Organic alkalinity data from estuary transects in Coastal Gulf of Maine (Pleasant, Maine; St. John, New Brunswick) in May and October of 2018 and 2019

Four organic alkalinity estuary transects, in May and October of 2018 and 2019, were completed in the Pleasant (Maine, USA) and St. John (New Brunswick, Canada) estuaries. Discrete samples were collected at intervals of salinity along each estuary. An underway measurements system was also operated during each transect (see "Related Datasets" section). Discrete samples were analyzed via a number of methods described below. Underway measurements were collected using the procedures described in Hunt et al. (2013).

Organic alkalinity is a poorly understood component of the estuarine and coastal ocean acid-base system. This lack of understanding makes assessment of ocean acidification vulnerability and inorganic carbon dynamics more difficult. However, the methods used to quantify organic alkalinity and its effects on the acid-base system are not standardized. In this work we examined several approaches for the measurement of organic alkalinity, and their application to inorganic carbon dynamics.