An algebraic/graphical tool to compare ecosystems with respect to their pollution V: cluster analysis and Hasse diagrams.

In case of large data matrices comparative evaluations of objects/regions with the technique of Hasse diagrams may be troublesome due to a messy system of lines in the graphical representation. Here fuzzy clustering leads to useful simplifications because regions with slightly different pollution pattern are grouped together. However, fuzzy clustering implies to introduce a threshold value for the membership of an object to a cluster and to select the best number of clusters. Therefore many arbitrarities evolve. Within the systematic study presented here we found that some objects are very stable against variations of the threshold value and the number of cluster whereas other objects behaves different. According to their behaviour we investigated a classification of the objects. Formal Concept Analysis shows that in some cases specific pollution pattern imply the membership to one of these classes. For example objects which are characterized by high Pb-, Zn-concentration and moderate S-concentration imply a high stability against variants of the clustering process. Further implications are described in the paper.

Predicting bioconcentration factors (BCFs) of polychlorinated bornane (Toxaphene) congeners in fish and comparison with bioaccumulation factors (BAFs) in biota from the aquatic environment.

Polychlorinated bornanes, the main components of Toxaphene, are bioconcentrated in aquatic organisms to a high extent. However, up to this time no bioconcentration tests with individual chlorinated bornanes in aquatic organisms have been performed. Therefore, the bioconcentration factors (BCFs) of seven selected persistent chlorinated bornane congeners which are regularly found in aquatic organisms, were predicted from their n-octanol/water partition coefficients (log Kow). Furthermore, these BCF values were compared with the measured bioaccumulation factors (BAFs) in zooplankton and different fish species from the aquatic environment.

Interactions of hydroxy-s-triazines with sodium dodecyl sulfate-micelles investigated by micellar capillary electrophoresis.

The electrophoretic behavior of fourteen 4,6-diamino-s-triazines was investigated in the presence of an anionic surfactant (sodium dodecyl sulfate, SDS) using micellar capillary electrophoresis (MCE). The measurements were performed at the pH of zero charge of the hydroxytriazines and the existence of strong ionic and H-bond interactions of hydroxy-s-triazine species with the anionic micelles could be shown. Their migration behavior was compared to the n-octanol-water partition coefficients (log Kow) measured with reverse-phase HPLC and calculated with different fragment contribution methods. A partition model was proposed to understand the interactions of the three major hydroxy-s-triazine species: cationic, anionic and neutral (presenting enol and keto forms) with the charged SDS micelles taken as model for charged natural polyelectrolytes like humic substances. These results strongly indicate that hydroxy-striazines are polarized in the presence of the charged micelles and that they are essentially present in their keto form in the micellar phase (and enol form in the water phase), confirming previous studies suggesting the presence of zwitterionic resonance structures at a neutral pH around their isoelectric point.

A method to estimate the octanol-air partition coefficient of semivolatile organic compounds.

A multicolumn method for the estimation of the octanol-air partition coefficient (K(OA)) of semivolatile compounds is described. The method is based on the retention time of a compound on gas chromatographic columns of different selectivity and polarity. Log K(OA) values of polychlorinated biphenyls (PCB) were estimated with the novel multicolumn method. The results were in excellent agreement with previously published data using a generator column method. Therefore, we used our multicolumn method to estimate K(OA) for more than 100 PCB congeners.

Soil Adsorption Coefficients of s-Triazines Estimated with a New Gradient HPLC Method.

A high-performance liquid chromatography (HPLC) method employing gradient elution was developed to predict soil adsorption coefficients (K(oc)) from HPLC capacity factors. The gradient method allows for the determination of K(oc) values over a range of 4.4 orders of magnitude in a single experiment without adjustment of the solvent composition, as is required in isocratic HPLC measurements. The range of K(oc) estimated can easily be extended by using reference compounds with lower or higher log K(oc) values. Therefore, gradient HPLC is an appropriate screening method for K(oc) and was used to investigate s-triazine herbicides and their degradation products. Log K(oc) ranged from 0.8 for cyromazine to a maximum of 2.6 for anilazine and aziprotryne. HPLC-derived K(oc) values of s-triazines containing an azido group were higher than and those of hydroxy-s-triazines were lower than K(oc) values estimated according to the fragment contribution method of Meylan et al. (1992). According to this method, the log K(oc) of the keto form of hydroxy-s-triazines was >1 log unit higher than that of the enol form.

Indicator parameters for PCDD/F as a possible means to monitor emissions of toxicity equivalents from waste incinerators.

In the stack emissions from a hazardous waste incinerator we found highly significant correlations between 2,3,7,8-tetrachlorodibenzo-p-dioxin toxicity equivalents (I-TE) and pentachlorobenzene (CI5Bz) and between I-TE and heptachlorobiphenyl (CI7B). We therefore propose to utilize these substances as indicator parameters from which I-TE values can be estimated. Since they are easier to analyze than PCDD/F the use of indicator parameters such as CI5Bz and CI7B offers the chance to monitor I-TE emissions which are limited to 0.1 ng/m3 in many European countries.