An Acidic Bottom Feature associated with Wilkinson's Basin in the Gulf of Maine.
Joseph G. Kunkel, University of New England and UMass Amherst.
RARGOM 2014 Meeting, Boston University, September 30, 2014. Poster.

Niskin Bottle samples were taken by staff of the NOAA Ship H.B. Bigelow at the top and bottom of the water column on the NOAA NMFS Groundfish Survey of Fall 2008 and Spring 2009. Based on analysis of the bottom/top samples from Fall 2008 more extensive sampling was authorized for Spring 2009 when samples were taken routinely at all CTD locations when there was no Bongo deployment planned in legs 2-5. In addition 11 Seabird Carousel deployments were made consisting of vertical transects of up to 12 Niskin Bottle samples from bottom to top of the water column associated with features of interest, including the Hudson Canyon, Nantucket Shoals, Wilkinson's Basin and Gulf of Maine, Northeast Channel Gulf of Maine. The 11 vertical transects show some of the typical acidic top zone and acidic bottom zone in several of the transects. Of particular note, the transects around the Hudson Canyon identified it has an acidic bottom feature. The two transects of Wilkinson's Basin indicated a decline in pH to a low pH consistent with the more numerous top and bottom samples which indicate the Wilkinson's Basin acidic bottom extends southward through the Great South Channel. The acidic nature of Wilkinson's Basin was originally indicated in samples from Fall 2008 and substantiated by Spring 2009 samples. Of particular interest, the pattern of bottom pHs were reflected in the top samples routinely taken from the ships laboratory-surface-water sampling inlet. The Wilkinson's Basin anomalous feature is also reflected in data analyzed by NOAA researchers reporting in the recent NERACOOS NE-Can Ocean Acidification Webinars.

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