NASA's EMIT Sensor Detects Water Pollution Off California Coast

A recent study published in the *Science of the Total Environment* highlights the ability of NASA's Earth Surface Mineral Dust Source Investigation (EMIT) sensor to detect water pollution along the California coastline, particularly at the mouth of the Tijuana River in San Diego County. Originally designed to map minerals on land, EMIT has now proven effective in identifying water quality issues, specifically sewage contamination in coastal waters. This innovative use of hyperspectral imaging technology could significantly enhance monitoring efforts and public health safety in marine environments.

The study, authored by Eva Scrivner, a doctoral student at the University of Connecticut, and co-authored by Christine Lee from NASA's Jet Propulsion Laboratory (JPL), demonstrates how EMIT can complement traditional water sampling methods. During their research, they observed a substantial wastewater plume flowing from the Tijuana River, which is notorious for discharging millions of gallons of treated and untreated sewage into the Pacific Ocean every year. Previous studies have established that contaminated coastal waters can adversely affect human health and marine ecosystems, posing risks to beachgoers, fishermen, and local wildlife.

Scrivner emphasized the significance of EMIT's findings, stating they represent a 'smoking gun' for identifying wastewater presence in the Tijuana River plume. The study compared EMIT's spectral analyses with ground-based water samples, revealing the presence of phycocyanin, a pigment associated with harmful cyanobacteria. This technology allows scientists to monitor areas that are challenging to access or where traditional sampling could be cost-prohibitive and time-consuming.

Christine Lee noted that EMIT's capabilities could further enhance existing online water quality dashboards that inform the public about safety at beaches. “From orbit, you are able to look down and see that a wastewater plume is extending into places you haven’t sampled,” Lee stated, suggesting that EMIT could serve as a diagnostic tool that prompts closer examination of water quality in affected regions.

The EMIT instrument, launched in July 2022, utilizes advanced imaging spectroscopy techniques developed at JPL since the 1980s. These techniques, initially aimed at mapping terrestrial minerals and dust, have been successfully adapted for marine applications. The ability to detect subtle spectral signatures in the visible and infrared wavelengths allows scientists to analyze the chemical composition of water bodies with unprecedented detail.

Given the environmental challenges posed by increasing urbanization and climate change, the implications of this research are profound. As pollution in coastal waters becomes an ever-pressing issue, especially in regions like Southern California, the potential applications of EMIT could aid in the timely detection of environmental hazards, thereby contributing to better public health outcomes and marine resource management.

In conclusion, the innovative deployment of NASA's EMIT sensor not only expands the frontiers of remote sensing technology but also provides a critical tool for ensuring water quality and safeguarding public health. As researchers continue to explore its capabilities, EMIT stands as a promising asset in the fight against water pollution worldwide.