Naphthalene sorption to organic soil materials studied with continuous stirred flow experiments
- Danish Inst. of Agricultural Sciences, Tjele (Denmark). Dept. of Crop Physiology and Soil Science
- Univ. of Amsterdam (Netherlands). Dept. of Physical Geography and Soil Science
Estimation of sorption-desorption kinetics of hydrophobic contaminants in soils and sediments is a prerequisite for assessing the risk of hazardous compounds and for studying the feasibility of bioremediation treatments. Naphthalene sorption studies were carried out with four organic soil materials, using a batch sorption technique and a continuously stirred flow (CSF) cell. Reproducibility of the CSF experiments were tested, and an experiment with different inputs showed that experimental results were independent of input pulse length. Single-particle and multi-particle linear driving force models and bicontinuum models were tested. When the sorption coefficient K{sub om} was fixed at the values obtained from the batch experiments, the RMSE modeling error increased with increasing N{sub 2} surface area, S{sub N2}, of the soil materials. The high RMSE for soil materials with a high N{sub 2} surface area was the result of strong sorption-desorption non-singularity, most probably due to a larger fraction of the applied naphthalene diffusing to slow sorption sites. A dual resistance sorption model was able to accurately describe the data with two free parameters. However, parameter uncertainty resulted from the simultaneous optimization of the rate parameter, {alpha}, and K{sub om}. The combination of batch sorption experiments, input-response experiments, and model exercises give supporting evidence that sorption kinetics of hydrophobic organic compounds to soil OM are controlled by (i) rapid pore diffusion toward S{sub N2} ({alpha} = 0.1 h{sup {minus}1}) and (ii) slow diffusion into the soil organic matter structure ({alpha} = 0.01--0.001 h{sup {minus}1}).
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 678087
- Journal Information:
- Soil Science Society of America Journal, Vol. 63, Issue 2; Other Information: PBD: Mar-Apr 1999
- Country of Publication:
- United States
- Language:
- English
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