ALT Marsh, with interconnected islands and channels, as seen from above. Credit: Georgia Department of Natural Resources
ALT 9 panel plot showing how estimates of GPP (upper row), ER (middle row), and NEP (bottom row) differ between rates estimated from DIC (x axis) or DO (y axis) across three river sites. GPP and ER from DO is higher than that from DIC at most sites, with PQs ranging from 1.45-1.95 and RQs ranging from 0.8-1.5.
ALT Fig 1: "A conceptual diagram showing biogeochemical cycling of CO2 and DO (O2) in alkaline rivers. CO2 is one of the components in the total DIC pool, while HCO3- accounts for the majority under most conditions. Due to the DIC speciation, CO2 saturation gradient and air–water fluxes are less than those of DO. DIC is used to accurately compute carbon mass balances. In the simplest possible scenario, ecosystem-level photosynthetic and respiration quotients (PQE and RQE) stoichiometrically link changes in DIC and DO. Aqueous CO2 and its hydrated form H2CO3 are not differentiated, and are combined as CO2. Bubbles in the figure only represent the relative magnitude of gas flux and do not indicate the formation of bubbles. DIC, dissolved inorganic carbon; DO, dissolved oxygen."
ALT Three panels illustrating the relationship between NEP (x axis) and CO2 emissions (y axis) for three sites and DO versus DIC metabolism models. CO2 emissions are higher when NEP is lower for all three sites when using the DIC model; there is only a relationship between NEP and CO2 for the DO at one of three sites.
ALT Announcement of "The Society for Freshwater Science 2024 SFS Fellows" with the SFS logo in the upper right corner. The announcement: "2024 SFS Fellow "Dr. Robert Hall "Flathead Lake Biological Station "University of Montana" On the right of the announcement is a photo of Dr. Hall.
ALT TOC image from the article
ALT How are Arctic Ocean carbon cycling processes changing in a warming climate? Three sampling transects in the Arctic capture different water masses entering and exiting the Arctic. We expect to measure differences in the dissolved organic matter chemistry at molecular level to characterize the marine changes with increased terrestrial inputs from Arctic rivers as temperatures rise and sea ice declines. Come work with collaborators across the US and in Europe to learn more and get involved with Arctic Ocean research!
ALT How are carbon cycling patterns in the Upper Clark Fork River changing in response to large restoration efforts to remove metal-laden sediments? River samples were collected throughout the year to monitor ecosystem health since 2017. We expect to measure differences in the dissolved organic matter chemistry to characterize signals of ecosystem health since restoration began in 2013. We ask: are metals complexing with dissolved organic molecules in ways that affect metabolism at the microscopic level? Will that influence energy dynamics up the trophic levels? Come work with collaborators in Montana and across the US to find out!
ALT A composite image from the article showing a smiling researchers standing on a bank of long grass next to three units capable of measuring the alkalinity of water autonomously. Shown as insets (from right to left) are images of a lone unit as well as clustered units submerged in water, and a graph highlighting the unit's operation over the course of months.
