The removal of weathered-in PCBs from clayey soil by surfactant washing is demonstrated at bench scale. Spent surfactant solution was treated for recycle at bench scale by countercurrent liquid-liquid extraction for the removal of nonvolatile contaminants, and by thin film aeration in packed columns for removal of volatile organics. A correlation of micelle/water partition coefficients with octanoll water partition coefficients reported earlier by Valsaraj et al. is extended to several additional compounds. Mathematical models for batch-batch, batch-continuous flow, and countercurrent flow surfactant soil washing are described, and the effects of the model parameters are discussed.

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This chapter reviews the literature relating to environmental processes that affect mineral dissolution reactions and the generation of acid mine drainage (AMD), the fate and transport of metal contaminants within the environment, the toxic influences of metals and mine drainage on aquatic species, characterization of abandoned mines and their potential for contamination, and technologies for remediation of mining-impacted systems or removing metals from wastewater streams. SITE CHARACTERIZATION AND ASSESSMENTAslibekian and Moles (2003) performed an environmental risk assessment of metal-contaminated soils in the vicinity of an abandoned silver mine in Tipperary, Ireland. The authors report a procedure for conducting preliminary evaluation of environmental risk and found that the most affected areas were floodplains located 2-3 km downstream from the site that were influenced predominantly by surface runoff and seasonal groundwater seepage from the abandoned mine. A study by Tarras-Wahlberg and Lane (2003) investigated sediment-associated metal transport (Cd, Cu, Hg, Pb, and Zn) in the Puyango river basin, Ecuador. The site was assessed by combining both the suspended sediment rating method and Monte Carlo simulations for wet and dry years.The authors report that in wet years, the metal polluted sediment load accounted for a small proportion of the yield estimates whereas the in dry years the metal-polluted 1685 sediments had a more significant effect and posed a more severe environmental impact. Fleit and Lakatos (2003) studied the accumulation of metals (Cd, Hg, Pb, Cu, and As) in river sediments and uptake of the metals by fish in the Tisza and Azamos Rivers (in Romania) following mining related spills. The study results indicate that the bioavailability of the metals varied within the river systems; however, the metal content of the fish was found to be lower than regulatory standards. In an effort to identify the effects of a waste mine tailing detention pond on water quality in the Mediterranean Sea near northern Cyprus (Greece), Gokcekus and co-workers (2003) conducted a study that combined water sampling and wave modeling techniques. A combined sediment and water quality study was performed in January and May 1999 by Hudson-Edwards et al. (2003) on the Agrio-Guadiamar river systems (Aznalcollar, Spain), which had been the site of a mining spill in April 1998. The authors report that following initial clean-up operations, the sediment metal concentrations were still higher than pre-spill conditions and reactive sulfidic material continued to undergo oxidation reactions, as indicated by higher dissolved metal concentrations in May 1999 compared to January 1999. The authors also report the following sequence of sediment mobility: Zn>Cd>Cu>Pb>As.A number of studies were performed to characterize water quality and sedimentassociated metals in the Odiel River (Huelva, Spain). Sainz et al. (2003b) attempted to characterize the primary sources responsible for mine drainage within the basin -mine dumps, active m...

reviews literature published in 2004 pertaining to environmental processes that affect mineral dissolution reactions and the generation of acid mine drainage (AMD), the fate and transport of metal contaminants within the environment, the toxic influences of metals and mine drainage on aquatic organisms and plant species, characterization of abandoned mines and their potential for contamination, and technologies for remediation of mining-impacted systems or removing metals from acid drainage wastewater streams. Since there are a great number of studies focusing on minerals in subsurface environments, this review will be limited in scope to mineral systems influenced by mining activity or anthropogenic disturbances related to mining. SITE CHARACTERIZATION AND ASSESSMENTThis section of the review highlights published works relating to the quantitative description of mining sites or mineral systems. Included in this description are several new techniques for predicting whether a particular site will be prone to producing pollution. In a study aimed at assessing whether flooded underground mines were homogeneous throughout their depth profile, Nuttall and Younger (2004) reported that 1859 hydrochemical stratification did in fact occur in a flooded mine in Frances Colliery, Scotland. The authors reported that for this particular system, less polluted water tended to collect at the top of the water column with much of the more polluted water remaining at the bottom. Upon disturbing the stratification, it was found that the mixed concentrations of iron and zinc were about 100 times higher than the concentrations measured in the undisturbed surface water.Several studies have used spectroscopic techniques to assess metal contamination in sediments. A study of arsenic speciation in several mining waste piles and contaminated soils in the Czech Republic was performed by Filippi et al. (2004) using X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive microanalysis (EDAX). The study found that although the native arsenic mineralogy amongst the three mining areas researched was very similar in nature and origin, the arsenic was associated with different products in the sediment and waste piles, suggesting that site-specific conditions were the primary factors in controlling the fate of arsenic. Osan et al. (2004) characterized the anthropogenic particles in river sediment in the Romanian part of the Tisza catchment area following failure of a tailings dam. The authors utilized single-particle electron probe X-ray microanalysis (EPMA) and synchrotron radiation-based microbeam X-ray emission and absorption methods to identify trace element content, heterogeneity, and heavy metal speciation. Overall, it was found that the majority of the heavy metals released from the tailings area remained in a stable sulfide form, thereby limiting the metal mobility to the river. Characterization of the heavy metal pollution and acid drainage from an abandoned lead-and zinc-sulfide mine in Turkey by Aykol et al. (20...