Journal Issue: International Journal of Soil: Volume 2, Issue 2
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2009-04-08
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Lead in Soil - An Examination of Paired XRF Analysis Performed in the Field and Laboratory ICP-AES Results
Binstock, David A; Gutknecht, William F; McWilliams, Andrea C
A major aspect of lead hazard control is the evaluation of soil lead hazards around housing with lead-based paint applied to specific exterior surfaces. The use of field-portable X-ray fluorescence (FPXRF) to do detailed surveying, with limited laboratory confirmation, can provide lead measurements in soil (especially for planning and monitoring abatement activities) in a more timely manner than laboratory analysis. To date, one obstacle to the acceptance of FPXRF as an approved method of measuring lead in soil has been a lack of correspondence between field and laboratory results. In order to minimize the differences between field and laboratory results, a new protocol has been developed for field drying and sieving of collected samples for field measurement by FPXRF. To evaluate this new protocol, composite samples were collected in the field following both HUD Guidelines and American Society for Testing and Materials (ASTM) protocols, measured after drying and sieving by FPXRF, and returned to the laboratory for confirmatory inductively coupled plasma atomic emission spectroscopy (ICP-AES) analysis. Evaluation of study data from several diverse sites revealed no statistical difference between paired FPXRF and ICP-AES measurements when samples were dried and sieved to less than 250 µm particle size.
Background Versus Risk-Based Screening Levels - An Examination of Arsenic Background Soil Concentrations in Seven States
Vosnakis, Kelly A.S.; Perry, Elizabeth
Arsenic is often present in soils naturally or from historical anthropogenic activities. Arsenic is commonly a constituent of potential concern at environmental remediation sites, even where there is no reason to suspect a release. Site risks are frequently driven by arsenic, and risk-based screening levels below background are not uncommon. However, determining whether arsenic concentrations are consistent with background typically requires an extensive background data set. The ability to gain access to representative background locations owned by third parties is problematic at best in any characterization study. Consequently, many sites undergo characterization and potentially remediation for arsenic concentrations in soil that may in reality be representative of background (natural or anthropogenic). This study examines a large soil arsenic background data set to provide insight on typical concentrations of arsenic that are naturally occurring or represent anthropogenic background. Between 1995 and 2001, over 1,600 background soil samples were collected from 189 sites in Kentucky, Maryland, New York, Ohio, Pennsylvania, Virginia, and West Virginia. Samples were collected using strict Quality Assurance/Quality Control procedures under a United States Environmental Protection Agency (USEPA) Superfund Administrative Order on Consent (AOC) and were analyzed by USEPA-approved laboratories. All data were verified and 10% underwent detailed data validation. Arsenic concentrations in samples retained for statistical analysis ranged from 1.1 mg/kg to 89 mg/kg. Data are evaluated by state and by geology and are compared to USEPA and state risk-based screening levels (RBSLs). Some standard background threshold values (BTVs) are derived for each state and distinct geology. The BTVs are greater than RBSLs. This extensive, regional data set should be considered by all stakeholders involved in relevant risk-based decisions related to arsenic in soils. The consideration of this data set and the BTVs may aid in the appropriate identification of arsenic in soils below typical background concentrations. In turn, the use of BTVs may aid in identifying where risks are truly elevated relative to background, and thus where remediation may or may not be appropriate.
Updated Massachusetts Indoor Air Quality Threshold Values: A Case Study
Stromberg, Richard G; Gaito, Steven T; Bell, Caitlin
A sudden heating oil release occurred below a concrete slab of a residence in Massachusetts. The oil entered an open sump in the basement and migrated to a nearby stream. Remediation included deployment of absorbent booms, limited soil excavation, and in-situ treatment with hydrogen peroxide. Soil, sediment, groundwater, and indoor air samples were analyzed to delineate the extent of contamination, verify that remedial efforts were successful, and determine if a vapor intrusion pathway existed. Indoor air samples were collected on three events: at the time of release, after remedial activities, and four months later. Indoor air analytical results were compared to the new draft Threshold Values published by the MassDEP Indoor Air Working Group (June 2008). In each sampling event, various compounds were detected above the applicable Threshold Values. As suggested by the MassDEP, multiple lines of evidence were investigated to determine whether the exceedances were attributable to the release. The presence of mothballs, the construction and operation of the home heating system, analytical evidence of a potential historical release, and soil and groundwater analytical data were used as lines of evidence that a vapor intrusion pathway did not exist.
Bio-geochemical Factors that Affect RDX Degradation
Felt, Deborah R; Bednar, Anthony; Arnett, Clint; Kirgan, Robert
Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) is a secondary high explosive that has been identified as a contaminant of concern in groundwater and soil as a result of military training activities (Wani et al., 2002). Remediation technologies that have been proposed for use on these training ranges include in situ techniques. An obstacle to using in situ approaches for the treatment of RDX contaminated soils and groundwater is the lack of information concerning the biogeochemical factors that influence transformation. This research compares paired (biotic and poised abiotic systems) RDX degradation experiments in which Eh-pH conditions conducive to RDX degradation were established. Degradation of RDX under iron-reducing conditions was studied in biological and chemical systems. The redox conditions created by the biological systems were simulated by poised chemical systems in order to compare RDX transformation. The poised chemical systems used an iron-ligand complex to achieve the necessary Eh values for RDX degradation. RDX degraded in both biological and chemical systems and final reaction solutions from both systems were analyzed to determine which degradation pathway was followed. The results from this effort will expand the basic knowledge of energetic transformation over a range of biologically-induced conditions, by isolation of enzymatic pathways from abiotic redox mechanisms.
Chemical-Physical Treatments Of Marine Contaminated Sediments – A Comparison
Gente, Vincenzo; Geraldini, Serena; La Marca, Floriana; Gabellini, Massimo; Palombo, Francesco
Managing of sediments coming from dredging operations in ports, harbor areas and navigation waterways has to deal with huge quantities of highly contaminated material. As a matter of fact, due to routine operations, to the need of deepening fairways and ports and, eventually, to remediation activities, every year more than 200·106 m3 of dredged materials are produced throughout Europe. Chemical-physical treatments are generally used in order to separate a contaminated fraction from a clean one in order to reduce the quantity of sediments to be disposed of. Within this research work, carried out by the Department of Chemical Material Environment Engineering of Sapienza University of Rome and ISPRA (High Institute for Environmental Protection and Research), former ICRAM, sediments coming from a harbor area characterized by metal contamination have been treated adopting three different technologies: sieving, hydro-cycloning and flotation. Results show that sieving, hydro-cycloning and flotation are able to separate products in which metal contaminants generally present lower concentration compared to that of untreated dredged sediments. Nevertheless, in order to further reduce metal content in the cleaned fraction, the examined treatment cannot stand alone as a single step, but a multi steps or a combination of treatments have to be considered.