School of Forest Resources, University of Washington, Seattle, Washington 98115-2100, USA.
Ecol Appl. 2010 Sep;20(6):1542-55. doi: 10.1890/08-0680.1.
In 2008, the hypoxic zone in the Gulf of Mexico, measuring 20 720 km2, was one of the two largest reported since measurement of the zone began in 1985. The extent of the hypoxic zone is related to nitrogen and phosphorous loadings originating on agricultural fields in the upper Midwest. This study combines the tools of evolutionary computation with a water quality model and cost data to develop a trade-off frontier for the Upper Mississippi River Basin specifying the least cost of achieving nutrient reductions and the location of the agricultural conservation practices needed. The frontier allows policymakers and stakeholders to explicitly see the trade-offs between cost and nutrient reductions. For example, the cost of reducing annual nitrate-N loadings by 30% is estimated to be US$1.4 billion/year, with a concomitant 36% reduction in P and the cost of reducing annual P loadings by 30% is estimated to be US$370 million/year, with a concomitant 9% reduction in nitrate-N.
2008 年，墨西哥湾缺氧区的面积达到了 20720 平方公里，是自 1985 年开始对该区域进行测量以来报告的两个最大缺氧区之一。缺氧区的范围与源自美国中西部上游农田的氮和磷负荷有关。本研究将进化计算工具与水质模型和成本数据相结合，为密西西比河流域上游制定了一个权衡前沿，以确定实现养分减少的最低成本和所需的农业保护措施的位置。该前沿使政策制定者和利益相关者能够明确看到成本和养分减少之间的权衡。例如，估计每年减少 30%硝酸盐-N 负荷的成本为 14 亿美元/年，同时磷减少 36%；每年减少 30%磷负荷的成本估计为 3.7 亿美元/年，同时硝酸盐-N 减少 9%。
