In Denmark, eutrophication of coastal areas is one of the major challenges in meeting the requirements from the European Water Framework Directive (WFD). This eutrophication is mainly a cause of excessive nitrogen loads from agricultural production, which can be reduced by implementing abatement measures. The cost-effectiveness of a land use policy may vary depending on the abatement measures used and where they are implemented. Taking account of the spatial heterogeneity of costs and effects in the choice of abatement measures significantly reduces the cost of meeting WFD targets. Targeting of regulation to identify least cost options to reduce nitrogen has for many years focused on agricultural abatement measures. However, the marginal costs of reductions in agriculture have now increased to an extent, where it has become relevant also to reconsider other sectors. We set out to compare nitrogen abatement measures across agriculture and waste water treatment at a national level, acknowledging heterogeneity in marginal costs across spatial location as well as differences in reduction requirements across catchments. In the analysis, we combine data on costs and effects of abatement measures at a fine spatial scale to estimate marginal costs within the two sectors at a national level for Denmark. The model minimizes the costs of meeting the specific required nitrogen load reduction targets for all catchments and finds the composition and spatial location of the optimal abatement effort. We find that waste water treatment abatement measures are only relevant in two coastal catchments, where they mainly serve as a supplement due to insufficient potential for agricultural land in rotation to provide all the N load reductions. Furthermore, we find that the pressure on agricultural land to reduce nutrient loads is very high in some catchments, implying that abatement measures such as land retirement where abatement costs are high enters the optimal solution due to their high level of effectiveness. Recommendations and average costs vary across catchments, indicating that results are not easily translated to generic national-level policy design.

在丹麦，沿海地区的富营养化是满足欧洲水框架指令 (WFD) 要求的主要挑战之一。这种富营养化主要是农业生产中氮负荷过高的原因，可以通过实施减排措施来减少这种情况。土地使用政策的成本效益可能因所采用的减排措施及其实施地点而异。在选择减排措施时考虑成本和影响的空间异质性，可显着降低实现 WFD 目标的成本。多年来，旨在确定降低氮含量的最低成本选择的监管目标一直集中在农业减排措施上。然而，农业减少的边际成本现在已经增加到一定程度，也需要重新考虑其他部门。我们着手在国家层面比较农业和废水​​处理的氮减排措施，承认不同空间位置的边际成本的异质性以及不同流域的减排要求的差异。在分析中，我们结合了精细空间尺度上减排措施的成本和效果数据，以估计丹麦国家层面这两个部门的边际成本。该模型最大限度地降低了满足所有流域所需的特定氮负荷减少目标的成本，并找到了最佳减排努力的组成和空间位置。我们发现废水处理减排措施仅与两个沿海集水区相关，由于轮作农业用地的潜力不足以提供所有 N 负荷减少，因此它们主要用作补充。此外，我们发现在某些流域，农业用地减少养分负荷的压力非常大，这意味着减排措施（如减排成本高的土地退休）由于其高效率而成为最佳解决方案。建议和平均成本因流域而异，表明结果不容易转化为通用的国家级政策设计。这意味着减排措施，如减排成本高的土地退休，由于其高效率而成为最佳解决方案。建议和平均成本因流域而异，表明结果不容易转化为通用的国家级政策设计。这意味着减排措施，如减排成本高的土地退休，由于其高效率而成为最佳解决方案。建议和平均成本因流域而异，表明结果不容易转化为通用的国家级政策设计。