Analytical performance during ratiometric long-term imaging of pH in bioturbated sediments

• In this study, the long-term analytical performance of a high-resolution ratiometric imaging sensor for pH was quantitatively determined The sensor was applied in an experimental microcosm to Illustrate biogeochemical consequences from mining activities by the chemosymbiotic bivalve Thyasira sarsi. Utilizing time-correlated pixel-by-pixel calibration protocols during imaging, close 10 90% of the pixels were associated with a precision (S D) of <0.05 pH units at the end of an experimental period of 17 days For comparison, a precision of <0 05 pH units was achieved for less than 50% of the pixels throughout experiments using conventional pre-sample calibration procedures. The average standard deviation of pixels was 001 pH units. Image analysis of single pixel derivatives and pH measurements over time suggested that T. sarsi affect pH distributions and general sediment geochemistry more than would be expected based on the small size of the bivalves. A significant decrease of pH in the overlying water suggested a considerable release of reduced compounds from the exhalent stream of the thyasirids. Strong pH gradients were demonstrated not only across the sediment-water interface but, also associated with bioturbation activities immediately adjacent to T. sarsi burrowing tracts, inhalant tubes and pedal tracts in the sediment maim. Gradients of up to 1 16 pH units per mm were observed. (C) 2010 Elsevier B V All rights reserved

Ämnesord

NATURVETENSKAP  -- Kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences (hsv//eng)

Nyckelord

pH optode

Fluorescence imaging

Thyasira sarsi

Bioturbation

BY-PIXEL CALIBRATION

MARINE-SEDIMENTS

GULLMAR FJORD

FLUOROSENSOR

SENSOR

PROBE

WATER

DISTRIBUTIONS

OXIDATION

TURNOVER

Publikations- och innehållstyp

ref (ämneskategori)

art (ämneskategori)