WASHINGTON (dpa-AFX) - An instrument built at NASA's Jet Propulsion Laboratory to map minerals on Earth is now revealing clues about water quality. A recent study found that EMIT, or Earth Surface Mineral Dust Source Investigation, was able to identify signs of sewage in the water at a Southern California beach.
The authors of the study examined a large wastewater plume at the mouth of the Tijuana River, south of Imperial Beach near San Diego. Every year, millions of gallons of treated and untreated sewage enter the river, which carries pollutants through communities and a national reserve on the U.S.-Mexico border before emptying into the Pacific Ocean. Contaminated coastal waters have been known to impact human health - from beachgoers to U.S. Navy trainees - and harm marine ecosystems, fisheries, and wildlife.
For decades scientists have tracked water quality issues like harmful algal blooms using satellite instruments that analyze ocean color. Shades that range from vibrant red to bright green can reveal the presence of algae and phytoplankton. But other pollutants and harmful bacteria are more difficult to monitor because they're harder to distinguish with traditional satellite sensors.
The introduction of EMIT marks the difference, NASA says. The hyperspectral instrument orbits Earth aboard the International Space Station, observing sunlight reflecting off the planet below.
Scientists compared EMIT's observations of the Tijuana River plume with water samples they tested on the ground. Both EMIT and the ground-based instruments detected a spectral fingerprint pointing to phycocyanin, a pigment in cyanobacteria, an organism that can sicken humans and animals that ingest or inhale it.
Christine Lee, a scientist at JPL in Southern California and a coauthor of the study, noted the potential for EMIT to detect water-quality standards.
Lead author Eva Scrivner said that the findings 'show a 'smoking gun' of sorts for wastewater in the Tijuana River plume.' She added that EMIT could be useful for filling data gaps around intensely polluted sites where traditional water sampling takes a lot of time and money.
The technology behind EMIT is called imaging spectroscopy, which is also useful to support areas ranging from agriculture to forest health and firefighting, NASA said in a press release.
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