Variation of environmental forcings and the potential for changes in carbonate chemistry of the San Juan Archipelago

The carbonate chemistry of the San Juan Archipelago is extremely varied between regions of low to high tidal flushing. Salinity seems to be a driving parameter of the carbonate system through its effects on alkalinity. Freshwater from the Fraser River may control the environmental characteristics of water moving through the archipelago. In areas of low flushing, biological effects may strongly influence the carbonate chemistry. The effects of upwelling, especially on the west side are understudied. Overall, the water of the different sounds, channels, and straits of the islands are exchanged and equilibrated by mixing during strong spring tides. It is important to understand the interplay between environmental and biological controllers of carbonate chemistry to interpret changes that may be observed with the advent of ocean acidification

Variation in Carbonate Chemistry throughout the San Juan Archipelago

Due to the dynamic nature of the water masses in the San Juan archipelago, the carbonate chemistry has not yet been well defined in space and time. For this short-term study during a neap to spring tidal cycle in mid July 2011, we analyzed water samples as far west as Kellett Bluff and as far east as East Sound for dissolved inorganic carbon (DIC), total alkalinity (TA), temperature, and salinity at depths of 10 meters. As expected, we found variability across space and time that may be in part explained by a freshwater signal from the Fraser River, differences in flow and flushing rates, the physical geography and the resultant estuarine and ocean circulation. With continued and more expansive sampling, this data will have pertinence for the larger and future dialogue about ocean acidification in coastal environments

Spatial and Temporal Variability in Carbonate Chemistry in San Juan Archipelago

This is the first study that characterizes the carbonate parameters in the Salish Sea surrounding the San Juan Archipelago. Water samples were collected from 9 sites on multiple days and analyzed for total alkalinity and dissolved inorganic carbon. Results show high spatial and temporal variability in carbonated parameters. Levels of pCO2 roughly fluctuated between 400 and 950 μatm. The sites are likely highly influenced by freshwater pulses and tidal exchanges. Stark differences between areas of hypothesized high and low water retention were not observed within this sampling scheme

Carbonate chemistry of the San Juan Archipelago: A baseline field study for future ocean acidification research

Natural variability in the carbonate system is difficult to control in the lab. Furthermore, environmental carbonate chemistry data over small spatial scales is lacking. We measured discrete water samples across various flushing regimes in the San Juan Archipelago every other day during low slack tide over one neap to spring tidal transition. After analyzing these samples for temperature, salinity, total alkalinity and dissolved inorganic carbon, we plotted these variables across space and time. Our data suggest that although carbonate chemistry varies through space and time, biological processes and tidal cycles may have a significant influence on the local marine chemistry. Our study aims to inform those interested in ocean acidification research about the natural variation of various carbonate system parameters in the San Juan Archipelago

FY 2008 Infrared Photonics Final Report

Through the duration of the NNSA Office of Nuclear Nonproliferation Research and development (NA-22) ITAS lifecycle project, the Infrared Photonics research has been focused on developing integrated quantum cascade (QC) laser technology to enable next-generation remote sensing designs. Our team developed the concept of the integrated QC laser transmitter and originated and promoted the vision of mid-infrared (3–12 μm) wavelength photonics. Sustained NA-22 project funding produced the QC laser transmitter that is now deployed in follow-on projects. Our team produced nationally recognized cutting-edge research in the area of infrared transparent chalcogenide photonics. Three technical staff were recruited from outside PNNL and hired to support this research. This project also supported student research at the national laboratory, including high school, undergraduate, and graduate students. This provided a derivative benefit to NA-22, PNNL, and the educational institutions through training and mentoring next-generation students in science and technology. The student support was also the catalyst to develop research collaborations with two universities that are internationally recognized for their chalcogenide glass research

Refractive Index and Thermo-Optic Coefficients of Ge-As-Se Chalcogenide Glasses

Seventeen glasses in the Ge-As-Se ternary glass-forming region have been fabricated and analyzed to provide input for optical design data and to establish composition- and structure-based relationships to aide development of novel chalcogenide glasses with tailored optical functionality. While known that Ge addition to binary As-Se glasses enhances the mean coordination number (MCN) of the network and results in increased Tg and decreased CTE, this work highlights the impact on optical properties, specifically mid-wave (λ = 4.515 μm) index and thermo-optic coefficient (dn/dT). Trends in property changes were correlated with an excess or deficiency of chalcogen content in the glassy network as compared to stoichiometric compositions. Transitions in key optical properties were observed with the disappearance of Se–Se homopolar bonds and creation of As–As homopolar bonds which are associated with the Se-rich and Se-deficient regions near the stoichiometry, respectively. A second transition was observed with the creation of GeSe ethane-like structures, which are only present in strongly Se-deficient networks. Fitting dn/dT values with a simplified version of the thermal Lorentz–Lorenz formulation yielded a linear relation between the quantity (n−3∙dn/dT) and the CTE, which can be used to predict compositions with the near-zero dn/dT required for athermal optical systems