Experimental Evaluation of Temporal Particle Agglomeration and Metal Partitioning of Urban Rainfall-Runoff
Rainfall-runoff quantity and quality control presents unique challenges due to the complexity and variability of hydrology and rainfall-runoff chemistry as well as the variable nature of constituent-producing processes in the environment. This study investigates two fundamental processes in rainfall-runoff: temporal particle agglomeration and metal partitioning between the solid and aqueous phase. A series of rainfall-runoff events were captured at an urban, Portland concrete cement (PCC) paved site in Baton Rouge, Louisiana and characterized with respect to particle gradation and metal phase fractions (dissolved and particulate) over time from a well-mixed, batch experimental system. Results indicate that equilibria and kinetics of natural particle agglomeration are inversely related to rainfall-runoff volume pH. Further, the average velocity gradient induced on a fully mixed system aids in particle agglomeration by entraining a larger fraction of the total particle gradation for particle-to-particle interaction. Following rainfall-runoff volume phase fractionation and ICP-MS analysis, metal partitioning was found to be in operational equilibrium at the naturally-occurring pH at the point of sample capture at the urban Baton Rouge site. Rainfall-runoff partitioning was compared between similar transportation land use sites in Baton Rouge, LA (544-m2 of PCC pavement) and Cincinnati, Ohio (300-m2 of asphalt pavement). Results suggest that the nature of the roadway material at Baton Rouge and elevated dissolved hardness cause both the state of equilibrium partitioning as well as a higher degree of particulate-bound partitioning. Partitioning is significantly particulate-bound for Cu, Zn, and Cd at the Baton Rouge site with arithmetic mean fp values of 0.72, 0.64, and 0.97, respectively as compared to fp values at the Cincinnati site of 0.04, 0.04, and 0.29 for these metals. While Pb was mostly particulate-bound for both the Baton Rouge and Cincinnati sites, the metal is significantly more particulate-bound at the Baton Rouge site with an fp value of 0.98 as compared to 0.68 for Cincinnati.
Advisor:Marty Tittlebaum; Frank Cartledge; J. J. Sansalone; John H. Pardue
School:Louisiana State University in Shreveport
School Location:USA - Louisiana
Source Type:Master's Thesis
Keywords:civil environmental engineering
Date of Publication:06/11/2003