Compilation of continuous water quality monitoring data from National Estuary Program estuaries and assessment with consideration for carbonate chemistry dynamics
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Estuaries provide a link between riverine and coastal waters while serving as dynamic environments of economic, ecologic, and recreation importance. They provide habitat for organisms, are of significant ecological and economic importance, and often include calcifying organisms such as clams, oysters, crabs, and lobsters. This importance creates a vulnerability to anthropogenic stressors and places an emphasis on monitoring water quality at sufficiently high temporal resolution to observe system health. Throughout the U.S. EPA National Estuary Program (NEP), nationally significant estuaries that are threatened by pollution, development, or overuse are monitored for conditions to inform management and protection. This includes a suite of water quality monitoring stations to observe water temperature, salinity, pH, and DO. Furthermore, some NEPs deploy sensors to continuously measure additional parameters such as the partial pressure of carbon dioxide (pCO2) or collect discrete water samples for total dissolved inorganic carbon (DIC) or alkalinity measurements. These additional measurements can be used to calculate the full carbonate system including the saturation states of calcite and aragonite (¿Ar). These saturation states provide information on whether water conditions favor the formation or dissolution of calcium carbonate, a key proxy for calcifying organisms health. The goals of this study are to: (1) compile over 10 million individual observations of monitoring data from 14 NEP estuaries within the Atlantic, Gulf, and Pacific coasts, (2) calculate the full carbonate system and saturation states, where possible, and (3) assess the time series of calculated carbonate saturation states against the water quality standards of pH and DO for each estuary.