An Underwater Methane Sensor Based on Laser Spectroscopy in a Hollow Core Optical Fiber.

Existing sensors for measuring dissolved methane in situ suffer from excessively slow response times or large size and complexity. The technology reported here realizes improvements by utilizing a hollow core optical fiber (HFC) as the detection cell in an underwater infrared laser spectrometer. The sensor operates by using a polymer membrane inlet to continuously extract dissolved gas from water.

Development of a quantum cascade laser absorption spectrometer for simultaneous measurement of C-O and O-O clumping in CO.

Rationale: Dual clumped isotope paleothermometry determines carbonate formation temperatures by measuring the frequency of C-O (∆) and O-O (∆) pairs in carbonates. It resolves isotopic kinetic biases and thus enables more accurate paleotemperature reconstructions. However, high-precision measurements of O-O clumping using current techniques requires large sample sizes and long acquisition times.

Corals and sponges are hotspots of reactive oxygen species in the deep sea.

Reactive oxygen species (ROS) are central to diverse biological processes through which organisms respond to and interact with their surroundings. Yet, a lack of direct measurements limits our understanding of the distribution of ROS in the ocean. Using a recently developed in situ sensor, we show that deep-sea corals and sponges produce the ROS superoxide, revealing that benthic organisms can be sources and hotspots of ROS production in these environments.

Toward a New Era of Coral Reef Monitoring.

Coral reefs host some of the highest concentrations of biodiversity and economic value in the oceans, yet these ecosystems are under threat due to climate change and other human impacts. Reef monitoring is routinely used to help prioritize reefs for conservation and evaluate the success of intervention efforts. Reef status and health are most frequently characterized using diver-based surveys, but the inherent limitations of these methods mean there is a growing need for advanced, standardized, and automated reef techniques that capture the complex nature of the ecosystem.

Design Optimization of a Submersible Chemiluminescent Sensor (DISCO) for Improved Quantification of Reactive Oxygen Species (ROS) in Surface Waters.

Reactive oxygen species (ROS) are key drivers of biogeochemical cycling while also exhibiting both positive and negative effects on marine ecosystem health. However, quantification of the ROS superoxide (O) within environmental systems is hindered by its short half-life. Recently, the development of the diver-operated submersible chemiluminescent sensor (DISCO), a submersible, handheld instrument, enabled in situ superoxide measurements in real time within shallow coral reef ecosystems.

Development of a Deep-Sea Submersible Chemiluminescent Analyzer for Sensing Short-Lived Reactive Chemicals.

Based on knowledge of their production pathways, and limited discrete observations, a variety of short-lived chemical species are inferred to play active roles in chemical cycling in the sea. In some cases, these species may exert a disproportionate impact on marine biogeochemical cycles, affecting the redox state of metal and carbon, and influencing the interaction between organisms and their environment. One such short-lived chemical is superoxide, a reactive oxygen species (ROS), which undergoes a wide range of environmentally important reactions.

Dissolved gas sensing using an anti-resonant hollow core optical fiber.

Sensors that measure dissolved gases directly are needed for environmental, industrial, and biomedical applications. Here we present a hollow core fiber optic sensor capable of measuring dissolved methane gas in liquids using only nanoliters of sample gas. The sensor is based on an anti-resonant hollow core fiber combined with a permeable capillary membrane inlet that extracts gas from the liquid for analysis.

Development of a Handheld Submersible Chemiluminescent Sensor: Quantification of Superoxide at Coral Surfaces.

Reactive oxygen species (ROS) are produced via various photochemical, abiotic, and biological pathways. The low concentration and short lifetime of the ROS superoxide (O) make it challenging to measure in natural systems. Here, we designed, developed, and validated a DIver-operated Submersible Chemiluminescent sensOr (DISCO), the first handheld submersible chemiluminescent sensor.

Open-path spectroscopic methane detection using a broadband monolithic distributed feedback-quantum cascade laser array.

Methane is a powerful greenhouse gas that has both natural and anthropogenic sources. The ability to measure methane using an integrated path length approach such as an open/long-path length sensor would be beneficial in several environments for examining anthropogenic and natural sources, including tundra landscapes, rivers, lakes, landfills, estuaries, fracking sites, pipelines, and agricultural sites. Here a broadband monolithic distributed feedback-quantum cascade laser array was utilized as the source for an open-path methane sensor.

Deep Ultraviolet Light Emitting Diode (LED)-Based Sensing of Sulfur Dioxide.

With the recent development of deep ultraviolet (DUV) light emitting diodes (LEDs) comes the possibility of targeting absorption bands of several gases, including sulfur dioxide (SO). SO has strong absorption bands in the 300 nm spectral region. The low cost and small size of DUV LEDs, coupled with their spectral coverage, makes them viable sources for new gas sensors.