title: The effect of vegetation and soil texture on the nature of organics in runoff from a catchment supplying water for domestic consumption.
abstract: The influence of vegetation and soil texture on the concentration and character of dissolved organic matter (DOM) present in runoff from the surface and sub-surface of zero order catchments of the Myponga Reservoir-catchment (South Australia) was investigated to determine the impacts of catchment characteristics and land management practices on the quality of waters used for domestic supply. Catchments selected have distinct vegetative cover (grass, native vegetation or pine) and contrasting texture of the surface soil horizon (sand or clay loam/clay). Water samples were collected from three slope positions (upper, middle, and lower) at soil depths of ~30 cm and ~60 cm in addition to overland flows. Filtered (0.45 μm) water samples were analyzed for dissolved organic carbon (DOC) and UV-visible absorbance and by F-EEM and HPSEC with UV and fluorescence detection to characterize the DOM. Surface and sub-surface runoff from catchments with clay soils and native vegetation or grass had lower DOC concentrations and lower relative abundances of aromatic, humic-like and high molecular weight organics than runoff from sandy soils with these vegetative types. Sub-surface flows from two catchments with Pinus radiata had similar DOC concentrations and DOM character, regardless of marked variation in surface soil texture. Runoff from catchments under native vegetation and grass on clay soils resulted in lower DOC concentrations and hence would be expected to have lower coagulant demand in conventional treatment for potable water supply than runoff from corresponding sandy soil catchments. However, organics in runoff from clay catchments would be more difficult to remove by coagulation. Surface waters from the native vegetation and grass catchments were generally found to have higher relative abundance of organic compounds amenable to removal by coagulation compared with sub-surface waters. Biophysical and land management practices combine to have a marked influence on the quality of source water used for domestic supply.
authors.affiliation: Centre for Water Management and Reuse, School of Natural and Built Environments, University of South Australia, South Australia 5095, Australia.
authors.forename: John
authors.initials: J
authors.lastname: Awad
authors.affiliation: Centre for Water Management and Reuse, School of Natural and Built Environments, University of South Australia, South Australia 5095, Australia; State Key Laboratory for Environmental Aquatic Chemistry, CAS, Beijing, China; Barbara Hardy Institute, University of South Australia, South Australia 5095, Australia. Electronic address: John.VanLeeuwen@unisa.edu.au.
authors.forename: John
authors.initials: J
authors.lastname: van Leeuwen
authors.affiliation: Centre for Water Management and Reuse, School of Natural and Built Environments, University of South Australia, South Australia 5095, Australia.
authors.forename: Dawit
authors.initials: D
authors.lastname: Abate
authors.affiliation: School of the Environment, Flinders University, Bedford Park, South Australia 5042, Australia.
authors.forename: Markus
authors.initials: M
authors.lastname: Pichler
authors.affiliation: School of the Environment, Flinders University, Bedford Park, South Australia 5042, Australia.
authors.forename: Erick
authors.initials: E
authors.lastname: Bestland
authors.affiliation: School of Physical Sciences, University of Adelaide, North Terrace, South Australia 5005, Australia.
authors.forename: David J
authors.initials: DJ
authors.lastname: Chittleborough
authors.affiliation: South Australian Research and Development Institute, P.O. Box 397, Adelaide, SA 5000, Australia.
authors.forename: Nigel
authors.initials: N
authors.lastname: Fleming
authors.affiliation: Centre for Water Management and Reuse, School of Natural and Built Environments, University of South Australia, South Australia 5095, Australia.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Cohen
authors.affiliation: Centre for Water Management and Reuse, School of Natural and Built Environments, University of South Australia, South Australia 5095, Australia.
authors.forename: Joel
authors.initials: J
authors.lastname: Liffner
authors.affiliation: Centre for Water Management and Reuse, School of Natural and Built Environments, University of South Australia, South Australia 5095, Australia; Australian Water Quality Centre, SA Water Corporation, 250 Victoria Square, Adelaide, South Australia 5000, Australia; State Key Laboratory for Environmental Aquatic Chemistry, CAS, Beijing, China.
authors.forename: Mary
authors.initials: M
authors.lastname: Drikas
mesh_terms: D004784:Environmental Monitoring; D008956:Models, Chemical; D010944:Plants / Q000737:chemistry*; D012987:Soil / Q000737:chemistry*; D013021:South Australia; D014872:Water Movements; D014873:Water Pollutants / Q000032:analysis*; D014881:Water Supply
chemical_list: D012987:Soil; D014873:Water Pollutants
keywords: Fluorescence-EEM; Land use; Molecular weight; Organic carbon; Sub-surface flow; Surface runoff