Effect-Directed Toxicity Assessment of the Surface Water of Chao Phraya River by Integrating a Panel of Bioluminescent E. coli with ICP-OES and HPLC-DAD

This study presents an effect-directed analysis (EDA) combining Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES), High-Performance Liquid Chromatography-Diode Array Detection (HPLC-DAD), and five bioluminescent Escherichia coli bioreporters to map surface water toxicity along a 372-km gradient of the Chao Phraya River, Thailand. Evaluating cytotoxicity, genotoxicity, metabolic disturbance, oxidative stress, and quorum sensing via a new Toxic Index (TI) and Dynamic Time Warping (DTW) kinetic alignment, the panel unmasked complex cellular stress gradients.

Although ICP-OES revealed localized mercury spikes (119 μg/L), metals contributed minimally to overall toxicity. Instead, upstream freshwater exhibited severe, multi-pathway stress (Total Toxicity Index, TTI ∼ 2.48) statistically associated with trace bioactive organic fractions isolated via solid-phase extraction. In complex urban matrices, DTW effectively exposed non-monotonic toxicity masking.