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Nonionic organic sorbates in aqueous solutions are mainly absorbed by the organic phase of sediments and soils. The movement of such organic chemicals in soils can be predicted if reliable sorption estimates can be obtained. A method for estimating accruate partition coefficients is therefore presented. The method is applicable to nonionic chemicals and incorporates the properties of sorbents and sorbates.

The uptake of phenol by soil minerals geothite, kaolinite and montmorillonite and by organic substances lignin, chitin, cellulose, collagen and activated carbon was investigated. The results showed that the biopolymers sorbed 2-45 times more phenol than the minerals. The energetics of the reactions involved, the sorption coefficients as well as the effects of polarity on sorption reactions are presented.

Reports on phenol sorption by soil organic compounds cellulose, chitin, collagen, lignin and activated carbon. Reaction of phenol with soil minerals; Relation of phenol uptake to polarity and heat of wetting of biopolymers; Energetics of uptake of phenol by ligning and activated carbon.

Chromium speciation in naturally contaminated soils appears more complex than spiked studies have shown. This study characterized Cr speciation (oxidation states; availability; molecular geometry) intended to highlight the genesis of immobile Cr(VI) species in long-term tannery waste-contaminated soils. In a series of samples obtained from Shuitou in China, chemical extraction methods showed that Cr(III) was dominant(>96.7% of total Cr), with Cr(VI) concentration up to 144 mg kg -1 . Of the total Cr(VI) present, immobile Cr(VI) represents >90%. Synchrotron-based X-ray near-edge structure spectroscopy (XANES) showed the occurrence of Cr(VI), which was not removed by phosphate buffer extraction, confirming a significant amount of immobile Cr(VI) fractions in soils. X-ray fluorescence maps exhibited the heterogeneous distribution of Cr in soils associated with both Mn and Fe. Such a distribution suggests Cr(III) oxidation to Cr(VI) by Mn oxides and a possible immobilization of both Cr(III) and Cr(VI) onto Fe (hydr)oxides. Linear combination fitting of XANES spectra revealed that fractional weights (%) in samples were CrFeO 3 (49.3-53.6), CrOOH (22.3-30.8), and CaCrO 4 (13.2-25.3). Our results demonstrate that (i) Cr(VI) is immobilized in soils and (ii) mechanisms of Cr(VI) immobilization are CaCrO 4 precipitation and recrystallization with Fe (hydr)oxides.