Award: OCE-1841092

Project Outcomes Report Award Number: 1841092 Project Title: EAGER: Development of a Prototype Sensor Package to Quantify In-Situ Rates of Aquatic Carbon Cycling Processes PI: Collin Ward, Woods Hole Oceanographic Institution The principal objective of this project was to develop a novel, prototype sensor package capable of quantifying high-frequency, in-situ rates of aquatic carbon (C) cycling processes. These processes included photosynthesis, microbial respiration, and photochemical oxidation. This proposal sought funding to design and build a sensor package capable of independently quantifying these processes and to conduct initial tests of the sensor package in a controlled seawater tank facility and coastal sea grass environments. This included testing the system integration (pumping and electronic controls, data storage) and the UVC LED-based biofouling mitigation system. We met our goals and objectives via the following major activities: - Designing, building, and validating the prototype sensor package - Designing, building, and validating a UVC LED biofouling unit to minimize biofouling in in-situ chambers. - Deployment of the prototype sensor package in a coastal seagrass environment. - Development of prototype LED reactor assembly to quantify wavelength dependence of photochemical reactions in aquatic ecosystems (Ward et al., 2021; ES&T Letters). - Application of LED reactor to dissolved organic carbon cycling in arctic surface waters (Bowen et al., 2020; GRL) and crude oil weathering at sea (Freeman and Ward, In Press, Science Advances). - Researching and writing a science communication piece on the pervasive role that LED technology plays in ocean sciences (Ward, In Press, EOS) - Curator and host of A Sea Change: Oceanographers Learn From Psychologists About Systemic Racism in America We witnessed the following project outcomes: ? The biofouling system uses 220 mW 275 nm UVC LEDs that successfully minimize boifously throughout week to month long incubations (Figure 1). ? We successfully deployed the unit in a coastal seagrass environment (Figure 2), measuring hourly rates of C cycling processes (Figure 3). The preliminary findings demonstrate that the sensor package is capable of resolved oxygen fluxes over timescales of hours. ? This project also supported the design and validation of a new instrument that uses high-powered LEDs to determine how photochemical reaction efficiencies and thus rates throughout the water column vary by sunlight wavelength. The new system is 10-fold faster, 10-fold less expensive, much simpler to use, highly portable, and generates data of equal quality as past technologies (Figure 4). ? We used the LED reactor to make the first predictions of how the DOC photo-mineralization flux will change with increased inputs of permafrost DOC to arctic surface waters in a future, warmer climate (Figure 5). We found that rates of photo-mineralization of permafrost DOC were two-fold higher than DOC currently draining from arctic soils. We concluded that Earth system models underestimate arctic amplification of global warming by 14% because they do not consider photo-mineralization of DOC to CO2 occurring after permafrost soil C has been flushed to sunlit surface waters. ? We used the LED reactor to estimate the fraction of Deepwater Horizon surface oil that were transformed into compounds that dissolved into the Gulf of Mexico. We estimated that 4-14% (best estimate 8%) of Deepwater Horizon surface oil was photo-oxidized, comparable in magnitude to other widely-recognized oil fate processes (e.g., stranding on coastlines, biodegradation, evaporation; Figure 6). ? We wrote a piece in EOS about how LED technology is revolutionizing the way scientists and engineers study the ocean. Two sections of the piece focus on science supported by this project (i.e., UVC treatment of biofouling, and using LEDs to probe the wavelength dependent of aquatic photochemical reactions). This piece will be published online and in print in January 2022, an issue focused on new technology for earth science research. ? We curated a symposium where psychologists share their research about diversity, equity, and inclusion (DEI) issues with the oceanographic community. The first event was attended by ~300 people (not including online views of the recording) and exit-survey data revealed it was a success. Summary statement: Overall, we met or exceeded our goals of this EAGER project, leading to a greatly enhanced understanding of the opportunities and obstacles of in-situ incubation systems. The findings without question position us to build a next-generation sensor package that leverages the knowledge gained from this prototype package. Moreover, knowledge gained from this project facilitated multiple impactful contributions to the peer-reviewed literature, and likely many more to come. Lastly, the project supported multiple broader impact efforts, including a published paper in EOS and a workshop that helped oceanographers learn about cutting-edge diversity, equity, and inclusion research. Last Modified: 12/17/2021 Submitted by: Collin Ward