§ Dr. David ClarkTo ask the Minister of Agriculture, Fisheries and Food whether he is monitoring the input of nutrients, including nitrates and phosphates, into the North sea; and if he will give the results of any such monitoring.
§ Mr. Donald Thompson[holding answer 18 July 1989]: My Ministry monitors the input of nutrients to the sea arising from sea disposal operations licensed under the Food and Environment Protection Act 1985. Such inputs are a very small proportion of the total nutrient inputs into the North sea, of the order of 1 per cent. for nitrates and less than 3 per cent. for phosphates.
Water authorities record inputs of nutrients from rivers to estuaries. This monitoring shows that there has been no change in nitrate inputs in the last 10 to 15 years. Phosphate inputs have shown a detectable rising trend.
Ministry scientists have examined records of nitrate concentrations in sea water in winter, the period of maximum and stable nitrate concentrations. These show that there has been a cyclical pattern in nitrate concentrations but no consistent rising trend. The same cyclical pattern occurs throughout the mid and southern North sea and is believed to reflect climatic or other long-term changes rather than anthropogenic nitrate inputs.
It is known that a substantial proportion of the nutrients entering the estuary do not reach the sea. An 287W investigation is now in preparation by MAFF scientists and others to establish the scale on which the removal processes involved occur.