Development of a passive sampling methodology for measurement of time-averaged nutrient concentration in stormwater flow and receiving waters

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A lack of current and historical nutrient monitoring data with appropriate spatial and temporal scale has been a hindrance to cumulative effects assessments, and the development of environmental protection and management strategies for control of eutrophication in watersheds in Canada and internationally. The difficulty and expense of conducting water quality sampling has undoubtedly contributed to the poor monitoring record. The overall objective of this proposed research program is to develop and test an improved sampling methodology for selected nutrient pollutants in effluent and streamflow. Research Objectives: Short term: Develop an innovative, simple and reliable sampling methodology for passive detection and quantification of time-averaged nutrient concentration (nitrate and phosphate) in stormwater flow and within receiving waters. Passive meaning the method will not require a power supply, data logger or collection of water samples for the determination of time-averaged concentration. The focus will be upon a methodology for quantifying mean nutrient concentration in intermittent precipitation event-based discharges into receiving waters. The methodology will be initially developed under controlled laboratory conditions that simulate environmental conditions in stormwater collection systems. Long term: Apply the passive sampling methodology in conjunction with conventional flow monitoring for the study of stormwater nutrient pollutant mass loading into and within receiving water environments. For example studies such as: the influence of landuse types and land management practices upon stormwater quality and mass loading of nutrient pollutants into receiving waters, and measurement of spatial and temporal changes in nutrient pollutant distribution within receiving waters. Scientific Approach: Aim 1: Investigate the application of anion ion exchange resin membranes for the capture and retention of nutrient species (nitrate and phosphate) from stormwater under typical conditions within storm sewers and at stormwater outfalls. Aim 2: Investigate the kinetics of ion exchange reactions on anion exchange resin membranes for typical stormwater composition and environmental conditions. Based upon the kinetic studies, relate the mass capture of nitrate and phosphate on the ion exchange resin membranes to the time averaged nutrient species concentration in the sampled water environment. Aim 3: Investigate the application of the passive sampling methodology for study of nitrate and phosphate concentration and mass flow in stormwater collection systems by conducting parallel field tests with conventional time series volumetric sampling methods. Aim 4: Investigate the application of the passive sampling methodology for study of nutrient mass flow in receiving water environments. In particular, investigate the use of the sampling methodology to document two and three dimensional distribution of nutrient pollutants in receiving waters. Novelty and Significance: The passive sampling methodology developed will have no requirement for power supplies, electronic probes, trigger mechanisms, pumps, volumetric sampling or sample bottles. Hence the methodology will not be subject to the failures and reliability issues that commonly occur in pump and sample systems, or with ion specific electronic probe based monitoring systems. Further the proposed passive sampling methodology will be relatively low cost, reliable and easy to deploy in urban and/or remote locations due to its simplicity. Hence the development of the passive sampling methodology has the potential to greatly facilitate the establishment of much more comprehensive nutrient monitoring networks within watersheds for improved environmental assessment and protection.