GRADIENTS OF CHLOROPHYLL A AND WATER CHEMISTRY ALONG AN EUTROPHIC RESERVOIR WITH DETERMINATION OF THE LIMITING NUTRIENT BY IN SITU NUTRIENT ADDITION

摘要

Alton Water, Suffolk, UK, is a linear reservoir, with input water pumped into the northwest end and drawoff tower in the main basin at the southeast end. The reservoir had an eutrophic to mesotrophic gradient in 1995 and 1996, primarily due to differences in summer. In 1995 mean summer chlorophyll a concentration at the northwest end was 95 + - 34 mu g/l`, 24 times that in the main basin. Total phosphorus, orthophosphate, nitrate and ammonium concentrations significantly decreased along the length of the reservoir, whilst Secchi depth increased. The first two components of principal