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Abstract There is limited information on how the nutrient and freshwater input affects water column carbonate chemistry in the estuaries along the northern Gulf of Mexico. In this study, we assess the seasonal and spatial variability in carbonate chemistry in the Barataria Basin, a eutrophic estuary adjacent to the mouth of the Mississippi River. Eleven stations were sampled along a salinity gradient during the winter (January), spring (April), summer (July), and fall (October) of 2021. Surface and bottom water samples were collected for the analyses of dissolved inorganic carbon (DIC); total alkalinity (TA); and nitrite plus nitrate (NO₂ + NO₃), phosphate (PO₄), and dissolved silica (SiO₄). Dissolved CO₂(pCO₂) was measured in the surface water. Seasonal surface DIC and TA values ranged from 1553 to 2582 μmol kg⁻¹and 1217 to 2217 μmol kg⁻¹, respectively. DIC and TA varied seasonally and showed an increasing trend from fresh stations to saline stations. The highest DIC and TA values were observed during the fall season, likely due to the increased contribution of DIC and TA from adjacent marshes as a result of enhanced porewater exchange. In contrast to DIC and TA, pCO₂decreased with the increase of salinity. The seasonal and spatial patterns in carbonate chemistry could not be explained solely by physical mixing and reflected complex interactions between biogeochemical processes driven by nutrient supply and temperature as well as tidal flushing and material exchanges with adjacent marshes. 

As the need for more broad-scale solutions to environmental problems is increasingly recognized, traditional hierarchical, government-led models of coordination are being supplemented by or transformed into more collaborative inter-organizational networks (i.e., collaboratives, coalitions, partnerships). As diffuse networks, such regional environmental planning and design (REPD) efforts often face challenges in sharing and using spatial and other types of information. Recent advances in semantic knowledge management technologies, such as knowledge graphs, have the potential to address these challenges. In this paper, we first describe the information needs of three multi-stakeholder REPD initiatives in the western USA using a list of 80 need-to-know questions and concerns. The top needs expressed were for help in tracking the participants, institutions, and information products relevant to the REDP’s focus. To address these needs, we developed a prototype knowledge graph based on RDF and GeoSPARQL standards. This semantic approach provided a more flexible data structure than traditional relational databases and also functionality to query information across different providers; however, the lack of semantic data expertise, the complexity of existing software solutions, and limited online hosting options are significant barriers to adoption. These same barriers are more acute for geospatial data, which also faces the added challenge of maintaining and synchronizing both semantic and traditional geospatial datastores.