Brown, Sally LKates, Norah2019-08-142019-08-142019-08-142019Kates_washington_0250O_20398.pdfhttp://hdl.handle.net/1773/44269Thesis (Master's)--University of Washington, 2019Bioretention is an effective means of treating urban runoff, however, organic soil components are known to export P and Cu. Drinking water treatment residuals (WTRs) are cost-effective P sorbents and may also be useful in Cu retention. To optimize bioretention soil mixtures (BSMs), predictive measures of P and Cu mobility are needed for application across a range of materials. A series of batch studies was conducted with WTRs and organics to determine the relationship between P and Cu export and soil physiochemical characteristics. Materials were incubated separately and in combination, and net release was calculated on a mass basis from the media. P release from combinations increased with increases in either phosphorus saturation index (PSI) or phosphorus saturation ratio (PSR), determined by oxalate or Mehlich 3 extraction, respectively. Variation in P release increased at higher PSI and PSR values, but decreased at low values (PSI < 0.5, PSR < 1). Keeping the PSI and PSR of BSMs low should help reduce or eliminate P release from bioretention systems and improve water quality. Other factors, including total C of media and specific surface area of WTRs, were also significant but contributed only moderately to an explanation of the variation seen. Total Cu was a predictive factor of Cu release from the combinations, however, variation in this response was high and the predictive strength of total Cu as an explanatory variable was low.application/pdfen-USCC BY-NC-NDBioretentionCopperGreen Stormwater InfrastructurePhosphorusSoil ScienceStormwaterEnvironmental scienceWater resources managementForestryThesis