Woznicki Sean A, Kraynick George, Wickham James, Nash Maliha, Sohl Terry
Center for Public Health and Assessment, Office of Research and Development, United States Environmental Protection Agency, Research Triangle Park, North Carolina, USA.
City of Minneapolis Department of Public Works, Division of Water Treatment and Distribution Services, Minneapolis, Minnesota, USA.
J Am Water Resour Assoc. 2023 Mar 25;59(4):726-742. doi: 10.1111/1752-1688.13109.
Continued alteration of the nitrogen cycle exposes receiving waters to elevated nitrogen concentrations and forces drinking water treatment services to plan for such increases in the future. We developed four 2011-2050 land cover change scenarios and modeled the impact of projected land cover change on influent water quality to support long-term planning for the Minneapolis Water Treatment Distribution Service (MWTDS) using Soil Water and Assessment Tool. Projected land cover changes based on relatively unconstrained economic growth led to substantial increases in total nitrogen (TN) loads and modest increases in total phosphorus (TP) loads in spring. Changes in sediment, TN, and TP under two "constrained" growth scenarios were near zero or declined modestly. Longitudinal analysis suggested that the extant vegetation along the Mississippi River corridor upstream of the MWTDS may be a sediment (and phosphorus) trap. Autoregressive analysis of current (2008-2017) chemical treatment application rates (mass per water volume processed) and extant (2001-2011) land cover change revealed that statistically significant increases in chemical treatment rates were temporally congruent with urbanization and conversion of pasture to cropland. Using the current trend in chemical treatment application rates and their inferred relationship to extant land cover change as a bellwether, the unconstrained growth scenarios suggest that future land cover may present challenges to the production of potable water for MWTDS.
氮循环的持续变化使受纳水体面临更高的氮浓度，并迫使饮用水处理服务机构为未来此类浓度的增加制定计划。我们制定了四种2011 - 2050年土地覆盖变化情景，并使用土壤水评估工具对预计的土地覆盖变化对进水水质的影响进行建模，以支持明尼阿波利斯水处理配送服务（MWTDS）的长期规划。基于相对不受限制的经济增长预测的土地覆盖变化导致春季总氮（TN）负荷大幅增加，总磷（TP）负荷略有增加。在两种“受限”增长情景下，沉积物、TN和TP的变化接近零或略有下降。纵向分析表明，MWTDS上游密西西比河走廊沿线的现存植被可能是一个沉积物（和磷）陷阱。对当前（2008 - 2017年）化学处理施用量（每处理水量的质量）和现存（2001 - 2011年）土地覆盖变化的自回归分析表明，化学处理率的统计学显著增加在时间上与城市化以及牧场向农田的转变一致。以化学处理施用量的当前趋势及其与现存土地覆盖变化的推断关系作为风向标，不受限制的增长情景表明未来的土地覆盖可能给MWTDS的饮用水生产带来挑战。
