Copper speciation survey from UK marinas, harbours and estuaries

The use of copper in antifouling paints has increased in the UK in the last 20 years as TBT and several other organic biocides have been phased out. To assess the probable impact of copper on estuarine systems a survey was undertaken to measure the different fractions of copper present in the water column at current usage. The different fractions measured were; labile copper, (LCu) considered as both the free copper ions and inorganically bound copper, the total dissolved copper (TDCu) present, and the difference between them taken as the organically bound likely non-toxic copper fraction. The survey considered sites with different levels of boat use, namely marinas, harbours and estuaries, differing physical parameters of suspended and dissolved organic matter, different seasons of the year and different depths in the water column all of which control speciation behaviour. Suspended particulate matter (SPM) values were measured at all sites and increased from West to East coast locations (5.7-34.4 mg/l). Dissolved organic matter (DOM) values ranged from 0.58 to 2.2mg/l C. The total dissolved copper concentrations ranged from 0.30 to 6.68 microg/l, with labile fraction ranging from 0.02 to 2.69 microg/l, and most labile copper concentrations below 1 microg/l. None of the yearly mean copper measurements exceeded the 76/464/EEC EQS of 5 microg/l. Of the 306 measurements, only one dissolved copper value in one season was above 5 microg/l. This ratio of labile to total copper was between 10 and 30%. The results from this survey suggest that if toxicity of copper is due to the labile fraction then using the total dissolved copper concentrations as an indicator of impact overestimate the risk by a factor of four times.