Managing nitrogen deposition: Leveraging NERC science for better pollution policy.

Fossil fuel burning and intensive agriculture lead to air pollution in the form of reactive compounds of nitrogen (N) which cause impacts on the environment and human health. Nitrogen deposition has been estimated to cost the economy of the European Union E70-320 Billion per year. Managing this threat is a key challenge to regulatory organisations such as the Scottish Environment Protection Agency (SEPA). To permit new polluting activities SEPA is required to determine whether it is beyond reasonable scientific doubt that a proposed pollution source will have no adverse effect on conservation priority sites. SEPA's decisions must be robust and defensible but establishing whether a new development will have any adverse effect is often difficult. Modelling tools for assessing potential exposure to N deposition are well-established but tools for assessing ecological response to this loading are known to be simplistic. Nevertheless, difficult decisions need to be made: if new pollution sources are inappropriately permitted they may lead to loss of biodiversity and ecosystem services but if new pollution sources are inappropriately refused this may cause unnecessary economic harm. With SEPA currently undertaking a broad review of air pollution policy now is an ideal time to assess how recent scientific advances can be applied in practise to produce a more robust pollution permitting process. This proposal focuses on three areas where there is the potential for recent NERC-funded science to have a transformative impact on SEPA's policies and procedures:

1) Meaningful metrics of nitrogen deposition. SEPA's current approach to managing N is based on steady state principles but there is widespread acknowledgement that ecological impacts actually reflect the long-term history of pollution exposure. Current metrics may lead to inappropriate decisions but alternative metrics have not been available. This project will combine new N deposition modelling results with national vegetation datasets to develop metrics which realistically reflect the levels and periods of N deposition which matter to plants.
2) Vegetation-based screening thresholds. SEPA's current approach to assessing impacts from N deposition assumes that impacts develop gradually however recent research has demonstrated the presence of threshold responses. If these thresholds can be robustly characterised it may be possible to use them as a screening tool to permit new nitrogen sources in locations where they are unlikely to do harm but not in situations where they may have disproportionate impacts. This project will use recently-developed threshold-detection techniques to quantify thresholds in vegetation datasets, test their robustness and explore how they can be incorporated in existing processes.
3) Modelled baselines for N deposition assessment. SEPA's current approach does not fully accommodate pre-existing N deposition impacts on habitats prior to a new emissions source being permitted. A recently-developed modelling framework may allow quantification of pre-existing harm from N deposition allowing initial screening of sites prior to more detailed assessment and allowing SEPA to better target their resources.

For each of these proposed tools and metrics we will conduct rigorous testing to establish their robustness. We will work with key actors in SEPA and outside organisations to establish how each tool could be incorporated into the existing permitting framework and the advantages and disadvantages relative to current approaches. We will use case studies of previous permit applications to assess whether such tools would have led to different decision making and will thoroughly evaluate these cases. We believe that by building on the latest science there is the possibility to develop pollution policy which is more robust, more defensible and which better achieves its goals.