Envirotech (formerly W.S. Ocean Systems) nutrient monitors were attached to the Chesapeake Bay Observing System's (CBOS) Choptank River and Pocomoke River buoys. These sensors employ standard analytical procedures to record nitrate, phosphate, and ammonium concentrations at programmable intervals and can operate autonomously for weeks to months without servicing.

Autonomous in situ nutrient monitoring is a significant advancement over traditional hand sampling techniques that are both labor intensive and limited in duration. These advantages provide scientists with previously unattainable and continuous portrayals of current ecosystem dynamics.

Pictures (clockwise from upper-left) 1. Inside the supplemental reagent housing of a nutrient sensor. 2. Nutrient sensor array.3. Nutrient sensors entering the Choptank River. 4. CBOS Choptank River buoy. 5. Divers attaching the sensors to the CBOS buoy. 6. Telemetry antenna and meteorological sensors on CBOS buoy.