Groundwater nitrate contamination necessitates reliable and efficient methods for source tracking and process understanding. Although dual nitrate isotopes (δ15N-NO3- and δ18O-NO3-) are powerful tracers, their application is limited by their high cost and analytical complexity. Optical spectroscopy of dissolved organic matter (DOM) offers a rapid and cost-effective alternative. Here, we evaluated and advanced the use of DOM fluorescence as an integrative proxy for predicting groundwater nitrate dynamics. Although significant, individual optical indices showed weak correlations with nitrate indicators (R2 = 0.14-0.25, p R2 = 0.27-0.62, p p R2 = 0.60-0.76, p R2 = 0.56-0.68, p R2 = 0.45-0.99, p R2 = 0.40-0.86, p < 0.01). These findings established FIR as a viable, cost-effective, and rapid proxy for nitrate and isotopic screening prior to large-scale water quality assessment.
Cao et al. (Thu,) studied this question.