Characterization of Dissolved Organic Matter in Groundwater and Surface Water in Managed Artificial Recharge Demonstration Site Using Fluorescence 3D EEM-PARAFAC

Most studies have focused on the characterization of dissolved organisms during surface water or water treatment processes such as rivers, lakes and wetlands, there is a few research for the compositional changes of dissolved organic matter due to groundwater migration. The purpose of this study was to investigate the effect of nearby surface water on the groundwater pumping test by monitoring the compositional variation of fluorescent dissolved organic matter in groundwater during the pumping test to evaluate applicability and feasibility of artificial recharge.

In this study, we have characterized the fluorescent dissolved organic matter (DOM) in the surface water (IK-A IK-D) and groundwater (IK-E IK-H) samples in KIGAM managed artificial recharge demonstration site in Sangju, Kyoungsang Province, Korea by excitation-emission (EEM) fluorescence spectroscopy coupled with parallel factor analysis (PARAFAC). The fate of major DOM components at pumping well (SPW-1) were also monitored to assess the interaction between aquifer and near wetland (IK-A) during the pumping test.

Two humic-like components (C1, humic-acid and C2, fulvic-acid) and two protein-like components (C3, tyrosine and C4, tryptophan) were identified in the groundwater and surface water. The components C1 and C2 were detected showing significantly high intensity in wetland (IK-A), reservoir (IK-B) and brook (IK-C) samples, while very weak fraction in the groundwater-like samples (IK-D IK-H). During pumping test, the fluorescence intensity of humic-acid components slightly increased while tryptophan component significantly decreased in SPW-1 which is well correlated with the trend of biological index (BIX) values. The fluorescent pattern at SPW-1 had been similar with that of near wetland over time indicating possibility of inflow from wetland.

This study provides the potential application of EEM-PARAFAC analysis to understand the characteristics of DOM in the groundwater and assess the aquifer connectivity with near surface water.