Urease-Hemmtest für wirkungsbezogene Untersuchungen der Bindungsformen von Kupfer in Wässern und Bodeneluaten

Urease Inhibition Test for Effect-related Investigations of Copper Speciation in Water and Soil Extracts In 80 different water samples, the inhibition effect of cupric ions was measured by application of a simple urease inhibition test. In relation to the total copper concentration, the inhibition permits an effect-related classification of drinking water, rain water, spring water, surface water, leakage water, wastewater, and soil extracts. Drinking water contains high parts of cupric ions in the free hydrated form. Their copper content results in high urease inhibition and is caused by using copper pipes in house plumbing. In leakage water, wastewater, and soil extracts, cupric ions are mainly complexed by organic compounds in the sample matrix. Hence, the inhibition effects are low. In soil extracts, the urease inhibition increased after an UV-decomposition procedure, but a decreasing effect was observed for a surface and a drinking water sample, respectively. The chemical oxygen demand and UV-absorbance at 255 nm measured before and after the procedure were correlated to the content of organic compounds, i.e., humic acid. In most samples, the organic matrix was not decomposed completely. The oxidizing decomposition apparently forms further complexing agents, which suppress the inhibition effect of cupric ions. In the rain water samples investigated, the content of organic compounds depended on rain intensity. The chemical oxygen demand and UV-absorbance, respectively, were low for rain water collected during strong rain periods and increased with decreasing rain intensity. The rain water trickled over sheet-lead roof showed an increase of urease inhibition compared with the simultaneously collected rain. Consequently, a decomposition of organic matrix could be demonstrated in rain water by use of the urease inhibition test.     

Heavy Metal Load of Sediments of the River Gurk (Carinthia/Austria) — Merits and Limitations of Sequential Leaching Schwermetallbelastung des Sediments der Gurk in Kärnten — Vorzüge und Einschränkungen sequentieller Löseverfahren

By means of the analysis of sediments cored in the small river Gurk (Carinthia/Austria), the input of Ag, Cd, Ce, Cr, Hg, La, Mo, Ni, V, and W from a chemical industrial plant could be detected. To estimate the actual load, and to obtain data for comparison with other sites, both unsieved fine sediments and sediments sieved to 20 μm were investigated from the same cores. Environmental mobilities of toxic heavy metals (Co, Cr, Cu, Ni, Zn) have been shown by sequential leaching following Tessier/Förstner. In the last step, HNO₃ leaches a purely geogenic fraction, which is fairly constant along the investigated river. Whereas the additional Cr from the input of the chemical plant is mainly found in the oxalate-leachable fraction, short-time-load to unpolluted sediments in the laboratory is found mainly in hydroxylamine/acetic acid. Both is due to the high affinity of Cr to Fe- and Mn-oxides. Adsorption/desorption experiments reveal that the low carbonate content of the Gurk sediments increases the importance of Fe/Mn-oxides for the sorption of Cr compared to other samples containing carbonate. The Ni-load was primarily found in weak-acid-leachable and oxalate-leachable fractions. Similarly, the oxalate-leachable fraction is dominant for adsorption of other metals and phosphorus. Other interelement relationships among the amounts leached, which are attributable partly to carbonate-, silicate-, organic or coating phases, have been found by means of factor analyses together with marker fractions for each type.