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Analytik, Vorkommen und Verhalten aromatischer Sulfonamide in der aquatischen Umwelt
Hartig, Claudia
Subject of this PhD-thesis are the analysis and behaviour of aromatic sulfonamides as organic micropollutants in the aquatic environment. On the grounds of their widespread application, bacteriostatics as well as benzene- and toluenesulfonamides (BTS) are investigated. Analysis of the sulfonamides consists of solid-phase extraction (LiChrolut EN) and HPLC-MS/MS. Limits of detection vary from 0.1-20 ng/L. The MS/MS detection is carried out in SRM mode. Matrix effects of the investigated secondary municipal effluent and surface water result in ionisation enhancement for most sulfonamides. The quantitation is carried out by internal calibration (stable isotopically-tagged internal standard). For identification purposes, product ion scans and SRM are utilised, false positive results are thus excluded as far as possible. As physicochemical methods for the removal of sulfonamides, nanofiltration and adsorption on powdered activated carbon (PAC) are investigated in laboratory systems. Nanofiltration with a membrane of a molecular weight cut off of 1000 g/mol leads to rejection rates of 50-75% at pH 5.4 and of 75-90% at pH 8 for the bacteriostatics. Rejection rates of BTS amount to 10-45% at both pH values. In single component solution, sulfmethoxazole and N-n-butylbenzenesulfonamide are well adsorbable on PAC. In spiked microfiltered secondary effluent, their adsorbability drops markedly. Filtration of this effluent with a tight ultrafiltration membrane leads to a better adsorbability of the sulfonamides in the permeates as compared to the feed water. Biological degradation is tested in aerobic batch tests (Zahn-Wellens) as well as in aerobic and anaerobic/anoxic soil columns. In the batch tests, all bacteriostatics are degradable. Two metabolites are identified. From their structure, the structure of the degradation products of the other bacteriostatics can be deduced. Three BTS are easily degradable and another three BTS are non-degradable in this test. In the soil columns, the degradability before a background-DOC is investigated. At continuous spiking with small amounts under aerobic conditions, the twelve tested bacteriostatics are degradable. The degradation rate depends on the heteroaromatic moiety. Six examined BTS are non-degradable under these conditions. At peak spiking with high concentrations, none of the sulfonamides is degraded aerobically whereas under anaerobic/anoxic conditions, two out of nine investigated bacteriostatics and four out of eight BTS are partially eliminated. Secondary effluents, receiving waters, surface waters, bank filtrates and raw waters are analysed for sulfonamides. In the investigated Berlin area, the bacteriostatics sulfmethoxazole, sulfadiazine, and sulfamerazine and the BTS N-n-butylbenzenesulfonamide, N-ethyltoluenesulfonamide, N-(phenylsulfonyl)sarcosine, and N-methylbenzenesulfonamide are detected. Effluent concentrations of municipal waste water treatment plants amount to 1-2000 ng/L, depending on the sulfonamide. It is shown that sulfonamides in the other water compartments originate from these treatment plants. Concentrations here range from 0-250 ng/L, depending on dilution and biological degradation. Waters from other regions exhibit different sulfonamide compositions and concentrations. In bank filtration, the concentrations depend on the water carrying path of the sulfonamides through the underground with the redox milieu as the most influential parameter.
