Assessing diurnal and seasonal nitrate behavior in large rivers using Nitratax in-situ sensors

• Main Author: Bark, Candice Lynn
• Other Authors: Schnoor, Jerald L.
• Format: Others
• Language: English
• Published: University of Iowa 2010
• Subjects: Diurnal; In-situ; Nitrate; Pattern; Seasonal; Sensor; Civil and Environmental Engineering
• Online Access: https://ir.uiowa.edu/etd/777; https://ir.uiowa.edu/cgi/viewcontent.cgi?article=1962&context=etd

The long-term study for the environmental-hydrologic observatory in Pool 16 of the Mississippi RIver includes installing modern sensors to continuously record the nutrient loads at the entrance, the exit and in other pertinent locations of Pool 16. Multiple monitoring locations allows more accurate modeling of nutrients and the sensors can be strategically placed to record nutrient load patterns due to floods, seasonal patterns due to agricultural trends and/or weather, the function of nutrient processing within the pool, or other major occurrences (Carver, 2008). The fact that no other organization has the current ability to record continuous, real-time nutrient data within the Mississippi River provides reason that the Pool 16 observatory may have a significant part in redefining nutrient transport in the Upper Mississippi River Basin and the understanding of the Gulf hypoxia (Carver, 2008). Six high-tech sensors have been deployed in Pool 16 from 2008-2010 recording real-time data such as nitrate, dissolved oxygen, turbidity, temperature and pH. The sensors have collected real-time data at the following locations (Figure 1.3): * Lock and Dam 15 * mouth of the Rock River * along the river bank at the town of Buffalo, IA * in the backwaters of Andalusia Island * along the river bank at LACMRERS * Lock and Dam 16. The collected data now needs to be analyzed not only to understand the data patterns, but to determine whether the data is reliable and makes sense. The main data series that this study focuses on is nitrate concentrations. Nitrate data is analyzed based on the natural patterns observed, how nitrate concentrations are affected by occurrences, and how nitrate patterns are directly related to other measured data such as dissolved oxygen and temperature. The sensors also need to be researched to determine if they are the best piece of technology for our needs and whether the sensors are able to record reliable data. Therefore, the objectives of this study are as follows: * Deploy several sensors in a short amount of time in Pool 16 to determine the efficiency of longer term deployments. * Investigate diurnal phenomena in highly time resolved nitrate concentration data from Pool 16. * Investigate seasonal patterns in nitrate concentration data collected from sensors. * Compare diurnal phenomena and seasonal patterns in nitrate concentrations for the Raccoon River and the Mississippi River. * Evaluate sensor performance and data reliability.