Chloroacetic acids (CAAs) and trifluoroacetic acid (TFA) are widely distributed environmental pollutants. The origin of CAAs is still under debate, while TFA is considered to be a major atmospheric degradation product of recently introduced hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs). Because of the phytotoxic potential of the CAAs, i.e., monochloroacetic acid (MCA), dichloroacetic acid (DCA) and trichloroacetic acid (TCA) and the persistence of TFA, these compounds are of considerable environmental concern. Hence, it is important to know their fluxes and their spatial and temporal distribution in the environment. In this study, the occurrence and mass fluxes of MCA, DCA, TCA, and TFA were assessed on a regional scale over Switzerland, based on more than 1000 concentration measurements in rain and snow, surface water, ground water, and waste water. Among different precipitation events, the measured concentrations varied significantly from <11 ng/L to 7100 ng/L. However, no statistically different average haloacetic acid (HAA) concentrations among six precipitation sampling sites located in various areas in Switzerland were observed (range of average concentrations: MCA 1430-2770 ng/L, DCA 390-1370 ng/L, TCA 95-380 ng/L, TFA 33-220 ng/L). The similar average HAA concentrations in precipitation at a remote site close to the free troposphere at an elevation of 3580 m above sea level (Jungfraujoch) and at a site which receives precipitation which scavenged the Earth's boundary layer (urban site Dübendorf/Zürich) suggests that HAAs are derived from well mixed precursor(s) in the atmosphere. When moving from precipitation to surface waters (i.e. rivers), the TFA/CAA ratios increased by a factor of 10-11 for TFA/MCA and TFA/DCA, and by a factor of 1.2 for TFA/TCA. Mass flux calculations show, that precipitation is the dominant source of the HAAs, particularly of MCA, DCA and TFA (>95%). In the case of TCA waste water effluents contributed 27% of the total input. The results indicate that compared to the CAAs, TFA is quite persistent in the aquatic and terrestrial environment, and may thus accumulate in soils and ground water.

Sediments contaminated with organotin compounds (OTs), in particular triorganotins (TOTs), are abundant in areas with high shipping activities. To assess the possible remobilization of these highly toxic compounds from such sediments, a profound understanding of their sorption/desorption behavior is necessary. In this work the extent and reversibility of sorption of OTs to sediments has been investigated using contaminated freshwater harbor sediments and two certified OT containing marine sediments. Experiments conducted with perdeuterated OTs showed that sorption of OTs to sediments is a fast and reversible process involving primarily particulate organic matter (POM) constituents as sorbents. The organic carbon-normalized sediment-water distribution ratios (DOC, expressed in L/kgOC) determined in the laboratory were consistent with in-situ DOCs obtained from OT concentrations measured in sediment and pore water samples from two dated sediment cores. For both butyl- and phenyltin compounds the log DOC values were in the range of 4.7-6.1, and the following sequence was observed: DOC (tri-OT) > or = DOC (di-OT) > or = DOC (mono-OT). However, the differences were much less pronounced than would have been expected for hydrophobic partitioning of the corresponding compounds into POM. These results support our hypothesis from earlier work with dissolved humic acids that OT sorption to sediments occurs primarily by reversible formation of (innerspere) complexes between the tin atom and carboxylate and phenolate ligands present in POM. Because of the high DOC values (i.e. log DOC > or = 4) the diffusion of OTs from deeper sediments to the surface will be rather slow, and thus a major release from undisturbed sediments is not expected. However, because OTs readily desorb, any resuspension of contaminated sediments (e.g., by the tide, storms or dredging activities) will lead to enhanced OT concentrations in the overlaying water column. Furthermore, in contrastto polycyclic aromatic hydrocarbons (PAH) where large fractions may be tightly bound (in)to soot or other carbonaceous materials, OTs will be more readily bioavailable due to the fast and reversible sorption/desorption behavior.

The extraction of two methylated anilines and three chlorinated phenols by solid-phase microextraction (SPME) fibers coated with polyacrylate was investigated as a function of pH. Only the neutral species of the acids and bases partitioned into the polymer. Extraction kinetics were accelerated for the hydrophobic phenols at pH values around their acidity constant. This is presumably due to a reconstitution of the neutral species in the unstirred aqueous layer adjacent to the polymer surface by the charged species through the fast acid-base equilibrium. Although the charged species is not taken up into the polymer, liposome/water distribution ratios could be measured up to a pH value, where 99% of the compounds were present as charged species. The partition coefficients of the neutral and charged species were extrapolated from the pH profiles of the liposome/water distribution ratios. The resulting values were slightly lower than those measured with equilibrium dialysis. The discrepancies are discussed with respect to differences in the experimental conditions and the possibility of matrix effects during SPME measurements.

A very efficient technique for the analysis of six butyl-and phenyltin compounds in biota samples has been developed. No special equipment is needed for sample preparation, which is based on cold methanolic digestion with subsequent aqueous ethylation and liquid-liquid extraction. For samples of only 40 mg of biological materials, method detection limits ranging from 4 to 52 ng/g were achieved using gas chromatography/mass spectrometry. Relative recoveries for the individual butyl-and phenyltins, referring to perdeuterated organotin analogues as internal standards, ranged from 96 to 107%. Organotin concentrations in insect larvae (Chironomus riparius) and a reference mussel tissue (CRM 477) were determined with excellent precision (RSD <5%), and the measured butyltins in CRM 477 were in good agreement with the certified values. Comparison with accelerated solvent extraction confirmed high accuracy, and application for a bioconcentration experiment with phenyltins demonstrated the robustness and suitability of the method for routine analyses. The procedure allows fast, reliable, and simple determination of organotin compounds in lowsize biological samples, which was demonstrated for bioconcentration experiments.