French tourists and oyster farmers will be spending more time in the waters of western France next summer. This past July, water quality management groups PONSEL and SAUR launched two buoys with water quality sensors in the Etel River, known for its oyster farming, and Quiberon Bay, a popular summer vacation spot. The test study showed that the buoys could have other applications because they are user-friendly, energy efficient and transmit data quickly.
The sensors were implemented to fill a need for continuous real-time data. Agricultural runoff infiltrates the bay and the river with nitrates while industrial activity and shipwrecks near the Etel River can also pollute the water. Water quality in Quiberon Bay can suffer in the summer due to increased population density and sailing regattas. In both bodies of water, a bacteriological analysis determined if water was safe for oyster cultivation or human recreation activity. However, this process was time consuming as it required water samples to be taken to a lab and time for results to process. As the old saying goes, time is money. In the cause of Etel River oyster farming, if bacteria results showed poor water quality, the oysters could not be sold until it improved. In some cases, it could be days before another test was completed. To keep oyster sales afloat and tourists in the water, SAUR wanted to find a correlation between physical-chemical parameters and bacteriologic parameters.
PONSEL and SAUR installed four PONSEL DIGISENS sensors in each lightweight buoy: optical dissolved oxygen, optical turbidity, pH/ORP and conductivity/salinity. The sensors communicated with a data logger which sent data via cellular telemetry to a web server every 10 minutes. The data was checked daily. If physical and chemical parameters were out of a healthy range when bacteriological parameters were, data from the sensors could show when parameters were out of range so oyster farming could return to regular business more quickly than before.
The sensors were useful in Quiberon Bay to determine the influence of tourist activity on water quality, as the bay experiences heavy traffic during the summer months.
A report from PONSEL stated that technicians were surprised with the low power consumption of the system. The system is available to rent for other short-term water quality measurement projects. This could be particularly useful in France due to new, strict effluent limitations.