2. Identifying and Classifying the Sources and Uses of Xenobiotics in Urban Environments

The sources and uses of xenobiotics in urban environments are very diverse, making structured approaches to source and use classification a fundamental requirement for effective pollution management. This chapter provides a general introduction to the topic of substance source and use identification, highlighting the key differences between different types of sources (e.g. processes vs. commodities; natural vs. anthropogenic etc.) and different types of uses (e.g. active vs. passive; dispersive vs. non-dispersive, etc.). Examples of relevant classification systems and their applications are also given, and the diversity of potential xenobiotic sources and uses is clearly demonstrated through the description of a series of ‘archetypes’ (i.e. model examples). The chapter concludes with an overview of useful source tracking approaches (e.g. database mining, marketing surveys, forensic approaches etc.).