Minimalizing Non-point Source Pollution Using a Cooperative Ion-Selective Electrode System for Estimating Nitrate...

Area of Science:

• Agricultural Science
• Environmental Science
• Analytical Chemistry

Background:

• Nitrate nitrogen (NO3-N) is crucial for crop growth but excessive levels lead to soil leaching and non-point source pollution.
• Current laboratory-based absorbance methods for NO3-N measurement are time-consuming and unsuitable for field applications.
• Ion-selective electrodes (ISEs) offer rapid soil nitrate ion (NO3-) measurement but face calibration complexities due to temperature and interfering ions.

Purpose of the Study:

• To develop an all-solid ISE system integrated with temperature and pH sensors for automated soil NO3-N concentration measurement.
• To establish a soil water content calibration function to enhance measurement accuracy and reduce errors.
• To evaluate the performance and field applicability of the developed ISE system compared to traditional methods.

Main Methods:

• Development of an all-solid ISE system incorporating a temperature sensor and a pH electrode.
• Establishment of a soil water content calibration function to compensate for environmental variables.
• Performance evaluation including stabilization time, slope, linear range, limit of detection, relative standard deviation, and recovery rate.

Main Results:

• The soil water content calibration function reduced the relative error by 13.09%.
• The ISE system demonstrated a stabilization time of less than 15 seconds, a slope of -51.63 mV/decade, and a linear range of 10^-5-10^-2.2 mol/L.
• Achieved a limit of detection of 0.5 ppm for NO3-N, relative standard deviation below 3%, and recovery rates of 90-110%, with a high correlation (R^2=0.9952) against UV-Vis spectroscopy.

Conclusions:

• The proposed all-solid ISE system provides a reliable, rapid, and accurate method for in-field soil NO3-N measurement.
• The integrated calibration function effectively mitigates interference from temperature and other ions, enhancing field usability.
• The system's performance meets the requirements for practical application in precision agriculture and environmental monitoring.