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Analysis of Autonomous Seawater pH Data and Instrument Calibration Verification Method

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Title:Analysis of Autonomous Seawater pH Data and Instrument Calibration Verification Method
Authors:Wadnal, Eric
Contributors:De Carlo, Eric (advisor)
Oceanography (department)
Global Environmental Science (department)
Keywords:ocean acidification
climate change
method development
Date Issued:2016
Publisher:University of Hawaiʻi at Mānoa
Place of Publication:Honolulu
Abstract:Recently ocean acidification (OA) has received increased attention from scientists
due to its potential adverse effects on marine ecosystems, so obtaining an accurate and
precise pH measurement in the coastal ocean is critical. This project aims to obtain the
most precise pH measurements possible using a pH spectrophotometer, and will use these
measurements to correct time series data collected by three PMEL MAPCO2 buoys
around Oahu and determine the data’s reliability. Two of the buoys are located on
fringing reefs of the south shore and one on the barrier reef in Kaneohe Bay. Other
parameters with time series data are then used to analyze influences on the coastal pH
around Oahu. For each buoy location, bottle samples were collected in situ at times
corresponding to when the SeaFET, a pH instrument attached to the buoy, is programmed
to measure pH. Bottle data were used to calibrate the time series data collected by the
SeaFET. Spectrophotometrically measured pH differed from the SeaFET measurements
by a small, yet significant value.
Analysis of the data shows positive correlations between pH and dissolved
oxygen at both south shore buoys, as well as a less well defined relationship with
chlorophyll and turbidity. There are also clear diel cycles in pH due to photosynthesis,
and seasonal changes in the times at which pH peaks each day. The pH data collected at
each of the three locations can be considered reliable based on the spectrophotometric
measurements, and each of the three locations isa influenced by slightly varying factors.
Pages/Duration:48 pages
Rights:All UHM dissertations and theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission from the copyright owner.
Rights Holder:Wadnal, Eric
Appears in Collections: Global Environmental Science Theses

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