Who’s Minding the Planet? 35 INTERNATIONAL WATERS BUILDING A NETWORK Each monitoring station is equipped with an EXO2 multiparameter sonde from YSI. Every 30 minutes, the sondes capture measurements of a wide range of water quality parameters including temperature, conductivity, salinity, total dissolved solids , dissolved oxygen (DO), pH, and florescent dissolved organic matter (fDOM). Mohamed Abd Elnasser of Giga Systems notes that continuous monitoring provides a rich perspective on pollution events that would go unseen in a grab-sample program. "Continuous monitoring in a 30-minute time interval made it better to catch any short-period event that is likely to be missed if the same sites were monitored in traditional, discrete ways," he explains. "Monitoring different parameters at the same time can give some patterns of dependencies between different parameters, can give data more meaning, and can be used as a means of discarding non-logical data and spikes." BUILDING AWARENESS Data from the string of water quality monitoring stations has already had a range of benefits, starting with getting a handle on the levels and types of pollution along various reaches of the river. "The main reason is to realize the effect of these pollution sources, to have evidence of any violations, and to track the action taken to minimize these bad behaviors and the results of applying regulation," says Abd Elnasser. "Another reason is to use the data as a valuable source in research." A bonus, Mostafa told Abd Elnasser, is that dischargers near the water quality monitoring stations have become more conscientious about the quality of water they release into the river—even before the new laws take effect. FENDING OFF FOULING One of the challenges of continuous monitoring in a highly polluted environment like the Nile River is maintaining accurate measurements without succumbing to fouling. On a massive network of monitoring stations along the Nile, Cairo-based Giga Systems team helped Egyptian Ministry of Environmental Affairs technicians outfit 20 YSI EXO2 sondes with a heat-shrink protective cover and copper anti-fouling tape. Each sonde was deployed inside a PVC tube drilled with holes that allow water to flow past the sensors from all sides. And the sensors themselves are built and maintained to resist the buildup of foreign material. "Its central wiper is a good means of guaranteeing good sensor condition along extended deployment periods with minimal maintenance," notes Mohamed Abd Elnasser, after-sales and technical support engineer for Giga Systems. "Optical sensors are more accurate and eliminate the concerns of traditional electrochemical and membrane technology. And the sensors being made of titanium and the ability to add anti-fouling kits made it the best choice for long-term continuous measurement." Mostafa Ahmed of Giga Systems teams up with Dr. Sayed Mostafa along the Nile monitoring network. Photo Courtesy: Mahmoud Diab