2004 Progress Report: Contaminant Release During Removal and Resuspension

EPA Grant Number: R828773C004
Subproject: this is subproject number 004 , established and managed by the Center Director under grant R828773
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).

Center: HSRC (2001) - South and Southwest HSRC
Center Director: Reible, Danny D.
Title: Contaminant Release During Removal and Resuspension
Investigators: Tomson, Mason B. , Thibodeaux, Louis J. , Kan, Amy T. , Valsaraj, Kalliat T.
Institution: Rice University , Louisiana State University - Baton Rouge
EPA Project Officer: Lasat, Mitch
Project Period: October 1, 2001 through September 30, 2006 (Extended to September 30, 2007)
Project Period Covered by this Report: October 1, 2003 through September 30, 2004
Project Amount: Refer to main center abstract for funding details.
RFA: Hazardous Substance Research Centers - HSRC (2001) Recipients Lists
Research Category: Hazardous Waste/Remediation , Nanotechnology , Land and Waste Management

Objective:

This Hazardous Substance Research Center (HSRC) project is divided into two interrelated parts. The Rice University group is conducting the laboratory test aimed at simulating key elements of the metal release process following dredging resuspension of bed-sediment residing solid particles. The Louisiana State University (LSU) group is attempting to develop a theory-based simple and practical model to track the metal release process kinetics. Data generated by the Rice University group will be utilized by the LSU group in model development, refinement, and testing. The overall product will be an algorithm to estimate metal concentrations in solution emanating from the mud clouds produced during dredging or storm events. It will contain a combination of empirical data and semi-theoretical modeling. From all evidence we have collected, a purely a priori theoretical model approach is not currently possible.

Being able to predict the concentrations of metals is key in evaluating aquatic organism exposure levels and uptake quantities for risk assessment purposes. Algorithms are needed for both the water column and the bed-sediment surface layers. Providing these algorithms is the overall goal of this combined Rice University and LSU project.

During resuspension, generally the largest physical-chemical effect, with respect to heavy metal sorption, is the change in redox of the freshly disturbed sediments. At the point of dredging the sediments are suspended in the river bottom and there is an immediate increase in solid surface area and a corresponding immediate change in the physical-chemical parameters that characterize the water. Following these immediate changes there will be several time scales that are applicable: (1) the slower redox processes; (2) the desorption kinetics; (3) the kinetics of iron oxide precipitation and fines production; and (4) the relative rates of redeposition of the fine particles.

The objective of the Rice University portion of the research project is to understand the dynamics and kinetics of heavy metal release processes during sediment resuspension events.

The objective of the LSU portion of the project is to adopt this existing bi-phasic kinetic model and use it for the metal release process.

Progress Summary:

Louisiana State University Portion
Principal Investigator: L.J. Thibodeaux

Approach to Model Development for Metals Release

The rationale for adoption of the model is based on the following findings:

  • A kinetic-based chemical release model is more realistic. Equilibrium based resuspension models have been used and are being used for contaminant release from resuspended particles. Although appropriate for some applications, equilibrium models will uniformly over-predict the soluble fraction in the water column; this is the key fraction. Transport kinetics-based models allow the characterization of the rate of approach to the equilibrium state and the incorporation of other key rate processes.
  • Simple laboratory experiments are involved in generating the necessary site-specific empirical data for inclusion in the semi-theoretical bi-phasic release algorithm. Several experimental protocols have evolved and are “standardized” so that they realistically reflect the process of desorptive release demonstrated by sediment particles resuspended into the water column. The key environmental chemistry conditions that need to be maintained in order to realistically mimic the resuspension process are: rapid particle contact with water, appropriate field values of the solid-to-water ratios, aerobic water conditions, and an infinite sink for the de-sorbing fractions. For organic chemicals, the protocols have reached a mature state of development, whereas for metals the apparatus and protocols are still being developed. Maintaining constant pH and aerobic conditions in the slurry has been a challenge, these being the two most important parameters that affect the metal release process. However, it appears that the Rice University group has developed an apparatus and a protocol that provides the necessary control of these parameters.
  • In the case of organic chemical, an extensive set of data has accumulated in the literature over the past five years based on the bi-phase model that includes a fast fraction release rate constant (kfast, day-1), a slow fraction rate constant (kslow, day-1), and the fast fraction mass φ fast on the sediment (φslow = 1-φfast). Our review of this literature indicates it does an excellent job of fitting virtually all data sets for both field samples and laboratory-inoculated samples alike. These organic chemicals include volatile hydrocarbons, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and pesticides. One outstanding feature of the data we have assembled to date is that both rate constants appear to be chemically independent. The data on the fast fraction mass quantity appear to follow no discernible behavior pattern. The effect of particle size on the model parameters is unknown. This parameter is typically not measured or not reported. Although numerous theoretical models have been proposed based on classical kinetic transport and thermodynamic processes, none has been found that provides a consistent explanation to the empirical evidence observed for the range of properties displayed by the five classes of compounds noted (Birdwell et al., 2004).
  • The simple form of the bi-phase model allows its direct incorporation into species mass balance for developing algorithms of the chemical release from resuspended particles. The chemical flux from the mobile (i.e., fast) fraction and the desorption-resistant (i.e., slow) fraction are both first order. This feature facilitates easy mathematical incorporation of the other processes involved. The other processes in addition to the flux from the two fractions include: (1) the rate of solid particle placement into the water column; (2) the particle settling rates; (3) the kinetic approach to thermodynamic equilibrium; (4) the evaporation to air; and (5) the on-bottom continued desorption rate. A dredge resuspension kinetic-based chemical release model has been developed and tested using conditions at a dredging site where Aroclor-1242 was the contaminant of interest. For proof-of-concept purposes, a simple version was used in which longitudinal dispersion was absent and a single particle sediment size was assumed. A closed analytical algorithm was the result; this inclusion of dispersion and several particle sizes will likely require a numerical solution (Thibodeaux and Birdwell, 2004).

Recommendations and Rationale for Close-out Budget

The modeling aspects of this project are mature. The bi-phase model has been theoretically rationalized and developed to the state that it will be proposed for use in applications of dredging in the remediation of contaminated sediments. The publication of this kinetic model will provide the users with an alternative to the traditional chemical equilibrium modeling approach. Based on the data and findings developed in year >04 at Rice University, the model will be extended to include metal releases from contaminated sediments. The budget proposed below is to cover the cost of finishing the development of the model to the extent it can be cast in a user-friendly format and placed upon the HSRC South/Southwest (S/SW) Website for access by potential users. Manuscript presentation, review, and acceptance in an appropriate journal must procede the website offering. These two tasks will involve one-half months’ time of the principal investigator and 2 months’ time of a graduate assistant.

Rice University Portion
Principal Investigators: M. Tomson, A. Kan

Project Rationale

In resuspension of contaminated sediments, heavy metals, such as Pb, Cd, Cu, Ni, Zn, and As represent several special challenges and will be the focus of this HSRC research. For example, DiGiano, et al., observed that the dredging elutriate test (DRET) protocol corresponds reasonably well to field dredge tests for PCBs and probably for other organic contaminants during dredging, but not for the heavy metals. This notion was further explained by Myers, et al.: “… but this approach is not recommended for application to release of dissolved metals during dredging because the rapid and pronounced change in redox and the complicated environmental chemistry of metals make equilibrium approaches highly unreliable and uncertain.” The overall objective of this research is to determine and quantify the processes responsible for heavy metal release during resuspension events based upon key physical and physical-chemical variables, such as particle size, aggregation status, total dissolved solids (TDS), total suspended solids (TSS), pH, redox, acid volatile sulfide (AVS), solution composition, and organic matter content in the sediment and overlying water. Five specific testing hypotheses are proposed:

  1. To test the hypothesis that, though there is a number of unique combinations of sediments, it is possible to identify a few key parameters that can be used to predict heavy metal release and thereby the potential for ecological exposure. We will simulate resuspension events in the laboratory, study the kinetics of heavy metal release during resuspension, and identify a few key parameters controlling contaminant transportation.
  2. Heavy metal release has been found to be multiphasic, with one set of processes controlling the early resuspension and a completely different set of processes important at times in excess of a few hours. Both rate processes need further study.
  3. Particle fines are released upon initial resuspension. These fines do not resettle rapidly, yet they have been found to contain many times the heavy metal load on a mg/g basis. These fines will facilitate the migration of many of the most dangerous heavy metals. Furthermore, it is just these fines that will impact the existing organisms. Understanding these issues will be a priority.
  4. Lastly, the possibility to identify a potential remediation plan that can be used to prevent heavy metals release during resuspension events and dredging will also be investigated. Attention has been and will continue to be focused on the impacts of resuspension on fines versus settleable particles and short versus long time frames. Along with creating a new bioavailability test for metals.

Approach

Methodology. Most work has been done on Trepangier and Anacostia River sediments. Both sediments have been characterized for their reactive metal contents (Table 1), metal distribution in various fractions by sequential extractions before and after resuspension (Figures 1 and 2), and AVS analysis. Both sediments contained significant concentrations of Zn, Cu, Ni, and Pb. Trepangier sediments also contained significant concentration of As. The Pb concentration in Trepangier sediment was 2.2 times greater than the U.S. Environmental Protection Agency’s (EPA’s) sediment quality guidelines probably effect concentration (PEC; i.e., above which harmful effects are likely to be observed). Laboratory scaled resuspension experiments were run where pH, and Eh were either monitored or controlled and the release of heavy metals in solution was analyzed to identify the cause and effect of various factors that control the release of heavy metals into the water body. The heavy metal release was tested with different pH, Eh profiles: (1) Trepangier, aerated (varying Eh and controlled neutral pH by calcite); (2) Trepangier, aerated, no EDTA (varying both Eh and pH); and (3) Trepangier, aerated, addition of EDTA (varying both Eh and pH). Resuspension experiments were also performed with a proposed new bioavailability test for heavy metals. The new test uses a chelating ion exchange resin in contact with the sediment to determine the bioavailable metal concentrations.

Table 1. Acid Extraction of Metals and Anions From Trepangier and Anocostia Sedimentsa

Sediments

Trepangier

Anacostia

Sediment Quality Guidelineb
(μg/g)

Ions

Conc. (μg/g)

Conc. (μmol/g)

Conc. (μg/g)

Conc. (μmol/g)

 

Fe

88296.5

1582.4

16647.4

298.34

 

Ca

8778.9

219.5

3774.1

94.35

 

Mn

862.2

15.7

252.3

4.60

 

Zn

196.4

3.0

336.6

5.15

459

Co

7.6

0.1

16.9

0.29

 

Ni

17.0

0.3

31.8

0.54

48.6

Cu

23.0

0.4

79.0

1.24

149

Pb

281.3

1.4

116.3

0.56

128

S

15274.3

477.3

734.1

22.94

 

As

22.3

0.3

1.5

0.02

33

P

6799.8

219.3

1747.5

56.37

 

AVS

 

130.0

 

5.00

 

OC (%)

 

8.1

 

3.70

 

a Sediments were digested with 1 N HCl for 24 hours. Amorphous and crystalline Fe and Mn oxyhydroxides, carbonate, and hydrous aluminosilicates should have been dissolved by this digestion procedure.
b The values are sediment quality guidelines determined by EPA (EPA 905/R-00/007, June 2000) that reflect PECs.

Fractional Distribution of Metal Ions

Figure 1. Anoxic Trepangier Bayou Sediments in a 0.01 M NaCl Solution
Figure 1. Anoxic Trepangier Bayou Sediments in a 0.01 M NaCl Solution

Figure 2. Trepangier Sediment, After 7 Days Resuspension in a 0.01 M NaCl Solution
Figure 2. Trepangier Sediment, After 7 Days Resuspension in a 0.01 M NaCl Solution

Output/Accomplishments. From a large number of tests, we have concluded that heavy metal release is driven by a complicated sequence of reactions, redox, biological activities, pH-driven desorption/dissolution, precipitation of iron and manganese oxides and fines production, and re-adsorption of certain heavy metals. In the following is a summary of key findings.

  1. More than 99% of the AVS is oxidized in 6 days of aeration. Forty percent of total S was released from oxidation of AVS and 60% was from pyrite. The oxidation of AVS and pyrite seems to be the primary source of the increased acidity in the solution, according to the following reactions:
  2. 2 FeS, solid + 9/2 O2 + 5 H2O ® 2 Fe(OH)3, solid + 2 SO42- + 4 H+ (1)
    FeS2, solid + 15/4 O2 + 5/2 H2O ® 2 FeOOH, solid + 2 SO42- + 4 H+ (2)

    Figure 3a shows the last two data points sitting on the phase boundary between Fe2+ and Fe2O3 indicating the possible precipitation of the iron oxyhydroxides. This could explain in Figure 3b the decrease in Fe concentration after day 3.

  3. The binding forms, which are exchangeable, carbonate, oxide, and sulfide/organic matter phases, of the heavy metals and As in Trepangier sediment significantly changed before and after resuspension experiments (Figures 1 and 2). The dominant fractions of Co, Ni, Zn, Cd, and Mn shifted from either carbonate, oxide, or sulfide/organic matter phases to the exchangeable phase. Fe, As, and Pb in the carbonate and sulfide/organic matter phases decreased considerably. This confirms the precipitation of ferric oxyhydroxides and their strong ability to scavenge for As and Pb. The binding pattern of Cu remains the same except for a slight increase in the exchangeable phase after aeration. This confirms the strong complexation between Cu and organic matter, which possibly remains stable during the time scale of our resuspension experiment.
  4. It is clear that the resuspension of anoxic sediment in oxic waters not only induces heavy metal release to the aqueous phase, but also alters their binding form in the sediment as well. Zn, Pb, Ni, Co, and Cd transformation from strongly bonded species (oxidic, cabonatic, sulfidic) to more weakly bonded species (exchangeable) would increase the mobility and bioavailability of these metals in the aquatic environment. Over extended periods of dredging, the change in binding forms of the solid phase is likely a bigger concern than that in the solution phase.

    In Trepangier, sulfide oxidation provides the primary source of metal release and the release pattern of Mn, Zn, Ni, Cd, and Co in this study is very similar to that of S during our resuspension experiments (Figure 4). However, our sequential extraction results indicate that the solution concentration of most metals exceeds their total concentration in the sulfide/organic matter phase. For example, the solution concentration of Zn at the end of the resuspension at 20 g/L is about 2450 μg/L, which is 5 times greater than the total Zn associated with the sulfide/organic matter phase. Therefore, metal sulfide minerals could not be the primary source of Zn. We believe the major portion of Zn released is from oxides in the sediment since the oxide fraction decreases sharply after resuspension. So following the same reasoning, we propose that during resuspension of Trepangier Bayou sediment, oxides are a major source for Zn, Cd, and Mn release, carbonates are important for Fe, Mn, Co, Ni, and Pb, and sulfide/organic matter is a dominant source for Pb and Cu.

  5. In Figure 5a the effect of calcite on the solution pH and Eh during a Trepangier sediment resuspension is shown. Dramatic changes in pH and Eh are observed when the sediment suspension is aerated without the addition of calcite. In contrast, there is little change in pH and a moderate change in Eh with the addition of calcite. Figure 5b shows the percentage release of the metals with and without addition of calcite. Significant release of metals is observed without the addition of calcite but little to no release is seen after the addition of calcite. This is consistent with the Eh-pH plot (Figure 6a) where the oxidative dissolution of FeS2 and FeCO3 was predicted with no addition of calcite whereas possible phase transformation of FeS2 to FeCO3/Fe2O3 is suggested in the presence of calcite.
  6. While the release of metals is quenched by the addition of calcite, the release of S, primarily due to the oxidation of AVS and FeS2, is similar in both systems. There are two explanations for this finding. For metals initially bound with sulfide, the release of the metals are masked by the precipitation of metal carbonates and/or oxides or by their readsorption onto newly formed iron carbonate and oxyhydroxides. For metals that originally bond to carbonate or oxide phases, they will not be released since they are stable at a neutral pH. We conclude that the increased acidity is the direct cause of significant mobilization of most metals.

  7. Figure 6a and 6b show the metal solution concentration after 5 hours and 3 days resuspension in the presence of 0.001 M EDTA. The amount of S release is not affected by the addition of EDTA throughout the whole experiment, suggesting that the addition of EDTA has limited affect on the oxidation of iron sulfides. In contrast, there is a significant effect on metal release at neutral pH with the addition of EDTA. It enhances the solution concentration of Fe, Co, Ni, Zn, and Cu. In comparison, when the solution pH drops to 4.2, the metal concentration in solution in the presence and absence of EDTA is similar in both solutions. In other words, the effect of EDTA at a low pH on metal release is negligible, which is possibly overshadowed by the acid dissolution of metal-containing minerals. Given that the addition of EDTA enhances metal release at a neutral pH but has little effect on sulfide oxidation, it is hypothesized that non-sulfidic phases such as carbonates and oxides are likely major sources of these metals. This conclusion is consistent with our findings from the sequential extraction results before and after resuspension.


  8. A new bioavailability test for heavy metals was developed and the test was used to determine the bioavailability of Anacostia sediment during resuspension. As shown in the previous results, the aqueous phase heavy metal can be readsorbed onto the newly formed ferric oxyhydroxides. Therefore, a conventional test, e.g., DRET, will not be adequate to measure the bioavailability of heavy metal during dredging. The proposed test allows for the resin to be in direct contact with the sediment and therefore a better assay to quantify the bioavailability of heavy metal. To test the bioavailability, an ion-chelating resin (Chelex 100 from BioRad) was in contact with sediment during resuspension in oxic conditions (Figure 7, left). The resin was separated from sediment and water with a set of mini-sieves (Figure 7, right). The resin, a styrene divinylbenzene copolymer containing paired iminodiacetate ions, which act as chelating groups in binding polyvalent metal ions, is used because of its chelating ion exchange properties and good selectivity for the heavy metals. Table 2 shows the percentage of metals in Anacostia sediments that was bioavailable. Between 10 and 67% of Pb, Co, Ni, and Zn become bioavailable during 6 hours of resuspension. The seemly high bioavailability of Ni may be due to systematic contamination in the ICP-MS and will be further tested. Table 3 compares the percentage of the bioavailable metals that is adsorbed on the resin versus the percentage that stays in the water. For Pb, Co, Zn, about 10–15% of the metals are bioavailable from the total metal concentration that is in the sediment, and 83–94% of the metal absorbs to the resin. Note that a conventional test, similar to that of DRET, will only detect the amount of heavy metals that remain in aqueous phase, and therefore will significantly underestimate the bioavailability of heavy metals in realistic conditions. The new bioavailability assay appeared to be very reproducible and easy to perform.

Figure 3a.
Figure 3a. Eh-pH plot of Fe Species and Solid Phases for the Trepangier Sediment (20 g/L) in a 0.01 M NaCl Solution Following 6 Days of Aeration. For phase boundaries, solid lines are drawn at an activity of total dissolved Fe of 10–6, dissolved S of 10–6, and pCO2 = 100. Dashed lines are drawn at [Fe] =10–4, [S] =10–4, and pCO2 = 10–2.

Figure 3b.
Figure 3b. Plots of Solution Metal and Sulfur Concentrations as a Function of Aeration Time During Resuspension of Trepangier Sediment in a 0.01 M NaCl Solution

Figure 4.
Figure 4. Comparison of the Release Pattern of Metals (Zn, Ni, Co, Mn, and Cd) and Sulfur as a Function of Aeration Time During Resuspension of Trepangier Sediment in a 0.01 M NaCl Solution. To simplify the comparison, the solution concentrations of S, Mn, and Zn were divided by 2000, 120, and 25, respectively.

Figure 5a.
Figure 5a. Eh-pH Plot for Fe Species and Solid Phases for Trepangier Sediment in a 0.01 M NaCl Solution Following 7 Days Resuspension in the Presence ( Symbol.) and Absence of Calcite (Symbol.). Phase boundaries drawn at assumed activity: [Fe] = 10–6, [S] = 10–6, and pCO2 = 100.

Figure 5b.
Figure 5b. Percentage of Metal Release to the Water Column Following 7 Days Aeration of Trepangier Sediment (40 g/L) in a 0.01 M NaCl Solution in the Presence and Absence of Calcite

Figure 6a.
Figure 6a. 5 Hours Aeration of Trepangier Sediment (20 g/L) in Artificial River Water in the Absence and Presence of EDTA (0.1 mM). The unit of the Y-axis is mg/L for Fe, S, and Mn and μg/L for As, Co, Ni, Zn, Pb, and Cu.

Figure 6b.
Figure 6b. 3 Days Aeration of Trepangier Sediment (20 g/L) in Artificial River Water in the Absence and Presence of EDTA (0.1 mM). The unit of the Y-axis is mg/L for Fe, S, and Mn and μg/L for As, Co, Ni, Zn, Pb, and Cu. The solution concentrations of S and Zn were divided by 5 and 25, respectively.

Figure 7.
Figure 7. Proposed New Dredging Elutri

Table 2. Percentage of Heavy Metals in Anacostia Sediments That Become Bioavailable During 6-Hour Resuspension Experiment

 

Resuspension #1

Resuspension #2

Pb

10

15.08

Co

7.58

10.72

Ni

66.89

47.87

Zn

12.86

11.69

Table 3. Percentage of the Bioavailable Heavy Metals That Resides in the Water Phase and on the Resin Phases During Resuspension.

 

Resuspension #1

Resuspension #2

 

% in H2O

% on resin

% in H2O

% on resin

Pb

16.87

83.13

8.89

91.11

Co

14.22

85.78

16.71

83.29

Ni

6.48

93.52

13.49

86.51

Zn

3.75

96.25

6.36

93.64

Recommendations and Rational for Subsequent Work

More work is needed to determine the generality of the metal classifications and binding. Van Den Berg, et al., indicated that dissolved metal concentrations in the water column were not significantly influenced by dredging activities. Instead, the increased level and mobility of metals is in the suspended particulate matter and is a more serious problem. There needs to be continued work to refine and modify the proposed new bioavailability test for heavy metals so that it can predict the fate and amount of metals released before dredging is done. This area of research seems to have a considerable benefit since it can provide a test that will be able to quantify what is going on in the system and give information that can lead to the potential impact on the system and a remediation plan.

Students Supported

Xuekun Cheng
Lili Cong
Heather Shipley
Sujin Yeon

Future Activities:

Rice University Portion
Principal Investigators: M. Tomson, A. Kan

Proposed Efforts Over the Next Year. The fundamental overall goals of this research remain as stated in the original proposal, to understand the impact of dredging on heavy metal release during resuspension and subsequent settling. The research is designed around three tasks: resuspension experiments; model systems; and controlling contaminant release and refining and testing of the new heavy metal bioavailability DRET.

  1. Conduct resuspension experiments on more fresh sediments with distinct variation in sediment character such as AVS, carbonate content, etc. Additional uncontaminated and contaminated sediments will be obtained from rivers or bayous in LA coordinated by Louis Thibodeaux. Sediment samples and redox conditions will be preserved as undisturbed as possible. Associated or overburden water will either be used directly or simulated in the laboratory. The impact of known changes in sediment/solution conditions during resuspension will be simulated with these field sediments, including redox and dissolved oxygen, pH, ionic strength, and temperature. The change in composition and binding during resuspension will be thoroughly characterized.
  2. Based upon results from the first two years of study, emphasis will be placed on the central role of redox processes in controlling the fate of heavy metals during dredging. Specifically, it has been observed that even redox systems release fewer heavy metals when well buffered. Many of the redox processes are subject to cycling from anoxic to aerobic by changes in dissolved oxygen, bacterial activity, and light effects. All of these processes are potentially active in many typical dredging conditions as the sediments migrate up and away from the bottom, are consumed by extant organisms, and possibly resettle. Some of the sediments will spend sufficient time in different environments to cause redox changes and concomitant changes in heavy metal availability. The standard DRET test was our base test but, by using the proposed new bioavailability test for heavy metals, we will see how these factors might change the release of metals; added variations designed to simulate a stream, bayou, etc., better will also be conducted.

  3. Model the mobility of heavy metal release during a resuspension event using a few predominant mechanisms. Once the range of interest for a particular contaminant–solid combination has been identified, the method of “constant composition” desorption will be used for a few combinations to obtain precise stoichiometry, kinetics, and equilibrium information at a fixed chemical potential driving force. Key samples will be used for extensive characterization by modern surface methods, such as atomic force microscopy (AFM) and extended range X-ray absorption fine structure (EXAFS).
  4. More experimental and theoretical modeling will be done examining the impact of biological processes and films on the availability of heavy metals. Some of this work will be done in the next task topic of mitigating the release of heavy metals by various methods. This will require both thermodynamic and kinetic models to better understand the induction and inhibition effects.

  5. Refine and modify the proposed new bioavailability test for heavy metals. This test will be used on different sediments and metals to better predict the fate and amount of metals released during resuspension. Once more lab resuspension experiments are done with this method, it can then be tested out in the field.
  6. The relative interplay between immediate physical-chemical changes, redox, heavy metal desorption, and redeposition for real sediments will be modeled by changing one parameter at a time. Change in solution and solid surface redox is expected to be the most important parameter controlling heavy metal release during dredging. How this redox varies and thereby alters the kinetics of heavy metal release is not known, but is probably related to sediment properties such as how the metals are bound to the sediment and in what form. Once key descriptors have been identified, simplified assays and predictors will be developed for routine use. The final hypothesis to be tested is that sorption and desorption of heavy metals can be modeled using readily available or measurable properties of sediments and dredged materials, along with properties of potentially impacted surface water bodies. Understanding the key physical and chemical parameters that affect heavy metal desorption during dredging and resuspension will enable regulators and field practitioners to reliably predict the environmental risk in specific dredging operations.

    At the end of the next year of research, we will be in a position to test our models and best treatment options in the field. Laboratory studies and modeling will be to a point where we will propose to test our physical, chemical, and transport models at a field site. For this reason, effort will be spent identifying such a site with HSRC Science Advisory Committee and LSU guidance.


Journal Articles on this Report : 12 Displayed | Download in RIS Format

Other subproject views: All 47 publications 14 publications in selected types All 12 journal articles
Other center views: All 279 publications 92 publications in selected types All 63 journal articles
Type Citation Sub Project Document Sources
Journal Article Chen W, Kan AT, Newell CJ, Moore E, Tomson MB. More realistic soil cleanup standards with dual-equilibrium desorption. Ground Water 2002;40(2):153-164. R828773 (2004)
R828773 (Final)
R828773C001 (2004)
R828773C004 (2002)
R828773C004 (2004)
R826694C700 (Final)
R831718 (Final)
  • Abstract from PubMed
  • Full-text: Environmental Expert-Full Text- PDF
    Exit
  • Abstract: Wiley-Abstract
    Exit
  • Other: ResearchGate-Abstract & Full Text - PDF
    Exit
  • Journal Article Chen W, Lakshmanan K, Kan AT, Tomson MB. A program for evaluating dual-equilibrium desorption effects on remediation. Ground Water 2004;42(4):620-624. R828773 (2004)
    R828773 (Final)
    R828773C004 (2004)
    R825513C023 (Final)
    R825513C024 (Final)
    R831718 (2005)
    R831718 (Final)
  • Abstract from PubMed
  • Full-text: NationalGroundWaterAssociation-Full Text PDF
    Exit
  • Abstract: Wiley-Abstract
    Exit
  • Journal Article Cheng XK, Kan AT, Tomson MB. Uptake and sequestration of naphthalene and 1,2-dichlorobenzene by C60. Journal of Nanoparticle Research 2005;7(4-5):555-567. R828773 (2004)
    R828773 (Final)
    R828773C004 (2004)
    R831718 (2005)
  • Abstract: Springer-Abstract
    Exit
  • Journal Article Cheng X, Kan AT, Tomson MB. Naphthalene adsorption and desorption from aqueous C60 fullerene. Journal of Chemical and Engineering Data 2004;49(3):675-683. R828773 (2004)
    R828773 (Final)
    R828773C004 (2003)
    R828773C004 (2004)
    R831718 (2005)
  • Abstract: ACS-Abstract
    Exit
  • Journal Article Gao Y, Kan AT, Tomson MB. Critical evaluation of desorption phenomena of heavy metals from natural sediments. Environmental Science & Technology 2003;37(24):5566-5573. R828773 (2004)
    R828773 (Final)
    R828773C004 (2002)
    R828773C004 (2003)
    R828773C004 (2004)
  • Abstract from PubMed
  • Abstract: ACS-Abstract
    Exit
  • Journal Article Gao Y, Wahi R, Kan AT, Falkner JC, Colvin VL, Tomson MB. Adsorption of cadmium on anatase nanoparticles-effect of crystal size and pH. Langmuir 2004;20(22):9585-9593. R828773 (2004)
    R828773 (Final)
    R828773C004 (2003)
    R828773C004 (2004)
    R831718 (2005)
  • Abstract from PubMed
  • Full-text: Rice University-Full Text PDF
    Exit
  • Abstract: ACS-Abstract
    Exit
  • Journal Article Gao Y, Kan AT, Tomson MB. Response to comment on "Critical evaluation of desorption phenomena of heavy metals from natural sediments". Environmental Science & Technology 2004;38(17):4703. R828773 (2004)
    R828773 (Final)
    R828773C004 (2004)
    R831718 (2005)
  • Abstract: ACS-Abstract
    Exit
  • Journal Article Kan AT, Fu G, Tomson MB. Effect of methanol on carbonate equilibrium and calcite solubility in a gas/methanol/water/salt mixed system. Langmuir 2002;18(25):9713-9725. R828773 (2004)
    R828773 (Final)
    R828773C004 (2004)
  • Abstract: ACS-Abstract
    Exit
  • Other: Rice University-Prepublication PDF
    Exit
  • Journal Article Kan AT, Fu G, Tomson MB. Effect of methanol and ethylene glycol on sulfates and halite scale formation. Industrial & Engineering Chemistry Research 2003;42(11):2399-2408. R828773 (2004)
    R828773 (Final)
    R828773C004 (2003)
    R828773C004 (2004)
  • Abstract: ACS-Abstract
    Exit
  • Journal Article Kan AT, Fu G, Tomson MB, Al-Thubaiti M, Xiao AJ. Factors affecting scale inhibitor retention in carbonate-rich formation during squeeze treatment. SPE Journal 2004;9(3):280-289. R828773 (2004)
    R828773 (Final)
    R828773C001 (2004)
    R828773C004 (2004)
  • Abstract: SPE Journal-Abstract
    Exit
  • Journal Article Kan AT, Fu G, Tomson MB. Adsorption and precipitation of an aminoalkylphosphonate onto calcite. Journal of Colloid and Interface Science 2005;281(2):275-284. R828773 (2004)
    R828773 (Final)
    R828773C004 (2004)
    R831718 (2005)
  • Abstract from PubMed
  • Full-text: ScienceDirect-Full Text HTML
    Exit
  • Abstract: ScienceDirect-Abstract
    Exit
  • Other: ScienceDirect-Full Text PDF
    Exit
  • Journal Article Tomson MB, Fu G, Watson MA, Kan AT. Mechanisms of mineral scale inhibition. SPE Production & Facilities 2003;18(3):192-199. R828773 (2004)
    R828773 (Final)
    R828773C004 (2004)
  • Full-text: Rice-PDF
    Exit
  • Abstract: OnePetro-Abstract
    Exit
  • Supplemental Keywords:

    heavy metals, dredging, bioavailability, sediment resuspension,, RFA, Scientific Discipline, Waste, Water, Contaminated Sediments, Analytical Chemistry, Hazardous Waste, Hazardous, Environmental Engineering, dewatering, vegetative dewatering, dreging, microbial degradation, bioavailability, biodegradation, resuspension, contaminated sediment, contaminated soil, bioremediation of soils, kinetcs, phytoremediation, dredged sediments, bioremediation

    Relevant Websites:

    http://www.hsrc-ssw.org Exit

    Progress and Final Reports:

    Original Abstract
  • 2002 Progress Report
  • 2003 Progress Report
  • 2005
  • 2006
  • Final

  • Main Center Abstract and Reports:

    R828773    HSRC (2001) - South and Southwest HSRC

    Subprojects under this Center: (EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
    R828773C001 Bioturbation and Bioavailability of Residual, Desorption-Resistant Contaminants
    R828773C002 In-Situ Containment and Treatment of Contaminated Sediments: Engineering Cap Integrity and Reactivity
    R828773C003 Phytoremediation in Wetlands and CDFs
    R828773C004 Contaminant Release During Removal and Resuspension
    R828773C005 HSRC Technology Transfer, Training, and Outreach