Field and Laboratory Tests of Flow-Proportional Passive Samplers for Determining Average Phosphorus and Nitrogen Concentration in Rivers

Abstract

Flow responsive passive samplers offer considerable potential in nutrient monitoring in catchments; bridging the gap between the intermittency of grab sampling and the high cost of automated monitoring systems. A commercially available passive sampler was evaluated in a number of river systems encapsulating a gradient in storm response, combinations of diffuse and point source pressures, and levels of phosphorus and nitrogen concentrations. Phosphorus and nitrogen are sequestered to a resin matrix in a permeable cartridge positioned in line with streamflow. A salt tracer dissolves in proportion to advective flow through the cartridge. Multiple deployments of different cartridge types were undertaken and the recovery of P and N compared with the flow-weighted mean concentration (FWMC) from high-resolution bank-side analysers at each site. Results from the passive samplers were variable and largely underestimated the FWMC derived from the bank-side analysers. Laboratory tests using ambient river samples indicated good replication of advective throughflow using pumped water, although this appeared not to be a good analogue of river conditions where flow divergence was possible. Laboratory tests also showed good nutrient retention but not elution and these issues appeared to combine to limit the utility in ambient river systems at the small catchment scale.

Changing climate and nutrient transfers: Evidence from high temporal resolution concentration-flow dynamics in headwater catchments

“…Nutrient data (total phosphorus (TP), total reactive phosphorus (TRP), and nitrate (NO 3 −)), were determined in-situ with a Hach Lange combined Sigmatax sampling module and Phosphax analyser Jordan et al, 2013;Perks et al, 2015). A flowthrough reservoir was refreshed at 30-min intervals, from which samples were drawn for TP and TRP analyses.…”

Prediction of storm transfers and annual loads with data-based mechanistic models using high-frequency data

“…TP concentration was determined in situ at 30 min intervals with a Hach Lange combined Sigmatax sampling module and Phosphax analyser using acid digestion and colorimetry (Jordan et al, 2007(Jordan et al, , 2013Perks et al, 2015). Total P loads for each hour were determined by multiplying discharge (averaged to 30 min resolution) by TP concentration for each 30 min and summing to give hourly totals:…”

High-resolution monitoring of nutrients in groundwater and surface waters: process understanding, quantification of loads and concentrations, and management applications

“…A number of studies (e.g. Rozemeijer et al, 2010c;Cassidy and Jordan, 2011;Jordan et al, 2013;Huebsch et al, 2015) compare several sampling instruments and monitoring strategies (Table 2). Various continuous monitoring methods, in particular those described in the papers presented in this special issue, are listed in Table 2.…”