Agricultural runoff fuels large phytoplankton blooms in vulnerable areas of the ocean
Agricultural runoff fuels large phytoplankton blooms in vulnerable areas of the ocean
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DOI：
10.1038/nature03370
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发表时间：
2005-03-10
期刊：
影响因子：
64.8
通讯作者：
Matson, PA
中科院分区：
文献类型：
--
作者：
Beman, JM;Arrigo, KR;Matson, PA
世界上大多数海洋的生物生产力受向地表水供应营养物质的控制。营养物质(包括氮、铁和磷)的供应和去除之间的相对平衡决定了哪些营养物质限制了浮游植物的生长。尽管氮限制了大部分海洋的生产力(1，2)，但热带和亚热带的很大一部分地区是由极端的氮消耗来定义的。在这些地区，微生物反硝化作用从水柱中去除生物可利用的氮素，造成相对于其他营养物质的大量短缺(3-5)。在这里，我们证明热带和亚热带海洋的缺氮地区极易受到氮污染的影响。尽管自然营养浓度和生产力很高(6-8)，但富含氮的农业径流为加利福尼亚州海湾的大量浮游植物提供了燃料(54-577公里(2))。径流对生物过程产生强烈和持续的影响，在80%的情况下，在农田施肥和灌溉后的几天内刺激了水华。我们预计，到2050年，27%-59%的氮肥将用于缺氮海洋生态系统上游的发展中地区。我们的发现突出了这些生态系统目前和未来对农业径流的脆弱性。
Biological productivity in most of the world's oceans is controlled by the supply of nutrients to surface waters. The relative balance between supply and removal of nutrients - including nitrogen, iron and phosphorus - determines which nutrient limits phytoplankton growth. Although nitrogen limits productivity in much of the ocean(1,2), large portions of the tropics and subtropics are defined by extreme nitrogen depletion. In these regions, microbial denitrification removes biologically available forms of nitrogen from the water column, producing substantial deficits relative to other nutrients(3-5). Here we demonstrate that nitrogen-deficient areas of the tropical and subtropical oceans are acutely vulnerable to nitrogen pollution. Despite naturally high nutrient concentrations and productivity(6-8), nitrogen-rich agricultural runoff fuels large (54 - 577 km(2)) phytoplankton blooms in the Gulf of California. Runoff exerts a strong and consistent influence on biological processes, in 80% of cases stimulating blooms within days of fertilization and irrigation of agricultural fields. We project that by the year 2050, 27 - 59% of all nitrogen fertilizer will be applied in developing regions located upstream of nitrogen-deficient marine ecosystems. Our findings highlight the present and future vulnerability of these ecosystems to agricultural runoff.