Determining the effectiveness of best management practices to reduce nutrient flows in urban drains managed by the Water Corporation: Part 2 Literature Review

[摘要] The efficiency of the best management practices (BMPs) to reduce nutrient concentrations and loads in Perth’s urban main drains is poorly understood. Results from the other cities cannot be reliably extrapolated because of Perth’s unusually sandy catchments and the major contribution of groundwater to the nutrient loads in the streams and drains. The research project, funded by the Water Corporation and CSIRO Flagship Water for a Healthy Country, has been established to address the issues associated with the generation and transfer to surface water of nutrients in the selected catchments with the following objectives: 1.Define the existing water quality issues, including nutrient speciation, concentrations, and their relation to drainage hydrological characteristics;2.Define the relationship between water quality and land use, water management in the catchment, climate and opportunities for structural interventions; and3.Establish the requirements for BMPs which are most likely to address the issues identified and relevant technology (in-situ treatments) based upon Western Australian, national and international experience. This report provides a review of literature on the transfer of nutrients within urban environments as related to the potential sources and pathways which may exist and the nutrient transformation processes which occur.More specifically nutrient sources, pathways and processes are discussed in relation to the Perth metropolitan area situated on the Swan Coastal Plain. The merits of a variety of structural and non-structural nutrient control measures or BMPs are also discussed in general and in the specific context of their applicability for implementation in the Perth metropolitan area.The review provides information related to typical nutrient sources in the urban environment, including inputs from rainwater, impervious surface, vegetation, fertiliser, and wastewater.Nutrient concentrations associated with the identified nutrient sources are tabulated, and the potential nutrient attenuation or enrichment processes are related to the nutrient transfer from the sources to the surface water bodies. The literature suggests that these natural attenuation processes currently play a major role in reducing nutrient transfer from the urban environment into surface water bodies in Perth.Over 120 published papers and reports were reviewed, summarising the current national and international knowledge on in-situ water quality control BMPs and their ability to attenuate various nutrient species and the associated limitations. Reduction of nutrients through the application of BMPs occurs through the enhancement natural attenuation processes which may be absent or ineffective in the natural environment or urban setting. It was demonstrated that no one single BMP provides treatment for all nutrient species potentially present in fresh surface waters. This was due to the need for widely different environmental conditions required to remove different nitrogen and phosphorus species. For example, under anaerobic conditions promoting nitrate loss through denitrification, phosphate may be released due to the reductive dissolution of iron (III) oxide onto which the phosphate is adsorbed.Assessment of structural and non-structural BMPs in Perth is currently limited. Future focus should be placed on assessing the removal efficiency of current BMPs, especially load based assessments over peak flow events and during baseflow periods where residence times are at their greatest.

[发布日期] 2010-03-01 [发布机构] CSIRO

[学科分类] 地球科学(综合)