Oceans cover about 70% of the earth's surface, but they remain largely unexplored.

Of particular importance is understanding chemical changes to determine how organisms and ecosystems respond to intense population and environmental stressors.

SRI's Marine Technology Program has significant experience designing and deploying oceanographic sensors to study chemical changes in marine environments, including ocean acidification, nutrient run-off from excessive fertilization, quantitative dissolved gas measurements, and identification of a wide range of volatile compounds from pollutants and other sources.

SRI's technologies could, for example, be used to map oil plumes resulting from the Deepwater Horizon spill in the Gulf of Mexico.

Tools developed by SRI include

- MICA Multi-parameter Inorganic Carbon Analyzer
- SEAS Spectrophotometric Elemental Analysis System
- Underwater Mass Spectrometer
- Remotely Operated Underwater Vehicles

Studying Ocean Acidification with MICA

Latest-generation MICA system

Carbon dioxide, a greenhouse gas thought to be involved with global warming, can dissolve in water, forming carbonic acid, which leads to reduced pH (or an increase in acidity) and reduces the concentration of carbonate, a substance that is required by organisms such as shellfish, mollusks, and corals to form their shells. In turn, this impacts nutrition patterns for marine mammals and fish, disrupting the food chain and the balance of the entire ecosystem.

MICA (Multi-parameter Inorganic Carbon Analyzer), has been developed by SRI in collaboration with scientists in the College of Marine Science at the University of South Florida. It is a compact system for shipboard measurements of carbon-system parameters and is the only instrument to-date that has demonstrated measurement of all four carbon system parameters, allowing for accurate measurements to fully understand ocean acidification:

1. pH
2. Total dissolved inorganic carbon (CT)
3. Partial pressure of CO₂ (pCO₂)
4. Total alkalinity (AT)

Learn more about MICA (PDF)

Studying Chemical Changes in the Ocean with SEAS

SEAS II configured with a battery

Understanding complex chemical processes is a crucial task for marine scientists, and it requires the ability to measure chemical concentrations with very high fidelity. SRI's SEAS (Spectrophotometric Elemental Analysis System) is an oceanographic instrument that allows accurate measurement of chemical properties in situ.

Supported by novel optical technology, SEAS has a sensitivity of parts per trillion that exceeds most laboratory-grade instrumentation. It measures nutrients, pH levels, and trace metals, which allow researchers to study how the oceans support microscopic plants and animals. Fish and other sea life depend on these microscopic organisms for survival.

Because the instrument takes measurements while submerged, results are free from contamination that is typically associated with collecting samples and transporting them to a laboratory.

SEAS has been developed in collaboration with the University of South Florida. To date, 10 SEAS instruments have been deployed around the world, in several cases to depths of 1,000 meters. Sites include Hawaii, the North Pacific, the Gulf of Mexico, the Hillsborough River in Florida, the Florida Keys, Florida's Tampa Bay, Florida Bay, and the U.S. Atlantic Coast.

Learn more about SEAS (PDF).

Underwater Mass Spectrometer

Underwater mass spectrometer without main pressure housing

Of critical importance in ocean research is the ability to perform in-situ detection and quantification of dissolved gases and volatile organic compounds (VOCs). SRI International has developed underwater membrane introduction mass spectrometry (MIMS) systems capable of performing such analyses.

The underwater MIMS systems have been deployed on a wide variety of platforms for a number of applications in coastal oceanographic, estuarine, and freshwater research. Types of deployments include shallow-water monitoring for pollutants (VOCs) in tethered/moored scenarios, as well as onboard autonomous and remotely controlled unmanned vehicles or towed behind ocean vessels. For example, the underwater mass spectrometer was recently towed in the Santa Barbara basin for detection and mapping of methane and other oil-related hydrocarbons.

In addition, by recording the position of the vehicle/MS system using global positioning system (GPS) technology, and time matching to concurrent MS data, SRI has demonstrated that chemical maps can be created to show spatial chemical concentration variations with unprecedented resolution.

The UMS has been used to quantify multiple dissolved gases and VOCs in subsurface plumes. In March 2009, SRI quantified target chemical compounds, such as methane, to depths of 1000m at the Gulf of Mexico MC118 site. Having the ability to measure in situ many of the dissolved gases and other volatile compounds in this region, SRI is well qualified to study the extent and impact of the subsurface oil plume resulting from the Deepwater Horizon spill.

Learn more about SRI's underwater mass spectrometer and chemical sensors program.

Remotely Operated Underwater Vehicles

To measure the health of marine ecosystems, SRI has also developed underwater autonomous and remotely operated vehicles.

Autonomous Underwater Vehicles

SRI's AUV has been developed to perform high-precision, wide-area bottom surveys, ship hull scans, and water column measurements. Payloads can be custom-made to accommodate a wide variety of marine sensors. This system has proven a reliable vehicle for detailed micro bathymetric surveys, as well as ship hull scans, utilizing some of the most advanced sensors available today. A relatively small size and low weight make the AUV easy to transport and deploy from small low-cost "work boat" vessels.

This AUV is configurable for specific surveys, including

- Mapping: Survey quality inertial navigation, high-resolution 3D and imaging sonars
- Port Security: Custom-designed to survey ship hulls while at sea and to perform mine countermeasures
- Science: Habitat characterization, chemical sensing, fisheries surveys

For operations at sea, SRI's AUV can be operated from a variety of platforms. A two-person crew is required. Operating personnel are provided by SRI.

Remotely Operated Vehicle

SRI's ROV system is a unique, highly reliable underwater science, survey, and port security tool that has demonstrated outstanding performance in high-resolution 3D digital imaging, geological and biological sampling, and zero visibility operation. SRI's ROV features fiber optic communications, ample subsea power, 200 pounds of reserve buoyancy, and great stability to support a variety of sensor payloads. These features also allow for quick and easy integration of customer provided payloads.

This ROV is configurable for specific surveys, including:

- Mapping: Survey quality inertial navigation, high-resolution 3D and imaging sonars
- Port Security: Custom-designed to survey ship hulls while at sea and perform mine countermeasures
- Science: Habitat characterization, chemical sensing, fisheries surveys
- Emergency Response Operations: The system's high mobility and advanced capability provide for rapid mobilization and fast transit in emergency situations

SRI's ROV has been operated worldwide with or without its 20-foot shipping container/command and control center. A three-person crew is recommended for a 10-12 hour day (longer operational hours are available). Operating personnel are provided by SRI.

Other Capabilities

SRI's MicroScience Engineering Laboratories and Engineering Chemical Sensing Group have developed chemical sensors and systems to analyze aquatic environments. These efforts are part of a broader Marine Technology Program, through which SRI offers expertise that includes optical sensors and systems, and portable underwater mass spectrometry. And to help understand and prevent adverse environmental events, researchers in SRI's Physical Sciences Division study fracture physics and conduct failure analyses.

Learn more about SRI's Marine Technology Program in our brochure (PDF).

Contact Us

Larry Langebrake
Director, Marine Technology Program
727.498.6736

For information about our work in related areas, visit SRI's Physical Sciences Division and Engineering and Systems Division.