Phoebe Zito Jennifer McGuire Dalma Martinovic-Weigelt Isabelle M. Cozzarelli Barbara A. Bekins Robert G. M. Spencer David C. Podgorski 2018 <p><span>Groundwater samples containing petroleum-derived dissolved organic matter (DOM</span>_HC<span>) originating from the north oil body within the National Crude Oil Spill Fate and Natural Attenuation Research Site near Bemidji, MN, USA were analyzed by optical spectroscopic techniques (i.e., absorbance and fluorescence) to assess relationships that can be used to examine natural attenuation and toxicity of DOM</span>_HC<span><span>&nbsp;</span>in contaminated groundwater. A strong correlation between the concentration of dissolved organic carbon (DOC) and absorbance at 254 nm (</span><i>a</i>₂₅₄<span>) along a transect of the DOM</span>_HC<span>plume indicates that<span>&nbsp;</span></span><i>a</i>₂₅₄<span><span>&nbsp;</span>can be used to quantitatively assess natural attenuation of DOM</span>_HC<span>. Fluorescence components, identified by parallel factor (PARAFAC) analysis, show that the composition of the DOM</span>_HC<span><span>&nbsp;</span>beneath and adjacent to the oil body is dominated by aliphatic, low O/C compounds (“protein-like” fluorescence) and that the composition gradually evolves to aromatic, high O/C compounds (“humic-/fulvic-like” fluorescence) as a function of distance downgradient from the oil body. Finally, a direct, positive correlation between optical properties and Microtox acute toxicity assays demonstrates the utility of these combined techniques in assessing the spatial and temporal natural attenuation and toxicity of the DOM</span>_HC<span><span>&nbsp;</span>in petroleum-impacted groundwater systems.</span></p> application/pdf 10.1021/acs.est.8b00016 en American Chemical Society Examining natural attenuation and acute toxicity of petroleum-derived dissolved organic matter with optical spectroscopy article