title: Improved urban stormwater treatment and pollutant removal pathways in amended wet detention ponds.
abstract: Dissolved and colloidal bound pollutants are generally poorly removed from stormwater in wet detention ponds. These fractions are, however, the most bio-available, and therefore three wet detention ponds were amended with planted sand filters, sorption filters and addition of precipitation chemicals to enhance the removal of dissolved pollutants and pollutants associated with fine particles and colloids. The three systems treated runoff from industrial, residential and combined (residential and highway) catchments and had permanent volumes of 1,990, 6,900 and 2,680 m(3), respectively. The treatment performance of the ponds for elimination of total suspended solids (TSS), total nitrogen (Tot-N), total phosphorous (Tot-P), PO(4)-P, Pb, Zn, Cd, Ni, Cr, Cu, Hg were within the range typically reported for wet detention ponds, but the concentrations of most of the pollutants were efficiently reduced by the planted sand filters at the outlets. The sorption filters contributed to further decrease the concentration of PO(4)-P from 0.04 ± 0.05 to 0.01 ± 0.01 mg L(-1) and were also efficient in removing heavy metals. Dosing of iron sulphate to enrich the bottom sediment with iron and dosing of aluminium salts to the inlet water resulted in less growth of phytoplankton, but treatment performance was not significantly affected. Heavy metals (Pb, Zn, Cd, Ni, Cr and Cu) accumulated in the sediment of the ponds. The concentrations of Zn, Ni, Cu and Pb in the roots of the wetland plants were generally correlated to the concentrations in the sediments. Among 13 plant species investigated, Rumex hydrolapathum accumulated the highest concentrations of heavy metals in the roots (Concentration Factor (CF) of 4.5 and 5.9 for Zn and Ni, respectively) and Iris pseudacorus the lowest (CF < 1). The translocation of heavy metals from roots to the aboveground tissues of plants was low. Therefore the potential transfer of heavy metals from the metal-enriched sediment to the surrounding ecosystem via plant uptake and translocation is negligible.
authors.affiliation: LIMNOS Company for Applied Ecology, Ljubljana, Slovenia. darja@limnos.si
authors.forename: Darja
authors.initials: D
authors.lastname: Istenič
authors.forename: Carlos A
authors.initials: CA
authors.lastname: Arias
authors.forename: Jes
authors.initials: J
authors.lastname: Vollertsen
authors.forename: Asbjørn H
authors.initials: AH
authors.lastname: Nielsen
authors.forename: Tove
authors.initials: T
authors.lastname: Wium-Andersen
authors.forename: Thorkild
authors.initials: T
authors.lastname: Hvitved-Jacobsen
authors.forename: Hans
authors.initials: H
authors.lastname: Brix
mesh_terms: D000042:Absorption; D002947:Cities; D003102:Colloids / Q000032:analysis; D003718:Denmark; D004784:Environmental Monitoring / Q000379:methods / Q000706:statistics & numerical data*; D005618:Fresh Water / Q000032:analysis*; D019015:Geologic Sediments / Q000032:analysis*; D019216:Metals, Heavy / Q000032:analysis / Q000493:pharmacokinetics; D009584:Nitrogen / Q000032:analysis; D010758:Phosphorus / Q000032:analysis; D011891:Rain; D031804:Rumex / Q000378:metabolism; D013057:Spectrum Analysis; D014874:Water Pollutants, Chemical / Q000032:analysis*; D018508:Water Purification / Q000379:methods*
chemical_list: D003102:Colloids; D019216:Metals, Heavy; D014874:Water Pollutants, Chemical; D010758:Phosphorus; D009584:Nitrogen