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A qualitative classification for the evaluation of the heavy metal contamination in river ecosystems
... In the Upper, Middle and Lower Danube the heavy metal contamination in the water suspended matter, fine sediments and fish was studied. A general increase in the lower section, which is reflected most clearly in cadmium and mercury (Hg) was reported [25]. Using an evaluation scheme [25] "very heavy pollution" levels (III-IV) and excessive pollution levels (IV) and higher concentrations of Cd, Cr, Cu, Hg and Zn in the lower reaches of the LDR were found [26]. ...
... A general increase in the lower section, which is reflected most clearly in cadmium and mercury (Hg) was reported [25]. Using an evaluation scheme [25] "very heavy pollution" levels (III-IV) and excessive pollution levels (IV) and higher concentrations of Cd, Cr, Cu, Hg and Zn in the lower reaches of the LDR were found [26]. ...
... According to the mean values of heavy metals in sturgeon muscle, the river or marine habitats were ecologically classified [25] ( The high content of lipids in sturgeon body makes them prone to bio-accumulation of heavy metals in their organs, including the gonads. Although not exceeding the maximum permissible limits for human consumption, heavy metals were detected in caviar samples collected from Persian sturgeon [10], as well as in gonad tissue analysed in this study, except the gonad of a 6 years old stellate sturgeon male (commercial tag 5885) captured in Zatoane area (in the Black Sea). ...
This study investigates bio-accumulation of heavy metals in tissues of sturgeons of the North-Western Black Sea and
Lower Danube River (LDR). Samples (10 – 30 gr) of liver, muscle, fat, gonads and skin tissues collected in October 2003 from 21 adult specimens of three sturgeon species: Acipenser stellatus (10), A. gueldenstaedtii (2), and Huso huso (9) were analysed for content in Cd, Cu, Zn, Pb, Mn, Fe and Ni, using VARIAN Spectra A100. The highest concentrations of Zn, Cu and Cd were found in liver and the smallest in muscles of sturgeons. The highest heavy metal content was detected in tissues of stellate sturgeons, followed by Russian sturgeons. In all three species Cd and Cu content of the liver as well as of the stellate sturgeon muscle surpassed the admitted limits for human consumption (Cd – 0.05;
Zn - 50; Cu – 5.0; Pb – 0.3 [mg / kg wet weight]). In view of a future re-opening of the commercial fishing of wild sturgeons it is strongly recommended testing the heavy metal level prior delivering sturgeon products to the market. Avoiding human consumption of liver of sturgeons captured in the LDR is strongly recommended as well. In the case of Cd a bio-accumulation with age of sturgeons was visible. In all species males seem to accumulate more heavy metals in their tissues. We explain this as effect of more frequent spawning migration of males in the LDR, the major contamination source. Beluga sturgeons show less heavy metal bio-accumulation of tissues.
... The concentrations of Cu found in the Reconquista River are about six times higher than those in the Las Catonas Stream, while the As and Cd are slightly higher and Cr is a bit lower (Cantera et al., 2018). According to the qualitative classification for the evaluation of heavy metal contamination in river ecosystems (Wachs, 1998), this water system is moderately polluted for Cr, very heavily polluted for Cd and excessively polluted for Cu. Water pollution in the Reconquista River is attributed either to the release of numerous industrial effluents into the river with little or no previous treatment (Mondino, 2007;Rigacci et al., 2013), or to other anthropogenic sources, such as domestic wastewaters, fossil fuel combustion, leakage of metal-containing motor oils, municipal waste disposal and building, which are currently encountered in the basin (Mondino, 2007). ...
The mineralogical and geochemical characterization of sediments of the Reconquista River allows analyzing the geochemical partition of trace elements in one of the most polluted water courses of Argentina. The low dissolved oxygen and high ammonia contents, together with the high chemical oxygen demand, attest to the poor water quality. Ammonia, Cd and Cu content in surficial water exceeds the maximum guidelines for freshwater in Argentina. The recent sediments of the uppermost bed are enriched in organic matter (OM), sulfur, Zn, Cu and Pb. The enrichment factor is moderate, and the geoaccumulation index (Igeo) for Cu and Pb indicates uncontaminated to moderately contaminated sediments. The positive and significant correlation between As, Cr, Pb and Zn with the iron content suggests that their retention is controlled by the amount of iron oxy (hydr)oxides in the sediments, probably combined with the silt + clay abundance. In comparison with its tributary, the Las Catonas Stream, the Reconquista River, has less OM and trace elements in the sediments and more dissolved trace elements in the interstitial water. We interpret that OM is the main sorbent of the trace element. In the absence of OM, the iron oxy (hydr)oxides and the silt + clay fraction are a less efficient substitute. Consequently, the interstitial waters of the Reconquista River are enriched in these elements. Therefore, minor changes in the environmental conditions may generate significant release of hazardous trace elements from the sediments to the interstitial water and, in turn, to the surficial water of the river. As most of the big cities and the agricultural activities of Argentina are developed on the loessic substrate, the understanding of its interaction with polluted waters is crucial.
... The absence of loricated genera probably obeys to the lowest iron concentrations registered at this site. According to Wachs' (1998) classification for the evaluation of heavy metal contamination in rivers, the stretch comprising S1 corresponds to a heavily to excessively polluted river. The other sites comprised in this study showed no definite pattern and were alternatively classified between moderately to excessively polluted. ...
study of water chemistry, phytoplankton, and algal bioassays indicated distinct regions of a large river ecosystem. Abstract The monitoring of river phytoplankton and several hydrological, physical and chemical variables, in combination with bioassays using Selenastrum capricornutum Printz, allowed the characterisation of three distinct reaches of the Lower River Luja´nLuja´n. The upstream stretch, characterised by the lowest depth and discharge, registered the highest nutrient, dissolved heavy metal and chlorophyll a concentrations in accordance with low phytoplankton diversity and the occurrence of several species typical of organically polluted lowland rivers. A downstream improvement, concomitant to increasing river discharge, is revealed by a progressive decrease of organic pollution parameters even though algal toxicity is registered through bioassays. The water input from the Parana´RiverParana´River through the G. Arias Channel plays an important role in the regulation of the limnology of the Lower Luja´nLuja´n River. As a result of marked increasing discharge, depth and width, there is a decrease in nutrient concentration and phytoplankton density and an increase in dissolved oxygen concentration. Likewise, algal growth rates in the bioassays showed less toxic effect. #
... As for the WQIs calculated for both sampling sites, the values were around 3-6 indicating high pollution for both sites. Wachs (1998) proposed a water quality classification system of rivers according to their concentrations of several heavy metals. In this case, after considering the measured concentrations of heavy metals that were above the regulatory guidance levels (Table 1), the toxicological quality of the river samples corresponded to grades III and IV (very heavily polluted). ...
The toxicological water quality of the Lujan River (Argentina) was monitored during one year seasonal samplings. Water samples were collected at two points and their toxicological profiles were compared: S1 (reference site), located downstream of a major city and S2, located further downstream, beyond a joint urban sewage and industrial discharge point. A number of abiotic parameters were determined and three water quality indices (WQIs) calculated on the samples. Laboratory toxicity bioassays were conducted exposing Lithobates catesbeianus larvae to samples; a third group of animals were exposed to tap water (controls). Hepatic biomarkers were determined: catalase (CAT), glutathione-S-transferase (GST) and superoxide dismutase (SOD) activities, lipid peroxidation (LPO) and GSH content; CF and HSI were calculated. The scores of the WQIs corresponded to a high pollution condition at both sampling points. ANOVA showed significant differences between sampling sites and controls mainly in CAT activity, GSH content and GST in autumn.
... As for the WQIs calculated for both sampling sites, the values were around 3-6 indicating high pollution for both sites. Wachs (1998) proposed a water quality classification system of rivers according to their concentrations of several heavy metals. In this case, after considering the measured concentrations of heavy metals that were above the regulatory guidance levels (Table 1), the toxicological quality of the river samples corresponded to grades III and IV (very heavily polluted). ...
The toxicological water quality of the Lujan River (Argentina) was monitored during one year seasonal samplings. Water samples were collected at two points and their toxicological profiles were compared: S1 (reference site), located downstream of a major city and S2, located further downstream, beyond a joint urban sewage and industrial discharge point. A number of abiotic parameters were determined and three water quality indices (WQIs) calculated on the samples. Laboratory toxicity bioassays were conducted exposing Lithobates catesbeianus larvae to samples; a third group of animals were exposed to tap water (controls). Hepatic biomarkers were determined: catalase (CAT), glutathione-S-transferase (GST) and superoxide dismutase (SOD) activities, lipid peroxidation (LPO) and GSH content; CF and HSI were calculated. The scores of the WQIs corresponded to a high pollution condition at both sampling points. ANOVA showed significant differences between sampling sites and controls mainly in CAT activity, GSH co...
... He concluded that there is a general increase in the lower section, which is reflected most clearly in cadmium and mercury (Hg). Using his evaluation scheme (Wachs 1998) found "very heavy pollution" levels (III-IV) and excessive pollution levels (IV) and (Bloesch 1999). ...
... He concluded that there is a general increase in the lower section, which is reflected most clearly in cadmium and mercury (Hg). Using his evaluation scheme (Wachs 1998) found "very heavy pollution" levels (III-IV) and excessive pollution levels (IV) and (Bloesch 1999). ...
... He concluded that there is a general increase in the lower section, which is reflected most clearly in cadmium and mercury (Hg). Using his evaluation scheme (Wachs 1998) found "very heavy pollution" levels (III-IV) and excessive pollution levels (IV) and (Bloesch 1999). ...
... The concentration ranged between 7.3 and 116.9 mg kg −1 dw and was an average of 10 times higher than the geological background concentration of 1.6-6.7 mg kg −1 dw that has been determined for forested upstream regions. Fiftyseven percent of the samples were critically or highly polluted according to Wachs (1998). The effects on organism emergence and reproduction were shown in laboratory experiments at copper concentrations of 59-105 mg kg −1 dw (Roman et al., 2007), highlighting the ecotoxicological relevance of the copper concentrations detected in the sediment phase. ...
The present study was performed to characterise in-stream pesticide exposure within the Palatinate vineyard region in south-west Germany, evaluate the influence of buffer strip widths and identify mitigation measures for the relevant entry pathways. In-stream water and sediment samples that were taken at nine sampling sites of different buffer widths following intense rainfall, and edge-of-field runoff that were sampled in erosion rills were analysed regarding 28 active ingredients of pesticides including copper. In-stream samples contained a mix of 8±4 pesticide compounds, resulting in total pesticide concentrations of 1.4–8.9μgl−1 for water and 16–670μgkg−1dw for sediment. Following an exceptional rainfall event with a previous 34-day drought period, pesticide concentrations reached 7.0–83.4μgl−1. Fungicides were the most important pesticides found and were significantly correlated with the pesticide application frequency and rate. The calculated toxicity values per sample (TUmax) indicated that both organic pesticides and copper concentrations likely cause ecotoxicological effects in the field. The buffer strip width was of little importance for pesticide in-stream concentrations because pesticide entry occurred mainly via the field path network and erosion rills. Pesticide in-stream concentrations were significantly and positively correlated with the concentrations detected in erosion rills (R2=0.56). As possible risk mitigation measures, we suggest the implementation of grassed field paths and vegetated ditches or wetlands.
... He concluded that there is a general increase in the lower section, which is reflected most clearly in cadmium and mercury (Hg). Using his evaluation scheme (Wachs 1998) found "very heavy pollution" levels (III-IV) and excessive pollution levels (IV) and (Bloesch 1999). ...
The ecological status of the Danube River and its fisheries prior to 1988 has been summarised by Bacalbasa-Dobrovici (1989) for the first International Large River Symposium. Since then the situation has changed in many ways: the trends of river–floodplain disintegration initiated by the major river regulation schemes in the nineteenth and early twentieth centuries accelerated. Moreover, further hydropower dams were built along the course of the river and its major tributaries, further reducing the ecological integrity of the river floodplain systems in several stretches. On the other hand, a number of mitigation schemes were initiated e.g. in Austria, Hungary and Romania in order to compensate for the continuing losses of riverine landscapes. The measures taken to control water pollution were partially successful and water quality along the river has shown a general improvement. The overall deterioration of riverine habitats due to pollution, river engineering and land use is reflected in the high number of endangered fish taxa. The main cause for the decline of many species is the continuing loss of riverine littoral habitats due to river engineering Therefore the main focus of river management in several of the riparian countries is on the conservation of riverine biota, a stronger incorporation of ecological aspects in river engineering and the development of restoration programmes. Several international schemes have been proposed to undertake concerted action to improve the overall situation. There is a sound scientific basis for ecologically orientated river management along the Danube: over the past 20 years, environmental conditions, fish ecology and fisheries have been intensively studied at several research institutions by means of large-scale field surveys and experimental studies. These results allow the present ecological status to be redefined. New concepts for commercial and recreational fisheries as well as floodplain restoration were developed. The present contribution synthesises recent developments in fish ecology and fisheries of the Danube and concentrates on key management issues.
... The absence of loricated genera probably obeys to the lowest iron concentrations registered at this site. According to Wachs' (1998) classification for the evaluation of heavy metal contamination in rivers, the stretch comprising S1 corresponds to a heavily to excessively polluted river. The other sites comprised in this study showed no definite pattern and were alternatively classified between moderately to excessively polluted. ...
The monitoring of river phytoplankton and several hydrological, physical and chemical variables, in combination with bioassays using Selenastrum capricornutum Printz, allowed the characterisation of three distinct reaches of the Lower River Luján. The upstream stretch, characterised by the lowest depth and discharge, registered the highest nutrient, dissolved heavy metal and chlorophyll a concentrations in accordance with low phytoplankton diversity and the occurrence of several species typical of organically polluted lowland rivers. A downstream improvement, concomitant to increasing river discharge, is revealed by a progressive decrease of organic pollution parameters even though algal toxicity is registered through bioassays. The water input from the Parana River through the G. Arias Channel plays an important role in the regulation of the limnology of the Lower Luján River. As a result of marked increasing discharge, depth and width, there is a decrease in nutrient concentration and phytoplankton density and an increase in dissolved oxygen concentration. Likewise, algal growth rates in the bioassays showed less toxic effect.
... In Germany, the saprobic index is well established to evaluate the biodegradable organic pollution in running waters (Friedrich, 1990). Systems to monitor heavy metals (Wachs, 1998), and acidification (Brakke et al., 1994) have been developed. However, no biological indicator system has yet estimated the pesticide contamination of small streams via benthic macroinvertebrate indicators. ...
The knowledge system LIMPACT estimates the pesticide contamination of small lowland streams with agricultural catchment areas. The system considers the abundance of 39 macroinvertebrate taxa during four timeframes (T1: March/April, T2: May/June, T3: July/August and T4: September/October) within one year. The four diagnoses Not Detected (ND), Low (L), Moderate (M) and High (H) pesticide contamination represent a calculated annual toxic sum without any specification of the chemical agents. In this paper we present a new model-based implementation with set-covering relations including diagnosis exclusions. This type of knowledge base outperforms the former rule-based implementation in size and complexity, knowledge acquisition costs and explanatory characteristics. We were able to extract a common and average appearance of taxa in the specific group of streams. A wide range of common taxa with a tendency to more taxa in less severely contaminated streams. Only a few taxa indicate exclusively a specific contamination class. For the exclusion conditions there was a clear trend for more taxa to exclude streams in the High category than in the other classes.
Predicting the composition of benthic macroinvertebrate fauna in rivers is not a trivial task, both because of the number of species to be modelled and because of the complexity of biotic and abiotic relationships that determine their distribution. However, the composition of the benthic macroinvertebrate fauna usually provides very useful insights into the ecological quality of lotic systems, as these organisms are very sensitive to disturbance. Benthic macroinvertebrates are relatively sedentary and long-lived, with life cycle durations ranging from a few months to 2-3 years, and they show a wide range of adaptations to local environmental conditions. They represent a continuous monitoring system of the water body where they are living, but they are also very easy to collect and to identify, at least at an intermediate taxonomic level. Therefore, benthic macroinvertebrates are widely used as biological indicators (Hellawell 1986) and, in particular, they have been used for many years as a source of information for computing several biotic indices that are now used worldwide to assess biological water quality (e.g., Metcalfe 1989, Resh et al. 1996, Lammert and Allan 1999). In this study, the Italian IBE index (Ghetti 1997), derived from the Extended Biotic Index proposed by Woodiwiss (1981) was used as a reference for selecting ecologically homogeneous taxa. Several different biotic indices have been developed, as they had to be suited to ecoregional characteristics in order to provide correct diagnoses of the riverine ecosystem quality. Most indices, however, share the same rationale that is based on the identification of sensitive taxa and on the recognition of the ecological role of other taxa. The main advantage of this approach with respect to more thorough community structure analyses lies obviously in its simplicity. In fact, even people with a limited taxonomic background can be easily trained to carry out rapid surveys aimed at the computation of biotic indices. A more complex approach to the assessment of the ecological status of streams and rivers is based on the prediction of the whole community structure. In the case of benthic macroinvertebrate fauna, different modelling techniques based on ecological knowledge and monitoring data are now available. In the United Kingdom, the work by Wright et al. (1984) led to the prediction of community types on the basis of environmental data by means of a multivariate analysis procedure. This appraoch was then extended and used in the River Invertebrate Prediction and Classification System (RIVPACS) (Wright et al. 1993b), which provides estimates of the ecological quality at a given site by comparing the observed macroinvertebrate fauna composition with the expected one. The RIVPACS approach has also been adapted to other ecoregions. For instance, the Australian River Assessment Scheme (AUSRIVAS) (Simpson and Norris 2000) is based on the RIVPACS approach, although it has been expanded and adapted to each Australian ecoregion. Another method that is closely related to RIVPACS and AUSRIVAS is the benthic assessment of sediment (BEAST) (Reynoldson et al. 1995), that is based on quantitative data about macroinvertebtare fauna instead of presence/absence data only. Even though the RIVPACS approach proved to be very effective, it has limits related to the non-linearity, complexity and dynamic nature of biotic responses to environmental characteristics. Moreover, the development of an assessment system based on the RIVPACS rationale requires a considerable amount of work and thorough statistical analyses. A new generation of empirical techniques for analysing and modelling complex ecological data in a more simple and straightforward way is now emerging. Among these new modelling methods Artificial Neural Networks (ANNs) play a relevant role and represent a useful tool when relationships among data are unknown and/or non-linear. ANNs learn from examples and do not require a priori theoretical models, nevertheless they are able to model complex temporal and spatial patterns and to reproduce the behaviour of very complex systems (Recknagel and Wilson 2000). During the last 10 years, ANNs have been applied to various ecological fields (see, for instance, Lek and Guegan 2000), including studies relating community characteristics with environmental variables (e.g., Chon et al. 1996, Recknagel 1997, Recknagel et al. 1997, 1998, Guégan et al. 1998) and modelling habitat suitability (e.g., Paruelo and Tomasel 1997, Ozesmi and Ozesmi 1999). As for the particular case of macroinvertebrate fauna, Pudmenzky et al. (1998) and Walley and Fontama (2000) recently developed ANN approaches that are aimed at the same goals and ecoregions as AUSRIVAS and RIVPACS respectively. Our study was focused on a benthic macroinvertebrate data set provided by the Latium Regional Environmental Protection Agency and it is aimed at testing different strategies for modelling the presence or absence of macroinvertebrate benthic taxa on the basis of environmental variables, using ANN models.
Excessive intake of nickel (Ni) is known to produce adverse health effects in humans, including carcinogenicity and allergenicity. The main route of exposure for humans is diet, including fish. There is, however, little information concerning Ni content in freshwater fish in Poland. The aim of the study was to determine the concentrations of Ni in meat tissues of three fish species from north eastern Poland and assess toxic potential to healthy and susceptible sub-groups of individuals. The settings for the study lakes span a range of anthropogenic influence from protected areas to a basin with a town and several villages and another one influenced by a pesticide tomb leakage. Fish were netted and kept frozen until analysis. After defrosting, the fish were filleted and minced. The ashed samples were dissolved in nitric acid and analyzed for Ni by flame atomic absorption spectrometry. Roach meat contained 6.6–23 µg kg Ni, bream 9.5–178 µg kg, and carp 16.5–139 µg kg. These concentrations are low, indicating that the fish were not excessively contaminated with the metal. Consuming a 250 g portion of fish would result in an average nickel intake of 4 µg for roach,
The situation of most of the Argentine rivers is very serious due to the amount and range of pollutants, principally as a
consequence of industrial development with an inadequate regulatory framework and a deficit of decades in matters of sanitary
substructure and waste treatment.
Freshwater quality monitoring in Argentina was based on water chemistry and bacteriology, with measurements of only the main
variables required for the determination of quality indexes. A multidisciplinary approach considering simultaneous evaluation
of a number of factors and processes that in an integrative picture determine its characteristics was poorly developed or
lacking. The use of biota for monitoring the aquatic environments has been relatively uncommon compared to abiotic variables.
The Reconquista River is a typical lowland watercourse situated in the Buenos Aires Province. Located in a temperate subtropical
region, it flows into an international river, Río de la Plata, which is part of the second largest hydrogeographic system
of South America, after the Amazon, and the fifth largest in the world. The river receives the output of 80 small tributaries,
and one of them, the Morón creek, should be highlighted as it marks the limit between the medium and the lower sections of
the river. During the dry season the entire stream is composed of sewage and industrial wastes and known as an “open sewer.”
The river is the second most polluted waterway of Argentina. There is a great variety of industrial activities settled on
its basin. Some 10,000 plants, most of them located on the margins of the river, discharge their untreated effluents into
the river and use large quantities of water in processing, cooling, and cleaning. Approximately 20% of these industries discharge
a total BOD load of approximately 150,000 kg d-1, which is equivalent to an organic loading capacity of 2.5 million population.
To monitor water quality of the main course of the Reconquista River, the following principal approaches have been adopted:
(a) measurement of approximately 30 physical and chemical variables, (b) determination of biological parameters (phytoplankton
and zooplankton abundance, diversity, and community structure, microbiology), (c) acute and prolonged in situ and laboratory toxicity tests with algae, tadpoles, and fish (fry and juveniles) as sentinel organisms, (d) monitoring of
alterations in specific physiological and biochemical markers of exposure in fish, and (e) determination of water quality
indexes based on the physicochemical profile of the samples.
The studies were carried out during a span of 15 years on samples regularly taken in three to five sites covering the length
of the river’s main bed. The most relevant outcomes of the study can be summarized as follows.
Spatial variation of the DO was from 7–8 mg L-1 in S1 down to 0-0.3 mg L-1 in S5, indicating water in Bancalari was in permanent anoxia.
COD/BOD ratios oscillated between 11 (in S1) and 4 (in S4–S5), suggesting the presence of important amounts of nonbiodegradable
organic matter.
The presence of domestic sewage indicators and municipal wastes as chlorides, orthophosphates, inorganic N compounds (NH4+, NO2-, NO3-) and phenols were found in all samples, with a clear-cut increase in concentration down river up to values well above MPQs.
Total heavy metal concentrations always exceeded widely MPQs established by Argentine law for protection of freshwater life.
At all locations organochlorine insecticide levels varied between 40- and 400 fold above legal limits.
When considering physicochemical parameters altogether in a spatial and temporal perspective, it becomes evident that there
was a progressive but sustained alteration of the water quality downriver, especially after the confluence of the Morón creek,
and, that the deterioration increased with time.
River water showed an alarming degree of bacterial pollution, which was temporally and spatially highly variable.
Environmental physicochemical toxicity data were closely correlated with the results of both acute and sublethal chronic toxicity
bioassays.
It was concluded that only an integrated analysis of chemical and biological parameters coupled with toxicity tests will offer
a realistic view of the state of water quality in the Reconquista River.
The interplay of the geochemistry of the lower stretch of the Luján River is analyzed with its natural geomorphology (basin
features), local hydrometeorology (tidal regime and “sudestada” events) and the impact of polluted tributaries. Major ions,
dissolved heavy metals and limnological variables were analyzed using multivariate techniques. The water quality of the mainstream
of the Luján River, flowing through urbanized and industrialized areas is strongly and positively influenced by the input
of the Paraná River through deltaic watercourses and is negatively impacted after receiving the discharge from polluted watercourses.
The longitudinal spatial variations evidenced major discontinuities in the Lower Luján Basin, showing clearly the riverine
and the deltaic water influenced zones. Seasonal variations were also marked and were either temperature driven or associated
with the estuarine cycle and the “sudestada”.
KeywordsMajor ion dynamics-Luján River-Hydrological system
To deal adequately with water quality problems in the Netherlands "integrated water management" is now the guiding principle. For this, monitoring is essential. Monitoring is also a valuable instrument when dealing with accidental spills. The objectives, developments and results obtained for water quality monitoring in the Netherlands are described. The paper ends with conclusions concerning the demands to make upon the monitoring system and the developments that can be foreseen. The last conclusion is that, for the time being, the monitoring stations cannot fulfil the early warning function completely. The specialised laboratory remains necessary for additional investigations. This paper is based on a lecture delivered at the Flemish International Scientific Congress "Surface Water Quality in the European Community", organised by WEL, Antwerp, Belgium.
In 1990 the Swedish Agency for Environmental Protection presented new guidelines for ambient water quality classification. The article briefly reviews the new classification scheme and its method of grading pollution impacts. The classification scheme is supposed to strengthen water management at the municipal and regional level.
1982 b: Schwermetallgehalt von Fischen aus der Donau.-2. Wasser-Abwasser-Forsch
- B Wachs
Fische als Indikatoren für SchwermetallBelastungen.-Münchener Beitr. Abwasser-, Fischerei-u. Flußbiol
- B Wachs
Chrom und Nickel in Flußfischen.-Ztschr. angew
- B Wachs
Limnotoxizität und Ökobewertung der Schwermetalle sowie entsprechende Qualitätsziele zum Schutz aquatischer Ökosysteme.-Münchener Beitr. Abwasser-, Fischerei-u. Flußbiol
- B Wachs
Schwermetalle in Wasser-Organismen-Bioakkumulation,-magnifikation und-retention.-Sicherheit in Chemie u
- B Wachs
1985 a: Bioindicators for the heavy metal load of river ecosystems.-Symposia Biologica Hunga-ria
- B Wachs
Ökobewertung der Schwermetallbelastung des Main-Regnitz-Gebietes anhand der Geo-und Bioakkumulation sowie der Immissionen.-Münchener Beitr. Abwasser-, Fischerei-u
- B Wachs
1992 a: Passives Quecksilber-Monitoring in einem hochkontaminierten Fließgewässer bei abnehmender Belastung.-Münchener Beitr. Abwasser-, Fischerei-u. Flußbiol
- B Wachs
Inland Waters Directorate, Water Quality Branch, 1979-1983: - Environment Canada
- Ottawa Canada