The present volume is a collection of papers presented in a National Seminar held in Visva-Bharati, Santiniketan, from fourth to sixth September 1987. Various constraints delayed the publication of the papers presented at the time but to make amends a large number of papers have been revised and iupdated Environmental science is a multidisciplinary subject and the many factors demand that specialists from many -fields should come together and co-operate. This book is the result of such academic co-operation and naturally the areas covered are diverse.