Nitrogen (N) and phosphorus (P) inputs throughout the Mississippi/Atchafalaya River Basin (MARB) have been linked to the Gulf of Mexico hypoxia and water-quality problems throughout the MARB. To describe N and P loading throughout the MARB, SPAtially Referenced Regression On Watershed attributes (SPARROW) models were previously developed based on nutrient inputs and management similar to 1992 and 2002. In this study, refined SPARROW models were developed with higher resolution basin delineation, updated (2012) source inputs, improved calibration (load) targets, and additional statistical techniques than used in the previous SPARROW models. Based on the refined models, consistent with past models, N and P loads/yields were the highest from the central part of the MARB (Corn Belt) and along the Mississippi River. Agricultural activities remained the most important N and P source, but more so for N because its input, which could now be distinguished from atmospheric deposition, could be estimated. Natural loss of P from geologic material throughout the MARB was an important source, contributing about 23% of the total P from the MARB, and resulted in specific areas, such as Kentucky and Tennessee, being larger sources of P than previously estimated. This information can help managers decide where efforts will have the largest effects (highest ranked areas) on reducing nutrient loading to the Gulf hypoxia and what are the most important sources of N and P in these areas.

中文翻译：

---

来自密西西比/阿查法拉亚河流域的氮和磷的来源和输送：使用 2012 年麻雀模型的更新

整个密西西比/阿查法拉亚河流域 (MARB) 的氮 (N) 和磷 (P) 输入与整个 MARB 的墨西哥湾缺氧和水质问题有关。为了描述整个 MARB 中的 N 和 P 负荷，先前基于类似于 1992 和 2002 年的营养输入和管理开发了流域属性空间参考回归模型。 在本研究中，使用更高分辨率的流域划定开发了精细的 SPARROW 模型，更新 (2012) 源输入、改进的校准（负载）目标以及比以前的 SPARROW 模型中使用的更多统计技术。基于改进的模型，与过去的模型一致，来自 MARB（玉米带）中部和密西西比河沿岸的 N 和 P 负荷/产量最高。农业活动仍然是最重要的 N 和 P 来源，但对 N 更是如此，因为现在可以估计其输入，现在可以将其与大气沉降区分开来。整个 MARB 地质材料中磷的自然损失是一个重要的来源，约占 MARB 总磷的 23%，并导致肯塔基州和田纳西州等特定地区成为比先前估计的更大的磷源。这些信息可以帮助管理人员确定哪些努力将对减少海湾缺氧的养分负荷产生最大影响（排名最高的区域），以及这些区域中最重要的 N 和 P 来源是什么。整个 MARB 地质材料中磷的自然损失是一个重要的来源，约占 MARB 总磷的 23%，并导致肯塔基州和田纳西州等特定地区成为比先前估计的更大的磷源。该信息可以帮助管理人员确定哪些努力将对减少海湾缺氧的养分负荷产生最大影响（排名最高的区域）以及这些区域中最重要的 N 和 P 来源是什么。整个 MARB 地质材料中磷的自然损失是一个重要的来源，约占 MARB 总磷的 23%，并导致肯塔基州和田纳西州等特定地区成为比先前估计的更大的磷源。该信息可以帮助管理人员确定哪些努力将对减少海湾缺氧的养分负荷产生最大影响（排名最高的区域）以及这些区域中最重要的 N 和 P 来源是什么。