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

化石燃料燃烧和集约化农业导致以活性氮化合物(N)形式存在的空气污染，对环境和人类健康造成影响。据估计，氮沉积每年给欧洲联盟的经济造成700-3200亿欧元的损失。应对这一威胁是苏格兰环境保护局(SEPA)等监管机构面临的关键挑战。为了允许新的污染活动，环保总局需要确定拟议的污染源是否在合理的科学怀疑范围内不会对保护优先地点产生不利影响。国家环保总局的决定必须是可靠的和可辩护的，但要确定一个新的发展是否会产生任何不利影响往往是困难的。用于评估潜在的氮沉积暴露的建模工具是成熟的，但用于评估对这种负荷的生态反应的工具已知过于简单化。然而，需要做出艰难的决定：如果不适当地允许新的污染源，它们可能导致生物多样性和生态系统服务的损失，但如果不适当地拒绝新的污染源，这可能会造成不必要的经济损害。由于国家环保总局目前正在对空气污染政策进行广泛审查，现在是评估如何将最近的科学进步应用于实践以产生更强有力的污染许可过程的理想时机。这项建议侧重于最近NERC资助的科学有可能对国家环保总局的政策和程序产生变革性影响的三个领域：1)有意义的氮沉积指标。国家环保总局目前管理氮的方法是基于稳态原则，但人们普遍承认，生态影响实际上反映了污染暴露的长期历史。当前的指标可能会导致不适当的决策，但尚未有替代指标可用。该项目将把新的氮沉积模拟结果与国家植被数据集结合起来，开发出真实反映对植物有影响的氮沉积水平和时期的指标。2)基于植被的筛选阈值。国家环保总局目前评估氮沉积影响的方法假定影响是逐步发展的，然而，最近的研究表明存在阈值反应。如果能够很好地确定这些阈值的特征，就有可能将其作为一种筛选工具，允许在不太可能造成危害的地点使用新的氮源，但不允许在可能产生不成比例影响的情况下使用。该项目将使用最近开发的阈值检测技术来量化植被数据集中的阈值，测试其稳健性，并探索如何将其纳入现有过程。3)氮素沉积评估的基线模型化。国家环保总局目前的办法不能完全适应在新的排放源获得许可之前对栖息地造成的预先存在的氮沉积影响。最近开发的建模框架可以量化氮沉积造成的先前存在的危害，允许在进行更详细的评估之前对地点进行初步筛选，并允许国家环保总局更好地确定其资源目标。对于这些建议的工具和指标中的每一个，我们都将进行严格的测试，以确定其健壮性。我们将与国家环保总局和外部组织的主要行为者合作，确定如何将每个工具纳入现有的许可框架，以及相对于当前方法的优势和劣势。我们将使用以前许可证申请的案例研究来评估这些工具是否会导致不同的决策，并将彻底评估这些案例。我们相信，通过建立在最新科学的基础上，有可能制定出更强有力、更具防御性和更好地实现其目标的污染政策。

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.