Kruti Oza, Center for Environmental Systems, Stevens Institute of Technology, Castle Point on Hudson, Hoboken, NJ 07030, Tel: 201-216-5681, Fax: 201-216-8303, Email: koza@stevens.edu
Washington Braida, Center for Environmental Systems, Stevens Institute of Technology, Castle Point on Hudson, Hoboken, NJ 07030, Tel: 201-216-5681, Fax: 201-216-8303, Email: wbraida@stevens-tech.edu
Christos Christodoulatos, Center for Environmental Systems, Stevens Institute of Technology, Castle Point on Hudson, Hoboken, NJ 07030,  Tel: 201-216-5675, Fax: 201-216-8303, Email: christod@stevens-tech.edu
Dimitris Dermatas, Stevens Institute of Technology, Civil, Environmental, and Ocean Engineering Department, Castle Point on Hudson, Hoboken, NJ 07030, Tel: 201-216-8926, Fax: 201-216-5352, Email: ddermata@stevens-tech.edu
Michael Los, TACOM-ARDEC, US Army Heavy Metals Office, Picatinny Arsenal, Picatinny, NJ 07806, Tel: 973-724-7038, Fax: 973-724-2034, Email: mlos@pica.army.com

Tungsten heavy alloys (WHA) are currently been considered for use in new munitions systems.  Our research indicates that under common environmental conditions, metallic tungsten and WHA will dissolve resulting in tungsten dissolved concentration in the mg/l level.  As a result of that, there is a potential need for development of remedial technologies addressing the removal of tungsten from contaminated aqueous streams.  This research presents preliminary data on the use of an innovative Ti-based sorbent for the remediation of tungsten contaminated aqueous streams.  Column studies were performed to assess the suitability of the sorbent and the influence of phosphate on tungsten uptake by the sorbent was also assessed.  The sorbent proves to be successful in removing dissolved tungsten and other alloying elements (iron, copper).  Phosphate anions appears to compete with tungsten for the active sites of the sorbent resulting in an early breakthrough of tungsten and diminishing sorbent’s tungsten sorption capacity. Distribution coefficients for tungsten alone and in the presence of phosphate were estimated by fitting the 1D advection-diffusion model to the experimental data.

Use of Silica-Supported, Modified Silica Based Reagents in the Remediation of Cadmium(II), Nickel(II), Silver(I) and Lead(II) Ions: An Environmental Cleanup Technology

Craig A. Bowe, Department of Mathematics and Sciences, Saint Leo University, PO Box 6665, Saint Leo, FL 33574-6665, Tel: 813-630-5595, Fax: 813-630-5722
Dean F. Martin, Distinguished Service Professor, Institute for Environmental Studies, Department of Chemistry, University of South Florida, 4202 East Fowler Avenue, Tampa, FL 33620, Tel: 813-974-2374, Fax: 813-974-8756

The pollution of freshwater sources by dissolved heavy metals is a major environmental problem faced worldwide.  Treatment of freshwater sources by treated silica based composites is an inexpensive, alternative environmental cleanup technology that is an emerging field.  Previous work describing the use of silica-supported reagents has established the possibility of using known chelating agents supported on silica based support for the removal of such heavy metals as lead, cadmium, copper, silver, and nickel from aqueous media.  Silica based materials are currently being used as a solid support for various straight-chain monofunctional and bifunctional compounds such as mercaptans and mercaptoalcohols.  The use of mercapto alcohols which have been attached covalently to the silica matrix has also been investigated.  The current study reports the results of an investigation involving the use of these composites in the removal of cadmium(II), nickel(II), silver(I) and lead(II) ions from standard aqueous solutions. 

Evaluation of Heavy Metal Availability in the Mining Areas of Bulgaria

Penka S. Zaprjanova, Institute of Tobacco and Tobacco Products, Markovo, 4108, Bulgaria, Tel: 359 32 275282, Fax: 359 32 695156, Email: tti@pl.bia-bg.com
Violina R. Angelova, University of Agriculture, Dept. of Chemistry, Mendeleev Street 12, Plovdiv, 4000, Bulgaria, Tel: 359 32 6126 242, Fax: 359 32 635920, Email:violina@au-plovdiv.bg 
Krasimir I. Ivanov, University of Agriculture, Dept. of Chemistry, Mendeleev Street 12, Plovdiv, 4000, Bulgaria, Tel: 359 32 6126 240, Fax: 359 32 635920, Email:kivanov@au-plovdiv.bg

An evaluation of content and availability of Pb Zn and Cd in mining regions of the East Rhodopes, Bulgaria was made. The preliminary survey showed that the soils in the evaluated region are heavily polluted by heavy metals (Pb - above 2000 mg/kg, Zn – above 1300 mg/kg and Cd - above 12 mg/kg).   The data of the total content however does not provide enough information about the quantity of these heavy metals accessible and potentially available by plants. In order to clarify this question we defined the mobile forms of Pb, Zn and Cd with the help of various extragents (salts solutions, chelating stuff and weak acids), as well as their content in dominant grass species. It was established that despite the low рН values, the light mechanical composition and the weak humus content in the soils of the surveyed region, the part of the mobile forms of heavy metals is considerably below the expected. Only 15% of the total quantity of cadmium and 8 % of the total quantity of the Pb and Zn are potentially assimilable by plants. This was decisively confirmed as well by the analyses made on the plant samples. The obtained results are explained by the established fact that heavy metals in the surveyed region are found principally under the form of weakly soluble and difficult for assimilation by plants sulphides. The main conclusion is that the total heavy metal content cannot be used as an explicit criterion for ecological evaluation of soils with regard to their exploitation for agricultural activities.

Seasonal Variation of Particulate Heavy Metals in Tambaraparni River Estuary, East Coast of India

N. Jayaraju, Department of Geology, S.V.University, Tirupati-517 502, India, Email : naddimi_raju@yahoo.com

The paper attempts to present the variability of the Particulate Heavy Metals (PHM)  in terms of time and space.  Temporal and spatial variability of PHMs (Cr, Cu, Fe, Mn and Zn) were investigated  in the estuarine setting.  The results revealed that the spatial variability was insignificant for all the studied metals.  Nevertheless, temporal fluctuations seem to be significant.  Two district behaviours, in general, were noticed for PHMs : 1) Metal Concentration (MC) increases together with waterflow (Cu and Fe) and  2) Concentration decreases with increasing waterflux (Cr, Mn and Zn).  The Cu and Fe behaviour is probably due to strong association of those metals with surface runoff, although their sources seem to be distinct.  Cu may be associated in the sugarcane plantations.  Iron may be originated from the regional soils  rich in Iron oxides.  The opposite trend observed for Cr, Mn and Zn probably reflects the importance of the industrial and urban effluent as a secondary source of these elements for the system.  Their behaviour is probably associated with the dilution effect caused by the input of a suspended matter poor in these metals originated from the surface runoff during the monsoon season.

Apatite from Different Natural Sources and its Suitability for Remediation of Contaminated Media

Anna S. Knox and D. I. Kaplan, Westinghouse Savannah River Company, Building 999-W, Aiken, SC 29808, Tel: 803 819 8406, Fax: 804 819 8416, Email: anna.knox@srs.gov

Researchers have reported that apatite, a calcium-phosphate mineral, immobilized Pb and other ions such as Mn, Co, Cu, Cd, Zn, Mg, Ba, U, or Th in contaminated media. Immobilization of these elements occurs due to precipitation, adsorption and isomorphic substitution.

Nine commercially available phosphate minerals, representing >95% of the phosphate production in the country, were evaluated for suitability for remediation of contaminated media. The following were approaches will be addressed in this paper: solubility, concentration of trace metals, and leachability of trace metals.  Processed and mined rock phosphate contain high total concentration of As, Co, Cr, Cu, and Sr, however, they did not exceed the RCRA TCLP limits. The use of stronger extractants indicated that these elements were very strongly bound by most apatite material; therefore, if they were applied to contaminated sediment at a rate sufficient for remediation, they would not increase environmental risk. The biogenic apatite (fish bone) contained significantly lower metal impurities than processed and mined rock phosphate and was appreciably more soluble, i.e., it had a logK_sp of -45.2 compared to -57.0 for the mined rock phosphate samples. 

There are many phosphate sources that can safely and effectively be used in remediation of contaminated soils.  By combining biogenic and mined phosphate it will be possible to obtain a wide range of phosphate solubility, permitting rapid immobilization of contaminants, while at the same time providing a slow release of phosphate for continued sediment treatment.

Environmentally Sound Technologies for Integrated Wastewater Treatment of Nickel Electroplating Facilities

G. Kochetov, V. Ternovtsev, Kiev National University of Construction and Architecture, 31 Povitroflotsky Pr., 03680, Kiev, Ukraine, Tel: 38-044 241-5530, Email: kochetov @ knuba.edu.ua

To increase of resource conservation and eliminate adverse environmental impacts of industrial facilities cost-efficiently, it is necessary to apply complex wastewater treatment and waste-recycle technologies.  Our previous research works allowed us to develop integrated low-waste technologies for treatment of mixed wastewater flows generated by electroplating, etching and degreasing processes with reuse of valuable heavy metals.

We believe, that the most promising option for addressing the wastewater treatment problems is associated with development of separate compact installations for treatment of individual industrial wastewater flows. Separation of wastewater  according to core components allows one to develop of small-scale closed circuit water supply systems and to regenerate valuable metals much easier. The current works were aimed on development of a cost-efficient integrated technology for treatment of wastewater of nickel electroplating facilities. For the time being, nickel electroplating operations are used extensively.  As a result, the problem of a efficient technology for recovery of this expensive metal  from wastewater flows  is fairly relevant. At the base of the ion-exchange technology we proposed several alternative systems for treatment of rinsing wastewater flows of nickel electroplating installations. Integrated application of different methods (ion exchange - reagent treatment of eluate and subsequent ion exchange - electrodialysis) allows one to select an optimal option for a local wastewater treatment system, tailored to specific local conditions.

Besides that, we have developed several treatment technologies for toxic nickel-containing exhausted solutions and solid waste (sludge). The technologies allow to obtain valuable marketable products: nickel salts, pigments for ceramic tile manufacture,  ingredients for ground enamel coatings for steel wares. We also proposed a technology for regeneration of exhausted nickel electrolyte solutions by extraction of detrimental components.  Our technologies have been tested at industrial sites and we recommend them for large-scale implementation. Implementation of these technologies would facilitate addressing environmental and economic problems by industrial enterprises.

New Heap-Leaching Method for Pb and Cu Contaminated Soils

Domen Lestan, Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, 1000 Ljubljana, Slovenia, Tel: +386 1 423 1161, Fax: +386 1 423 1088, Email: domen.lestan@bf.uni-lj.si
Neza Finzgar, University of Ljubljana, Jamnikarjeva 101, 1000 Ljubljana, Slovenia, Tel: +386 1 423 1161, Fax: +386 1 423 1088, Email: neza.finzgar@bf.uni-lj.si
Bostjan Kos, Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, 1000 Ljubljana, Slovenia, Tel: +386 1 423 1161, Fax: +386 1 423 1088, Email: bostjan.kos@bf.uni-lj.si

Soil remediation methods can be grouped into “harsh” techniques that efficiently alleviate the risk but destroy soil structure and fertility and “gentle” techniques that preserve or restore soil fertility. Heavy metal soil washing by chelators could qualify as gentle method, especially if the extraction is done via on site heap-leaching and not by extracting a soil slurry in a closed reactors. The main problem of current heap leaching technologies is the separation of metals  from waste chelator solution after soil extraction. This issue was addressed for Pb and Cu contaminated soils by using biodegradable chelator [S,S] stereoisomere of ethylenediamine disuccinate (EDDS), and by introducing heaps with horizontal permeable barriers constructed either in the heap bottom or as a separate bed. EDDS is low toxic, produces benign degradation products and is naturally present in the soil (produced by the soil actinomycete Amycolatopsis orietalis). New remediation method is a two-step process. First; heavy metals are mobilized by application of chelator solution into the soil. Water-soluble, biodegradable metal-chelator complexes are washed from contaminated soil by irrigation and introduced into the barrier (bed). Second step; metal-chelator complexes are microbially degraded in the barrier (bed). Released ions of metals chemically react with the sorbents in the barrier (bed) to form insoluble products and, consequently, accumulate in the barrier (bed). Contaminant-free solution exiting barrier (bed) is collected and reused for heap irrigation in a closed loop. When the targeted level of soil cleansing is reached, in one or several cycles of chelator addition, the barrier (bed) material, saturated with heavy metals, is disposed. Pb and Cu soil content, fractionation and bioavailability (Ruby's physiologically based extraction test, phytoavailability) were determined before and after remediation.

Sorption of Zn and Pb by Goethite in the Presence of Microorganisms 

Perelomov Leonid, Tula State University, Department of Medicine, Lenin Avenue, 92, Tula, 300600, Russia, Tel: (7-910)-552-99-45, Email: perelomov@rambler.ru
Kandeler Ellen, Dr. of Sci., Prof., University of Hohenheim, Institute of Soil Science, Emil Wolff Street, 27, Stuttgart, Germany, Email: kandeler@uni-hohenheim.de

The objectives of this study were to determine the effect of soil microorganisms on the amount of forms of Zn and Pb retained on goethite precipitated as coatings on a sand matrix and to evaluate accumulation of heavy metals in the biomass of soil microorganisms using extractive approach. Mixed colonies of microorganisms from top horizons of grey forest soil and urban soil after growing were used. Suspensions of microorganisms were inoculated into vessels with goethite precipitated on quartz sand. Variants with microorganisms and no inoculum controls were incubated at 22º C for 20 days. To determine the loss of metals from solution, operationally defined forms of elements were recovered from surface. Concentrations of Pb and Zn in the equilibrium solutions were measured also. Exchangeable forms of metals were determined by adding 1,0 M KNO₃. Nonexchangeable forms of Zn and Pb were recovered by dissolving the oxide using 0,3 M NH₂OH-HCl in 1 M HNO₃. Microorganisms have a significant effect on adsorption of Pb by goethite. At the variants with living microorganisms concentrations of metal were increased in the sorption solutions and diminished on surface of iron mineral, especially in the nonexchangeable fractions. Microorganisms affect on the Zn adsorption by goethite at high concentrations of the metal. The amount of adsorbed Zn is decreased due to diminishing of element concentration in the exchangeable fraction. Organic matter of microorganisms, which was prepared by autoclaving, has more role in the accumulation of Pb, but biomass of living microorganisms – in the accumulation of Zn. A direct determination of accumulation of heavy metals by soil microorganisms in the solution of 2,0 M KCl as well as in the solution of 1M CH₃COONH₄ with pH of soil samples is not possible. Perhaps, there is readsorption of metals releasing from microorganisms on the surface of soil components.

A Metal Detector Study to Locate Inactive, Un-Maintained Small Arms Firing Range Impact Areas

W. Andy Martin, Applied Research Associates, Inc., 119 Monument Place, Vicksburg, MS 39180, Tel: 601-634-3710, Fax: 601-634-4844, Email:  andy.martin@ara.com     
Victor F. Medina, U.S. Army Corps of Engineers-Engineer Research & Development Center,  3909 Halls Ferry Road, Vicksburg, MS 39180, Tel: 601-634-4283, Email:  victor.f.medina@erdc.usace.army.mil
Joseph R. Marsh, U.S. Army Corps of Engineers, Seattle District, 4735 E Marginal Way S, Seattle, WA 98134, Tel: 206-764-6170, Email:  Joseph.R.Marsh@nws02.usace.army.mil
Kym Takasaki, US Army Corps of Engineers, Seattle District, Seattle, WA 98134, Tel: 206-764-3322, Email:  Kym.C.Takasaki@nws02.usace.army.mil

Precise locations of older firing ranges at many military bases are often unavailable, because the records for training have either been destroyed or are vague and non-descriptive. We conducted an “environmental forensics study” of a 25-acre site at a large military facility in order to locate impact areas of a Thompson sub-machine gun range that was last used over 50 years ago.  Preliminary assessment activities included historical map and aerial photography review, site visits, and interviews with range control personnel, which suggested sub-machine gun training in the general area.  However, site visits did not indicate any visual features signifying range use, and the site had been overgrown with vegetation covering all traces of bullets.  We used a Garrett Infinium metal detector to successfully locate several small impact areas.  The impact rounds were identified, marked, and the location coordinates were identified using GPS.  The study was completed in 4 days, and at a fraction of the cost of physical.  The characterization will be used in future development of the site. 

Average Particle Size Ratios and Chemical Speciation of Copper and Zinc in Road Dust Samples

Adnan M. Massadeh, Department of Medicinal Chemistry and Pharmacognosy, Faculty of Pharmacy, Jordan University of Science and Technology, P.O. Box 3030, Irbid 22110, Jordan, Fax: 00962-2-7095019, Email: massadeh@just.edu.jo
Qasem M. Jaradt, Chemistry Department, Faculty of Science, Mutah University, Al-Karak, Jordan

Road dust samples were taken from areas of high traffic flows in Irbid city; Jordan. A series of <90, 90-<106, 106-<125, 125-<250, 250-<1000 and 1000-< 2000 mm of road dust particle size fractions were investigated throughout to evaluate the ratio between metal content in each particle size fraction and total metal contents. Atomic absorption spectrometry technique was used throughout. Sequential procedure was used for chemical speciation in road dust samples of <90mm. This procedure permits a reproducible evaluation of the partitioning of Cu and Zn among the various chemical forms in which they are present in street dust. Two reference standard materials BCR-CRM 142R and NIST-SRM 2709 were tested to validate the proposed method. Results show that there was no significant between the measured values for Cu and Zn and their certified values with RSD of less than 5%.  

Keywords: copper, zinc, chemical speciation, road dust, atomic absorption spectrometry.

Management of Lead in Soil during Highway Construction or Urban Redevelopment Projects: A National Perspective

Kathleen Sellers, PE, AMEC Earth and Environmental, 239 Littleton Road, Suite 1B, Westford, MA 01886, Tel: 978-692-9090, Fax: 978-692-6633, Email: kathleen.sellers@amec.com
Maria Pologruto, AMEC Earth and Environmental, 239 Littleton Road, Suite 1B, Westford, MA 01886, Tel: 978-692-9090, Fax: 978-692-6633, Email: maria.pologruto@amec.com

Construction crews working in industrialized areas often encounter lead contamination in soil. Although lead is a naturally occurring element found in small amounts everywhere, the soil near heavily-used streets and roads has typically accumulated lead in excess of natural levels due to the historic use of anti-knock lead compounds in gasoline and the use of lead tire weights. Other sources of lead in surface soil include lead-based paint and crude oil/gasoline at ambient levels. Lead may pose a public health threat if leached into groundwater or ingested by children. The need to manage lead-contaminated soil appropriately can add significantly to a construction project’s cost and schedule. Different states and highway authorities address this problem  differently. The authors will review the criteria, guidelines and case studies established in several states, including California, Michigan, New Jersey, and Massachusetts. Common themes and practical insights will be discussed in the paper.

Removal of Cr (VI) through Biosorption by Soil

Neetu Tewari, Ph.D., Centre for Environmental Management of Degraded Ecosystems, University of Delhi, Delhi (India)-110016, Tel: 91-11-26581682, Email: neetutiwari@hotmail.com
Prof. P. Vasudevan, Ph.D, Centre for Rural development and Technology, Indian Institute of Technology, Delhi, India-110016, Tel: 011-91-26591038 (O), 26591813 (R), Email: padmav10@hotmail.com
Prof. B.K.Guha, Ph.D, Department of Chemical Engineering, Indian Institute of Technology, Delhi, India-110016, Tel: 011-91-26591038 (O), 26591813 (R), Email: bkguha_iitdelhi@rediffmail.com

Industrial effluents are major sources of chromium pollution. Hazardous effects of Cr (VI) are well documented. Many removal technologies are present for chromium-laden effluents. Adsorption is widely used among them but high cost of adsorbents used, has led the focus on some cost effective alternative adsorbents. So keeping in view the cost and availability, Soil was used for the biosorption of Cr (VI) from aqueous solution. Biosorption equilibrium, kinetic and desorption was studied in a batch system. Equilibrium data fitted well to Langmuir isotherm model. The maximum sorption capacity of Soil was found to be 10.2 mg/g at an initial pH of 2.0 and 50^o C temperature. Kinetics was studied under varying initial concentration of Cr (VI) and dose of soil. It was found that in both the cases biosorption followed pseudo-second order kinetics. The sorption was biphasic; the first phase was rapid followed by second slow phase. The equilibrium was achieved within two hours. For the recovery and reuse of metal desorption studies are important. In the present study desorption data showed that ~ 98% Cr (VI) could be desorbed using 0.1N NaOH. The biosorption cycle was found to be effective upto three sorption and desorption cycles. Soil may be used as a sorbent for Cr (VI) removal.

The Pollution of Soils with Heavy Metals

Vasile Viman Ph.D, Anca Mihaly Cozmuta Ph.D, Gheorghe Vatca PhD., eng. Leonard Mihaly Cozmuta, Dorin Suticau, North University of Baia Msare, Victor Babes Street No. 62A, 4800 Baia Mare, Romania, Tel: 0040-262-427466; Fax: 0040-262-275368, Email: v_viman@hotmail.com

In areas where have been developed ores extraction activities, theirs processing in order to obtain the contented metals produces the pollution of air, waters and soils with sedimentable powders which contain heavy metals.

In searched area the ores contain Pb, Cu and Zn as major components and Cd, Au, Ag as minor or traces components.

Extracted ores are up-graded by flotation and the resulted concentrates are processed pyrometallurgical in order to obtain Pb, Cu Zn or hydrometallurgical to Au obtain. All these stages are potentially soil pollutant sources because of waste dumps generated by the mines, waste waters coming from flotation process and suspensions or sedimentable powders from pirometallurgy.

In order to evaluate the soil’s pollution level with heavy metals were established  the points for collection the samples placed at different distances from pollutant sources. The samples were collected from surface and both 20 and 30 cm depth of the soil.

A weight of 0.1 – 0.2 g of each dried and calcinated sample was dissolved using the acid disintegration in a microwave oven. The obtained solutions were diluted with bi-distillated water and analyzed using ICP-AES method.

The obtained concentrations are in range 420-5121 ppm for Pb, 151-992 ppm for Cu and 371-3122 ppm for Zn.

Based in these results can be noticed a decrease of concentrations of elements with the increase of distance from the pollutant sources. Near the sources the concentrations of heavy metals exceed the maximum admitted limits and the variation with depth are irregular.

The types of chemical combinations of metals and the properties of soil as pH, texture, structure, ionic exchange capacity, permeability and size of particles both influence the mobility of heavy metals in soil.

High pollution level of soils has negative consequences of crops that can be decreased up to 50%. Also, the losses in the forestry are around 40%, because of low quality of wood. Indirectly are affected the human health because the pollution affects the plants and animals used in food industry.

Investigation and Consideration of Second Pollution State of Yang-Fu-Mountain Landfill

Huang Wei, College of Architecture and Civil Engineering, Wenzhou University, Wenzhou, Zhejiang, China, 325035, Tel: 86 577 88325469, Fax: 86 577 86689611 , Email: hwei92120@yahoo.com
Shu Ke, College of Applied Technology, Wenzhou University, Wenzhou, Zhejiang, China, 325035, Tel: 86 13758464078
Liu Wen Guang, College of Applied Technology, Wenzhou University, Wenzhou, Zhejiang, China, 325035, Tel: 86 13868755168

The experiments have been made to test the content of heavy metals in soil near a landfill in Yang Fu Mountain in Wenzhou in order to make sure if it will have any affection to the life of the dwellers near it. With the help of high precisely electronic coupling plasma emission spectrum instrument (ICP-AES), the result shows that, some heavy metals’ pollution indexes, such as Mn, Pb, Cu, Cr, Cd, which are compared with the national and local codes, are in very high levels.

Metals Remediation Compound (MRC™):  A New Slow-Release Product for In Situ Metals Remediation 

Anna Willett, Regenesis, 1011 Calle Sombra, San Clemente, CA  92673, Tel: 949-366-8000, Fax: 949-366-8090, Email: awillett@regenesis.com
Stephen S. Koenigsberg, 1011 Calle Sombra, San Clemente, CA  92673, Tel: 949-366-8000, Fax: 949-366-8090, Email: steve@regenesis.com

Contamination of groundwater by metals has not been widely addressed by engineered in situ remediation technologies, despite the documentation of metals contamination at greater than 50% of sites from the National Priorities List and at Department of Defense and Department of Energy locations.  Metals Remediation Compound (MRC^™) is a slow-release metals remediation product that removes dissolved metals from groundwater via in situ immobilization (precipitation and/or sorption to soil particles).  The immobilized metals are stable under reducing conditions and may be stable under oxidizing conditions, depending on the identity of the metal and site-specific geochemistry.   

MRC consists of an organosulfur compound esterified to a carbon backbone.  This organosulfur ester is embedded in a polylactate matrix, making MRC a thick, viscous liquid.  Upon injection into an aquifer, the organosulfur compound is slowly released when MRC’s ester bonds are cleaved via hydrolysis by water and microbial enzymatic action.  The organosulfur moiety interacts with metal ions, either to complex them or to reduce them and complex them sequentially.  These complexes sorb strongly to soil, filter media, or other solid supports.  MRC also slowly releases lactate, which acts as an electron donor and carbon source for naturally-occurring bacteria and creates the optimal conditions for metals immobilization by the organosulfur compound.  For sites with mixed metal and chlorinated solvent contamination, MRC provides a substrate for accelerated reductive dechlorination and metals immobilization.

MRC’s ability to remove dissolved metals, such as arsenic, copper, chromium, cadmium, mercury, and lead, from solution has been tested in the laboratory and verified in situ via injection into metals-contaminated aquifers.  Results from these laboratory investigations and field applications will be presented.

Roadside Accumulation of Heavy Metals in Soils in Franklin County, MA and Surrounding Towns

Trevor L. Woodard, B.S., University of Massachusetts, Dept. of Plant & Soil Science, Stockbridge Hall, Amherst, MA 01003-9246, Tel: 413-545-3862, Email:  twoodard@alumni.bates.edu
Dula Amarasiriwardena, Ph.D., Hampshire College, School of Natural Sciences, Amherst, MA 01002, Tel: 413-559-5561, Email: dula@hampshire.edu
Baoshan Xing, Ph.D., University of Massachusetts, Dept. of Plant & Soil Science, Stockbridge Hall, Amherst, MA 01003-9246, Tel: 413-545-5212, Email: bx@pssci.umass.edu

Metals play an important role in the environment.  However, some metals can build up to levels in soils toxic to biota.  This is thought to be the case with a number of metals increasingly found in roadside soils, most likely due to anthropogenic activities.  Soil samples were collected along roads in towns in Franklin County, MA (including some adjacent towns).  This was done by sampling local sites in triplicate of soil 0.5 meters from the edge of the road and 10 to 15 centimeters deep (a mix of A and B horizons).  Descriptions of the road (paved or dirt) and car counts (to evaluate use) were done.  Four sites were in natural areas and represent non-polluted soils. Soils analyzed were sequentially extracted into five phases (exchangeable, carbonate, Fe/Mn oxides, organic matter, and residual) for inductively coupled plasma atomic emission spectrometry (ICP-AES) analysis for V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Pd, Cd and Pb.  Results should indicate soil fertility, anthropogenic accumulations of heavy metals and their bioavailability, and the potential need for remediation.  Preliminary results indicate increased Pb along high-traffic areas.

Effect of Sulfate and Phosphate on Adsorption of Molybdate and Tetrathiomolybdate by Pyrite

Nan Xu, Center for Environmental Systems, Stevens Institute of Technology, Castle Point on Hudson, Hoboken, NJ 07030, Tel: 201-216-5329, Fax: 201-216-8303, Email: nxu@stevens.edu
Washington Braida, Center for Environmental Systems, Stevens Institute of Technology, Castle Point on Hudson, Hoboken, NJ 07030, Tel: 201-216-5681, Fax: 201-216-8303, Email: wbraida@stevens-tech.edu
Dimitris Dermatas, Stevens Institute of Technology, Civil, Environmental, and Ocean Engineering Department, Castle Point on Hudson, Hoboken, NJ 07030, Tel: 201-216-8926, Fax: 201-216-5352, Email: ddermata@stevens-tech.edu
Christos Christodoulatos , Center for Environmental Systems, Stevens Institute of Technology, Castle Point on Hudson, Hoboken, NJ 07030, Tel: 201-216-5675, Fax: 201-216-8303, Email: christod@stevens-tech.edu
Michael Los, TACOM-ARDEC, US Army Heavy Metals Office, Picatinny Arsenal, Picatinny, NJ 07806, Tel: 973-724-7038, Fax: 973-724-2034, Email: mlos@pica.army.mil

Molybdenum enrichment has been used as an accepted indicator for the presence of sulfidic, anoxic conditions or reduction condition during sediment deposition and genesis. To understand the mechanisms involved in retention by pyrite (FeS₂) of two major molybdenum species, molybdate (MoO₄^2-) and tetrathiomolybdate (MoS₄²), within natural anoxic environments, batch experiments were performed using of MoO₄^2-- and MoS₄^2-- pyrite suspensions in 0.1M NaCl under anoxic conditions.  The pH range covered was from 3 to 10 and all experiments were performed at 25^oC.  The effects of sulfate and phosphate on the adsorption of MoO₄^2- and MoS₄^2- by pyrite were also studied. The results showed that MoO₄^2- and MoS₄^2- adsorption obeyed a Langmuir model at low pH. MoS₄^2- adsorbed strongly in the pH range from 3 to 5 while MoO₄^2- presents a maximum adsorption at pH 4.5, and decrease rapidly with increasing pH with complete desorption after pH 7.  On the other hand, 30% of the MoS₄^2- remained sorbed at pH values as high as 10. The adsorption of MoO₄^2- and MoS₄^2- decreased moderately with the addition of phosphate.  The degree of reduction of MoS₄^2- adsorption is lower than MoO₄^2-, which suggests that MoS₄^2- likely forms strong inner-sphere complexes. Sulfate and silicate had a negligible effect on the adsorption of MoO₄^2- and MoS₄^2-. 

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