Final Report: Role of Particles in Mobilizing Hazardous Chemicals in Urban Runoff

EPA Grant Number: R825513C021
Subproject: this is subproject number 021 , 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: Role of Particles in Mobilizing Hazardous Chemicals in Urban Runoff
Investigators: Wiesner, Mark R.
Institution: Rice University
EPA Project Officer: Hahn, Intaek
Project Period: January 1, 1992 through January 1, 1995
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 principal goal of this research was to obtain sufficient information on the characteristics of colloidal/particulate materials in urban runoff and in local rivers of the Houston Metropolitan Area to estimate loading of these particles and any associated contaminants into surface waters and sediments.

Three tasks were proposed in this research effort:

1.) Particle size distributions and the concentrations of target inorganic and organic contaminants were measured during background flow and storm water flow conditions at various locations in an urban watershed.
2.) The evolution of storm water quality over time at one location in the water shed was monitored during intensive sampling efforts during four storm events.
3.) The effect of particle aggregation as a transformation process affecting the fate of adsorbed contaminants was investigated.

Summary/Accomplishments (Outputs/Outcomes):

An electronic particle counter and light scattering device were used to obtain detailed information on particle size and concentration in the colloidal range on samples collected during storm events in Houston, Texas. Filtered and unfiltered samples were analyzed to identify dissolved and particulate fractions of heavy metals and organic contaminants. These data were used to identify significant differences in loadings and load characteristics between areas and thereby aid in the selection of 6 field sites. These data were integrated with a database on land use for the Houston Metropolitan Area using an existing Geographical Information System (GIS). Estimates of contaminant loadings from urban areas and the resultant in-stream concentrations of specific parameters were generated using the GIS and compared with values for these parameters measured in receiving waters.

Field observations confirmed the importance of storm events and urban runoff as a source of contaminants to urban waterways. Data obtained from storm progressions showed a considerable increase in the concentrations of suspended solids, organic carbon, metals and other measured contaminants in the runoff stream as a result of a storm event. During background conditions most of the suspended solid mass was confined to particle size fractions in the range of 0.45 µm to 20 µm. During storm conditions, larger particles were mobilized and swept into the stream and tended to dominate the suspended solids particle size distribution during peak flows. Increased loadings of suspended solids were reflected in a dramatic increase in the turbidity of the runoff stream.

Like the particle loading, the organic carbon concentrations in Brays Bayou also increased significantly during the storm period. However, organic carbon exhibited a bimodal distribution residing in both the particulate (above 0.45 µm) and colloidal (below 0.1 µm) fractions. Most of the organic carbon loading during storms appears to be related to suspended particles larger than 0.45 µm.

Some of the metals measured, such as chromium, iron and manganese, tend to be correlated with particles larger than 0.45 µm and with total organic carbon concentration during the storm. Zinc resided in both the particulate and the dissolved fractions. However, most of the changes during the storm event occurred in particulate classes. Chromium, iron, manganese, copper, and lead were confined mostly to particulate fractions. Strontium did not seem to be correlated to either suspended solids or organic carbon profiles and resided mostly in a dissolved fraction. Barium exhibited a bimodal distribution between the particulate fraction above 0.45 µm and the soluble fraction.

An enrichment in zinc concentrations on particles in storm water runoff was noted relative to concentrations reported for sediments in Galveston Bay. This substantial difference between zinc on particles in storm water runoff and sediments that presumably form as the result of the deposition of such particles, is attributed to the stripping of zinc from particle surfaces due to the high ionic strength environment of the Galveston bay estuary.

Dissolved atrazine and polyaromatic hydrocarbons in urban runoff were present in low concentrations during background conditions and increased only during very late stages of storm events, long after the stormwater flow had peaked.

Estimates of the particle collision efficiency factor, a, for particles in stormwater and background flow were similar and are typical of values reported for particles in other surface waters (on the order of 10-2). Although the collision efficiency factors of these particles are relatively low this is compensated by the high particle concentrations produced during a storm event. High particle concentrations tend to favor particle aggregation over a relatively short period of time. The rate of particle aggregation was observed to increase with particle concentration and ionic strength.

Data from experiments investigating the role of particle aggregation in transforming the size distribution of a marked polcyclic aromatic hydrocarbon, fluoranthene, suggest that the time scale for adsorption and aggregation are comparable to Brays Bayou. The particle size distributions changed very little in time-prolonged experiments suggesting that the aggregation process was break-up limited after approximately 1 hour. Fluoranthene was found to be predominately partitioned to particles larger than 3 µm as the suspended solids concentration and the ionic strength of the solution increased.

In summary, urban stormwater runoff is a significant source of suspended sediment and associated contaminants to receiving waterways. Different contaminants are "eluted" from the urban watershed at different times during strom events. Metals measured in runoff during this study reside in various size fractions and show different extents of association with suspended particles. These particles have a considerable potential for aggregation in a relatively short period of time under storm conditions. The rate and extent of aggregation are sufficient to significantly affect the fate and transport of any associated contaminants. The time scale for adsorption of fluoranthene used in this work as a model compound in experiments investigating the role of particle aggregation in transforming contaminant size distribution appears to be the same as that for the aggregation.

Journal Articles on this Report : 2 Displayed | Download in RIS Format

Other subproject views: All 10 publications 4 publications in selected types All 2 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 Characklis GW, Wiesner MR. Particles, metals, and water quality in runoff from large urban watershed. Journal of Environmental Engineering 1997;123(8):753-759. R825513C021 (Final)
not available
Journal Article Grout H, Wiesner MR, Bottero J-Y. Analysis of colloidal phases in urban stormwater runoff. Environmental Science & Technology 1999;33(6):831-839. R825513C021 (Final)
  • Full-text: ACS Publications Full Text
  • Other: ACS Publications PDF
  • Supplemental Keywords:

    stormwater runoff, water quality, and suspended solids., RFA, Scientific Discipline, Geographic Area, Waste, Water, Ecosystem Protection/Environmental Exposure & Risk, Chemical Engineering, Contaminated Sediments, Environmental Chemistry, State, Fate & Transport, Wet Weather Flows, Hazardous Waste, Ecology and Ecosystems, Hazardous, Environmental Engineering, fate and transport, environmental technology, sediment treatment, hazardous waste management, hazardous waste treatment, risk assessment, hydrologic dynamics, contaminated marine sediment, soil and groundwater remediation, contaminated sediment, runoff, kinetics, urban runoff, modeling, chemical contaminants, contaminated soil, marine sediments, remediation, chemical kinetics, hydrology, Texas (TX), pollutant - sediment interaction, GIS, currents, hazardous chemicals, stormwater runoff, groundwater, aquifer fate and treatment, technical outreach, contaminant transport models

    Progress and Final Reports:

    Original Abstract
  • 1992
  • 1993

  • 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