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The book is for those interested in modeling exposure to chemicals. It contains two parts: part one is the text book which allows the reader to learn about the dynamic behavior of chemicals in our environment. Basics of exposure estimation, mathematics and chemistry are explained in the first chapters, followed by a guide to exposure models for all environmental media. Part two is the software tool "Cemos" (Chemical exposure model System) which includes nine exposure models, a substance database with twelve data sets, data estimation routines, quality assurance tools and a hypertext online help. The disk is quickly installed and runs on DOS 3.3 or higher (up to WINDOWS NT). The comprehensive Cemos manual is also included. It is identical to the online help. All equations used in the program are described in detail, making the calculations fully transparent. Exercises with solutions, example calculations and a database help the reader to learn about and apply exposure models

Das Buch wendet sich an alle, die Interesse an dem immer wichtiger werdenden Gebiet der Schadstoffausbreitung in der Umwelt haben. Der didaktisch gut aufbereitete Text erleichtert den schnellen Einstieg ohne überflüssigen mathematischen Ballast und ermuntert zum Selbststudium. Die Modelle werden Schritt für Schritt und nach einem einheitlichen Konzept erläutert. Übungsaufgaben im Buch und die Diskette mit Modelling-Software (ChemoS) sowie eine Substanz- und Umweltdatenbank für IBM-PC und Kompatible und Übungsdatensätzen sichern und festigen das erworbene Wissen und erlauben eigene Berechnungen

All chemicals form non-extractable residues (NER) to various extents in environmental media like soil, sediment, plants and animals. NER can be quantified in environmental fate studies using isotope-labeled (such as 14 C or 13 C) tracer compounds. Previous NER definitions have led to a mismatch of legislation and state of knowledge in research: the residues are assumed to be either irreversibly bound degradation products or at least parts of these residues can be released. In the latter assumption, soils and sediments are a long-term source of slowly released residues. We here present a conceptual experimental and modeling approach to characterize non-extractable residues and provide guidance how they should be considered in the persistence assessment of chemicals and pesticides. Three types of NER can be experimentally discriminated: sequestered and entrapped residues (type I), containing either the parent substance or xenobiotic transformation products or both and having the potential to be released, which has indeed been observed. Type II NER are residues that are covalently bound to organic matter in soils or sediments or to biological tissue in organisms and that are considered being strongly bound with very low remobilization rates like that of humic matter degradation rates. Type III NER comprises biogenic NER (bioNER) after degradation of the xenobiotic chemical and anabolic formation of natural biomolecules like amino acids and phospholipids, and other biomass compounds. We developed the microbial turnover to biomass (MTB) model to predict the formation of bioNER based on the structural properties of chemicals. Further, we proposed an extraction sequence to obtain a matrix containing only NER. Finally, we summarized experimental methods to distinguish the three NER types. Type I NER and type II NER should be considered as potentially remobilizable residues in persistence assessment but the probability of type II release is much lower than that of type I NER, i.e., type II NER in soil are "operationally ...