Nitrat-Bestimmung in Oberflächengewässern als Beispiel der Anwendung der UV-Derivativspektroskopie in der Umweltanalytik

Artificial nitrate solutions and a large number of membranefiltered nitrate-containing water samples from Mecklenburgian lakes and rivers were investigated in the spectral range of 200… 260 nm with a dual beam spectrophotometer. By the formation of derivative spectra there are achieved a higher spectral resolution and the elimination of undesired disturbing effects since first- and higher-order derivatives are formed. As it is known, the direct spectrophotometric nitrate determination is influenced by organic substances and some inorganic ions of natural waters. As a result, the UV derivative spectroscopy of 2nd order is recommended as a suitable technique of nitrate analysis for surface waters with a high degree of accuracy and precision – detailed reports on investigations being given. Compared with the equivalent salicylate method, however, the expenditure of the UV derivative spectroscopy described is considerably lower.     

Qualitätsanforderungen an Oberflächengewässer: Zielvorgaben,Qualitätsziele und chemische Gewässergüteklassifizierung

Quality Requirements for Fresh Waters: Water Quality Targets, Water Quality Objectives, and Chemical Water Quality Classification In the Federal Republic of Germany, water quality requirements for the protection of inland surface waters against hazardous substances are formulated on the basis of a quality targets derivation concept developed jointly by the Federal Government and the Federal States. The quality requirements were termed “water quality targets” in order to make it clear that the values derived are orientational values rather than legally binding limit values. The international comparison of quality requirements for surface waters shows that, on the whole, the national quality targets ensure a high level of protection. According to present scientific knowledge, impairments of uses, such as supply of drinking water, or risks to aquatic communities need not to be expected if the quality targets are complied with. A comparison of water quality data with the water quality targets makes it possible, on the one hand, to identify those substances whose inputs must be further reduced; on the other hand, it also shows that, for a number of substances, there is no need at present for concern over their adversely water quality. A further differentiation of the aquatic hazard potential of pollutants allows a water quality classification system to be developed on the basis of the quality targets derivation concept. The basic elements of this water quality classification system are presented, and its application is explained by way of examples.     

Zielvorgaben für Pflanzenschutzmittelwirkstoffe und andere Schadstoffe in Oberflächengewässern

Quality Targets for Pesticides and Other Pollutants in Surface Waters Surface waters are not only adversely affected by industrial and municipal wastewaters but also by diffuse sources. For the control of the ecological water quality, so‐called quality targets are set. The quality targets are threshold concentrations for hazardous substances related to the protected goods like water ecosystems, drinking water supply, sediments, or fishing. In this paper, quality targets for the protection of aquatic life in surface waters were derived on the basis of a concept developed by the International Commission for the Protection of the Rhine (Internationale Kommission zum Schutze des Rheins – IKSR). The quality targets for the selected hazardous substances, which mainly belong to the chemical class of pesticides, were calculated using ecotoxicological results for species of bacteria, algae, fish, and small crustaceans, as the four trophic standards of the water ecosystem. In cooperation with the Federal Environmental Agency (Umweltbundesamt – UBA) the effect data were taken from ecotoxicological data bases. According to the concept of the IKSR, the lowest test result for the most sensitive species was multiplied by an assessment factor. This proceeding concerns the difficulty in describing the complex interactions in water ecosystems with toxicity data of single laboratory experiments for a few organisms. For seven pesticides quality targets below 0.1 μg/L were proposed. These results show that the ecotoxicologically based quality targets might be even lower than the limit values for pesticides in drinking water of 0.1 μg/L. But for most of the substances the determined values are significantly higher. The great concentration range of quality targets demonstrates distinctly that one standard concentration for all pesticides could not be given with regard to the different effects on aquatic organisms.     

Anforderungen an die Gütebewirtschaftung von Oberflächengewässern in tropischen und subtropischen Klimaten

A survey is given of the special conditions and their effects by means of a large number of examples. There should be pointed out especially the possible mass development of higher aquatic plants, partly high concentrations of turbidity-causing substances, the lack of oxygen even at slight water depths as well as the often high contents of pathogenic agents and a pronounced thermal stratification in storage reservoirs. Conclusions for the quality management are derived.     

Hydrochemische Ergebnisse zur Aufbereitung stark belasteter Oberflächenwässer und Uferfiltrate mit Kalkhydrat,Teil 1

Several laboratory-scale-tested variants of the treatment of organically loaded surface water samples with hydrated lime are described. Possibilities of the additional application of magnesium, aluminium and iron salts and of the anionic polymer “activated silicic acid” are discussed. The aim has been a considerably reduced application of metallic salts and precipitants at a maximum adsorption of organic pollutants. Another factor influencing crystallization and double hydroxide formation consists in low water temperatures, < 8°C. With the aid of a magnetic treatment disturbing effects were avoided and even increases of the rates of growth and sedimentation were achieved.     

Hydrochemische Ergebnisse zur Aufbereitung stark belasteter Oberflächenwässer und Uferfiltrate mit Kalkhydrat. Teil 2

Continuing the first part on this subject, the results of precipitation experiments are described by the example of the removal of humic acid and lignosulphonic acid. Moreover, to increase the number of process variants and in accordance with process methods after Haberer, there is proposed a two-stage chemical treatment, inter alia. According to the latest findings, already at the first stage a metallic salt dosing should be done, so that the purification effect can be improved. This new technique, termed “combination stage flocculation”, is based on new findings concerning the solubility behaviour of aluminium compounds at higher pH-values in the presence of magnesium salts, when slightly soluble aluminium-magnesium double hydroxides originate.     

Die neue EG‐Wasserrahmenrichtlinie: Bewertung der chemischen und ökologischen Qualität von Oberflächengewässern

The New EC Framework Water Directive: Assessment of the Chemical and Ecological Status of Surface Waters The main objective of the draft EC Framework Water Directive is the good quality of all surface waters. The directive provides for an assessment of the chemical status of surface waters (EU‐wide valid environmental quality standards for approximately 30 priority substances) and a five‐stage ecological classification of waters, comprising the stages high, good, moderate, poor, and bad. The starting point for the assessment are the reference conditions, which are defined as corresponding to high water quality and characterising a water status with no significant anthropogenic impact. The reference sites in the various water body types are to be selected using hydromorphological and physico‐chemical parameters and subsequently characterised by means of biological parameters. For surface waters, three groups of characteristics are provided for, namely: 1. with priority the biology – in the case of surface waters – with the four elements phytoplankton, macrophytes/phytobenthos, benthic invertebrate fauna, and fish fauna; 2. supporting the hydromorphology, e.g. flowing waters with the three elements hydrological regime, river continuity, and morphological conditions and 3. supporting the physico‐chemical conditions with the three elements general conditions, specific synthetic pollutants, and specific non synthetic pollutants (other than the priority substances of the chemical status).     

Zur Schlußreinigung konzentrierter Zuckerfabrikabwässer

The most important measure is that the freshwater demand of 0.5 m³ per t beet processing is strictly kept to or fallen below, to which a catalogue of measures with ten points is presented. The wastewaters which cannot be used again have to be stored prior to the final purification in order to compensate for quantities and concentrations, aerated storage ponds being successful for small sugar factories as the purification technology. For this, three cases are described as examples: supplementary equipment of two anaerobic ponds with a rod-roll aeration, by which within two months (May to July) the BOD₃ is reduced from 1,200 to 11 mg/l. The aeration of a pond of 12.5 ha (370,000 … 500,000 m³) by means of a centrifugal aerator (45 kW) does not lead to completely aerobic conditions: Accumulation up to 350 t BOD₅, 200 t organic acids at a reduction of 100 t sulphate, 45 t of which being converted via sulphides by photoautotrophic sulphur bacteria. This combination of anaerobic and aerobic processes is very economical. At aeration with ca. 1 W/m³ in the third case in summer there are achieved wastewater loads which are of a receiving-water quality.     

Verfahren zur Nitrateliminierung im Gewässer

In a storage reservoir with a hypolimnic volume of 3.5 hm³ the water contains 40 mg/l nitrate. A straw bale of 60 by 20 by 1.5 m was introduced as a reactor. Hypolimnic water having been polluted with a waste product of the fatty acid synthesis (30 … 20% formic, acetic, propionic, butyric and valeric acids) were pumped through it. By the use of a total of 43.8 t fatty acid mixture from June to August an additional oxygen depletion of 14 t O₂ is achieved and 49 t NO₃^? are removed at the same time. The ammonium concentration did not increase, the NO₂^? concentration, however, rose to 12 … 13 mg/l NO₂ at times. The fatty acids were used up save 0.1 mg/l. The increase of the NO₂^? concentration, of the number of germs and of the iron, manganese and phosphorus back solution due to the controlled anaerobic conditions is the drawback of the process.     

Elektrochemische Einschätzung des Oberflächenzustandes von Wasserreinigungskohlen

Electrochemical Characterization of the Surface of Activated Carbon Used in Water Treatment Plants. We tried to measure electrochemically those properties of activated carbons which are important for using them for water purification. A success was achieved with the electrochemical immersion potential U_i which is found to be a function of concentration of functional surface groups on the carbon surface. However, the expected direct proportionality for inert surfaces between BET surface area and amount of charge measured in recharge processes has not been observed.     

Oberflächenaktivität und bakterizide Wirksamkeit quaternärer Aminooligomere

We synthesized series of polyfunctional aminooligomers by means of condensation from polychlorparaffine with ethylenediamine. After modifying them with dimethylsulphate watersoluble oligomers of (quaternary) polyamines are obtained, which can be successfully used as biocides for treating circulating cooling-waters from different refinery plants. The products have low foaming and formed foam is unsteady. The bactericide properties of the successful samples are good. For the interval time for two to twenty hours of treatment at static conditions the microbe number value decreases by more than 99.99% at a 50 mg/dm³ dose of a biological active substance. At dosing it up to seventy-two hours the biomass is finely dispersed and does not precipitate on the walls of the chemical set-equipment.     

Die gaschromatographische Bestimmung von Diethylentriaminpentaessigsäure in Oberflächenwasser

Gaschromatographic Determination of Diethylenetriaminepentaacetic Acid in Surface Water. A method for the determination of diethylenetriaminepentaacetic acid (DTPA) is reported. The determination is based on the preconcentration on a strong base anion exchange resin, esterification with n-propanol and following gaschromatographic separation using a N-selective detector. The sensitivity of the method, including enrichment, is 1 μg/L in river water. The identity of DTPA in river water was proved by mass spectrography. The method can be used also for the quantitative determination of nitrilotriacetic acid (NTA), ethylenediaminetetraacetic acid (EDTA), cyclohexanediaminetetraacetic acid (CDTA) and ethyleneglycolbis-(2-aminoethylether)-N,N,N′,N′-tetraacetic acid (EGTA). The method was used to examine river water. An investigation along the river Rhine, taking grab samples from January and february 1992 showed that DTPA was present in some sampling places in similiar concentrations as NTA and EDTA.