Agricultural runoff fuels large phytoplankton blooms in vulnerable areas of the ocean

  title={Agricultural runoff fuels large phytoplankton blooms in vulnerable areas of the ocean},
  author={J. Michael Beman and Kevin R. Arrigo and Pamela A. Matson},
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, large portions of the tropics and subtropics are defined by extreme nitrogen depletion. In these regions, microbial denitrification removes biologically available forms… 
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Anthropogenic nutrient sources rival natural sources on small scales in the coastal waters of the Southern California Bight
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Comparison of natural and anthropogenic nutrient sources in the Southern California Bight
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The results support the hypothesis that aeolian mineral dust deposition promotes nitrogen fixation in the eastern tropical North Atlantic and show that community primary productivity was nitrogen-limited, and that nitrogen fixation was co-limited by iron and phosphorus.
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