification of the binding forms with sequential extraction showed that Cd and Zn exist in an easily available form. Therefore the remobilization is possible and an environmental hazard in the downstream areas must be considered. The anthropogenically caused portions of heavy metal concentrations decrease considerably with increasing distance to the mining region. The comparison of the concentrations of heavy metals in both years shows that the pollution is not only caused by the accident in January 2000. The increase of concentrations is based on the permanent input of pollutants into the rivers. The pollution is mainly caused by the erosion of exposed tailing dumps and the poor maintenance of the treatment plants.

Higher effectiveness of photoinactivation of bacterial spores, UV resistant vegetative bacteria and mold spores with 222 nm compared to 254 nm wavelength

Abstract: Eleven selected species of vegetative bacteria, bacteria spores and mold spores were irradiated with different doses of UV radiation of a 222 nm krypton-chloride excimer lamp and a 254 nm mercury lamp under laboratory conditions. Then the inactivation curves were determined. The necessary UV fluences for a respective reduction were higher for the excimer lamp for the tested vegetative bacteria of Bacillus cereus, Arthrobacter nicotinovorans, Staphylococcus aureus and Pseudomonas aeruginosa and slightly higher for the spores of Streptomyces griseus and Clostridium pasteurianum. However, less than 250 Jm 2 UV fluence with 222 nm was sufficient for a 4-log reduction, depending on the species. On the other hand, the UV fluences for the 254 nm mercury lamp were much higher for the bacterial spores of Bacillus cereus, Thermoactinomyces griseus and the bacteria of Deinococcus radiodurans and slightly higher for the mold spores of Aspergillus niger and Penicillium expansum. The results show that especially the germs with a higher UV resistance and those with more effective repair mechanisms can be inactivated more efficiently by the 222 nm excimer lamp. This may be due to the fact that low UV fluence mainly affects radiation sensitive microorganisms by DNA damage whereas at higher UV fluence (various) mechanisms of protein damage can presumably be held responsible for inactivation.

Local use of antibiotics and their input and fate in a small sewage treatment plant – significance of balancing and analysis on a local scale vs. nationwide scale

Abstract: Most antibiotics are only partially metabolised by patients before being discharged into the municipal sewage system along with patient excreta. Studies have shown that the majority of antibiotics pass through sewage treatment and are then released into the environment. Accordingly, investigations conducted in various countries have detected a number of antibiotics in the low μg or ng per litre range in different environmental compartments. Studies connecting mass balances of use on a local scale and of input and analysis of the antibiotic concentrations present in municipal sewage treatment plants are scarce. Data on local use of antibiotics and their relation to nationwide consumption are not available. This study investigated the use, input, and fate of antibiotics on a local scale and this data were compared with the German nationwide consumption. 42 antibiotics and 15 antimycotics were used in the mass balance consideration over a period of one year. It was found that the local pattern of usage differed only little from that found nationwide. Seasonal changes were minor and the concentrations actually measured were found to be in the expected range. Differences in both the identified occurrence and the concentrations of the target compounds were observed within and between the three sampling periods.

Longitudinal impacts of anthropogenic pressures on benthic macroinvertebrate assemblages in a large transboundary Mediterranean river during the low flow period

Abstract: Changes in lotic benthic macroinvertebrate assemblages along the transboundary Axios-Vardar River (Greece – Former Yugoslavian Republic of Macedonia) were examined in order to identify major anthropogenic impacts correlated to the benthic community composition during the low flow season. Macrozoobenthos and water samples were collected from 21 sites during summer 2000 and beginning of autumn 2001. Parallel to sampling, the recording of the physical structure of the sites took place using the River Habitat Survey (RHS) method. The multivariate techniques of FUZZY and Canonical Correspondence Analysis (CCA), as well as the Hellenic biotic score (HES) and the habitat quality scores (HMS, HQA) were applied to the data. Total dissolved solids and total suspended solids were found to be the primary factors affecting the structure of the observed communities. Additionally, species composition responded to anthropogenic activities, e. g. untreated sewage effluents, industrial discharges, agricultural runoff, intense water abstraction and impoundment. As expected, macrozoobenthos community composition shifted from sensitive to tolerant taxa where human impacts were most evident.

Nitrogen emissions into freshwater ecosystems: is there a need for nitrate elimination in all wastewater treatment plants?

Abstract: ba Technische Universit! t Dresden, Institut f" r Hydrobiologie, Dresden b Technische Universit! t Dresden und S! chsische Akademie der Wissenschaften zu Leipzig, Dresden Excessive inputs of phosphorus and nitrogen are the main reasons of eutrophication of inland waters and coastal areas. Large efforts have been made to control phosphorus, but the measures to reduce nitrogen emissions failed at least partly. While it was possible to reduce nitrogen emissions from industry and municipal wastewater treatment plants, diffuse sources are showing only very minor decline. Examples of limnetic, marine and coastal systems are given to review the current knowledge about nitrogen transformation and the effects of nitrate in the environment. When N is the limiting nutrient in a particular water body, this does not necessarily mean that phytoplankton is controllable by NO3 ‐ removal. In systems with problems due to a high redox-sensitive internal phosphorus load and under certain constraints, nitrate may be used as an ecotechnological measure to prevent anaerobic phosphorus release from sediments. Model simulations are used to demonstrate this. A schematic model of redox-mediated temporal phosphorus storage in riverine lake sediments with short retention time is proposed. We conclude that while anthropogenic nitrogen emissions are a global problem, no fast and simple single solution exists. Additional nitrogen removal in wastewater treatment will have no effect, as long as diffuse sources and nitrate concentrations in groundwater remain at a high level. Emission reductions should be achieved in an integrated way, taking direct and indirect effects into account. In this sense, case by case decisions and a new definition of “sensitive areas” are required.

Contamination of some reservoirs and lakes in Republic of Bulgaria by microcystins

Abstract: This paper presents the results from analyses of water samples from 15 Bulgarian reservoirs and lakes for detection of microcystins presence by high-performance liquid chromatography (HPLC) coupled to a ultraviolet (UV) and photo diode array (PDA) detector. In 3 of the studied drinking water reservoirs cyanobacterial blooms were not detected. Cyanobacterial blooms were observed in 6 of 12 investigated water bodies used for fishing and water sports. Microcystis was the dominant cyanobacterial genus. The concentration of total microcystins in the biomasses ranged from 8 to 1070 μg g -1 (d.w.). Microcystin-LR and microcystin-RR were the predominant microcystins, followed by microcystin-YR, Presence of dissolved microcystins was obtained in one water sample with concentration of total microcystins 1.64 μg L -1 . Presence of microcystin-LF and -LW or unknown peaks possessing characteristic microcystin-like UV-spectra were not detected. Those first results for occurrence of microcystins in some Bulgarian reservoirs and lakes are a contribution to the knowledge on their distribution.

Characterization of the sources of thermal spring- and well water in Jordan by rare earth element and yttrium distribution and stable isotopes of H2O

Abstract: Four types of thermal groundwater in Jordan were distinguished by Y and rare earth elements (REY) distribution patterns. Complementary to the stratigraphic origin of water in springs or of wells, REY patterns identify either recharge areas covered by basalt, limestones or sandstone, or interaction with basalt-limestone contact zones. This hydrochemical grouping does not always correspond with "common geological knowledge" of the aquifer lithology of the thermal water. Therefore, comparison of the hydrochemical signatures of REY patterns and the lithological source of water yield insight into transaquifer flow. Out of 44 analysed groundwater, 18 indicated down- and 3 upflow of water the latter due to step faults near the Rift system. During transaquifer flow REY patterns of groundwater from basalts and gypsum beds or gypsum-cemented sandstones are not changed by subsequent interaction with limestones, whereas in groundwater originating from dissolution of chalk and limestones REY patterns are adjusted to those typical for gypsum-bearing sediments. Cross plots of δ 18 O vs. δ 2 H reveal essentially two trends. The main trend of water from limestone aquifers define a mixing line of past to recent meteoric water with negligible contributions of Pleistocene water. Some water from Eocene aquifers plot on the local Mediterranean meteoric water line, others plot together with water from sandstone aquifers at enhanced δ 18 O values due to hydrothermal overprinting.

Climate change and agricultural pollution effects on the trophic status of a Mediterranean lake

Abstract: Trichonis Lake is the largest natural freshwater body in Greece with a surface area of 97 km 2 . It receives pollutants from numerous anthropogenic activities, especially from intensiye agricultural practices, urban sewages, stock grazing land and small industries. In this study, hydrologic and chemical parameters are assessed during two periods (1990-1991) and (2001-2002) to evaluate the effects of the climatic changes on phosphorous trends and consequently on the trophic status of Trichonis Lake. Even though large quantities of fertilizers are applied in the lake's catchment, phosphorus loads are still in the permissible level as estimated according to Vollenweider's relationship based on total phosphorus concentration. Due to relatively higher rainfall precipitation during the last years, an increased amount of the phosphorus entering into the lake system is flushed out, thus keeping the trophic status of the lake in oligotrophic levels. In contrast, lower rainfall rates during the first period (1990-1991) have led to the decrease in phosphorus flush out and its detainment into the lake water and sediment resulting to mesotrophic conditions. As the trophic status of the lake is mainly hydrologically dependent and thus unpredictable, effective management plans targeting the elimination of nutrient pollution loadings are necessary.

Numerical modelling of floodplain hydraulics and suspended sediment transport and deposition at the event scale in the middle river Elbe, Germany

Abstract: The objective of this case study was to calibrate and verify a detailed sediment transport model in a 4-kilometre stretch of the middle Elbe floodplains in Germany. The hydraulic RMA-2 model and the SED2d-WES sediment transport model were used. The sediment transport model was verified with a flood event by detailed measurements of surface water levels, flow velocities at six profiles, suspended sediment concentration and sediment deposition (by means of 10 sediment traps). Discharge was modelled for three steady-state conditions. Surface water levels could be calculated to an accuracy of less than 5 cm compared to measurements. The differences between calculated and measured velocities were with one exception smaller than 0.2 m/s (measured range 0.1...1.0 m/s). Simulated average sediment input amount to 35 g/(m 2 d) for the given flood event. The highest calculated sedimentation rates of 700 g/(m 2 d) (dry density 90 kg/m 2 ) took place in backwaters and abandoned channels. Twenty-five percent of the deposited sediment settled in the backwaters (which only account for 13 percent of the area). The most sensitive parameters of the sediment transport model were the settling velocity and critical shear stress. The modelling approach allowed a realistic spatial distributed calculation of sediment inputs into the floodplain of the Elbe River.

Benthic macrofauna in Tunca River (Turkey) and their relationships with environmental variables

Abstract: The numerical and proportional distributions of benthic macroinvertebrates in Tunca (Tundja, Tundzha) River (Edirne/Turkey) were determined from July 2002 to June 2003 at monthly intervals at four different stations. It was found that the benthic macrofauna consisted of 63% Oligochaeta, 24% Chironomidae larvae, and 13% Varia by numbers. According to the Shannon-Wiener index, Tunca River had a diversity of 1.36; station 2 and September were found to have the highest diversity while station 4 and December to have the poorest. According to Bray-Curtis similarity index, stations 2 and 3 and April and May were found to be the most similar to each other while stations 1 and 4 and August and January were found to be the most different from each other for the dynamics of the benthic macrofauna. Also some physicochemical parameters of the water (water temperature, electrical conductivity, pH, dissolved oxygen, chloride, total hardness, NO - 3 -N, NO - 2 -N, sulfate, phosphate, biochemical and chemical oxygen demands) were analyzed. Pearson correlation index supported the relationships between the dynamics of organisms and physicochemical variables. The relation between the number of macroinvertebrates and pH (r = +0.57, P < 0.05) was direct proportional while the relation between the number of macroinvertebrates and NO 3 - -N (r = -0.99, P < 0.05) was inverse proportional. Furthermore, the Chironomidae larvae of Bryophaenocladius muscicola and Mesosmittia flexuella were new records for Turkish Thrace region. High pH and supersaturated oxygen levels, hard water quality, second quality levels of NO - 3 -N, BOD, COD and fourth quality levels of NO - 2 -N as well as the density of 490 individuals m -2 for 124 taxa and the diversity of 1.36 showed that similar studies should be repeated periodically in Tunca to determine the future of the river.

Methods to calculate sedimentation rates of floodplain soils in the middle region of the Elbe River

Abstract: This study presents different methods to quantify the historic and recent sedimentation of flood-plain soils along the Elbe River. These methods include the comparison of surface elevations, the quantification of sedimentation with the aid of anthropogenic and geogenic tracers, sediment trap studies, and the calculation of load balances. Selected results from sites at the lower section of the middle Elbe River are presented and verified. The results show that several methods are suitable. In future work it should be possible, depending on the available soil and sediment data, to calculate sedimentation in Elbe River floodplain and the loss of retention volume for larger areas.

METEOR: a step-by-step procedure to explore effects of indicator aggregation in multi criteria decision aiding – application to water management in Berlin, Germany

Abstract: METEOR (METhod of Evaluation by ORder) is introduced as a new evaluation approach, based on partial order theory. METEOR combines transparent decision support and convenient tools for data analysis with the ability to include stakeholders' preferences in the decision process. The basic idea is a systematic step-by-step aggregation of indicators, including their weighting. We applied METEOR to evaluate the eco-hydrological effects of nine water management strategies upon the complex surface water system of Berlin and Potsdam, Germany. Altogether 14 river sections are defined, each of which is evaluated by a set of four hydro-chemical indicators. Aggregation of indicators was performed on two levels: spatially with respect to the river sections, and thematically to the four indicators themselves. The METEOR result is in good agreement with that obtained by the PROMETHEE approach. However, advantages of METEOR are (1) identification of sensitive steps of indicator aggregation, and (2) extraction of explanatory background information about advantages and disadvantages of scenarios. Both topics enhance the transparency of the evaluation process and thus support public acceptance of the decision.

Heavy metal inflow into the floodplains at the mouth of the river Weiße Elster (Central Germany)

Abstract: From 1998 to 2002 investigations were carried out to estimate both the quantity and quality (heavy metal contents) of suspended matter loads discharged into a floodplain area measuring approx. 5 km 2 of the Central German river Weise Elster, a tributary of the river Saale in the Elbe river basin. Flood sediments, suspended particulate matter, and floodplain soils were investigated especially for the main pollutants Cd, Zn, Cu, Pb, Cr, and Hg. Supplementary gamma spectroscopy examinations were performed to help to identify the age of deposits in order to estimate sedimentation rates for last decades. The recent flood sediments are contaminated by up to 33 times the geogenic background (Cd). Up to 55% of the total annual SPM load of the river Weise Elster is relocated into the investigated retention area in the flood-stricken year 2002. The sedimentation rates for the last 50 years vary between 0.5 mm/a and 1 mm/a in far away and rarely flooded parts and between 1 mm/a and 2 mm/a in the frequently flooded parts of the inflow of the retention area.

Sediment contamination in floodplains and alluvial terraces as an historical record of gold exploitation in the Carmo River basin, Southeast Quadrilátero Ferrífero, Minas Gerais, Brazil

Abstract: This paper describes the geochemistry of sediment samples placed in floodplains and alluvial terraces downstream from gold mines in the Carmo River basin, Quadrilatero Ferrifero, Minas Gerais, Brazil. The geochemistry signature Na 2 O, K 2 O, SiO 2 , CaO, MgO, Al 2 O 3 , Fe 2 O 3 , TiO 2 , P 2 O 5 , Mn, As, Cu, Zn, Ba, Ni, Cr, S, Co were analyzed in different facies from stratigraphic profiles. As, Cu, Zn, and Mn anomalies are mainly associated with the clayed facies deposited in floodplains and oxbow lakes, and with coarse-sediment facies deposited in the channel. The facies were accumulated by the gold exploitation activity in the region. The contamination of As, Cu, and Zn was controlled by minerals such as iron oxides and hydroxides (hematite, magnetite, and mainly goethite), manganese oxides, and sulfide-rich minerals. The As-bearing sediments of the region characterize one of the most As contaminated area of Brazil. Their main source is associated with gold exploration in the last three centuries.

The European Water Framework Directive 2000/60/EC in the evaluation of the ecological status of watercourses. Case study: the river Chienti (central Apennines, Italy)

Abstract: The quality of the river Chienti (eastern-central Apennines, Italy) has been evaluated according to the Water Framework Directive 2000/60/EC, taking into consideration both biotic (animal and vegetable) and chemical parameters. In studying the biotic component, two indices were used: the E.B.I, Extended Biotic Index (version adapted to the Italian rivers), based on macroinvertebrates, and the EPI-D, the Eutrophication and/or Pollution Index, based on diatoms. For both macroinvertebrates and diatoms, two samplings were conducted, one in June and the other in October 2003. Instead, according to the Italian Law 152/99 the chemical and bacteriological analyses were conducted monthly for the entire year. The results of biomonitoring and chemical-bacteriological analyses unanimously demonstrated a good ecological situation for the upper section of the Chienti, though the situation tends to worsen as the river continues its descent and undergoes increased anthropogenic pressure. Data obtained were correlated with Spearman's coefficients and principal component analysis. Both statistical calculations showed clear, direct correlation between the two biotic indices and an inverse correlation between these and the chemical and bacteriological parameters. However, a few differences of judgement that emerged among the various indices highlight the importance of using them simultaneously in order to obtain a more accurate diagnosis of the ecological status of the watercourses.

Geochemical characterisation and erosion stability of fine-grained groyne field sediments of the Middle Elbe River

Abstract: Because of the significant reduction of flow velocity relative to the main current there is an accumulation of sediment material in the centre of the groyne fields over time (years to decades) up to a maximum of 1.5 m. Based on the element- and compound-specific depth functions of this fine-grained material with high organic matter content the sedimentation history of the Elbe River sediments concerning the environmentally relevant nutrients and pollutants can be reconstructed. It could be shown that the fresh sediments are less polluted than the deeper older ones. During the extreme flood of the river Elbe in August 2002 the critical erosion shear stress in the groyne fields was high enough to remobilise a considerable portion of the sediment depot. The hazard to the environment is high due to the fact that a significant part of the remobilised polluted sediments was distributed over the recent floodplain which is normally used as pasture. Thus these groyne field sediments represent a temporary danger for the water quality of the river Elbe. But the hazard of the solids sedimented in the recent floodplain of the river can be viewed as long-lasting.

Spatial distribution and bonding forms of heavy metals in sediments along the middle course of the River Elbe (km 287ċ390)

Abstract: Sediments of eight groyne fields along the middle course of the River Elbe (river km 287...390) were geochemically studied. The 78 sediment samples were analysed for pH and grain size distribution. The grain size fraction < 2 pm was used for mineralogical and chemical analysis: semiquantitative clay mineral analysis; total element content (Al, Ca, Fe, K, Mn, Cd, Cr, Cu, Ni, Pb, Zn), total inorganic and organic C, and bonding form fractionation with a six-step sequential chemical extraction. The latter was performed on selected samples (n = 32). The sediments along the Elbe's course are still contaminated with heavy metals far above the local geogenic background level. An enrichment factor of more than 15 was calculated for zinc. Cr and Ni are the elements with the lowest enrichment. The bonding form analysis of selected heavy metals shows a dominance of relatively immobile bonding forms, e.g. the moderately reducible and the residual fraction, which implies a relative low mobility potential. Only Zn poses a higher potential threat to the environment, since it has a higher percentage of the first three extracted phases: adsorbed, carbonate, and easily reducible fraction.

Sources of mineralization and salinization of thermal groundwater of Jordan

Abstract: According to spider patterns five different types of thermal groundwater are distinguishable in Jordan. Each spider diagram comprises groups of elements which characterise soluble minerals of the aquifer such as halite, calcite, and gypsum, and leachable fractions of trace elements such as B, Ba, Br, Y, Cs, Rb, and U. In Jordan, mineralization of groundwater is largely controlled by dissolution of halite, carbonates, gypsum, and leaching diverse K-bearing minerals. Caused by interaction with Neogene basalts, limestones are silicified and mineralogically altered. Groundwater from these aquifers significantly differs in composition from those of the unaltered limestone aquifers. The benefit of spider patterns is that they visualise (i) chemical differences in groundwater from essentially similar aquifer rock such as young, old or thermally altered limestones and (ii) chemical similarities of groundwater produced from different geological formations. In contrast to spider patterns, ionic ratios widely overlap and do not unequivocally allow grouping of groundwater. δ 34 S(sulfate) varies between -4 and +29‰. Low values prove the presence of oxidised sulfides either of igneous origin or from sedimentary rocks. The spread of δ 34 S is caused by mixing with marine sulfate. All analysed water from Paleozoic rocks is replenished from younger aquifers. Considerable transaquifer flow exists more or less all over the Jordan territory. Salinization of sandstone-bound water along the rift escarpment is caused by a Na + -K + -SO 2 4 -HCO - 3 brine, whereas the wells Al Umari 1 and Wadi Araba 5 are affected by the presence of a Ca 2+ -Cl - brine.

Routine analysis of sediment pore water of high ionic strength

Abstract: Pore water of sediments plays an important role in aquatic systems as mediator and as the reactive zone between the sediment and surface water. Sediment pore waters with high ionic strength from acidified pit lakes were investigated to obtain information about the influence on the lake water quality. The analysis of soluble reactive phosphorus, nitrate, ammonium, silica, dissolved organic carbon, ferrous iron, sulfate, chloride, sodium, potassium, calcium, magnesium, manganese, and total dissolved iron was predetermined as the dataset required for evaluation of water quality. The data collection procedure was optimised by designing a methodology for stabilisation, dilution of pore water samples and adaptation of analytical methods. The developed methodology was evaluated with respect to the effort required in the laboratory under routine conditions. In the first round of analyses, 72% of 638 individual analyses from a random selection of pore water profiles were found to be within the calibration ranges. Remedial actions to handle the remaining 28% of invalid analytical results are exemplified. Differences between comparative analyses of some ions by continuous flow analysis, ion chromatography, and atomic emission spectroscopy were evaluated. The majority of results measured by ion chromatography differed on a highly significant level from results measured by atomic emission spectroscopy. Possible reasons, originating from the extreme sample matrix, are discussed. Finally, the designed methodology and the results of the method comparison are used to recommend the selection of analytical methods under specific conditions.

Benthic cyanobacterial assemblages as indicators of nutrient enrichment regimes in a Spanish river

Abstract: The relationships between cyanobacterial abundance and the physical and chemical characteristics of waters were studied to identify the environmental variables responsible for the changes in species composition observed in a river characterized by variations in water quality. Principal component analysis showed that some communities had significantly different species composition and relationships with environmental variables than others. These analyses allowed us to identify indicator species with contrasting responses to nutrient conditions. One of the four cyanobacterial groups distinguished in the analysis was negatively correlated with variables related to aspects of water disturbance, including nutrients. The results indicate that the eutrophication gradient structured species composition and affected cyanobacterial community distribution. Since organisms have an integrating response to their environment, the use of cyanobacterial assemblages to indicate eutrophication gradients could help in the assessment of water quality in aquatic ecosystems.

Effects of single and mixed diatom diets on the reproduction of copepod Calanus sinicus

Abstract: Under laboratory conditions, the potential influence of diatom diets on reproduction of zoo-plankton Calanus sinicus was studied. Four diatom diet ingredients: Skeletonema costatum (SC), Chaetoceros muelleri (CM), Phaeodactylum tricornutum (PT), diatom mixture (MIX) and a control diet: the flagellate Platymonas subordiformis (PS), were used at the same carbon concentrations of 2.0 mu g mL(-1) C. In a period of 17-day laboratory experiment, the effects of these algae diets on egg production and hatching success of the copepod Calanus sinicus were examined. The diets were analyzed for fatty acid content as an indicator of food quality. The results showed that the female survival of all treatments reached more than 80% except PT. Comparing to the initial value, egg production of Calanus sinicus was reduced in diatom diets (PT, CM), but remained in normal level in SC and MIX, indicating that some single diatom diets had a negative effect on the egg production of Calanus sinicus. Feeding with mixed food however can eliminate this negative effect. Among all the treatments, hatching success in filtered seawater was significantly higher than in algal exudates, indicating that not only diatoms but also other phytoplankton in certain concentration can release extracelluar substance that may inhibit eggs from hatching. Fatty acid analysis showed that both egg production rate and hatching success were negatively correlated to the ratio of 20:5 omega 3 and 14:0 in fatty acid composition.

Growth of Daphnia magna males and females fed with the cyanobacterium Microcystis aeruginosa and the green alga Scenedesmus obliquus in different proportions

Abstract: Laboratory experiments were used to study the sensitivity of both male and female Daphnia magna to a toxic cyanobacterium, Microcystis aeruginosa. Male and female D. magna were fed with M. aeruginosa and a green alga (Scenedesmus obliquus) in different mixtures that included 0%, 25%, 50%, 75% and 100% Microcystis. Growth of both males and females declined with increasing proportion of Microcystis in the diet. Males were slightly less sensitive to Microcystis than females with EC50 for growth inhibition at 72% and 63% Microcystis in the diet, respectively. On monospecific Microcystis diet, mortality rates for males (0.16 d-1) and females (0.17 d-1) were similar. The reproductive rate of females was the most sensitive endpoint with an EC50 of 42% Microcystis in the diet, whereas population growth rates were the least sensitive (EC50 of 74% Microcystis). Microcystis in the diet severely depressed growth and reproduction in Daphnia and poses a severe threat to its survival in which only a switch in reproductive strategy might provide Daphnia a refuge to a Microcystis environment that gradually becomes uninhabitable.

Nutrient accumulation and nutrient retention in coastal waters – 30 years investigation in the Darss‐Zingst Bodden chain

Abstract: Coastal waters are transitional zones between limnic waters and marine systems. The anthropogenic impact on these water bodies is high and a rapid change of trophic level was observed within the last 50 years. In the Darss-Zingst Bodden chain (southern Baltic Sea - Mecklenburg-West Pomerania, Germany), the change in trophic state during the last thirty years can be reconstructed by long-term monitoring of chemical, hydrographical and biological parameters with an up to daily resolution. Until the 1980s, increased input of the anthropogenic nutrient load from the catchment area has been documented. However, with the implementation of the HELCOM recommendations the input of phosphorus and nitrogen was reduced in the 1990s. In contrast to the reduction of nutrient inputs, a decrease in nutrient concentrations and primary production could not be observed. The reasons are a high internal nutrient load and the release of nutrients out of the sediments. Numerous research projects allowed the description and quantification of these processes. Today, the internal phosphorus pool exceeds the external phosphorus load several fold. These results are the scientific basis for the development of restoration strategies of coastal waters. The development of suitable management plans is necessary for the implementation of the EU Water Framework Directive to guarantee a good ecological state by 2015. The long time acquisition of monitoring data and voluminous complementary specific research projects was enabled by the local field research conditions of the Biological Station of the University of Rostock in Zingst.

Distribution and activity of ammonium-oxidizing bacteria in Nakivubo wastewater channel and wastewater treatment wetland, Uganda

Abstract: The pollution profiles of Nakivubo channel and wetland, and the spatial distribution of ammonium-oxidizing bacteria and the corresponding ammonium-oxidation activities along Nakivubo channel and we ...

Observations on impaired vitality of Unio crassus (Bivalvia: Najadae) populations in conjunction with elevated nitrate concentration in running waters

Abstract: A number of publications show relationships between impairment of vitality and reproduction as well as excessive shares of aged individuals within populations of Unio crassus with nitrate concentrations in the field. Our own examination of available data on nitrate concentrations in selected rivers of Brandenburg with known remainder populations of Unio crassus and of rivers without that species confirmed that above 2 mg L -1 NO 3 - -N Unio crassus populations are impaired. Current toxicity data on nitrate do not indicate any mechanism by which the observations can be explained. Probably high NO 3 - -N concentrations and the impaired production and vitality of Unio crassus populations share the same causes. These need to be identified.

Geochronology of anthropogenic contaminants in a dated sediment core of the Rhine River (Germany): emission sources and risk assessment

Abstract: A subaquatic sediment core was taken from the Rhine River to determine substance specific concentration profiles in correlation to time and depth. Based on these data emission histories were related for selected contaminants. Significant emission sources and emission pathways were compiled. In correlation to investigations of national and international monitoring programmes a significant reduction of environmental emissions up to a tenth of previous values were found since 1998. Some selected compounds, discharged by municipal and industrial activities, for example disinfectants (methyltriclosan), flame retardants (tris(chloropropyl)phosphate), chlorinated benzenes, anilines and naphthalenes, can be classified as significant synthetic substances in the scope of the Water Framework Directive. Because of their chemical characters, their persistence, bioaccumulation and ecotoxicity, as well as their occurrence within the sediment core, these compounds create a significant potential risk for water quality, but a reduction of these synthetic compounds to zero cannot be expected for the next future. In summary, this study provides a comprehensive reconstruction of the pollution history of anthropogenic contaminants, their fate and behaviour in the fluvial system. In addition, an estimation of the time period required for environmental measurements and monitoring programmes to improve, achieve and save a good status of the river systems are given.

Matrix effects on the photocatalytical degradation of dichloroacetic acid and atrazine in water

Abstract: The effect of different organic and inorganic aqueous matrices on the photocatalytical degradation of dissolved atrazine and dichloroacetic acid (DCA) with immobilized TiO 2 was investigated. Two series of experiments were carried out at pH values around 7.1 for the degradation of atrazine and around 5.3 for the degradation of DCA. It is shown that the effects of the water constituents are completely different for the various substances and pH ranges. In pure deionized water 95% of the initial amount p = 1 mg/L of atrazine were degraded within 24 hours. Tap water as matrix led to a distinct lower degradation rate (factor 3). The single additives chloride, sulfate, phosphate, carbonate and DOC showed no decrease in the degradation rate. Especially in the case of phosphate and carbonate there was even a significant promoting effect. DEDIA, the doubly desalkylated and not dechlorinated product, occurred in higher concentrations than in the experiment without additives. In pure deionized water ρ 0 (DCA) = 1 mg/L was completely degraded within 330 min. By addition of any tested substance, organic or inorganic, the degradation rate of DCA, which is strongly dependent on the adsorption on the TiO 2 surface, decreased clearly. In the case of tap water the degradation rate decreased by a factor of 7.5. From the checked inorganic ions phosphate showed the strongest effect followed by sulfate, chloride and carbonate. Added DOC also had a significant influence on the degradation rate.