Atmospheric aerosols alter oceanic activity

Atmospheric aerosols alter oceanic activity Oceans remain a key convergence point where anthropogenic and natural environmental effects can affect climate change and alter food chains. For example, mineral dust, soot, organic molecules, and other microscopic particles can become aerosolized in the atmosphere and provide nutrients and trace metals for phytoplankton in the open ocean. Adina Paytan et al. studied the effects of aerosol deposition on phytoplankton communities found in surface seawater in the Gulf of Aqaba of the northern Red Sea. Aerosols collected from an air-mass source in Europe doubled the amount of chlorophyll in phytoplankton communities in the gulf, including picoeukaryote algae and Synechococcus and Prochlorococcus cyanobacteria. In some experiments, however, aerosols from a Saharan source decreased the chlorophyll content. Both aerosols supplied bioavailable nitrogen and phosphorous, but the Saharan source contained high concentrations of copper, which is most often deposited by human activities and was toxic to the picoeukaryotes and Synechococcus cyanobacteria. The authors suggest that anthropogenic metal emissions into the atmosphere can potentially alter patterns of marine primary production in high aerosol, low chlorophyll areas, such as the Bay of Bengal and downwind of South and East Asia. — F.A.