Final Report: Particle Transport and Deposit Morphology at the Sediment/Water Interface

EPA Grant Number: R825513C022
Subproject: this is subproject number 022 , established and managed by the Center Director under grant R825513
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).

Center: HSRC (1989) - South and Southwest HSRC
Center Director: Reible, Danny D.
Title: Particle Transport and Deposit Morphology at the Sediment/Water Interface
Investigators: Wiesner, Mark R.
Institution: Rice University
EPA Project Officer: Hahn, Intaek
Project Period: January 1, 1995 through January 1, 1998
Project Amount: Refer to main center abstract for funding details.
RFA: Hazardous Substance Research Centers - HSRC (1989) RFA Text |  Recipients Lists
Research Category: Hazardous Substance Research Centers , Land and Waste Management


The study focused on deposits formed under two conditions of two extremes of fluid flow; quiescent settling and deposition from turbulent flow. This work was to answer specific questions including: "What does the interface look like?"; "What are the transport mechanisms that determine rate of deposition and the structure of the interface?"; and "What are the kinetics of formation of various portions of the interface?". One premise of the work was that the morphology of the interface is intimately related to, and in some cases predictable from the characteristics of the suspended particles and the local fluid flow. This study yields critical information needed to calculate mass transport across the sediment/water "boundary", to interpret data obtained from sediment cores, to determine sampling protocols for sediments, and to assess sediment remediation schemes.

Summary/Accomplishments (Outputs/Outcomes):

This work combined models for particle transport and transformation to describe the formation of the sediment/water interface under conditions in which particle deposition rather than resuspension dominate the overall flux of particles to and from sediment. The work was compose of four interrelated tasks: 1) particle deposition under different conditions of fluid flow experiments performed using laboratory suspensions of particles of various sizes and surface chemistries; 2) similar experiments were conducted using sediment material collected from Galveston Bay or another source; 3) experimental results were compared with numerical simulations of the deposition process; and 4) to better define the chemistry of the colloidal and fineparticle phases that exist in Galveston Bay.

Computer simulations were performed to predict the rate of fineparticle deposition and the structure of the deposit. The simulations involved fineparticle transport algorithms and morphology algorithms. Theoretical and simulated predictions of deposition rate and the morphology of simulated sediments were compared to the rate of deposition and morphology of laboratory sediments. Laboratory sediments were created in both zero flow and turbulent crossflow regimes.

Influence of Turbulence on Cohesive Fineparticle Deposition Rate and Morphology
Deposit density measurements are highly variable. It is unclear whether the variability is inherent in the system, or simply an artifact of the chemical freezing and drying process. Deposits formed under widely differing flow regimes do not display any significant difference in structure, as measured by fractal dimension. The influence of hydrodynamic diffusion and reorganization do not appear to significantly alter deposit structure from that of which would form in their absence. Both simulations and experiments suggest no difference in D with u*. Simulating reorganization by considering an artificially low probability of particles sticking upon collision more accurately predicts experimentally observed fractal dimensions. Qualitative features predicted by simulation were not observed. Again it is unclear whether the features existed prior to chemical freezing and drying of samples. The experimentally observed flux was far lower than that predicted by the McCave model. This model appears to underestimate the decrease in flux observed at higher particle concentrations due to viscous sublayer instability.

Colloidal Transport of Elements from an Urban Watershed during a Storm Event
Quantification of the colloidal material by ICP analysis and its morphological and chemical characterization by means of electron microscopy in surface waters during a storm event show that the chemical nature of the colloidal material varies during the storm event. There is a dominance of colloidal carbon at the beginning of the storm followed by a dominance of colloidal silica at the period of maximum water discharge. The different sources of material and the reasons for which colloidal materials enter the urban waterway at different times still are unknown. A watershed is a complex system where different water sources are connected to each other (streams, soil moisture and ground water). Different hypothesis can be suggested for temporal variability of colliodal materials. First, colloidal materials carried to the point of sampling may come from different locations upstream, each one with a different colloidal chemical signature. Second, the sources of colloidal material may be similar, but released at different times during the storm process. Thus the chemical signature seen at the point of sampling reflects that of the different loadings over time from similar sources. Finally, the colloidal material at any "one" location may actually represent a blend of material from surface runoff, soil moisture, and groundwater. Future work on smaller watersheds will aid in resolving this issue.

Deposit Morphology and Head Loss Development in Porous Media
Experimental observations of nondispersed latex particles filtered through a bed of spherical glass beads indicated that flow rate plays an important role in head loss development by influencing the morphology of the deposits as well as the deposit distribution along the depth of the bed. The distributions of the deposits along the depth of porous media was more uniform at higher velocities. Deposits formed at low filtration (Darcy) velocities produced higher specific head loss (head loss per unit particle mass deposited) compared to the deposits formed at higher velocities. The fractal dimensions of the deposits increased with increase in velocity at either end of the range of flow rate (0.002-0.4 cm/s) investigated. This is consistent with the low specific head losses observed at higher superficial velocities and with the theory of increasing fractal dimension as particle transport becomes more ballistic. The low fractal dimensions observed in the intermediate velocities (0.04 to approximately 0.15 cm/s) appear to be due to the formation of compact columnar structures. This conclusion was supported by Monte-Carlo simulations of colloidal deposition from 2-D stagnation flow which were performed to approximate particle deposition at the top of filter grains.

Hydrodynamics of Fractal Aggregates with Radially Varying Permeability
Hydrodynamic properties of fractal aggregates with radially varying permeability are usefully approximated by a constant porosity aggregates with appropriately averaged characteristics. A simple model coupling the Happel's cell model with fractal geometry is used to estimate the permeability of the aggregate as a function of radial distance. Resistance to the fluid flow through the aggregate is observed to increase with increasing fractal dimension of the aggregate. The fluid collection efficiency of the aggregate decreases with increasing fractal dimension and is closely related to the drag coefficient for the aggregate. For a given fractal dimension, the drag coefficient increases with aggregate size, while the fluid collection efficiency decreases. The drag on a porous aggregate is well approximated as that of an aggregate with a constant volume-averaged permeability.

The predicted ratio of the hydrodynamic radius of the aggregate to its radius of gyration compared well with an experimentally observed value reported in the literature, given the assumptions in the theoretical work and uncertainties in the experimental work.

Journal Articles on this Report : 4 Displayed | Download in RIS Format

Other subproject views: All 7 publications 5 publications in selected types All 4 journal articles
Other center views: All 392 publications 154 publications in selected types All 106 journal articles
Type Citation Sub Project Document Sources
Journal Article Grout H, Tarquis MA, Wiesner MR. Multifractal analysis of particle size distributions in soil. Environmental Science & Technology 1998;32(9):1176-1182. R825513C022 (Final)
  • Full-text: ACS Full Text
  • Other: ACS PDF
  • Journal Article Thill A, Veerapaneni S, Simon B, Wiesner M, Bottero JY, Snidaro D. Determination of structure of aggregates by confocal scanning laser microscopy. Journal of Colloid and Interface Science, 1998;204(2):357-362. R825513C022 (Final)
    not available
    Journal Article Veerapaneni S, Wiesner MR. Deposit morphology and head loss development in porous media. Environmental Science & Technology 1997;31(10):2738-2744. R825513C022 (Final)
  • Full-text: ACS Full Text
  • Other: ACS PDF
  • Journal Article Wiesner MR. Morphology of particle deposits. Journal of Environmental Engineering 1999;125(12):1124-1132. R825513C022 (Final)
    not available

    Supplemental Keywords:

    deposition, fluid flow, and suspended particles., RFA, Scientific Discipline, Waste, Water, Ecosystem Protection/Environmental Exposure & Risk, Chemical Engineering, Contaminated Sediments, Environmental Chemistry, Fate & Transport, Analytical Chemistry, Hazardous Waste, Ecology and Ecosystems, Hazardous, Environmental Engineering, environmental technology, sediment treatment, hazardous waste management, hazardous waste treatment, risk assessment, fate and transport, contaminated marine sediment, soil and groundwater remediation, biodegradation, contaminated sediment, kinetics, chemical contaminants, contaminated soil, bioremediation of soils, deposit morphology, marine sediments, remediation, chemical kinetics, hydrology, biotransformation, currents, anaerobic biotransformation, technology transfer, heavy metals, aquifer fate and treatment, technical outreach

    Progress and Final Reports:

    Original Abstract
  • 1995
  • 1996

  • Main Center Abstract and Reports:

    R825513    HSRC (1989) - 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).
    R825513C001 Sediment Resuspension and Contaminant Transport in an Estuary.
    R825513C002 Contaminant Transport Across Cohesive Sediment Interfaces.
    R825513C003 Mobilization and Fate of Inorganic Contaminant due to Resuspension of Cohesive Sediment.
    R825513C004 Source Identification, Transformation, and Transport Processes of N-, O- and S- Containing Organic Chemicals in Wetland and Upland Sediments.
    R825513C005 Mobility and Transport of Radium from Sediment and Waste Pits.
    R825513C006 Anaerobic Biodegradation of 2,4,6-Trinitrotoluene and Other Nitroaromatic Compounds by Clostridium Acetobutylicum.
    R825513C007 Investigation on the Fate and Biotransformation of Hexachlorobutadiene and Chlorobenzenes in a Sediment-Water Estuarine System
    R825513C008 An Investigation of Chemical Transport from Contaminated Sediments through Porous Containment Structures
    R825513C009 Evaluation of Placement and Effectiveness of Sediment Caps
    R825513C010 Coupled Biological and Physicochemical Bed-Sediment Processes
    R825513C011 Pollutant Fluxes to Aquatic Systems via Coupled Biological and Physicochemical Bed-Sediment Processes
    R825513C012 Controls on Metals Partitioning in Contaminated Sediments
    R825513C013 Phytoremediation of TNT Contaminated Soil and Groundwaters
    R825513C014 Sediment-Based Remediation of Hazardous Substances at a Contaminated Military Base
    R825513C015 Effect of Natural Dynamic Changes on Pollutant-Sediment Interaction
    R825513C016 Desorption of Nonpolar Organic Pollutants from Historically Contaminated Sediments and Dredged Materials
    R825513C017 Modeling Air Emissions of Organic Compounds from Contaminated Sediments and Dredged Materials title change in last year to "Long-term Release of Pollutants from Contaminated Sediment Dredged Material"
    R825513C018 Development of an Integrated Optic Interferometer for In-Situ Monitoring of Volatile Hydrocarbons
    R825513C019 Bioremediation of Contaminated Sediments and Dredged Material
    R825513C020 Bioremediation of Sediments Contaminated with Polyaromatic Hydrocarbons
    R825513C021 Role of Particles in Mobilizing Hazardous Chemicals in Urban Runoff
    R825513C022 Particle Transport and Deposit Morphology at the Sediment/Water Interface
    R825513C023 Uptake of Metal Ions from Aqueous Solutions by Sediments
    R825513C024 Bioavailability of Desorption Resistant Hydrocarbons in Sediment-Water Systems.
    R825513C025 Interactive Roles of Microbial and Spartina Populations in Mercury Methylation Processes in Bioremediation of Contaminated Sediments in Salt-Marsh Systems
    R825513C026 Evaluation of Physical-Chemical Methods for Rapid Assessment of the Bioavailability of Moderately Polar Compounds in Sediments
    R825513C027 Freshwater Bioturbators in Riverine Sediments as Enhancers of Contaminant Release
    R825513C028 Characterization of Laguna Madre Contaminated Sediments.
    R825513C029 The Role of Competitive Adsorption of Suspended Sediments in Determining Partitioning and Colloidal Stability.
    R825513C030 Remediation of TNT-Contaminated Soil by Cyanobacterial Mat.
    R825513C031 Experimental and Detailed Mathematical Modeling of Diffusion of Contaminants in Fluids
    R825513C033 Application of Biotechnology in Bioremediation of Contaminated Sediments
    R825513C034 Characterization of PAH's Degrading Bacteria in Coastal Sediments
    R825513C035 Dynamic Aspects of Metal Speciation in the Miami River Sediments in Relation to Particle Size Distribution of Chemical Heterogeneity