CONCENTRATIONS OF SUSPENDED CHLOROPHYLL-ALPHA IN THE HUMBER RIVERS

Concentrations of chlorophyll a have been determined at weekly interva ls for all of the major rivers feeding the Humber Estuary since Septem ber 1993, as part of the LOIS monitoring programme. Highest concentrat ions generally occurred in the two southern rivers, the R. Trent and t he R. Don, and also in the larger of the northern rivers, the R. Ouse and its main feeder, the R. Ure. High concentrations also developed on occasions in some of the other northern rivers, especially during the summer of 1995 when the unusually dry conditions led to low flows and extended retention times. Heavy pollution levels in the R. Aire and t he R. Calder, a major tributary of the Aire, were probably responsible for the consistently low concentrations recorded in these rivers. (C) 1997 Elsevier Science B.V.