Preprints
https://doi.org/10.5194/hess-2017-684
https://doi.org/10.5194/hess-2017-684
 
26 Jan 2018
26 Jan 2018
Status: this discussion paper is a preprint. It has been under review for the journal Hydrology and Earth System Sciences (HESS). The manuscript was not accepted for further review after discussion.

Comparison of high frequency, in-situ water quality analysers and sensors with conventional water sample collection and laboratory analyses: phosphorus and nitrogen species

Steven J. Granger1, Juan A. Qunicke1,2, Paul Harris1, Adrian L. Collins1, and Martin S. Blackwell1 Steven J. Granger et al.
  • 1Sustainable Agriculture Sciences, Rothamsted Research, North Wyke, Okehampton, Devon, EX20 2SB, UK
  • 2Instituto National de Investigación Agropecuaria, La Estanzuela, Ruta 50, Km. 11, Colonia, Uruguay

Abstract. The long-term collection of water samples for water quality analysis with high precision laboratory instrumentation is routine in monitoring programmes however, such sampling is labour intensive, expensive, and therefore undertaken at a low temporal frequency. Advances in environmental monitoring technology however, mean that it is now possible to collect high temporal frequency measurements for a wide range of water quality parameters without the need for the physical collection of a sample. The downside to this approach is that the data can be subject to more noise, due to environmental and instrument variables. This raises the question of whether high frequency, lower precision data are better than low frequency, higher precision data. This study reports the findings of an investigation of agricultural land drainage comparing measurements of total phosphorus (TP), total reactive phosphorus (TRP), ammonium (NH4-N) and total oxidised inorganic nitrogen (NOx-N) collected using both equipment in situ and concurrent water samples analysed in the laboratory. Results show that both in situ PHOSPHAX TP and NITRATAX NOx-N instruments can provide comparable data to that measured using samples analysed in the laboratory; however, at high discharge and low NOx-N concentrations, the NITRATAX can under report the concentration. In contrast, PHOSPHAX TRP and YSI sonde NH4-N data were both found to be incomparable to the laboratory data. This was because concentrations of both parameters were well below the instruments accurately determinable level, and because the laboratory data at low concentrations were noisy.

Steven J. Granger et al.

 
Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
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Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement

Steven J. Granger et al.

Steven J. Granger et al.

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Short summary
This manuscript looks at the measurement of water quality parameters through the collection of physical samples which are then analysed in an analytical laboratory compared to data generated by equipment placed in the environment. The advantage with this is that large volumes of data are collected at relatively low cost, however the instruments are not subject to the same scientific rigour as in the laboratory. A comparison of the two allows an assessment to be made of the two approaches.