Coupling centrifuge modeling and laser ablation inductively coupled plasma mass spectrometry to determine contaminant retardation in clays

Environ Sci Technol. 2009 Feb 15;43(4):1153-9. doi: 10.1021/es8020414.

Abstract

Quantifying the retardation (Rd) of reactive solutes as they migrate through low-permeability clay-rich media is difficult, thus motivating this study to assess the viability of combining centrifuge modeling and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) techniques. An influent solution containing Cl-, trace metals, and lanthanide species flowed at 1.0 mL x h(-1) through an undisturbed clay-rich core sample (33 mm diameter x 50 mm long) mounted in a UFA Beckman centrifuge operating at 3000 rpm (N factor = 876 g). During the 87 day experiment the hydraulic conductivity of the core was 3.4 x 10(-10) m x s(-1). Effluent breakthrough data indicate the Rd of Tl to be 10; incomplete breakthrough (non-steady-state) data for 145Nd and 171Yb suggest Rd values of >>75 and >>85, respectively. At the completion of the transport experiment, longitudinal sections of the core solid were analyzed for 145Nd and 171Yb using a Cetac laser ablation system coupled with an ICP-MS. The longitudinal core sections yielded Rd values of >10000 for 145Nd and 171Yb. This study demonstrates coupling these techniques can provide Rd values for a wide range of reactive solutes with relatively rapid testing of small-scale, low hydraulic conductivity core samples.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aluminum Silicates / chemistry*
  • Centrifugation
  • Chlorides / chemistry
  • Clay
  • Colloids
  • Lanthanoid Series Elements / chemistry
  • Lasers*
  • Models, Chemical*
  • Motion
  • Soil Pollutants / analysis*
  • Solutions
  • Spectrophotometry, Atomic / methods*
  • Trace Elements / chemistry
  • Water / chemistry

Substances

  • Aluminum Silicates
  • Chlorides
  • Colloids
  • Lanthanoid Series Elements
  • Soil Pollutants
  • Solutions
  • Trace Elements
  • Water
  • Clay