Volcanic ash fuels anomalous plankton bloom in subarctic northeast Pacific

• Published in: Geophysical research letters Vol. 37; no. 19
• Main Authors: Hamme, Roberta C., Webley, Peter W., Crawford, William R., Whitney, Frank A., DeGrandpre, Michael D., Emerson, Steven R., Eriksen, Charles C., Giesbrecht, Karina E., Gower, Jim F. R., Kavanaugh, Maria T., Peña, M. Angelica, Sabine, Christopher L., Batten, Sonia D., Coogan, Laurence A., Grundle, Damian S., Lockwood, Deirdre
• Format: Journal Article
• Language: English
• Published: Washington, DC Blackwell Publishing Ltd 01.10.2010; American Geophysical Union; John Wiley & Sons, Inc
• Subjects: Ashes; Bacillariophyceae; Biological oceanography; Carbon; Carbon dioxide; carbon export; Chemical oceanography; Deposition; Earth sciences; Earth, ocean, space; Exact sciences and technology; Fertilization; International trade; Iron; iron fertilization; Oceans; Phytoplankton; plankton bloom; subarctic Pacific; Volcanic ash; Volcanic eruptions; Volcanoes; United States; Arctic region; Aleutian Islands; polar regions; Alaska; Pacific Ocean; Northeast Pacific; North Pacific; IN, USA, Alaska, Aleutian Is; IN, North Pacific; Volcanic eruption; Carbon dioxide; algae; North America; greenhouse gas; fluorescence; carbon; pH; phytoplankton; plankton; Polar region; export; Thallophyta; volcanic ash; satellites; fertilization; Space remote sensing; Plantae; chlorophyll; Satellite observation; transport; Subpolar zone; extrapolation; diatoms; iron
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2010GL044629

Using multiple lines of evidence, we demonstrate that volcanic ash deposition in August 2008 initiated one of the largest phytoplankton blooms observed in the subarctic North Pacific. Unusually widespread transport from a volcanic eruption in the Aleutian Islands, Alaska deposited ash over much of the subarctic NE Pacific, followed by large increases in satellite chlorophyll. Surface ocean pCO2, pH, and fluorescence reveal that the bloom started a few days after ashfall. Ship‐based measurements showed increased dominance by diatoms. This evidence points toward fertilization of this normally iron‐limited region by ash, a relatively new mechanism proposed for iron supply to the ocean. The observations do not support other possible mechanisms. Extrapolation of the pCO2 data to the area of the bloom suggests a modest ∼0.01 Pg carbon export from this event, implying that even large‐scale iron fertilization at an optimum time of year is not very efficient at sequestering atmospheric CO2.