A survey of the nitrate and phosphate levels of inshore marine waters from Malta (Central Mediterranean)

Abstract

The nitrate and phosphate levels were monitored over a one-year period in three inshore localities in Malta. There were recorded no seasonal variations in nutrient levels at Marsaxlokk bay. At Mistra bay a slight decrease in nitrate-nitrogen was recorded during the autumn and winter periods. At both these locations, how- ever the nitrate-nitrogen was generally below llJig-atil and phosphate-phosphorus al- ways less than 0.2 /J1.g-atll. The values are typical of most areas in the Mediterranean. The concentrations of nutrients at Rinella creek were consistently manifold higher and peaked during the winter months. This, very probably, reflects the combined effects of organic pollution and rainfall on this very enclosed creek. Occasionally, short-lived high levels of nitrates were recorded at Marsaxlokk and Mistra bays. These seem to originate from agitation of bottom sediments.