Proc. Natl Acad. Sci. USA doi.10.1073/pnas.0811486106 (2009)

Atmospheric aerosols, which supply ocean phytoplankton with nutrients such as nitrates and iron, can have toxic effects too.

Adina Paytan at the University of California, Santa Cruz, and her colleagues found that some species of phytoplankton in Red Sea surface waters suffered when exposed to aerosol samples collected from the Sahara Desert in Africa, whereas they thrived on European aerosols. Copper may be to blame: it was present at much higher levels in African aerosols and can be toxic to phytoplankton.

Although desert dust supplies about two-thirds of atmospheric copper, human industrial emissions of the element are increasing rapidly. The researchers suggest that copper deposition could alter marine ecosystems by damaging phytoplankton in high-aerosol areas such as those downwind of industrial regions of south and east Asia.