title: Phosphorus in soil treatment systems: accumulation and mobility.
abstract: Septic tanks with subsequent soil treatment systems (STS) are a common treatment technique for domestic wastewater in rural areas. Phosphorus (P) leakage from such systems may pose a risk to water quality (especially if they are located relatively close to surface waters). In this study, six STS in Sweden (11-28 years old) were examined. Samples taken from the unsaturated subsoil beneath the distribution pipes were investigated by means of batch and column experiments, and accumulated phosphorus were characterized through X-ray absorption near edge structure (XANES) analysis. At all sites the wastewater had clearly influenced the soil. This was observed through decreased pH, increased amounts of oxalate extractable metals and at some sites altered P sorption properties. The amount of accumulated P in the STS were found to be between 0.32 and 0.87 kg m(-3), which in most cases was just a fraction of the estimated P load (<30%). Column studies revealed that high P concentrations (up to 6 mg L(-1)) were leached from the material when deionized water was applied. However, the response to deionized water varied between the sites. As evidenced by XANES analysis, aluminium phosphates or P adsorbed to aluminium (hydr)oxides, as well as organically bound P, were important sinks for P. Generally soils with a high content of oxalate-extractable Al were also less vulnerable to P leakage.
authors.affiliation: Division of Land and Water Resources Engineering, Royal Institute of Technology, Teknikringen 76, SE-100 44 Stockholm, Sweden; JTI - Swedish Institute of Agricultural and Environmental Engineering, Box 7033, S-750 07 Uppsala, Sweden. Electronic address: eveborn@kth.se.
authors.forename: David
authors.initials: D
authors.lastname: Eveborn
authors.affiliation: Division of Land and Water Resources Engineering, Royal Institute of Technology, Teknikringen 76, SE-100 44 Stockholm, Sweden; Department of Soil and Environment, Swedish University of Agricultural Sciences, Box 7014, S-750 07 Uppsala, Sweden.
authors.forename: Jon Petter
authors.initials: JP
authors.lastname: Gustafsson
authors.affiliation: JTI - Swedish Institute of Agricultural and Environmental Engineering, Box 7033, S-750 07 Uppsala, Sweden.
authors.forename: Elin
authors.initials: E
authors.lastname: Elmefors
authors.affiliation: Centre for Environmental and Climate Research (CEC), Lund University, SE-22362 Lund, Sweden.
authors.forename: Lin
authors.initials: L
authors.lastname: Yu
authors.affiliation: Department of Soil and Environment, Swedish University of Agricultural Sciences, Box 7014, S-750 07 Uppsala, Sweden.
authors.forename: Ann-Kristin
authors.initials: AK
authors.lastname: Eriksson
authors.affiliation: JTI - Swedish Institute of Agricultural and Environmental Engineering, Box 7033, S-750 07 Uppsala, Sweden.
authors.forename: Emelie
authors.initials: E
authors.lastname: Ljung
authors.affiliation: Division of Land and Water Resources Engineering, Royal Institute of Technology, Teknikringen 76, SE-100 44 Stockholm, Sweden.
authors.forename: Gunno
authors.initials: G
authors.lastname: Renman
mesh_terms: D000327:Adsorption; D017607:Aluminum Compounds / Q000737:chemistry; D004784:Environmental Monitoring; D010710:Phosphates / Q000737:chemistry; D010758:Phosphorus / Q000032:analysis*; D012987:Soil / Q000737:chemistry*; D013548:Sweden; D064091:Waste Disposal Facilities; D062065:Wastewater / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis; D056928:X-Ray Absorption Spectroscopy
chemical_list: D017607:Aluminum Compounds; D010710:Phosphates; D010758:Phosphorus; D012987:Soil; D062065:Wastewater; D014874:Water Pollutants, Chemical; C012714:aluminum phosphate
keywords: Column studies; On-site wastewater treatment; Phosphorus leakage; Removal mechanisms; Septic system; X-ray absorption spectroscopy