title: Sediment-seawater solute flux in a polluted New Zealand estuary.
abstract: We investigated the sediment-seawater solute flux at five sites in the polluted Avon-Heathcote Estuary, New Zealand, to provide a point of comparison for future studies of the effects of the closure of a major wastewater outfall into the estuary. Sediments collected in winters 2007 and 2008, and summer 2008, ranked consistently in organic matter content. Microelectrode profiling and sediment-core incubations revealed (1) a dominant role of microphytes in regulating solute flux causing significant differences in the dark and light sediment O₂ consumption (R(d), R(l)), total sediment O₂ utilisation (TOU(d), TOU(l)), and inorganic nutrient flux, (2) consistent ranking of sites in solute flux, and (3) a clear solute-flux signature of the wastewater effluent. Sediment near the wastewater outfall exhibited the highest absolute R and TOU(,) the lowest ratio R(l)/R(d,) the highest dark efflux of dissolved reactive phosphorus and ammonium, and the highest dark and light uptake of nitrate+nitrite.
authors.affiliation: School of Applied Science, Auckland University of Technology, Auckland 1142, New Zealand. kay.vopel@aut.ac.nz
authors.forename: Kay
authors.initials: K
authors.lastname: Vopel
authors.forename: Peter S
authors.initials: PS
authors.lastname: Wilson
authors.forename: John
authors.initials: J
authors.lastname: Zeldis
mesh_terms: D004784:Environmental Monitoring; D063366:Estuaries / Q000706:statistics & numerical data; D019015:Geologic Sediments / Q000737:chemistry*; D009520:New Zealand; D009584:Nitrogen / Q000032:analysis; D010758:Phosphorus / Q000032:analysis; D000644:Quaternary Ammonium Compounds / Q000032:analysis; D012623:Seawater / Q000737:chemistry*; D062065:Wastewater / Q000032:analysis / Q000737:chemistry / Q000706:statistics & numerical data; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D009584:Nitrogen; D010758:Phosphorus; D000644:Quaternary Ammonium Compounds; D062065:Wastewater; D014874:Water Pollutants, Chemical