Pete, Graham, and I have just published a paper on validating the proposed EQS for nickel by a comparison against field evidence from the UK.

This work looked at the effect of nickel on benthic macroinvertebrate communities, and various subsets of the community (mayflies, stoneflies, caddisflies, and snails). We found that compliance with the proposed EQS would not limit the ability of these kinds of aquatic communities to achieve good ecological status as it is determined by environmental regulators.

Whilst there might be no observable effect on the overall community when the EQS is complied with, there is the concern that particularly sensitive members of the community could be affected. In order to address this concern we performed similar assessments on mayflies, stoneflies, caddisflies, and snails. Mayflies, stoneflies, and caddisflies are often considered to be relatively sensitive to the effects of metals, although they may also be sensitive to a variety of other stressors, such as sewage pollution and habitat degradation. Some snails have been found to be particularly sensitive to nickel in laboratory tests, and our analyses confirmed that they are likely to be the most sensitive members of these aquatic communities.

We found that compliance with the proposed EQS of 4 μg l-1 “bioavailable nickel” is highly unlikely to cause an observable impact on snail communities. The thresholds that we derived were calculated in the presence of a variety of other contaminants, and demonstrate that the proposed EQS for nickel is protective in the presence of the mixtures of contaminants which are found in real field situations. The paper has been published in Environmental Science and Pollution Research and can be found here:

http://link.springer.com/article/10.1007/s11356-013-1851-2#