Set It & Forget It
Commercially-available in situ nutrient sensor samples for up to three months at a time.

Challenge
Coastal ecosystems need nutrients such as nitrogen and phosphorus to thrive. When stormwater carrying fertilizers and wastewater plant effluent washes into coastal waters, excess nutrients can fuel algal growth. This can lead to low oxygen conditions that can kill fish and other organisms. Although nutrient pollution is a pervasive, national problem that requires continuous monitoring, many coastal budgets cannot stretch further than the costs of monthly samples taken by hand.

Response
This CICEET project resulted in an affordable nutrient sensor that coastal managers can program to sample every hour, and leave in the field for up to three months. CICEET-sponsored researchers developed an in situ nitrate sensor that works by pumping in water, mixing it with reagents, and passing it through a flow cell spectrometer to measure and record nitrate concentration. Researchers successfully field-tested the sensor at three National Estuarine Research Reserve System sites: Elkhorn Slough, California; Weeks Bay, Alabama; and Apalachicola Bay, Florida.

Once installed in the field, the sensor was able to take samples every hour, for as long as 90 days. At Elkhorn Slough, researchers compared sensor data with information gathered by hand sampling. By correlating this with rainfall and tide data, they tracked the source of nitrate spikes generated by runoff from the surrounding agricultural fields—these would have gone unnoticed using less frequent sampling methods.

Researchers then adapted the sensor to measure phosphorus. Field tests near the Monterey Bay Aquarium Research Institute (MBARI) were successful. While the original model was based on wet chemistry techniques, next generation sensors, based on In Situ Ultraviolet Spectrophotometer (ISUS) technology, show great promise.

Impact
This sensor is now commercially available nationwide as the YSI 9600 Nitrate Monitor, a leading-edge instrument for continuous monitoring of nitrate levels in water. It monitors nitrate levels at operator-selected sampling intervals, using flow injection analysis technology combined with a chemical reaction sequence defined in literature from both U.S. Environmental Protection Agency methods and Standard Methods for the Examination of Water and Wastewater.

Learn More
For more information about the YSI 9600, contact YSI Tech Support:
T: 800.897.4151
E: environmental@ysi.com

Research was conducted by Dr. Jane Caffrey
Universities of West Florida and Santa Cruz
T: 850. 916.9748
E: jcaffrey@bellsouth.net

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