[Endotoxin Contamination and Correlation with Other Water Quality Parameters of Groundwater from Self-Contained Wells...

A survey of endotoxin activity in groundwater from 14 self-contained wells in PLA units stationed in Beijing was conducted by the kinetic-turbid assay of Tachypleus Amebocyte Lysate (TAL). Bacteriological parameters, including total cell counts detected by flow cytometry, heterotrophic plate counts (HPC), standard plate counts and total coliforms were analyzed. Additionally, suspended particles, turbidity, dissolved organic carbon (DOC), and UV₂₅₄ were investigated. Total endotoxin activities ranged from 0. 15 to 13.20 EU · mL⁻¹, free endotoxin activities ranged from 0.10 to 5.29 EU · mL⁻¹ and bound endotoxin activities ranged from 0.01 to 8.60 EU · mL⁻¹. Most of the endotoxins in heavily contaminated groundwater existed as bound endotoxins. As for total endotoxins, the sequence of correlation coefficients with other parameters was total cell counts (r = 0.88 ) > HPC (r = 0.79) > DOC (r = 0.77) > UV₂₅₄ (r = 0.57) > total coliforms (r = 0.50) > standard plate counts (r = 0.49) = turbidity (r = 0. 49) > total particles (r = 0.41). The sequence of correlations of the bound endotoxins with other parameters was total cell counts (r = 0.81) > HPC (r = 0.66) > total coliforms (r = 0.65) > turbidity (r = 0.62) > total particles (r = 0.58) > standard plate counts (r = 0.22). Free endotoxins were correlated with DOC and UV₂₅₄, r = 0.58 and 0.26, respectively. Result showed free endotoxins had a higher correlation with DOC, and a lower correlation with UV₂₅₄.