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Characterization of Urban Stormwater-borne Solids in Tehran Metropolitan City, Iran

Kazemi Parkouhi, Fatemeh | 2011

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 43121 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Tajrishy, Massoud
  7. Abstract:
  8. Stormwater-borne solids are a major contributor to water quality degradation. A large portion of water quality impaired surface waters is located in urban areas and stormwater runoff is a major source of contamination. Sediments have been identified as the most widespread pollutant in urban river and streams. Water quality of urban streams in Tehran was characterized by determining the PSD, total phosphorus (TP), orthophosphate, NO3, NO2, NH3, TSS, TDS, heavy metals and turbidity in six storm events and base flow. A total of 45 road-deposited sediment (RDS) samples were collected from three different land-use types (residential, intense traffic and educational) in Tehran for characterization of PSD and heavy metal concentrations. These characterizations are an important attribute to BMP selection and are essential to estimate pollutant wash-off characteristics and to minimize the impacts of pollutants on the water environment.
    The stormwater samples are found to consist predominantly of fine particles (50–80%, <75 µm). A decrease in concentration with sequential removal of particulates was obtained for total suspended solids, turbidity, total phosphorus and heavy metals. The maximum concentrations of total phosphorus (TP), orthophosphate, NO3, NO2, NH3, TSS, TDS in mg/L and turbidity in NTU were 16.5, 3.2, 17.7, 4.7, 4.2, 1436, 780 and 768, respectively. The concentration of pollutants were mostly highest in the smallest particle size fraction analyzed (75 µm). RDS samples are found to consist predominantly of fine particles (50–80%, <300 µm). The maximum mean concentrations of zinc, lead, copper, nickel and cadmium were 536, 422, 210, 97 and 23 mg/kg, respectively, with the highest metal concentrations found in samples from the intense traffic area except for cadmium. The concentration of heavy metals were mostly highest in the smallest particle size fraction analyzed (75 µm). Reducing the amount of fine particles in runoff before the stormwater reaches the receiving water is a typical method for decreasing the adverse impact on water bodies due to nonpoint source pollution. Small particulates are correlated with the higher concentrations of pollutants and treatment systems must be able to effectively remove fine particles in runoff to significantly reduce the pollutant loads. Fine particles may not be effectively treated with sedimentation and it is better to use filtration and permeable pavements for Tehran stormwater treatment
  9. Keywords:
  10. Particles Size Distribution ; Tehran ; Land-Use ; Particles Pollutant Association ; Road-Deposited Sediment

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