http://netedu.xauat.edu.cn/jpkc/netedu/jpkc2009/szylyybh/content/wlzy/1/Review%20of%20Arsenic%20in%20natural%20water%20-%20Smedly.pdf

A review of the source, behaviour and distribution of arsenic in natural waters

Solid phase microextraction with thermal desorption using fused silica optical fibers

The science of the total environment

The use of equilibrium expressions for sorption to natural particles in fate and transport models is often invalid due to slow kinetics. This paper reviews recent research into the causes of slow sorption and desorption rates at the intraparticle level and how this phenomenon relates to contaminant transport, bioavailability, and remediation. Sorption kinetics are complex and poorly predictable at present. Diffusion limitations appear to play a major role. Contending mechanisms include diffusion through natural organic matter matrices and diffusion through intraparticle nanopores. These mechanisms probably operate simultaneously, but the relative importance of each in a given system is indeterminate. Sorption shows anomalous behaviors that are presently not well explained by the simple diffusion models, including concentration dependence of the slow fraction, distributed rate constants, and kinetic hysteresis. Research is needed to determine whether adsorption/desorption bond energies may play a role alon...

Mechanisms of Slow Sorption of Organic Chemicals to Natural Particles

found that field-scale dispersivities are several orders of.magnitude greater than lab-scale values for the same material; it is generally agreed that this difference is a reflection of the influence of natural heterogeneities which produce irregular flow patterns at the field scale. Consequently, laboratory measurements of dispersivity cannot be used to predict field values of dispersivity. Instead field-scale tracer tests are sometimes conducted to estimate dispersivity at a particular site. Early efforts to document the scale dependence of dispersivity [Lallemand-Barres and Peaudecerf, 1978; Anderson, 1979; Pickens and Grisak, 1981; Beims, 1983; Neretnieks, 1985] were based on field values of dispersivity reported in the literature and the test scales associated with those values. These studies were useful in that they indeed documented field evidence of the scale effect, but they were lacking in that they did not assess the reliability of the data presented. Because we felt that the data would be more

A Critical Review of Data on Field-Scale Dispersion in Aquifers

Between 6,800 and 21,000 l of transformer oil containing polychlorinated biphenyls (Aroclor 1254) and chlorobenzenes were spilled when an underground pipe broke at a transformer manufacturing plant in Regina, Saskatchewan, Canada. Methods were developed to examine the surface and subsurface distribution of the contaminants. Contrary to initial expectations, large quantities of PCBs were found to have migrated both vertically and horizontally at the site. Polychlorinated biphenyls at concentrations of approximately 1000 mg/kg moved downward through granular fill and 9 m of fractured Regina clay. Contaminant migration along the interface of the clay and the upper unit of permeable granular fill probably accounts for the extensive lateral movement. It is argued that because of the low organic content of the geological units at the site (generally 0.9%) and the hydrophobicity of chlorinated organics like PCBs, contaminants at many locations exist in three phases: a dissolved aqueous phase, an absorbed phase, and an oily liquid phase. Movement of the oily liquid seems to be the most likely explanation for the migration of large quantities of PCBs downward through fractures in the clay and laterally through the granular fill.

A case study of a chemical spill: polychlorinated biphenyls (PCBs) 1. history, distribution, and surface translocation

High resolution spatial and temporal evolution of dissolved gases in groundwater during a controlled natural gas release experiment.

The geochemical mass transfer model WATEGM-SE is used to illustrate by example potential chemical reactions that can occur at a hypothetical low-temperature thermal energy aquifer storage facility....

Geochemical reactions associated with low-temperature thermal energy storage in aquifers

Groundwater recharge assessment in an upland sandstone aquifer of southern California

The dual formulation of flow in terms of potentials and stream functions is applied to a groundwater system containing a well-monitored chloride plume. It is found that field measurements of head alone, regardless of detail, are not sufficient to arrive at a description of the flow system that is meaningful within the context of a contaminant transport modeling study. Problems identified include the incompatibility of the time-specific hydraulic data with the longer time frame of the transport phenomenon and the susceptibility of the potential solution to numerical error. In overcoming these problems, plumebased data are used in the dual model of potentials and stream functions to determine the hydrogeologic parameters that are needed for the description of the flow system in a transport model. A companion paper reviews the underlying theory.

John A. Cherry

Papers

A case study of a chemical spill: polychlorinated biphenyls (PCBs) 1. history, distribution, and surface translocation

High resolution spatial and temporal evolution of dissolved gases in groundwater during a controlled natural gas release experiment.

Geochemical reactions associated with low-temperature thermal energy storage in aquifers

Groundwater recharge assessment in an upland sandstone aquifer of southern California

The Dual Formulation of Flow for Contaminant Transport Modeling: 2. The Borden Aquifer