Page 47: of Marine Technology Magazine (November 2014)

The USGS is using the new sensor tech- nology to collect nitrate concentration data every hour to improve the accuracy of nitrate load estimates to the Gulf of Mex- ico. The data can also be used to make it easier to detect changes in nitrate levels related to basin management and to track progress toward the goal of reducing the size of the dead zone.

“High frequency data from these sen- sors has revealed considerable variability in nitrate concentrations in small rivers and streams,” said Brian Pellerin, USGS researcher. “However, we were surprised to see nitrate concentrations vary by as much as 20 percent in a week in a river as large as the Mississippi River without similar changes in stream