This paper reports the results of an experimentalstudytesting a low-cost in situ chemical fixation method designed to reclaimarsenic-contaminated subsurface soils. Subsurface soils from severalindustrial sites in southeastern U.S. were contaminated with arsenicthrough heavy application of herbicide containing arsenic trioxide. Themean concentrations of environmentally available arsenic in soilscollected from the two study sites, FW and BH, are 325 mg/kg and 900mg/kg, respectively. The soils are sandy loams with varying mineralogicaland organic contents. The previous study [Yang L, Donahoe RJ. The form, distribution and mobility of arsenic in soils contaminated by arsenictrioxide, at sites in Southeast USA. Appl Geochem 2007;22:320 341]indicated that a large portion of the arsenic in both soils is associatedwith amorphous aluminum and iron oxyhydroxides and shows very slowrelease against leaching by synthetic precipitation. The soil's amorphousaluminum and iron oxyhydroxides content was found to have the mostsignificant effect on its ability to retain arsenic. Based on thisobservation, contaminated soils were reacted with different treatmentsolutions in an effort to promote the formation of insolublearsenic-bearing phases and thereby decrease the leachability of arsenic. Ferrous sulfate, potassium permanganate and calcium carbonate were usedas the reagents for the chemical fixation solutions evaluated in threesets of batch experiments: (1) FeSO4; (2) FeSO4 and KMnO4; (3) FeSO4,KMnO4 and CaCO3. The optimum treatment solutions for each soil wereidentified based on the mobility of arsenic during sequential leaching oftreated and untreated soils using the fluids described in EPA Method 1311[USEPA. Method 1311: toxicity characteristic leaching procedure. Testmethods for evaluating solid waste, physical/chemical methods. 3rd ed. Washington, DC: U.S. Environmental Protection Agency, Office of SolidWaste. U.S. Government Printing Office; 1992]toxic characteristicsleaching procedure (TCLP) and EPA Method 1312 [USEPA. Method 1312:synthetic precipitation leaching procedure. Test methods for evaluatingsolid waste, physical/chemical methods. 3rd ed. Washington, DC: U.S. Environmental Protection Agency, Office of Solid Waste. U.S. GovernmentPrinting Office; 1994]synthetic precipitation leaching procedure(SPLP). Both FW and BH soils showed significant decreases in arsenicleachability for all three treatment solutions, compared to untreatedsoil. While soils treated with solution (3) showed the best results withsubsequent TCLP sequential leaching, SPLP sequential leaching of treatedsoils indicated that lowest arsenic mobility was obtained using treatmentsolution (1). Treatment solution (1) with only FeSO4 is considered thebest choice for remediation of arsenic-contaminated soil because SPLPsequential leaching better simulates natural weathering. Analysis oftreated soils produced no evidence of newly-formed arsenic-bearing phasesin either soil after treatment. Sequential chemical extractions oftreated soils indicate that surface complexation of arsenic on ferrichydroxide is the major mechanism for the fixation process.

Providing an introduction, the scientific background, case studies and future perspectives of in-situ arsenic remediation technologies for soils, soil water and groundwater at geogenic and anthropogenic contaminated sites. The case studies present in-situ technologies about natural arsenic, specifically arsenate and arsenite, but also about organic arsenic compounds. This work covers geochemical, microbiological and plant ecological solutions for arsenic remediation. It will serve as a standard textbook for (post-)graduate students and researchers in the field of Environmental Sciences and Hydrogeochemistry as well as researchers, engineers, environmental scientists and chemists, toxicologists, medical scientists and even for general public seeking an in-depth view of arsenic which had been classed as a carcinogen. This book aims to stimulate awareness among administrators, policy makers and company executives of in-situ remediation technologies at sites contamined by arsenic and to improve the international cooperation on the subject.

This book presents a comprehensive and detailed description of remediation techniques for metal-contaminated soils derived from both natural processes and anthropogenic activities. Using a methodical, step-by-step presentation, the book starts by overviewing the origin of toxicants and the correlated comparative extent of contamination to the environment. The legal provisions as proposed or applied in different countries are then discussed to explain the global regulatory situation regarding soil contamination and the extent of consequent concern. The core part of this publication describes the major techniques for in situ or ex situ treatment of the contaminated soil to meet the regulatory limits. Finally, risk evaluation is incorporated, giving special attention to possible impacts during or after implementation of the remediation strategies. The intrusion of metals in soils mostly occurs from various anthropogenic activities, e.g., agricultural practices, industrial activities, and municipal waste disposal. The volumes of metal-contaminated soil are becoming greater than before and are ever-increasing due to rapid urbanization, intensified industrialization, and/or population booms in certain parts of the world. Hence, the options previously proposed, such as isolation of the contaminated site or movement of the contaminated mass to a secure disposal site after excavation, are becoming unsuitable from the economic point of view, and instead, decontamination alternatives are preferred. This book will help readers such as scientists and regulators to understand the details of the remediation techniques available to deal with the soils contaminated by toxic metals.

"Offers thorough coverage of the remediation of soils contaminated by hazardous wastes, including materials, analytical techniques, cleanup design and methodology, characterization of geomedia, monitoring of contaminants in the subsurface, and waste containment. Cites specific case studies in hydrocarbon remediation that offer a concise overview of possible technological approaches."