Alkalinity and Buffering in Estuarine, Coastal and Shelf Waters

• Main Author: Hunt, Christopher
• Format: Text
• Language: unknown
• Published: University of New Hampshire Scholars' Repository 2021
• Subjects: acidification; alkalinity; buffering; Ocean acidification
• Online Access: https://scholars.unh.edu/dissertation/2623; https://scholars.unh.edu/cgi/viewcontent.cgi?article=3622&context=dissertation

As anthropogenic climate change continues to elevate the amount of carbon dioxide (CO2) in the Earth’s atmosphere, the absorption of a large portion of this CO2 by Earth’s oceans has resulted in a steady decrease in pH. The consequent phenomenon of ocean acidification (OA) is a result of shifts in the carbonate chemistry system of the ocean- a system which can be analytically described by several factors, including total alkalinity (TA). TA in the oceans has been measured for over a century, but analytical and operational constraints have limited these measurements in time and space. Additionally, recent work has highlighted gaps in our knowledge of the species which collectively comprise TA. This dissertation describes efforts to examine TA through several novel applications: by deploying an automated TA analyzer aboard a survey vessel to map East Coast USA TA distributions, using the same analyzer in a long-term fixed coastal location to build a timeseries and examine seasonal biogeochemical dynamics, and measuring the concentrations and properties of the poorly understood organic component of TA in two Gulf of Maine estuaries. East Coast regional distributions of salinity (S) and TA generally agreed with prior findings, but linear TA:S regressions varied markedly over time and deviated from previously developed models. This variability is likely due to a combination of biological, seasonal, and episodic influences and indicates that substantial errors of ±10-20 μmol kg−1 in TA estimation from S can be expected due to these factors. This finding has likely implications for numerical ecosystem modeling and inorganic carbon system calculations. New results presented in Chapter 1 provide refined surface TA:S relationships, present more data in space and time, and improve TA modeling uncertainty. Coastal timeseries observations were collected hourly over 28 months representing all seasons between May 2016 and December 2019. Results presented in Chapter 2 indicated that endmember mixing explained most of the ...