Applications of Electron Microscopy, ArcGIS Spacial Analyst and MINTEQA2 Model to Predict Phosphate Minerals in River Sediments  

Asmare Atalay, Ph.D., Associate Professor, Virginia State University, P.O. Box 9061, Petersburg, VA  23831, Tel:  804-524-6721, E-mail: aatalay@vsu.edu
Carol Bronick, Ph.D., Postdoctoral Associate, E-mail: cbronick@aol.com, Tel:  203-907-8536
Kathleen Baker, Ph.D., Western Michigan University, Department of Geography, E-mail: Kathleen.baker@wmich.edu, Tel:  269-387-3345

Sediments are repositories of nutrients and other chemicals in surface waters. They are heterogeneous mixtures of assorted soil separates and organic matter. Phosphorus (P) flux into and out of sediments is controlled by P speciation and environmental conditions, such as temperature (T), dissolved oxygen (DO), redox conditions (Eh), and acidity/alkalinity (pH). This study was conducted to characterize chemical and physical parameters that affect P speciation in sediments of the James River, and to evaluate the experimental conditions under which sediment-bound P can become biologically available. Sediment cores were analyzed for T, pH, Eh, carbon (C) and metal ions. In a laboratory experiment, sediment samples were suspended in deionized water and equilibrated under different pH and aerobic/anaerobic conditions to assess P speciation and flux. The core sediment samples taken from a location near a former dairy farm showed the highest P concentrations while cores taken from downstream sites had lower P concentrations. Core samples with high P concentration correlated well with Fe and had non-uniform correlations with clay, Al and Ca that changed with cores depth. In controlled laboratory experiments, at pH 5, P was higher in anaerobic than in aerobic sediments. Higher Al precipitation occurred at low pH, which may reflect increased stability of Al phosphates in anaerobic conditions. Alternatively, increased Al concentration at pH 7 in aerobic conditions may indicate the stability of Al hydroxides as predicted by the MINTEQA2 speciation model. Elemental P distribution assessment using Scanning Electron Microscopy and application of ArcGIS Spacial Analyst inferred that at pH 4, P might be bound more to C and Al, than to Fe and Mn.

Low Density Dredge Residuals, a Significant Impact to offsite Surficial Sediments?

Michael Bock, ENVIRON International Corporation. 163 Commercial St, Suite 402, Portland, ME, 04101, Tel: 207-347-4413, Fax: 207-347-4384, Email: mbock@environcorp.com
Erik Martin, ENVIRON International Corporation. 163 Commercial St, Suite 402, Portland, ME, 04101, Tel: 207-347-4413, Fax: 207-347-4384, Email: emartin@environcorp.com

Dredge residuals can be classified as either material missed by dredging operations or material lost during transport to the surface. Due to hydrodynamic considerations, low density material is more likely to be lost during retrieval. Sediments contain significant quantities of clay particles that form low density (< 2.4 g cm^-3) organo-mineral aggregates. This low density fraction in sediments has been shown to be highly enriched in organic material and is likely to be similarly enriched in hydrophobic chemicals, specifically organic contaminants such as polycyclic aromatic hydrocarbons and Polychlorinated biphenyls. Our simple model predicts that the loss of this material during dredging operations may result in significant offsite deposition of low-density material that is highly enriched in chemicals of potential concern. This enrichment is initially limited to the top several centimeters and is therefore underestimated using typical sampling techniques that integrate the top 15 cm of the sediment column. The persistence of this enrichment is dependent on the nature of physical and biological turbation. If the population of the benthic community has significant numbers of particle size selective surface deposit feeders, such as those common in estuarine environments, this surficial enrichment is predicted to be more persistent than otherwise predicted based on bulk bioturbation rates. The predictions of this model are consistent with reports of post remediation increases in the concentrations of chemicals of concern in sediment and biota.

Investigation of the Changes of Permeability, Physical and Chemical Characteristics of Sediment Basins for Artificial Recharge in Bagh-e-Sorkh Region, Shahreza, Isfahan

S. S. Eslamian, Visiting Professor, Dept. of Civil & Environmental Eng., Princeton University, NJ 08544-5264, USA. Tel: (609) 258-8308, Email: eslamian@princeton.edu
A. Goudarzi, Postgraduate Student of Irrigation, College of Agriculture Eng., Isfahan University of Technology, IRAN. Tel: (98)665-232-2041, Email: ahmad_goir@yahoo.com
R. Nazari, PhD Student of the Graduate Center of City University of New York, USA, Tel: (212) 650 8011, Email: RNazari@gc.cuny.edu

In recent decades, with continuous droughts, demand for water has been increased and per capita renewable-water has been decreased in many countries which are faced with water limitation and scarcity. Considering the particular hydrologic conditions in Iran, seasonal floods and high intensity of rainfall are important and using artificial recharge projects is unavoidable to augment the water resources. The major problem with recharging projects is the entrance of sediments to the recharging basins. Due to depositing the floating particles, it is necessary to treat and recover permeability of the basins. In this paper, we compare permeability of the basins for artificial recharge in Bagh-e-Sorkh region of Isfahan. To measure the permeability, four double rings have been installed in different places for each basin’s bed and the permeability was measured. Also, some samples were taken from sediments of the region and some of their physical and chemical characteristics, such as soil texture, EC, and nourishing elements, were measured. The results showed that permeability for beds of the pounds highly decreased and had fallen to less than 10 (the first basin) to 25 percent (the fifth basin) of the initial value. Comparing the physical characteristics of sediments from the different pounds indicates that with increasing distance from the system starting point, the sediment depth is decreased and on the contrary the fine sediments are increased. Because of this, the sediment’s thickness was not so much influential in amount and the pace of the final permeability.

Rapid Dating of Recent Aquatic Sediments Using Plutonium as an Analogue for Cesium-137

Paul T. Gremillion, Ph.D., Civil & Environmental Engineering Department, Northern Arizona University, 69 McConnell Drive, Flagstaff, Arizona 86011, Tel: 928-523-5382, Fax: 928-523-2300, Email: paul.gremillion@nau.edu
Michael E. Ketterer, Ph.D., Department of Chemistry and Biochemistry, Northern Arizona University, 20 South Beaver St., Flagstaff, Arizona, 86011, Tel: 928-523-7055, Fax: 928-523-8111, Email: Michael.ketterer@nau.edu
Jaime L. Toney, M.S., Laboratory of Paleoecology, Bilby Research Center, Box 6013, Northern Arizona University, Flagstaff, Arizona 86011, Tel: 928-600-1694, Fax: 928-523-7290, Email: Jaime.toney@nau.edu

Studies of contaminated sediments commonly require coring in multiple locations and analysis of many individual layers to determine the spatial and temporal extents of contamination.  It is usually not economical to analyze every sediment layer from every core for the entire suite of analytical parameters, so two-tiered sampling plans are often implemented, in which screening analysis of the cores is first performed to determine the quality of each sediment core, whether contamination is likely present in the core, and the depth to which high-resolution sampling for a full-suite of analytical parameters is necessary.  These studies require establishing the sediment chronology and quality of the sediment record; preferred approaches involve analysis of ¹³⁷Cs and/or ²¹⁰Pb. ¹³⁷Cs, originating from stratospheric deposition from above-ground nuclear weapons tests, is first apparent in 1952-1954 and reaches an activity maximum in 1963-1964.  Depending on the ¹³⁷Cs activity, 5 grams sediment and a counting time of > 1 day/sample per may be required.  This “bottleneck” can result in costly delays in conducting second-tier field and laboratory work. 

We have demonstrated that plutonium, also present as a result of atmospheric weapons testing, can be rapidly analyzed by inductively coupled plasma mass spectrometry (ICPMS).  ^239+240Pu activities yield chronologies essentially identical to ¹³⁷Cs, but using much smaller sample sizes and far quicker turnaround times. Samples are dry-ashed, spiked with ²⁴²Pu tracer, leached with HNO₃, then Pu is separated using solid-phase extraction.  One analyst can prepare ~ 100 samples in 3-4 days and perform the ICPMS analysis in 1-2 days.  One implication of the rapid turnaround time is that in some cases second-tier analyses with short holding times can be performed on the original sediment cores, rather than requiring additional field work.  This paper will present comparisons between ^239+240Pu-ICPMS chronology and conventional ¹³⁷Cs results for several case studies. 

Numerical Prediction of Aggradation and Degradation in Alluvial Channel Flows 

Jaan H. Pu, University of Bradford, School of Engineering, Design & Technology, Bradford BD7 1DP, UK, Tel: (+44)-01274235475, Fax: (+44)-01274234525, Email: j.h.pu@bradford.ac.uk
Khalid Hussain, University of Bradford, School of Engineering, Design & Technology, Bradford BD7 1DP, UK, Tel: (+44)-01274234267, Fax: (+44)-01274234525, Email: k.hussain1@bradford.ac.uk

Bed aggradation and degradation are common phenomena in natural channel flows due to the existence of sediments. Powerful, and reliable numerical estimation models of such events are important in water management and river monitoring projects to accurately predict water and bed surface elevations.

In this paper, the shallow water equations together with sediment transport conservative equation are simulated and applied to unsteady water flow with the existence of moving alluvial bed boundaries. A proposed finite-volume model with Harten-Lax-van Leer (HLL) flux scheme is used to simulate the alluvial channel flows conservatively. Two separate applications are presented in this paper, bed aggradation, and degradation flows to demonstrate the capability of the proposed model.

The computed results of the bed aggradation and degradation applications are compared with the existing experimental data from laboratory flumes. Good agreements are obtained between the proposed numerical model and experimental results.

Studies on Degradation of ¹⁴C-HCH in Marine Environment Using Continuous Flow System

Sharad P. Kale, Nuclear Agriculture and Biotechnology Division, Bhabha Atomic Research Centre, Mumbai 400085, India, Tel: 91 22 25593830, Fax: 91 22 25505151, Email: skale@apsara.barc.ernet.in
Pramod D. Sherkhane, Nuclear Agriculture and Biotechnology Division, Bhabha Atomic Research Centre, Mumbai 400085, India, Tel: 91 22 25593830, Fax: 91 22 25505151, Email: pramod@apsara.barc.ernet.in

Persistent organic pollutants (POP) are compounds, which because of their vapour pressures and partitioning behaviour under ambient conditions, are persistent in and mobile in the environment and bioaccumulate in food chains. Chlorinated hydrocarbons have dominated the agricultural sector for more than 4 decades all over the world and are environmentally important POPs.  In India, HCH and DDT have remained integral parts of agriculture till recently. HCHs have been commercially available as either technical HCH, consisting of 55-70% of a-HCH and 10-18% as g-HCH or as lindane. China, India and Russia represented the largest producers and users of HCH in the 1980s. Lindane is the only isomer, which continues to be in use for pest control. Agricultural runoff ultimately reaches marine resources. These residues tend to settle down in marine sediment, which then acts as slow release source for their continued exposure to marine life. The fate and behaviour of these residues in marine sediments would be deciding factor in their entry to food chains. Degradation of ¹⁴C-HCH was studied under aerobic (moist) and anaerobic (flooded) conditions in marine sediments using a continuous flow system allowing a total ¹⁴C-mass balance for a period of 130 days.  Under both aerobic and anaerobic conditions, HCH underwent extensive degradation. About 22-26% of the applied ¹⁴C-activity was recovered as ¹⁴CO₂ under both these conditions. 45-55% of the applied ¹⁴C-activity was recovered as volatiles, possibly benzene. Later on this was confirmed by gas chromatography. The extractable ¹⁴C-residues accounted for about 7 and 12% under aerobic and anaerobic conditions respectively. HCH was the major compound in extractable residues as identified by TLC-autoradiographic procedures. The formation of bound residues was less than 5% under both moisture conditions and was not very significant environmentally. The nearly complete degradation of HCH residues under Indian conditions indicates that the chemicals that are persistent in temperate zones may not bioaccumulate in tropical or subtropical regions.

Sediment Contamination in Cubatão River, Santos and São Vicente Estuaries, São Paulo, Brazil

Marta C. Lamparelli,  CETESB - Companhia de Tecnologia de Saneamento Ambiental, Av. Prof. Frederico Hermann Jr., 345,  São Paulo-SP 05489-900,  Brazil, Email: martal@cetesb.sp.gov.br
José Eduardo Bevilacqua, CETESB - Companhia de Tecnologia de Saneamento Ambiental, Av. Prof. Frederico Hermann Jr., 345,  São Paulo-SP 05489-900,  Brazil,  Email: zeeduardob@cetesb.sp.gov.br
Valéria A. Prósperi, CETESB - Companhia de Tecnologia de Saneamento Ambiental, Av. Prof. Frederico Hermann Jr., 345,  São Paulo-SP 05489-900,  Brazil, Email: valeriap@cetesb.sp.gov.br
Rosalina P. A. Araujo, CETESB - Companhia de Tecnologia de Saneamento Ambiental, Av. Prof. Frederico Hermann Jr., 345,  São Paulo-SP 05489-900,  Brazil, Email: rosalinaa@cetesb.sp.gov.br
Marcelo P. Costa, CETESB - Companhia de Tecnologia de Saneamento Ambiental (present address: ANA – Agência Nacional de Águas, Setor Policial, Área 5, Quadra 3, Bloco BLM CEP 70610-200, Brasília. Brazil), Email: marcelo@ana.gov.br
Geraldo J. Eysink, CETESB - Companhia de Tecnologia de Saneamento Ambiental (present address: Consultoria Paulista de Estudos Ambientais S/C Ltda Rua Henrique Monteiro, 90 São Paulo S.P. 05423-020 Brazil) Email: sergiopompeia@consultoriapaulista.com.br
Sérgio Pompéia, CETESB - Companhia de Tecnologia de Saneamento Ambiental (present address: Consultoria Paulista de Estudos Ambientais S/C Ltda Rua Henrique Monteiro, 90 São Paulo S.P. 05423-020 Brazil) Email: sergiopompeia@consultoriapaulista.com.br

Studies in Cubatão Region and the adjacent Estuaries, in the 80´s, showed that water, sediment, mangrove and aquatic organisms were contaminated with inorganic and organic pollutants in toxic concentrations due to industrial activities (steel production, petrochemical plants and fertilizers manufacturing). Since then pollution control reduced industrial emissions, nevertheless, sediment contamination, Santos harbor dredging activities, bioaccumulation of contaminants are still important issues. In order to determine the degree of sediment contamination, its role in bioaccumulation and consequences to dredged material management, 23 sites in that region, including Santos Bay, were sampled, in 1999, for water, sediments, fish and shellfish. Samples were analyzed for heavy metals, PAHs, PCBs, PCDDs and PCDFs. Sediment results indicated an accumulation of TOC and Total N, and redox conditions indicated a strong decomposition of organic matter, especially in São Vicente and Santos Estuaries. Non point sources play a dominant role in organic accumulation due to insufficient waste municipal facilities. Considering the PEL (probable effect level) criteria, sediments were more contaminated at the Santos Estuary, where 5 million m³ are dredged every year, for PAHs (11% >763 μg/Kg as benzo[a]pirene) and heavy metals (Hg (8% >0,696 μg/g), Pb (5% >112 μg/g) and Zn (3% >271 μg/g)). BHC (17% >0,99 μg/Kg as gama-BHC) and PCBs (2% >189 μg/Kg) were also found above PEL. Total PAHs reached concentrations of 800 mg/Kg and 2,3,7,8 TCDD was present in the sediments. PCBs in migratory fish (mullet, snook) were lower than in resident fish (mojarra). Mullets from Cubatão River, however, had higher values of dioxin and furans, indicating that bioaccumulation occurs during migration. Low values of PAHs were observed, except for benzo[a]pyrene and dibenzo[a,h]anthracene in oysters. Higher values of contaminants were found in bottom feeding organisms (blue crabs) than in herbivore species (mangrove crabs). Blue crabs and mullets are probably receiving most of their contaminants body burdens through sediments and/or benthic organisms ingestion.

Post-Dredging Residual Contaminant Impacts are a Reality

Chris Leuteritz, Anchor Environmental, L.L.C., 2 Dundee Park, Suite 102, Andover, MA 01810, Tel: 978-474-9090, Fax: 978-474-9080, Email: cleuteritz@anchorenv.com

During the remediation of contaminated sediments, low cleanup levels are typically set by the regulatory community.  Dredging is often selected as the preferred remedial alternative to address contaminated sediments.  During the execution of the remedy, confirmation samples are typically collected following completion of dredging to the design elevation.  Typically these sampling results show recurring contaminant concentrations greater than the target remediation action level (RAL).  On some projects, additional dredge passes are then attempted to remove the sediments with contaminant concentrations greater than the RAL.  However, previous experience has indicated that these “cleanup passes” generate significantly diminished returns, as indicated by additional confirmation samples which show little or no reduction in concentration from the first pass dredging.  The use of cleanup pass dredging without a well-defined completion point can lead to cost overruns, schedule overruns, and fingers being pointed between regulators, contractors, engineers, consultants, and clients for the failure of the selected remedy to achieve RALs. 

Post-dredging residual contamination is a reality.  Data from several recent dredging projects suggests the contaminant concentration of these residuals will be approximately equal to the average contaminant concentration of the mass of material slated for dredging.  Additionally, the total mass of sediment characterized as residuals is ranges between 2 and 8 percent of the total contaminant mass of the original dredge prism. 

The likelihood of contaminated dredge residuals should be planned for during the design and permit negotiation phases of the project.  This is a critical step in the execution of a successful sediment remediation program involving dredging.

This paper presents the data from several projects regarding residual contamination after dredging.  Additionally, the paper will discuss options for managing this residual contamination.

Modeling Copper Transport in the Sediments of Torch Lake, Houghton County, MI

Cory McDonald, Michigan Technological University, 1400 Townsend Dr., Houghton, MI  49931, Tel: (906)487-3583, Fax: (906)487-2943, Email: cpmcdona@mtu.edu

Torch Lake, a Great Lakes Area of Concern located in the Keweenaw Peninsula of Upper Michigan, has been heavily impacted by local copper mining activities.  Toxic copper concentrations in surface sediments have nearly eliminated the benthic community.  The EPA selected the "No Action" alternative for the sediments, which relies on contaminated sediments being covered by new, uncontaminated sediments.  A model was developed to examine the diffusive transport of copper from the mining-era sediment into the post-mining sediment as well as from the post-mining sediment into the water column. The model was used to simulate the measured copper profiles in the sediments and to predict concentration profiles in the future.  Deposition of new sediments has attenuated the flux of copper from the sediments into the lake.  However, because “new” sediments contain more organic matter and therefore have a higher sorptive capacity for copper than the mining-era sediment, solid-phase copper concentrations in recently deposited sediment are actually twofold higher than concentrations in the original, "contaminated" sediments.  Because upward-diffusing copper is mostly retained in the new sediments, copper concentrations in surface sediments are not predicted to decline below the toxic threshold in the foreseeable future.

Options, Challenges and Lessons Learned in the Assessment and Remediation of Lake Contaminated Sediments

Tim Whalen, Golder Associates Ltd, #500 – 4260 Still Creek Drive, Burnaby, BC, V5C 6C6, Canada, Tel: 604-296-4273, Fax: 604-298-5253, Email: twhalen@golder.com
Simone Mol, Pottinger Gaherty Environmental Consultants Ltd. (PGL) 1200 - 1185 West Georgia St., Vancouver, BC, V6E 4E6, Canada, Tel: 604-895-7641, Fax: 604-682-3497, Email: smol@pggroup.com

A heavy equipment, fueling, maintenance and repair facility (“maintenance facility”) operated for almost 30 years adjacent to a lake on Vancouver Island, BC, Canada.  The maintenance facility included several diesel underground storage tanks (USTs) and oil pits. 

The maintenance facility was part of a former forestry townsite which included a sawmill, powerhouse, general store, school and associated residential buildings.  Logs were routinely stored on the lake pending processing at the sawmill.  The sawmill and maintenance shop operated from 1925 to 1952.  Following the shut down of the sawmill, the buildings and infrastructure including trestles connecting the maintenance facility and townsite across the lake were largely demolished.

In 1957, the water level in the lake was raised by three metres to regulate downgradient water flow which resulted in the flooding of portions of the former maintenance facility.  The lake is currently used for recreational and commercial purposes including a salmon hatchery.

In 2001, hydrocarbon-like sheen was observed emanating from the sediment near the former maintenance facility. An environmental investigation of the former maintenance facility upland area identified the presence of diesel and oil plumes leaching into the sediments.  Hydrocarbon concentrations up to 5% oil were measured in collected sediment samples.

The presentation will outline the challenges of investigating the sediments including issues caused by the flooding of the former industrial areas, the presence of layers of wood debris which made the collection of sediment samples difficult but also caused analytical interferences and general representiveness issues.  

The remedial options considered for the site will also be presented.  The implemented remediation including a combined approach of dredging, risk management and enhanced in-situ bioremediation.  A pilot study was undertaken to support enhanced bioremediation which included conducting treatability tests, designing a mechanism to deliver nutrients and developing a monitoring program. 

Biomonitoring in Handling and Remediation of Contaminated Sediments

Jonathan Mufandaedza Department of Biotechnology, Chinhoyi University of Science and Technology, P.O. Box 7724, Chinhoyi, Zimbabwe, Tel: +263-067-22203, Fax: +263-067-23726, Email: jmufandaedza@cut.ac.zw

In many countries of both the developed and the developing world, as well as countries in transition, issues of polluted aquatic soils are emerging and increased need is being felt to enter into biomoritoring research programs. Similarly agricultural activities in the region and Zimbabwe in particular are focusing much on the use of organopesticides, some of which are recalcitrant and are not biodegradable. These organopesticides and chemicals find their way into the natural water systems and into river sediments. Preliminary studies have shown that the CUT dam and Cold stream sediments have excessively high levels of heavy metals and organophosphates. The sediments and waters are highly contaminated and are a potential threat to both animal and human life. The research will establish extends of sediment contamination using biomarkers and to come up with sustainable solutions to mitigate further sediment contamination.

An Application of the Triad Approach to Maximize the Efficiency and Effectiveness of Remediation of Sediments 

Jill Ann Parrett, EA Engineering, Science, and Technology, Inc., 2350 Post Road, Warwick, Rhode Island, 02886, Tel: (401) 736-3440, Fax: (401) 736-3423, Email: jparrett@eaest.com
Timothy Regan, P.E., M.B.A., EA Engineering, Science, and Technology, Inc., 2350 Post Road, Warwick, Rhode Island, 02886, Tel: (401) 736-3440, Fax: (401) 736-3423, Email: tregan@eaest.com

In 2005, remedial activities were conducted at a former textile mill and electroplating facility abutting the Woonasquatucket River, an urbanized American Heritage Designated River, in North Providence, Rhode Island.   Contaminants of concern were chromium, primarily trivalent, and petroleum, primarily machine oils from plating wastes being discharged along the riverbank.  Previous environmental investigations were used in the preparation of a conceptual site model, which determined that these wastes had adversely impacted nearly 200 linear feet of riverbank soil and sediment within the river.  Due to potential adverse impacts of this contamination on the Woonasquatucket River, it was determined that impacted sediment and soil would be removed and transported off-site for disposal as part of a proposed Brownfield reuse proposal.

Through the Rhode Island Department of Environmental Management’s Voluntary Cleanup Program, site-specific remedial objectives were established to address the ecologically sensitive nature of the impacted media and system.   The remedial approach utilized a portable cofferdam system to bypass and de-water portions of the riverbed in conjunction with traditional excavation and engineered cap construction activities.  Because the full extent of contaminated sediment could not be defined prior to river diversion and the need for rapid assessment during remedial activities, EA implemented the Triad Approach to maximize the efficiency of the remedial activities.  To lessen the effects of diverting the river, EA’s site geologist performed sediment screening using a combination of x-ray fluorescence (XRF) technology and hydrocarbon test kits in a field laboratory setting.  These screening techniques provided real-time data to determine the extent of excavations without incurring equipment downtime pending receipt of laboratory data.  Using these real-time measurement technologies, the project scope and conceptual site model were adapted during work activities to fully address the heavy metal and petroleum contamination of riverbank soils and riverbed sediment.

In conclusion, implementing the Triad Approach allowed for increased efficiency, reduction of project costs, improvement in the effectiveness of the standard remedial approach, and lessening of adverse impacts to the environment.  

Assessment and Interpretation of Field Duplicates-A Case Study of a Complex Sediment Investigation

Stephen T. Zeiner, CEAC, CPC, Environmental Standards, Inc., 1140 Valley Forge Road, PO Box 810,Valley Forge, PA  19482,Tel: 610-935-5577, Fax: 610-935-5583, Email: szeiner@envstd.com
Joseph Kraycik, Environmental Standards, Inc., 1140 Valley Forge Road, PO Box 810,Valley Forge, PA  19482,Tel: 610-935-5577, Fax: 610-935-5583, Email: jkraycik@envstd.com
Dennis Callaghan, Environmental Standards, Inc., 1140 Valley Forge Road, PO Box 810,Valley Forge, PA  19482,Tel: 610-935-5577, Fax: 610-935-5583, Email: dcallaghan@envstd.com
Rock J. Vitale, CEAC, CPC, Environmental Standards, Inc., 1140 Valley Forge Road, PO Box 810,Valley Forge, PA  19482,Tel: 610-935-5577, Fax: 610-935-5583, Email: rvitale@envstd.com

For a high-profile river sediment characterization project located in the Northeast, multiple entities collected and analyzed samples over the last decade.  During that time-period, the regulator’s contractors collected several thousand samples that were analyzed for PCBs (Aroclors and congeners) and a variety of metals.  Subsequently, the responsible party and its contractors collected several thousand additional samples for the same target analytes.  Like most site characterization efforts, the collection and analysis of field duplicate samples was required.

During the evaluation of the historical site data prior to use for the generation of a conceptual site model, the project team was presented with the question of how to assess and utilize field duplicate data.  The project team evaluated a number of approaches and the pros and cons of each of several approaches and selected a single approach to evaluation and utilization of the field duplicate data.

This presentation includes a case study utilizing the experience from a large sediment site characterization that included multiple field contractors.  The work includes a discussion of the techniques used for the collection of field duplicate samples, the data quality assessment of the field duplicate sample results, and the use of the results in the conceptual site model. 

A Study on Major Elements and Trace Metals in Sediments from Dongting Lake, Central China

Yao Zhigang, Faculty of Earth Sciences, China university of Geosciences, Wuhan, Hubei, CHINA, 430074, Tel.: +86-27-67885100-8323, Fax: +86-27-67883006, Email: yzg123-68@cug.edu.cn
Bao Zhengyu, Faculty of Earth Sciences, China university of Geosciences, Wuhan,Hubei, CHINA, 430074, Tel.: +86-27-62867090, Fax: +86-27-67883006, Email: zybao@cug.edu.cn

Dongting Lake lies in the south of the middle Yangtze River, the biggest river in China. It is the second fresh-water lake, one of the most important reservoir lakes in Yangtze River valley, and a source for municipal drinking water and for tourism and recreation. Sedimental samples were analyzed for 17 element concentrations (Fe, K, Ca, Mg, Al, Si, Mn, Ti, N, C, P, Cu, Pb, Zn, Cd, Cr and Ni) at 88 locations. The work researched into the spatial distribution of trace metals and major elements in different areas of Dongting Lake. Surface sediment samples from the whole Dongting Lake were characterized by nutrient concentrations, namely, high Tot-org-c (1.16%) and Tot-N (0.11%) and low Tot-P (0.074%) and by high trace metal levels, that was, Cu, 46.76; Pb, 46.96; Zn, 125.6; Cd, 1.808; Cr, 84.72 and Ni, 39.12 mg•kg^-1. By comparison with other areas, it showed that the average concentrations of these 6 trace metals were relatively higher than those of the background values of water sediments from Yangtze River drainage area, especially Cd more than the threshold value for severely polluted soil. The assessment by index of geoaccumulation showed that the contamination of Cd reached moderate to strong pollution. To study the speciation of metals in the Lake sediments, six elements (Cd, Cr, Cu, Ni, Pb and Zn) in less than 0.074 mm grain size were subjected to sequential extractions. The elements analyzed were distributed in both the non-residual and residual phases except Cr that was found only in the residual fraction. The potential risk to Lake’s water contamination was highest in East Dongting Lake and Chenglingji based on the calculated individual and global contamination factors. Therefore, there is need to protect Dongting Lake from anthropogenic sources of pollution to reduce environmental risks.

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