Spectral Characteristics of Nitrogen and Phosphorus in Water

The concentration of nitrogen and phosphorus in the waters is an important indicator to affect water quality and determine the degree of water pollution. The development of hyperspectral remote sensing technology makes it possible to monitor the concentrations of nitrogen and phosphorus in different water areas. In this experiment, the spectral curves of different concentrations of nitrogen and phosphorus solutions were collected by using an imaging spectrometer under laboratory conditions. Then compare the spectral curves of different concentrations of sodium phosphate solution by PSR spectrometer, to analyze the sensitive bands of nitrogen and phosphorus. The experimental results show that for phosphorus, its concentration as a whole is positively correlated with the spectral reflectance. In the wavelength range of 450–630 nm, there is a strong positive correlation between the concentration of phosphorus and the spectral reflectance. The correlation coefficient is above 0.8, and the maximum positive correlation is 0.9 at 550, 603, and 740 nm. For nitrogen, its concentration as a whole is negatively correlated with the spectral reflectance. In the wavelength range of 560–850 nm, the correlation coefficient fluctuates within the range from −0.6 to 0.95, and the maximum negative correlation of 0.95 is achieved at 603, 670, and 807 nm.