Skip to main content


Title: Contaminants entering the sea : a report on contaminant loads entering the seas around England and Wales 1990-1993
Author: National Rivers Authority
Document Type: Monograph
The UK is required through various international agreements and commitments to reduce the quantities of certain hazardous substances and nutrients entering the sea from landbased sources. These substances have been selected for priority control because of their toxicity, persistence in the environment and potential to accumulate in marine life. Nutrients such as nitrogen and phosphorus have also been included in these commitments because of concerns about their potential under certain conditions to cause unnatural and excessive algal growth in estuaries and the sea. This report presents the progress that has been made in reducing the quantities of these contaminants entering the sea around the England and Wales coastline up to 1993. The UK is a Contracting Party of the 1974 Paris Convention, which is aimed at preventing and reducing marine pollution from land based sources. The UK has also joined in the commitments in the North Sea Declarations which, among other things, are aimed at achieving significant reductions of the inputs of specified contaminants to the North Sea between 1985 and 1995. In England and Wales, the National Rivers Authority is responsible for monitoring the inputs of these listed contaminants. It does this by measuring the loads of substances from direct industrial and wastewater discharges into estuaries and coastal waters, and by assessing the loads of substances entering the sea via rivers at the tidal limit. The monitoring programme has provided some important information on patterns and trends in inputs of contaminants to the sea over the last few years. It is clear that the relative contributions from different sources varies between different contaminants according to their pattern of use. For example, the main source of the metals mercury, cadmium, arsenic and chromium is direct industrial discharges to coastal waters, whereas a significant part of the overall input of nitrogen, copper, lead, zinc and nickel is carried via rivers, much of which originates from diffuse sources within river catchments. The levels of contaminant inputs monitored over the period 1990 to 1993 varied around the coastline. Loads of copper, zinc, lead, nitrogen and phosphate were highest into the North Sea, whereas cadmium and mercury inputs were greatest into the Irish Sea. Although inputs have been assessed using consistent methods since 1990, the data available for 1985 are limited, making it difficult in some cases to define a reliable baseline. However, where it has been possible to establish a baseline estimate for 1985, some clear trends have emerged. For the North Sea there have been substantial reductions in loads of mercury and cadmium and some reductions in the loads of copper, lead and chromium. Considering the overall inputs to the sea around the whole England and Wales coastline, there have been significant reductions in the loads of many of the priority metal contaminants. The exception to this is zinc, for which inputs have not significantly decreased since 1985. The NRA is continuing to address the need for pollution prevention and control of priority contaminants where this is needed to meet the required input reductions. Relative inputs of different contaminants have been quantified and prioritised as part of an overall strategy to reduce inputs from point sources and deal with, as far as possible, inputs from diffuse sources. This is being done within the context of the UK and European regulatory framework, drawing upon a range of different available mechanisms for prevention and control.
Publisher: National rivers Authority
Publication Date: 1995
Publication Place: Bristol
Subject Keywords: Pollution preventionPollution controlCoastal watersIndustrial wastesDirectives (European Union)Coastal waters
Geographic Keywords: EnglandWales
Extent: 51; + appendix
Total file downloads: 26

Download PDF    Display PDF in separate tab