Data summarised from National Rivers Authority Survey (TAPS 1995)

The information is presented in Table D1. The data were recorded as the number of samples that exceeded 0.1 mg l^-1, with no further information available on the highest concentrations reported. EQS exceedences were only seen infrequently with 6 sites (less than 2%) breaching relevant standards. Two EQS failures were reported for:

• total HCH (lindane) (EQS value = 0.02 mg l^-1 as an annual average concentration);
• one for azinphos-methyl (EQS value = 0.01 mg l^-1 as an annual average);
• one for pp-DDT (EQS value = 0.01 mg l^-1 as an annual average);
• one for endosulphan (EQS value = 0.0003mg l^-1 as an annual average);
• one for chlorfenvinphos (EQS value = 10 mg l^-1 as an annual average).

Data summarised from the >National Monitoring Programme Survey of the Quality of UK Coastal Waters= (MPMMG 1998)

Metal concentrations in estuaries were higher than at intermediate and offshore sites. This is interpreted as being a direct consequence of the proximity of estuarine sites to inputs, e.g. rivers. Within estuaries, there was also a general tendency for metal concentrations to decrease with increasing salinity. Where information is available, concentrations tended to be higher in those estuaries receiving inputs from industrial and/or domestic sources. Examples are cadmium (Severn), chromium (CIyde), lead (Tyne, Tees and Thames) and zinc (Tyne, Wear and Mersey).

Relative to metal concentrations in estuaries, those observed at intermediate and offshore sites were low and consequently of no real concern as regards compliance with EQSs. The data do, however, reveal some features of interest. Many of the metals included in the survey show higher concentrations in the southern rather than in the northern North Sea. This was attributed to the generally lower salinity in the southern North Sea, a consequence of the greater freshwater input from major rivers. A similar effect is evident for parts of the Irish Sea, where apparently high concentrations of metals can be attributed to the lower salinity of this area (CEFAS, 1997). Some metals are extremely particle-reactive, tending to be adsorbed onto suspended particles, with a consequent reduction in the dissolved phase concentration. Relatively high dissolved lead concentrations in the vicinity of Dogger Bank, observed in this and in other studies (Laslett, 1995), are attributed to the relatively clear waters of this area, where there is little removal onto particles.

Of all the median metal concentrations reported in the report, only two results (for zinc) exceeded the EQS for the metals included in the NMP survey (EQS values are: cadmium 2.5 mg l^-1, copper 5 mg l^-1, chromium 15 mg l^-1, lead 25 mg l^-1, mercury 0.3 mg l^-1, nickel 30 mg l^-1 and zinc 40mg l^-1, respectively).

Pesticides exceeding 0.1 mg l^-1 in estuaries and coastal waters in England and Wales in 1995 (unless otherwise indicated) (TAPS 1995)

Organic compounds monitored as part of the NMP survey were:

PCB; alpha-HCH; beta-HCH; gamma-HCH (lindane); dieldrin; aldrin; endrin; isodrin; HCB; PCP; DDT; HCBD; PAHs; carbon tetrachloride; chloroform; trifluralin; endosulfan; simazine; atrazine; azinphos-methyl; azinphos-ethyl; dichlorvos; fenitrothion; fenthion; malathion; parathion; parathion-methyl; trichloroethylene; tetrachloroethylene; trichlorobenzene; 1,2-dichloroethane and trichloroethane.

However, with the exception of HCH, atrazine, simazine, chloroform, carbon tetrachloride, trichloroethylene, tetrachloroethylene, trichloroethane and PCP, the compounds were found at concentrations below analytical limits of detection. Insufficient positive results were available for analysis and therefore these data were not presented in the NMP report. However, the detection limits used are generally well below the EQS concentrations, indicating low background concentrations in UK marine waters.

Median concentrations of HCH were below the EQS concentration of 20 ng l^-1 at all sites except the Thames at Woolwich. Individual results above EQS were found on the Tay, Ouse, Thames, Tamar, Mersey and Clyde. These elevated results were found in estuaries with either riverine sources (Ouse, Thames and Mersey) or in the vicinity of major urban conurbations which, in some cases, have known discharges (e.g. sewage discharges in the Thames and the combined effects of sewage and industrial discharges to the Clyde).

Generally, concentrations decline moving offshore, although concentrations in the outer Thames estuary off the East Anglian coast and south-eastern Irish Sea are higher than in the English Channel and Irish Sea off Northern Ireland. This may be due to transport of gamma-HCH on suspended particulate material.

The NMP stated that no atrazine and simazine data were available for sites in Scotland, Northern Ireland or offshore sites.

All results for atrazine and simazine were significantly lower than the proposed EQS concentrations (statutory EQS of 2 mg l^-1 (annual average) and a non-statutory EQS of 10mg l^-1 (maximum allowable concentration) as the sum of atrazine and simazine). The highest median concentrations of atrazine and simazine were found in the Humber and Ouse estuaries respectively. Elevated concentrations were also found in the Thames, Tamar, Severn and Mersey, all of which have riverine sources. The ratio of atrazine to simazine was found to vary from estuary to estuary, probably because of variations in rates of application of these herbicides in the catchments.

Concentrations of atrazine and simazine found in this survey are comparable with earlier surveys (MAFF 1993, 1994). However, concentrations found in the NMP survey in the Thames, Tamar and Mersey are at the lower end of the range reported by Evans et al (1993) for surveys carried out in 1991 and 1992. This may be due to reductions in inputs of triazine herbicides to the marine environment resulting from the ban on non-agricultural use during the first year of the NMP survey. Evans et al (1993) stated that peak concentrations were found during periods of highest pesticides use or after rainfall. The timing of the surveys is likely to substantially affect observed estuarine concentrations.

Of the 44 sites with results available, 13 had results in which all values were below the detection limit. Median concentrations of chloroform were below the EQS of 12mg l^-1 at all sites. Only one result (in the Wear estuary) was greater than the EQS. Elevated concentrations were also observed in the Tees and Mersey estuaries, which receive point source discharges of chloroform. The apparent elevated concentrations of chloroform in the Thames estuary, Solway Firth and off the Lune estuary are a consequence of relatively high limits of detection.

Of the 44 sites with results available, 24 sites had results in which all values were below the limits of detection. Median concentrations of carbon tetrachloride at all sites were almost one tenth of the EQS concentration of 12 mg l^-1. Only one result, for a sample collected in the Wear, approached the EQS concentration. However, all North Sea states were obliged to discontinue production, consumption and import by 1 January 1996.

Of the 30 sites with results available, 18 sites had results where all values were below the limits of detection. Median concentrations of trichloroethylene were all below the EQS of 10 mg l^-1. The highest individual concentration was found in the Wear estuary, which receives inputs of trichloroethylene from both river and point source discharges. Positive results were also recorded in the Severn and Mersey estuaries, which receive inputs of trichloroethylene from point source discharges and riverine sources.

Of the 29 sites with results available, 18 had results in which all values were below limits of detection. All results were at most one tenth of the EQS concentration of 10 mg l^-1. The highest median concentration was found in the Wear estuary which receives inputs of tetrachloroethylene. Positive results were recorded in the Humber, Severn and Mersey estuaries, all of which have point sources.

Of the 37 sites surveyed, 18 had results in which all values were below the limit of detection. All results were substantially below the proposed EQS of 100 mg l^-1 (annual average) for 1,1,1, trichloroethane. Positive results were recorded in the Tees, Severn and Mersey estuaries which receive inputs of trichloroethane from industrial point source discharges.

The EQS for PCP is 2,000 ng l^-1. Of the 41 sites with results available, 29 had results in which all values were below the limit of detection. Median results at all sites were at most one tenth of the EQS. The NMP survey found it difficult to comment on spatial variability of PCP because few results above the limit of detection were recorded.

The 10 PAH compounds for which data were considered within this assessment are a subset of those determined. The full data are presented elsewhere (Law et al 1997a).

The highest concentrations generally occur in major estuaries, particularly those of the Humber, Great Ouse, Thames and Tees. PAH concentrations at offshore sites were generally low or undetectable. Of the 39 samples taken at offshore locations (10 miles or more from the coast), only one (NMP station 245 off the River Tyne sampled in 1993) showed a significant concentration of PAH, and this was only for naphthalene (263 ng l^-1). Apart from this sample, PAHs were generally not detected in offshore waters. Higher concentrations were found in coastal and estuarine samples (although not in all), with total PAH concentrations ranging from none detected to 8.5 mg l^-1. Total PAH concentrations greater than 1 mg l^-1 were found at 14 sites, in the estuaries of the Rivers Tees, Humber, Great Ouse, and Thames. Of these 14 sites, 10 were in the lower reaches of the River Tees estuary, and particularly high concentrations were observed in the vicinity of Redcar Jetty. The PAH profile observed in the five samples collected off Redcar Jetty was dominated by two- and three-ring PAHs, probably derived from an adjacent steel plant. The other data probably reflect inputs from a wide range of combustion processes, involving both industrial and domestic sources.

Comparison of samples for which duplicate filtered/ unfiltered concentrations were determined indicated that, for the lower molecular weight PAHs, the major portion was present in the dissolved phase (e.g. samples from the River Tees), while for the higher molecular weight PAHs the major portion was adsorbed onto particles.

While investigation in the NMP survey was only considered a 'pilot' study, the results obtained suggested that concentrations were low or undetectable at intermediate and offshore sites. However, significant concentrations of PAH have been found in a number of estuaries.

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