High-resolution monitoring of groundwater quality in unconsolidated aquifers using UV-Vis spectrometry

Abstract In many countries, groundwater quality is routinely monitored in yearly or quarterly intervals. Such frequencies, however, may not be sufficient for investigations into the temporal dynamics of water quality, due to seasonal variability responses extreme events. One approach overcome this limitation use in-situ sensors, such as UV-Vis spectrometers. With a focus on nitrate an abundant contaminant, we explored suitability these sensors high-resolution monitoring shallow unconsolidated oxic aquifers. In-situ measurements four selected wells compared well with values from lab analyses determined pumped samples. Most importantly, our results revealed distinct patterns and, at two sites, pronounced short-term fluctuations concentrations concomitant observed precipitation, hydraulic head and temperature. thus causal relationship hydrological events land use, will unfortunately overlooked when following conventional sampling schemes risk non-representative time series if routine timed unfavorably. Finally, provide practical advice deployment sensor.