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dc.contributor.authorHuang, Jianyin
dc.contributor.authorBennett, William W
dc.contributor.authorTeasdale, Peter R
dc.contributor.authorKankanamge, Nadeeka Rathnayake
dc.contributor.authorWelsh, David T
dc.description.abstractA modified diffusive gradients in thin films (DGT) technique uses both a mixed binding layer (PrCH and A520E resins for NH4-N and NO3-N, respectively) and multiple binding layers (Metsorb binding layer for PO4-P overlying the mixed binding layer) for the simultaneous measurement of dissolved inorganic nitrogen (nitrate and ammonium) and phosphate in freshwater (INP-DGT). High uptake and elution efficiencies were determined for a mixed (PrCH/A520E) binding gel for dissolved inorganic nitrogen and an agarose-based Metsorb binding layer for PO4-P. Diffusion coefficients (D) obtained from DGT time-series experiments (conductivity 180 μS cm−1) for NH4-N, NO3-N and PO4-P agreed well with those measured using individual DGT techniques in previous studies, but were characterised over a wider range of ionic strengths here. D for NO3-N and PO4-P were constant over a range of ionic strengths (between 100 and 800 μS cm−1) while the diffusion coefficient for NH4-N decreased with increasing ionic strength, as reported previously. The measurement of NH4-N, NO3-N and PO4-P using the INP-DGT was independent of pH (3.5–8.5) and quantitative over varying ionic strength ranges (up to 0.004 mol L−1 NaCl for NH4-N, up to 0.014 mol L−1 NaCl for NO3-N and over 0.1 mol L−1 NaCl for PO4-P) for a 24 h deployment time. Performance of INP-DGT in synthetic freshwaters with differing conductivity indicated the three nutrients were affected differently, with NH4-N measurements being most sensitive. Representative performance was determined for NO3-N (90–330 μS cm−1) and PO4-P (all tested conductivities) over a 72 h deployment period and for NH4-N (<330 μS cm−1) over a 24 h deployment period. Field validations showed that the ratios of INP-DGT concentrations to the average concentrations from grab samples were generally between 0.80 and 1.13 over 24 and 48 h deployment periods. To ensure the representative performance of INP-DGT for all three nutrients, the conductivity should not exceed 400 μS cm−1 and deployment times should be no longer than 24 h. The results of this study have demonstrated that INP-DGT could provide a cost-effective monitoring technique for measuring time-weighted average concentrations of dissolved inorganic nutrients in many freshwaters.
dc.publisherElsevier Science
dc.relation.ispartofjournalAnalytica Chimica Acta
dc.subject.fieldofresearchAnalytical Chemistry not elsewhere classified
dc.subject.fieldofresearchAnalytical Chemistry
dc.subject.fieldofresearchOther Chemical Sciences
dc.titleA modified DGT technique for the simultaneous measurement of dissolved inorganic nitrogen and phosphorus in freshwaters
dc.typeJournal article
dc.type.descriptionC1 - Articles
dc.type.codeC - Journal Articles
gro.facultyGriffith Sciences, Griffith School of Environment
gro.hasfulltextNo Full Text
gro.griffith.authorWelsh, David T.
gro.griffith.authorBennett, Will W.
gro.griffith.authorRathnayake Kankanamge, Nadeeka
gro.griffith.authorHuang, Jianyin
gro.griffith.authorTeasdale, Peter R.

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