71. A number of samples exceed the Cefas Action Level 1 for concentrations of arsenic, chromiumand nickel with only one sample exceeding Cefas Action Level 1 for copper (Table 8.10). There was one exceedance of Action Level 2 for concentrations of arsenic recorded at station 30, however, this was the only station to exceed the Action Level 2 within the East Anglia THREE site. The majority of samples that have exceeded Cefas Action Levels 1 and 2 have done so only marginally, with those exceeding Action Level 1 remaining well below Action Level 2.
72.
Similarly, a number of samples exceed the TEL for concentrations of arsenic, chromiumand copper, with one sample also exceeding the TEL for zinc (Table 8.11). Samples from stations 43, 50 and 52 exceed the PEL for arsenic, with concentrations at station 30 also exceeding the PEL by a high amount. However, the majority of samples only marginally exceeded the TEL and PEL values.
73.
Overall, only one sample (station 30) exceeded Cefas Action Level 2 and four samples (stations 30, 43, 50, 52) exceeded TEL values for arsenic concentrations. The elevated levels of arsenic which were recorded are typical of the region and are associated with a history of arsenic waste disposal, estuarine and geological inputs and sea bed rock weathering (Royal Haskoning 2011).
74.
Station 49 is the only offshore sampling site within the East Anglia THREE site itself. At this station contamination levels are very low, with concentrations of all metals below Cefas Action Level 1 and Canadian Sediment Quality Guideline TEL values. Concentrations of Acenaphthene and Napthalene marginally exceed Cefas Action Level 1 at station 49; however, both results were well below Action Level 2.
75.
Concentrations of chromiumat station 54 exceed the PEL (Table 8.11) however it should be recognised that these concentrations do not exceed the Cefas action level 2 (Table 8.10). Levels of three PAHs were also recorded above the TELs, but none were above the PELs.
76. Detectable amounts of cadmium, mercury and lead were also recorded throughout the stations but all levels were below both the TEL and Cefas Action Level 1. Cadmiumlevels were below detectable levels for less than half of the stations and mercury was recorded at all but two stations, all of which were below both the TEL and Cefas Action Level 1. Levels of PCBs were below detectable levels at all stations.
77.
From the information and data presented above it can be concluded that baseline water and sediment quality of the study areas is generally good and site specific information in relation to concentrations of contaminants in sediments does not record significantly elevated levels.
Preliminary Environmental Information May 2014
East Anglia THREE Offshore Windfarm
Chapter 8 Marine Water and Sediment Quality Page 26
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