Schicksal von 4-Nonylphenol und Bisphenol A im System Boden/Klärschlamm bei der landwirtschaftlichen Klärschlammverwertung

摘要

The fate of the important industrial chemical nonylphenol and bisphenol A which were enriched during wastewater treatment processes and exposed to the environment using sewage sludge as an agricultural fertilizier were studied. Adsorption and degradation experiments were performed with [14C]-radiolabeled compounds. Sorption of 353-nonylphenol to sandy loam soil as well as to Na-bentonite and peat humic acids was high, desorption low. Sorption and desorption of nonylphenol was strongly correlated with the amount of suspended soil in water. An enrichment of nonylphenol in soil migt be possible. In competitive sorption studies between dissolved peat humic acids and Na-bentonite about 90% of nonylphenol was sorbed to the bentonite therefore an enrichment in sediments of surface waters is expected. This is confirmed in a large number of publications. Using solid peat humic acids in competitive sorption studies most of nonylphenol (ca. 80%) was enriched at the solid peat humic acids and not at the Na-bentonite. An enrichment of nonylphenol at soil organic matter therefore is to be expected. Sorption of bisphenol A to sandy loam is low there might be a risk of contamination of ground water because of bleeding using bisphenol A contaminated sewage sludge as an agricultural fertilizier. 353-nonylphenol was stabilizied with increasing amounts of sewage sludge in soil up to 25% of applied after 135 days of incubation. A volatilization of 5% of 353-nonylphenol in a sandy loam might be an important source of nonylphenol into the environment. A new metabolite which was less polar than the parent compound nonylphenol itself was identified as 4-(3,5-dimethyl-3-heptyl)-2-nitrophenol. Highest amounts of that metabolite found in degradation studies were 40% of applied. In degradation studies after 130 days in a soil/sewage sludge mixture 1:1 (m:m) all isomers of technical nonylphenol were metabolizied in the same order to the nitro-metabolite. In sandy clay loam and in loam no nonylphenol and no metabolites of nonylphenol could be detected after 135 days of incubation in degradation experiments. In bioavailability studies degradation rates of 353-nonylphenol decreased dramatically with additional Na-bentonite or additional peat humic acids in a sandy loamy soil. 70% of applied nonylphenol could be detected after 135 days of incubation in sandy loam with additional peat humic acids. After 145 days of incubation in sewage sludge no bisphenol A and no metabolites of bisphenol A could be detected. No mutagen action could be detected for nonylphenol, 353-nonylphenol, bisphenol A and the new metabolite 4-(3,5-dimethyl-3-heptyl)-2-nitrophenol in test assays used (Ames-assay, UMU-assay). In conclusion the risk using bisphenol A contaminated sewage sludge as an agricultural fertilizier might be poor, but using nonylphenol contaminated sewage sludge there might be an incalculable risk, specially considering the high amounts of the metabolite 2-nitro-nonylphenol.