The United States has more than 1000 individual areas of petroleum-contaminated soil at formerly used defense (FUD) sites located in cold regions. This paper investigates biotreatment systems based on exploiting naturally occurring phenomena in the rhizosphere — the soil adjacent to and influenced by plant roots. Rhizosphere-based remediation systems would be inexpensive to implement and maintain and would be applicable to remote or permafrost sites. Herein, this paper provides the rationale for using rhizosphere-based biotreatment systems and some initial results. In both laboratory and field studies, successful plant germination, plant growth, and root intrusion into and through contaminated soil are demonstrated.

Using a Captina silt loam in a 10-week laboratory study, the effects of vegetation and contamination on microbial numbers were compared. The vegetation treatments included an unvegetated control and a vegetated treatment seeded with bahiagrass (Paspalum notatum). The contamination treatments included an uncontaminated control and a treatment with 2000 mg pyrene kg-1 soil added. Microbial numbers at 10 weeks were not significantly influenced by the contaminant level of 2000 mg pyrene kg-1 soil compared to the control. However, microbial numbers were greater in the rhizosphere of the bahiagrass-vegetated soil compared to the unvegetated soil.

In a 34-week field study, total petroleum hydrocarbon (TPH) concentrations of a diesel-contaminated soil decreased significantly more in the rhizosphere+nutrient treatment compared to the control that was not vegetated or fertilized. Bacterial numbers in the field study were 287 times greater in the rhizosphere+nutrient treated soils than in the control treatments. Measurable TPH compounds in the plant tissue were insignificant. The data demonstrated that rhizosphereenhanced treatment of organic-contaminated soils can be effective in reducing soil petroleum concentrations and may be a cost-effective strategy particularly suited for treating cold-region sites where remediation options are limited by cost, remoteness of the site, and/or brevity of the treatment season.

The thermodynamic conditions within the active layer overlaying perennially frozen ground and in ground subjected to seasonal frost are such that there is continuing translocation of water and ice and the displacement of soil particles. The introduction of an immiscible hydrocarbon contaminant (Arctic diesel fuel) into this dynamic porous medium results in microstructural changes that take place as a function of both cryogenic processes and contaminant concentration. Micromorphological and scanning electron microscope observations combined with image analysis revealed evidence of reorganisation of silt microfabric and changes to intra-particle porosity. The degree of interaggregate porosity increased as a function of increasing concentration of the hydrocarbon contaminant. Intra-particle porosity within individual soil aggregates was observed to decrease as a function of increasing contaminant concentration.

The period from September 1996 to September 1998 represented a transition phase in the process of circumpolar Arctic cooperation on environmental protection, which had begun in 1991 with the establishment of the Arctic Environmental Protection Strategy and had been broadened with the agreement by the eight Arctic governments to create an Arctic Council. The genesis of the Arctic Council had been protracted due to diverging perspectives on various aspects of its functional scope, organisational structure, and funding and on issues of representation. This article discusses the extent to which the conflicts that had dogged the Council's genesis were resolved during its subsequent ‘post-natal’ period preparing for the Council's first ministerial-level meeting in Iqaluit in September 1998.

This paper examines the behaviour of ions of chemical elements in freezing and thawing soils and in ice, and analyzes the mechanisms and laws that govern the transfer of ions. Data are given on the ionic permeability of frozen soils and ice. The features characteristic of the interaction of frozen soils with salt solutions are described.

In the Arctic, thermal erosion results from ground thawing produced by heat transfer when water is flowing upon the frozen ground. A mathematical model has been proposed to determine the efficiency of the process and the rate of thermal erosion. Considering a constant heat-transfer coefficient, the resulting thermal flux at the groundsurface produces ground thaw, and the unfrozen sediments can be removed by the water flow. A particular case of an ablation model consists of an immediate removing of sediments by a strong flow and by the action of gravity. An experimental hydraulic device was built to test the authors' theoretical ablation model, describing a fluvial thermalerosionprocess. The effect of different parameters (Reynolds number, water temperature, ground-ice temperature) on the rate of thermal erosion for samples of frozen sand was investigated. Results from the experiments are in agreement with theoretical estimates using the mathematical model. Moreover, this study shows a hierarchy of parameters in terms of efficiency of the fluvial thermal-erosion process.

A discussion of the possible effects of the contaminants on the erosion rate leads the authors to propose two kinds of experiments: a contaminated frozen sample eroded by a water flow, varying in this case the thermophysical properties of the sample (density, specific heat capacity, a latent heat, and change of phase), and an experiment consisting of erosion of a frozen sample by contaminated flow. This second case is also complex due to many mechanical, hydrodynamic and thermal interactions at the ground surface. This paper reports results of thermal erosionfrom experiments with icesaturated sand. A pure ice sample is used to determine the heat-transfer coefficient.