Soil Washing Feasibility at a Manufacturing Gas Plant Site

Bench-scale treatability tests were carried out in order to evaluate performances of “physical” soil washing (particle size classification aimed at “concentrating” contamination in the fine fraction of the soil) and of a surfactant-aided soil-washing process on a brownfield soil, contaminated by high-molecular-weight Polycyclic Aromatic Hydrocarbons (PAHs). In the first case, soil was classified by wet particle separation using water, whereas it was extracted by water + surfactant in the second case. The chemical agent was selected among non-ionic synthetic and anionic biogenic surfactants (Triton X-100, Igepal CA-720, Brij-30, JBR 325), evaluating the kinetics of the desorption process and the extraction efficiency for different time of contact with soil. Surfactant concentration was selected by evaluating the extraction efficiency at the optimal time of contact. A surfactant-aided soil-washing process was tested, where soil was sequentially treated by fresh soil-washing solution (water + surfactant), and soil-washing solution was recycled for other contaminated soil. Transfer efficiency of PAHs and recovery of surfactant solution were evaluated     

Heavy Metal Contamination in the Brownfield Soils of Cleveland

The results esults of a survey of heavy metal contamination at Cleveland area brownfields and public spaces are presented. Soils were analyzed using a 24?h, 1N HCl extraction procedure. The study was conducted to seek brownfield soils that manifest properties of “old” sequestered contamination and to develop a better understanding of the nature and extent of heavy metal burdens at brownfield sites in the Greater Cleveland area. The results indicated that Cleveland brownfields commonly yield soil burdens well above remediation triggers for residential soils and often yield values above industrial remediation triggers. It was also discovered that public areas in the vicinity of brownfields commonly have heavy metal contamination significantly above background levels and occasionally above residential remediation triggers. These results indicate that brownfields redevelopment initiatives should proceed with caution. The appropriate remediation goals or restrictions must be imposed to control urban exposure to heavy metal contamination.     

A Statistical Evaluation of Sediment Quality Triad Benthic Community Measurements in PAH-Impacted Sediments at a Manufactured Gas Plant Site along the Hudson River

The sediment quality triad (SQT) assumes that three measurements (sediment chemistry, laboratory bioassay, and benthic macroinvertebrate counts) comprise an independent assessment of impact, which when integrated using a weight-of-evidence approach provides a comprehensive assessment of risk. An SQT assessment was conducted on 41 sediment samples collected adjacent to a manufactured gas plant site on the freshwater reach of the Hudson River in New York State. The assessment shows that the benthic macroinvertebrate data did not correlate with either sediment or pore water polycyclic aromatic hydrocarbon (PAH) concentrations, nor did these data show consistent relationships to the results of laboratory bioassay testing (Hyalella azteca 28-day survival or biomass). The benthic community across the site and reference areas was comprised of few taxa, all of which were pollution-tolerant organisms with tolerance values greater than or equal to five. Only in significantly impacted sediment samples with PAH concentrations in the thousands of milligrams per kilogram, pore water concentrations above 100 toxic units, and visible non-aqueous phase liquid present in the sample did the benthic macroinvertebrate data show a response. In contrast, sediment and pore water PAH measurements and H. azteca toxicity testing provided consistent interpretation of impact. These results illustrate that benthic macroinvertebrate data may contain less information value and be a more challenging line of evidence to interpret in triad studies conducted in certain ecological settings; in this case, a large-order river with a relatively depauperate benthic community dominated by species tolerant of PAHs.     

Estimation of Cd,Pb, and Zn Bioavailability in Smelter-Contaminated Soils by a Sequential Extraction Procedure

Chemical fractionation methods may be capable of providing an inexpensive estimate of contaminant bioavailability and risk in smelter-contaminated soil. In this study, the relationship between metal fractionation and methods used to estimate bioavailability of these metal contaminants in soil was evaluated. The Potentially BioAvailable Sequential Extraction (PBASE) was used for Cd, Pb, and Zn fractionation in 12 soils contaminated from Pb and Zn mining and smelting activities. The PBASE procedure is a four-step sequential extraction: extraction 1 (E1) is 0.5 M Ca(NO₃)₂, E2 is 1.0 M NaOAc, E3 is 0.1 M Na₂EDTA, and E4 is 4 M HNO₃. Metal bioavailability for two human exposure pathways, plant uptake (phytoavailability) and incidental ingestion (gastrointestinal, Gl, availability), was estimated using a lettuce (Lactuca sativa L.) bioassay and the in vitro-Gl Physiologically Based Extraction Test(PBET). Metal in the PBASE E1 fraction was correlated with lettuce Cd (P < 0.001) and Zn (P < 0.05) and was the best predictor of Cd and Zn phytoavailability. Only total metal content or the sum of all PBASE fractions, ΣE_1–4, were correlated (P < 0.001) with PBET gastric phase for Pb. The sum of the first two PBASE fractions, ΣE_1–2, was strongly correlated (P < 0.001) with Pb extracted by the PBET intestinal phase. The PBASE extraction method can provide information on Cd and Zn phytoavailability and Gl availability of Pb in smelter-contaminated soils.     

Assessment of Metal Availability in Soils from a Pb-Zn Mine Site of South-Central Spain

Heavy metal pollution of the soils around an abandoned Pb-Zn mine site located in the Alcudia Valley (South Central Spain) have been characterized by analysis of extractable and total metal concentrations in 60 samples of arable, pasture, and mine lands. The samples showed a broad range of size-particle distribution, cation exchange capacity, and pH values as well as high levels of total metal concentrations (up to 98510 mg kg^?1 of Pb, up to 20912 mg kg^?1 of Zn, and up to 61 mg kg^?1 of Cd). In order to assess the potential availability of metals the metal partitioning in two different soil size fractions (<2 mm and <63 μm) was determined using EDTA and CaCl₂ as sequestering reagents. The average contents of Pb, Zn, and Cd in the <63 μm particle size fraction for both extractions were higher than those of the <2 mm fraction due to the high metal adsorption capacity of the fine soil particles. Concentrations of heavy metals extracted by CaCl₂ were up to three orders of magnitude lower than those extracted by EDTA, because CaCl₂ only extracts the easily mobile fraction. Metal concentrations extracted by both procedures in the two granulometric fractions increased with total metal concentrations, thus increasing the potential environmental risk associated to heavy metal pollution.     

Human Health Risk Assessment of Soils Contaminated with Metal(loid)s by Using DGT Uptake: A Case Study of a Former Korean Metal Refinery Site

The human health risk of soils contaminated with As, Pb, Cu, and Zn was evaluated based on pseudo-total concentrations of metal(loid)s, the physiologically based extraction test (PBET), and diffusive gradients in thin films (DGT). Non-carcinogenic (NCR) and carcinogenic (CR) risks exceeded the U.S. Environmental Protection Agency criteria under both the residential and non-residential scenarios. Human bioavailable concentrations (PBET) were much lower than pseudo-total concentrations. The Hazardous Index of NCR (HI (NCR)) for the PBET in the studied soils was 67% and 94% less than that for pseudo-total concentration, respectively, under the non-residential and residential scenarios. Similarly, CR for the PBET was also 65% and 93% less for the two soils. The concentration of metal(loid)s accumulated in the DGT resin was highly correlated with the PBET-extractable concentration (R² > 0.649). Therefore, for both the CR and HI (NCR), the DGT-calculated risk was linearly related to the PBET-calculated risk for the studied soils under both scenarios. The results suggest that DGT uptake and PBET-extracted concentrations are good surrogates for risk estimation and that both J1 and J2 soils require remediation before their use for residential or non-residential purposes.     

Aspects Affecting Biosynthesis and Biotransformation of Secondary Metabolites in Plant Cell Cultures

Abstract

Biosensors are useful analytical devices that can be integrated with on-line process monitoring schemes. In this article, the principles and applications of these devices for bioprocess monitoring are considered. Several different types of biosensors are described, and the applications and limitations of flow injection analysis (FIA) for these applications are discussed. It is hoped that the background provided here can be useful to researchers in this area.     

Fenton's Reagent-Based In Situ Chemical Oxidation Treatment of Saturated and Unsaturated Soils at a Historic Railroad Site

A targeted treatment program utilizing in situ chemical oxidation was used to remediate diesel fuel-derived petroleum compounds in unsaturated and saturated soils at a historic railroad facility. This program consisted of multiple injections at varying depths within temporary Geoprobe® injection points. The actual treatment time was less than 3 months. Overall concentrations of volatile and semivolatile organic petroleum compounds were reduced by approximately 70%, while the total petroleum hydrocarbon concentration was reduced by nearly 50%. Treatment efficiency in unsaturated soil was similar to that in saturated soil. The results of the remedial program indicate that the effect of grain size of the subsurface materials on treatment efficacy is significant. The project has shown that the use of this technology can be as effective as other in situ treatment technologies used for treating subsurface diesel fuel contamination.     

Chemical Extraction of Arsenic from Contaminated Soils in the Vicinity of Abandoned Mines and a Smelting Plant Under Subcritical Conditions

Under subcritical conditions, we studied the chemical extraction of arsenic (As) from contaminated soils that were sampled from the vicinity of abandoned mines and a smelting plant in South Korea. The total initial concentrations of As in the soil samples from the Myungbong and Cheongyang mines and the Janghang smelting plant were 298.6, 145.6, and 103.7 mg/kg, respectively. X-ray photoelectron spectroscopy analysis showed that the species of As identified in the soil was As(+V), including As₂O₅ and AsO₄ ^3? _. At 20°C, only 27.4, 26.5, and 40.1% of the total As was extracted from the Myungbong, Cheongyang, and Janghang soil samples, respectively, with 100 mM of NaOH. As the temperature was increased to 300°C, the extraction efficiencies remarkably increased. However, to achieve the complete extraction of As from the soils, 100 mM of citric acid, EDTA, or NaOH was needed at 200, 250, or 300°C. Extraction with subcritical water at 300°C resulted in incomplete extraction of As from the soils. The results of these experiments indicate that extraction mechanisms other than oxidative dissolution of As(+III) species may be responsible for the enhancement of As extraction. Our results suggest that subcritical water extraction combined with extracting reagents can effectively remediate As-contaminated soil regardless of the As species.     

Plant Growth-Promoting Bacteria Facilitate the Growth of Barley and Oats in Salt-Impacted Soil: Implications for Phytoremediation of Saline Soils

Plant growth-promoting bacteria (PGPB) strains that contain the enzyme 1-amino- cyclopropane-1-carboxylate (ACC) deaminase can lower stress ethylene levels and improve plant growth. In this study, ACC deaminase-producing bacteria were isolated from a salt-impacted (～50 dS/m) farm field, and their ability to promote plant growth of barley and oats in saline soil was investigated in pouch assays (1% NaCl), greenhouse trials (9.4 dS/m), and field trials (6–24 dS/m). A mix of previously isolated PGPB strains UW3 (Pseudomonas sp.) and UW4 (P. sp.) was also tested for comparison. Rhizobacterial isolate CMH3 (P. corrugata) and UW3+UW4 partially alleviated plant salt stress in growth pouch assays. In greenhouse trials, CMH3 enhanced root biomass of barley and oats by 200% and 50%, respectively. UW3+UW4, CMH3 and isolate CMH2 also enhanced barley and oat shoot growth by 100%–150%. In field tests, shoot biomass of oats tripled when treated with UW3+UW4 and doubled with CHM3 compared with that of untreated plants. PGPB treatment did not affect salt uptake on a per mass basis; higher plant biomass led to greater salt uptake, resulting in decreased soil salinity. This study demonstrates a method for improving plant growth in marginal saline soils. Associated implications for salt remediation are discussed.     

A Practical Examination of the Use of Geostatistics in the Remediation of a Site with a Complex Metal Contamination History

Targeted remediation strategies offer the potential to treat only those areas where contamination exceeds predefined threshold levels. We used geostatistical techniques to characterize spatial distribution of heavy metals across a contaminated site, with the aim of delineating the contaminants, which is essential for successful implementation of targeted remediation strategies. Samples collected from three depths, 0–20 cm, 20–40 cm and 40–60 cm at 50 sample locations, were analyzed for As, Sb, Hg, Pb, Cd and Cu contents. The geostatistical analysis of this data enabled the identification of a number of contamination hotspots and trends. The visual interpretation of the data was supported by the statistical analysis in the form of Spearman's rank correlation coefficient. Additionally, classical statistics, based on the central limit theorem, showed that, in terms of obtaining the true mean for each of the contaminants within acceptable limits of precision, the site has been more than adequately sampled.It has been demonstrated that kriging can offer the potential to map the spatial distribution of contaminants. However, the possibility of an undetected hotspot remains, even when probabilistic modelling and a secondary phase of validatory sampling are employed. This together with the large number of samples required may preclude the commercial use of geostatistics in the remediation of contaminated land.     

Bioavailability of Potentially Toxic Elements in Foraged Fruits from a Former Industrial Site

Samples of foraged fruits from a former industrial site have been analyzed for potentially toxic elements (PTEs) (i.e., As, Cd, Cr, Cu, Ni, Pb, and Zn). The foraged fruit (blackberries, rosehips, and sloes) was gathered over two seasons along with samples of soil from the same sampling areas. All samples were acid digested, using a microwave oven, and then analyzed by inductively coupled plasma mass spectroscopy (ICP-MS). The concentration levels of the selected elements in foraged samples varied between not detectable limits and 24.6 μg/g (Zn). The soil-to-plant transfer factor was assessed for the PTEs. In all cases, the transfer values obtained were less than 1.00, indicating that the majority of the PTEs remains in the soil and that the uptake of PTEs from soil to plant at this site is not significant.     

A Rapid Method,Combining Microwave-Assisted Extraction and Gas Chromatography-Mass Spectrometry with a Database,for Determining Organochlorine Pesticides and Polycyclic Aromatic Hydrocarbons in Soils and Sediments

A rapid method for determining organochlorine pesticides and polycyclic aromatic hydrocarbons in soils and sediments was developed to allow pollution surveys to be performed in emergencies. The method involves microwave-assisted extraction and uses an automated identification/quantification system with a gas chromatography mass spectrometry database. A sample (3 g) is extracted with a 3:2 v/v hexane:water mixture (10 mL) for 30 min using a microwave-assisted extraction system at 120°C. The hexane extract is then cleaned using silica gel, then analyzed by gas chromatography mass spectrometry. The total analysis time is approximately 4 h. The precision of the quantitative results and accuracy of the analyte identification were determined. The total analyte concentrations were generally comparable to (61%–110% of) the concentrations determined using a Soxhlet extraction method, but the concentrations of individual high-molecular-weight polycyclic aromatic hydrocarbons were unacceptably low compared with the concentrations determined using the Soxhlet method. However, these compounds (e.g., benzo(ghi)perylene and indeno(1,2,3-cd)pyrene) were subsequently efficiently extracted using a hexane:water:ethanol mixture. The accuracy of identification was evaluated using accurate masses determined by gas chromatography time-of-flight mass spectrometry, and the mass error was 2 ppm for 21 of the 22 compounds identified using the new method.     

Gas phase photocatalytic degradation on TIO2 pellets of volatile chlorinated organic compounds from a soil vapor extraction well

The degradation of trichloroethylene (TCE, Cl₂C=CHCl) and tetrachloroethylene (PCE, Cl₂C=CCI₂) in a gas stream from a soil vapor extraction (SVE) well was demonstrated with an annular photocatalytic reactor packed with porous TiO₂ pellets in a field trial at the Savannah River Site in Aiken, SC. The TiO₂ pellets were prepared using a sol‐gel method. The experiments were performed at 55 to 60°C using space times of 10⁸ to 10¹⁰ g ? s ? mol^‐1 for TCE and PCE. Chloroform (CHCl₃) and carbon tetrachloride (CCl₄) were detected as minor products from side reactions. On a molar basis, the amounts CCl₄ and CHCl₃ produced were about 2 and 0.2% of the reactants, respectively.     

A chemiluminometric method for the determination of urea in serum using a three-enzyme bioreactor

A flow injection chemiluminometric assay for urea has been developed based on a minicolumn bioreactor packed with immobilized enzyme-bearing glass beads. The reactor contains immobilized urease, L -glutamate dehydrogenase and L -glutamate oxidase, aligned in this order (upstream to the downstream). When the sample is introduced into the bioreactor, urea is first hydrolysed by urease to produce ammonia, which is then converted into L -glutamate by L -glutamate dehydrogenase. L -Glutamate is finally oxidized by L -glutamate oxidase to produce hydrogen peroxide, which is quantified by measuring chemiluminescence emitted upon admixing with luminol and potassium ferricyanide. One assay cycle is completed within 1 minute. The method is sensitive (detection limit 0.5 nmol) and is linear in the range 0–30 mmol/l. It can be readily applied to the determination of urea in human serum, and requires no blank corrections for ammonia and/or L -glutamate present in serum samples.     

Flow injection analysis of blood L-lactate by using a Prussian Blue-based biosensor as amperometric detector

An amperometric l-lactate biosensor was fabricated by confining lactate oxidase in a Prussian Blue-modified electrode with a Nafion membrane. The detector was assembled in a flow injection apparatus and operated at -0.1 V. Conditions for optimal electrode response were determined by investigating the influence of the amount of immobilized enzyme, the sample volume, and the flow rate. At the established operational conditions, the biosensor exhibited negligible response from interfering species usually present in biological fluids. The stability of the biosensor was also investigated, and its sensitivity was maintained unchanged at certain experimental conditions. l-Lactate was determined in blood samples, and the influence of physical exercise on the results was clearly evidenced, demonstrating that the proposed amperometric detector is suitable for monitoring changes in the l-lactate levels in biological fluids.     

Development of a flow‐injection analysis system with fluorescence detection for gatifloxacin determination in organized medium

This work reports the development and optimization of a flow injection analysis system with fluorescence detection (FIA–FLUO) for gatifloxacin (GFX) determination in organized medium. The analytical system was based on the enhanced fluorescence of gatifloxacin in micellar medium containing sodium dodecyl sulfate (SDS) at pH 6.0. The influence of physical (carrier flow rate, sample volume and volume of reaction coil) and chemical (pH, concentration of buffer and concentration of SDS) parameters that could affect the performance of the FIA system was evaluated in order to reach optimum conditions in terms of sensitivity and analytical throughput. Under optimized conditions, the FIA–FLUO system allowed the injection of 40 samples per hour with a limit of quantification of 72 µg/L and a RSD of 3.5% at 0.20 mg/L. Real samples of commercial pharmaceutical formulations containing GFX were analyzed, and no statistical difference was observed between the results obtained using the developed system and those obtained using the reference method based on high‐performance liquid chromatography with UV detection. Copyright © 2014 John Wiley & Sons, Ltd.     

Use of a micro-expanded bed containing immobilised lysozyme for cell disruption in flow injection analysis

A method for cell disruption in Flow Injection Analysis (FIA) systems has been developed. The principle involves on-line cell disruption by means of immobilised lysozyme followed by an ultrasonic treatment. In order to avoid flow problems in the analytical system, the lysozyme was immobilised to Streamline^reg that was used in an expanded bed in the flow system. Samples of suspensions of Micrococcus lysodeikticus were treated and the success of the treatment was evaluated in terms of released protein and as a decrease in the optical density at 450 nm. The new technology offers a powerful tool in flow injection analyses for quantification of intracellular compounds. The concept of integration, i.e. combining cell disruption with handling of cell debris and assay procedure in one continuous flow process facilitates its use and increases the probability of reaching reproducible and reliable results.     

On-line monitoring of glucose and/or lactate in a fermentation process using an expanded micro-bed flow injection analyser

A novel flow injection biosensor system for monitoring fermentation processes has been developed using an expanded micro bed as the enzyme reactor. An expanded bed reactor is capable of handling a mobile phase containing suspended matter like cells and cell debris. Thus, while the analyte is free to interact with the adsorbent, the suspended particulate matter passes through unhindered. With the use of a scaled down expanded bed in the flow injection analysis (FIA) system, it was possible to analyse samples directly from a fermentor without the pretreatment otherwise required to extract the analyte or remove the suspended cells. This technique, therefore, provides a means to determine the true concentrations of the metabolites in a fermentor, with more ease than possible with other techniques.Glucose oxidase immobilised on STREAMLINE was used to measure glucose concentration in a suspension of dead yeast cells. There was no interference from the cell particles even at high cell densities such as 15 gm dry weight per litre. The assay time was about 6 min. Accuracy and reproducibility of the system was found to be good. In another scheme, lactate oxidase was covalently coupled to STREAMLINE for expanded bed operation. With the on-line expanded micro bed FIA it was possible to follow the fermentation with Lactobacillus casei.     

Acid-Generating and Leaching Potential of Soils in a Coal Waste Rock Pile in Northeastern China

The present study involved the assessment of potential generation of acid drainage and also metal leaching from an abandoned large (175 m) low sulfur waste rock pile—the dominant mine waste at the site—at the Haizhou coal mine. Laboratory-based static and column leaching tests on waste rock samples were conducted. The static tests were done for 8 composite samples collected from different parts of pile. A column study was performed using mixture of waste rock soil samples to assess metals attenuation process of background soils in vicinity of pile when rainwater reacts with low-sulfide waste rocks. Total concentration of major elements in solid samples was determined using dispersive X-ray fluorescence spectrometry (XRF) and chemical analysis of leachate were measured by inductively coupled plasma optical emission spectrometry (ICP-OES), ion chromatography and titration methods. The inverse geochemical modeling using PHREEQC was applied to explain possible mass transfer processes between column leachates of waste pile and background soils. Static tests (including acid–base accounting (ABA) and net acid generation (NAG)) and mineralogical information suggest that the waste rock is non-acid generating. The large amount of aluminosilicate minerals and probably trace amounts of carbonates with respect to low sulfur content of waste rock pile represents a potentially large source of neutralization potential according to static test results. It was also found that presence of inherent neutralizing materials in waste rock and also in surrounding background soils provide sufficient neutrality and possibly immobilize the trace and heavy metal contents of waste rocks and potentially protects water resources.