River pollution : an ecological perspective / S.M. Haslam ; illustrated by Y. Bower. Haslam, S. M. (Sylvia Mary), 1934- Stream ecology. Water Pollution Environmental aspects. QH541.5.S7 H37 1990 574.5/26323 20 574.526323 21 HAR Includes bibliographical references ([236]-249) and indexes. London ; Belhaven Press, c1990. c1990. 1990 Text xii, 253 p. : eng