IMPACTS OF CLIMATE CHANGE ON WATER POLLUTION
Dave Sheahan
Centre for Environment, Fisheries and Aquaculture Science (Cefas), Pakefield, Lowestoft
Supporting Evidence
Datasets for contaminants that are of relevance for investigation of climate change influence upon contaminant fate and effects in the marine environment relate to discharges to rivers and estuaries that will ultimately reach the sea and to monitoring data for coastal and offshore sites.
The Environment Agency manages a pollution inventory (established in 1998) to collect information on chemical and radioactive substances from industrial sites in England and Wales. This inventory covers the main emissions to controlled waters (river, estuary, sea) and sewer for different industry sectors. A similar pollutant release inventory has recently been made available by the Scottish Environmental Protection Agency. Data from these sources enables load calculations to be made and trends over time to be compared.
Figure 1 shows the change in concentration of a range of trace metals measured in UK surface waters at over 200 sites in England and Wales between 1980 and 2001. In each case, there is a decrease in dissolved metal concentration over this period. Figure 2 shows a similar decreasing trend in the concentration of some of the same trace metals in sediments of the River Mersey. The decrease shown in both cases is largely related to the control of various point sources such as industrial and sewage treatment works effluent discharges.
Figure 1 Median site mean trace metal concentrations and upper 90th percentile for six trace metals measured at over 200 surface water sites in the England and Wales in 1980 and 2001 (EA, 2000)
Various Departments and Agencies in the UK also contribute to monitoring programmes for the marine environment. Data on contaminants and biological effects from these programmes is integrated to provide an overview of the quality of the marine environment via the UK National Marine Monitoring Programme (NMMP). The NMMP ensures co-ordinated quality status monitoring between the UK Government Departments and agencies with environmental responsibilities. Phase one of the NMMP was carried out in 1993-95 and 1996-1998 by a spatial survey at monitoring stations in estuarine, intermediate and offshore locations. This included the National
Coastal Baseline Survey operated by the EA and its forerunner, the National Rivers Authority (NRA). Phase two of the programme (NMMP2) was started in 1999, concentrating on temporal trend monitoring and also introducing new biological effects studies. Based on over 100 locations, the programme monitors contaminants (trace metals, organic compounds) in water, sediment
and biota (shellfish and fish); biological effects (health status of organisms); nutrients in water; and temperature and salinity. A full description is given at http://www.defra.gov.uk/environment/water/marine/uk/science/monitoring.htm
Figure 2 Mean sediment trace metal concentration* measured in the River Mersey in 1974 and 1998 (Harland et al., 2000)
* trace metal concentration is normalised to 40% silt content
In terms of historical contamination in the marine environment data derive from surveys of UK estuaries and ports (Table 1. and 2). PAH concentrations measured in a number of English estuaries shows high concentrations of PAHs at some sites.
Table 1 PAH concentrations µg/kg dry weight in sediment samples from English estuaries collected between 1993 and 1996 (Jones and Franklin, 1998)
| Location |
Individual PAH range |
Total PAH range |
|---|---|---|
River Tyne |
<17-2417 |
236-10790 |
River Wear |
7-2264 |
753-12252 |
River Tees |
3-1973 |
581-7817 |
River Humber |
8-981 |
545-2972 |
River Thames |
13-1071 |
597-5350 |
Blackwater |
89-1542 |
4011-8463 |
River Exe |
n/d-876 |
n/d-4654 |
River Tamar |
<30-1102 |
6025-6194 |
River Mersey |
<5-1242 |
6-5236 |
Sediment metal concentration is also likely to be high in areas that are subject to dredging. The highest concentrations were measured at sites associated with industrial activity with the exception of some parts of Cornwall for which natural high background concentrations of arsenic are present.
Table 2 Mean metal concentration range measured in dredged material (mg/kg wet weight) sampled from English estuaries, 1995-1997. The number of samples exceeding OSPAR guidelines is also shown. Based on Cefas data(Jones and Franklin, 2000)
Metals sampled |
Mean concentration Range |
Number of sites exceeding OSPAR guidelines |
|---|---|---|
Arsenic |
3.94-44.00 |
6>50 |
Cadmium |
0.01-3.43 |
29>2.5 |
Chromium |
4.46-400.75 |
12>200 |
Copper |
4.70-314.07 |
29>200 |
Mercury |
0.01-2.44 |
24>1.5 |
Nickel |
0.90-28.64 |
1>100 |
Lead |
4.30-224.67 |
21>250 |
Zinc |
14.00-450.33 |
31>400 |
Please acknowledge this document as: Sheahan, D (2006). Impacts of Climate Change on Pollution in Marine Climate Change Impacts Annual Report Card 2006 (Eds. Buckley, P.J, Dye, S.R. and Baxter, J.M), Online Summary Reports, MCCIP, Lowestoft, www.mccip.org.uk
References
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Environment Agency General Quality Assessment (2000). Available at
http://www.environment-agency.gov.uk/yourenv/eff/1190084/water/213902/river_qual/gqa2000/
Harland, B.J., Taylor, D. & Wither, A. (2000). The distribution of mercury and other trace metals in the sediments of the Mersey Estuary over 25 years 1974-1998. The Science of the Total Environment 253 45-62.
Jones, J. & Franklin, A. (1998). Cefas. Monitoring and surveillance of non-radioactive contaminants in the aquatic environment and activities regulating the disposal of wastes at sea, 1995 and 1996. Aquatic Environment Monitoring report No.51.
Jones, J. & Franklin, A. (2000). Cefas. Monitoring and surveillance of non-radioactive contaminants in the aquatic environment and activities regulating the disposal of wastes at sea, 1997. Aquatic Environment Monitoring report No.52.
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Other Information sources
FRS (2006). NMMP programme, described in the ‘Green Book’. Available at http://www.marlab.ac.uk.