Online Evaluation of Water Quality by Mid-infrared Spectroscopy in River Network Areas of Suzhou City

Fifty typical stations were selected to measure mid-infrared spectroscopy in the river network areas of Suzhou city, on November 23, 2009 and five water quality parameters were analyzed for every measured station, including Total Phosphorous (TP), Total Nitrogen (TN), K, Mg and Cu. The correlations between the water quality parameters and spectral reflectance were analyzed. The single band, multiple linear regression and synergy interval partial least squares (SiPLS) models were built based on reflectance. The results show that, for TN and TP, the SiPLS models have the smallest RMSE and TN and TP can be detected efficiently by in situ mid-infrared spectral analysis (r>0.76). For the prediction of K, Mg, the results indicate that the optimal method is with the single band models of the reflectance and the concentration derived from the single band models are strongly correlated with the measured concentration (r>0.79). The study indicated that the water quality parameters can be monitored by mid-infrared spectroscopy technology, which would provide the water supply and conservancy authorities with referenced spatial information to manage water resources.