Review of robust measurement of phosphorus in river water: sampling, storage, fractionation and sensitivity

Abstract

This paper reviews current knowledge on sampling, storage and analysis of phosphorus (P) in river waters. Potential sensitivity of rivers with different physical, chemical and biological characteristics (trophic status, turbidity, flow regime, matrix chemistry) is examined in terms of errors associated with sampling, sample preparation, storage, contamination, interference and analytical errors. Key issues identified include:The need to tailor analytical reagents and concentrations to take into account the characteristics of the sample matrix. The effects of matrix interference on the colorimetric analysis. The influence of variable rates of phospho-molybdenum blue colour formation. The differing responses of river waters to physical and chemical conditions of storage. The higher sensitivities of samples with low P concentrations to storage and analytical errors.Given high variability of river water characteristics in space and time, no single standardised methodology for sampling, storage and analysis of P in rivers can be offered. 'Good Practice' guidelines are suggested, which recommend that protocols for sampling, storage and analysis of river water for P is based on thorough site-specific method testing and assessment of P stability on storage. For wider sampling programmes at the regional/national scale where intensive site-specific method and stability testing are not feasible, 'Precautionary Practice' guidelines are suggested. The study highlights key areas requiring further investigation for improving methodological rigour.

Efficiency of a constructed wetland for retention of sediment-associated phosphorus

“…One possible explanation could be an underestimation of the P load at the main wetland inlet. As noted by Jarvie et al (2002) it is hard to obtain representative samples when sampling water with a high proportion of PP. The measured TP loss from the arable land in S. Stene catchment was 0.26 kg/ha/yr (when sewage pipes and background leakage from forest had been accounted for), and a study of a drained clay soil situated in the same geographical area showed a very similar P loss of 0.29 kg/ha/yr (Ulén & Persson, 1999).…”

“…The concentrations can be both over-and underestimated, as it is difficult to capture the event-based movement of particles even if flow-proportional sampling is employed (Jarvie et al, 2002). Adding measurements of actual sediment accumulation and the sediment content of P could result in a better understanding of the fate of PP in wetlands.…”

Nutrient and light limitation of periphyton in the River Thames: Implications for catchment management

“…Soluble reactive phosphorus was determined using the phosphomolybdenum blue colorimetry method of Murphy and Riley (1962), as modified by Neal et al, (2000). Samples were analysed within 24 hours, to minimise errors associated with sample instability (House and Warwick, 1998;Jarvie et al, 2002a). SRP is considered equivalent to bioavailable phosphorus (House, 2003).…”

Sampling, sample treatment and quality assurance issues for the determination of phosphorus species in natural waters and soils

“…Autoclaving methods are generally straightforward, give reproducible results and use sealed vessels that are less prone to contamination [75,[82][83][84]. The following section is therefore a summary of different autoclaving techniques, combined with peroxydisulfate in either an acidic or alkaline media, for the determination of phosphorus in natural waters, soil solutions and sediments (see Table 2 ).…”