Sabo Robert D, Clark Christopher M, Compton Jana E
Center for Public Health and Environmental Assessment, Office of Research and Development, U.S. Environmental Protection Agency, Washington, D.C., United States of America.
Center for Public Health and Environmental Assessment, Office of Research and Development, U.S. Environmental Protection Agency, Corvallis, OR, United States of America.
Environ Res Commun. 2021 Apr 16;3:1-13. doi: 10.1088/2515-7620/abf296.
Ongoing water quality degradation tied to nitrogen and phosphorus pollution results in significant economic damages by diminishing the recreational value of surface water and compromising fisheries. Progress in decreasing nitrogen and phosphorus pollution to surface water over the past two decades has been slow. Limited resources need to be leveraged efficiently and effectively to prioritize watersheds for restoration. Leveraging recent nitrogen and phosphorus inventories for the years 2002, 2007, and 2012, we extracted relevant flux and demand terms to help identify US subbasins that are likely contributing a disproportionate amount of point and non-point source nutrient pollution to surface water by exploring the mean spatial distribution of terrestrial anthropogenic surplus, agricultural surplus, agricultural nutrient use efficiency, and point source loads. A small proportion of the landscape, <25% of subbasin area of the United States, contains 50% of anthropogenic and agriculture nitrogen and phosphorus surplus while only 2% of landscape contributes >50% of point source loads into surface water. Point source loads are mainly concentrated in urban areas across the country with point source loading rates often exceeding >10.0 kg N ha yr and >1.0 kg P ha yr. However, the ability for future upgrades to wastewater treatment plant infrastructure alone is unlikely to drive further improvement in water quality, outside of local water ways, since point source loads only account for ~4% of anthropogenic N and P surplus. As such, further progress in boosting nutrient use efficiency in agricultural production, usually lowest in areas of intensive livestock production, would likely contribute to the biggest gains to water quality restoration goals. This analysis and the corresponding database integrate multiple streams of information to highlight areas where N and P are being managed inefficiently to give decision makers a succinct platform to identify likely areas and sources of water quality degradation.
与氮磷污染相关的持续水质退化,通过降低地表水的娱乐价值和损害渔业,造成了重大经济损失。在过去二十年里,减少地表水氮磷污染的进展一直缓慢。需要有效利用有限资源,对流域恢复工作进行优先排序。利用2002年、2007年和2012年最新的氮磷清单,我们提取了相关通量和需求项,通过探索陆地人为过剩、农业过剩、农业养分利用效率和点源负荷的平均空间分布,来帮助识别美国可能对地表水造成不成比例的点源和非点源养分污染的子流域。一小部分景观,即美国子流域面积的不到25%,包含了50%的人为和农业氮磷过剩,而只有2%的景观贡献了超过50%的点源负荷进入地表水。点源负荷主要集中在全国的城市地区,点源负荷率通常超过10.0千克氮/公顷·年和1.0千克磷/公顷·年。然而,仅靠未来升级污水处理厂基础设施,不太可能推动局部水道以外的水质进一步改善,因为点源负荷仅占人为氮磷过剩的约4%。因此,提高农业生产中养分利用效率(通常在集约化畜牧生产地区最低)的进一步进展,可能对实现水质恢复目标有最大帮助。该分析和相应数据库整合了多方面信息,以突出氮磷管理效率低下的地区,为决策者提供一个简洁的平台,以识别可能导致水质退化的区域和源头。