With joy and pride parents observe the coming of age of their children, confer. , ence conveners the acceptance of their programmes, and editors the demand for their volumes. The scientific advisory board of the Gothenburg . . Symposia, the Springer publishing house of the proceedings and the editors are more than pleased with the fact that the demand for these books far exceeds the supply. The themes vocalized by the Gothenburg Symposia reHect research and development needs for the environment more than envisioned at the concep­ tion of the conferences. An environment-oriented analysis of the situation, not confined to the European community, furnishes the following results: (1) Due to the very high population density in many areas environmental quality is endangered; this has become apparent at the very moment in particular in the aqueous habitat and is corroborated by corresponding regulation proposals from the European Council. (2) Pollution control concepts and measures are developed to a varying degree in many countries of the world, reHecting in most instances the need for environmental protection and the closely related development of (judicial and technical) measures. In most instances these controlling and protective measures need to be intensified. (3) Thus, nearly all countries face the problem of developing and/or improving pollution control strategies, i. e. building new treatment plants, upgrading overloaded or outdated instal­ lations and designing new operating and controlling strategies for improved plant performance.