[en] Oil spilled onto water may eventually sink because it may be more dense than water (notably some Venezuelan crudes, heavy fuel oils, and residual products), lighter fractions of the oil may evaporate or burn off and leave a dense residue behind, or sediment particles may be incorporated into the oil in the surf zone of beaches. Some spill incidents are reviewed which indicate that oil sinking may be more widespread than is generally believed. The Haven incident at Genoa, Italy in 1991 involved explosions and a fire in a tanker carrying heavy Iranian crude. Surveys confirmed the presence of sunken oil offshore and along the coast. A series of test trawls recovered 1,435 kg of sunken oil, most of which was found in a rectangular area immediately southwest of the wreck measuring 141 km². A similar experience was found in the grounding of the Honam Jade off South Korea. The main part of the oil spill was set on fire, and the residue from the fire sank and affected the local crab fishery. The scope for recovering sunken oil is severely limited, largely to confined areas of sheltered water

No abstract available

[en] The lateral and vertical Gaussian plume dispersion parameters are estimated and compared with field tracer data collected at 11 sites. The dispersion parameter schemes used in this analysis include Cramer's scheme, suggested for tall stack dispersion estimates, Draxler's scheme, suggested for elevated and surface releases, Pasquill's scheme, suggested for interim use in dispersion estimates, and the Pasquill--Gifford scheme using Turner's technique for assigning stability categories. The schemes suggested by Cramer, Draxler and Pasquill estimate the dispersion parameters using onsite measurements of the vertical and lateral wind-velocity variances at the effective release height. The performances of these schemes in estimating the dispersion parameters are compared with that of the Pasquill--Gifford scheme, using the Prairie Grass and Karlsruhe data. For these two experiments, the estimates of the dispersion parameters using Draxler's scheme correlate better with the measurements than did estimates using the Pasquill--Gifford scheme. Comparison of the dispersion parameter estimates with the measurement suggests that Draxler's scheme for characterizing the dispersion results in the smallest mean fractional error in the estimated dispersion parameters and the smallest variance of the fractional errors

[en] Groundwater discharge represents a major pathway for the return to the biosphere of contaminants that are released to the subsurface environment. An understanding of the transport processes in groundwater discharge zones is therefore an important consideration in pathway analyses associated with the environmental assessment of proposed waste-management facilities. Shallow water tables are a common characteristic of groundwater discharge zones, particularly in humid climatic regions. In this paper, the results of field tests, laboratory tests and numerical simulations are used to show that under shallow water-table conditions, the zone of tension saturation can result in a rapid and highly disproportionate water-table response to precipitation. It is further shown that this response can result in complex migration patterns that would not be predicted by the classical approaches to solute transport modelling and that the response could result in large and highly transient inputs to surface water

No abstract available

No abstract available

[en] Environmental tritium concentrations will be measured near the Tokamak Fusion Test Reactor (TFTR) to help validate dynamic models of tritium transport in the environment. For model validation the database must contain sequential measurements of tritium concentrations in key environmental compartments. Since complete containment of tritium is an operational goal, the supplementary monitoring program should be able to glean useful data from an unscheduled acute release. Portable air samplers will be used to take samples automatically every 4 hours for a weak after an acute release, thus obtaining the time resolution needed for code validation. Samples of soil, vegetation, and foodstuffs will be gathered daily at the same locations as the active air monitors. The database may help validate the plant/soil/air part of tritium transport models and enhance environmental tritium transport understanding for the International Thermonuclear Experimental Reactor (ITER)

[en] Poster presentation

No abstract available

[en] Processes of localization and migration of K_i⁺Br_i^- interstitial dipole in KBr lattice were carried out by the computerized stimulation. Simulation was conducted by the MNDO quantum-chemical method. Clusters consist from 216 ions with accounting of relaxation of 114 ions of the defects surroundings. The computer calculation shows, that the K_i⁺Br_i^- dipole is localizing in the crystal lattice due to formation of chemical bond with ions of the neighboring surroundings. In this time the dipole can exists in two forms