Development and evaluation of the diffusive gradients in thin films technique for measuring nitrate in freshwaters

Huang, Jianyin; Bennett, William W.; Teasdale, Peter R.; Gardiner, Sean; Welsh, David T.

doi:10.1016/j.aca.2016.04.006

Cited by 38 publications

(66 citation statements)

References 46 publications

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“…Previous studies have reported very high concentrations of NO 3 −N and NH 4 −N at this site. 21,22 The Botanic Gardens is bordered by a golf club and a large residential area and contains a series of artificial ponds, dense with lilies and algae, which receive stormwater runoff from the surrounding areas and the gardens. Previous measurements at this site have found high NO 3 −N and NH 4 −N concentrations.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

“…DGT samplers were assembled as described previously. 21,22,34 The probes were stored in sealed plastic bags with 1−2 mL of deionized water prior to deployment.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

“…Sample Analysis. PrCH and A520E binding gels were eluted in 2 mL of 2 mol L −1 NaCl for 24 h, 21,22 and Metsorb binding gels were eluted in 1.5 mL of 1 mol L −1 NaOH for 24 h. 34 Eluates were diluted 5−10 times with deionized water to meet the acceptable concentration range of the analytical method. Prior to analysis, the pH of the Metsorb binding layer eluates were adjusted to a circumneutral pH using dilute HCl.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

“…where M is the mass of NH 4 −N, NO 3 −N, or PO 4 −P bound to the adsorbent (ng) corrected with the appropriate elution efficiency, 21,22,34 Δg is the diffusive layer thickness, D is the diffusion coefficient of inorganic nutrient ion through the diffusive layer (cm 2 s −1 ), A is the area of the probe exposed to solution (3.14 cm 2 ), and t is the deployment time (s…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

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“Diffusive Gradients in Thin Films” Techniques Provide Representative Time-Weighted Average Measurements of Inorganic Nutrients in Dynamic Freshwater Systems

Huang

Bennett

Welsh

et al. 2016

Environ. Sci. Technol.

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Nutrient concentrations in freshwater are highly variable over time, with changes driven by weather events, anthropogenic sources, modifications to catchment hydrology or habitats, and internal biogeochemical processes. Measuring infrequently collected grab samples is unlikely to adequately represent nutrient concentrations in such dynamic systems. In contrast, in situ passive sampling techniques, such as the "diffusive gradients in thin films" (DGT) technique, provide time-weighted average analyte concentrations over the entire deployment time. A pair of recently developed DGT techniques for nitrate (A520E-DGT) and ammonium (PrCH-DGT), as well as the Metsorb-DGT technique for phosphate, were used to monitor inorganic nutrients in different freshwater systems (i.e., streams and wetlands) with a range of environmental values and that were affected by different catchment types. Measurements of grab samples collected frequently (1-2 times daily, 8-10 a.m. and 2-4 p.m.) showed that concentrations of NH-N and NO-N changed dramatically in most of the studied freshwater systems over short time scales, while there were only relatively small fluctuations in PO-P. The DGT measurements were highly representative in comparison with the average nutrient concentrations obtained from daily grab samples over short-term (24 h) and long-term (72 h) deployments. The ratios of DGT-labile concentrations to the average concentrations from grab samples were between 1.00 and 1.12 over the studied deployment periods. The results of this study confirmed that DGT measurements provided a reliable and robust method for monitoring NH-N, NO-N, and PO-P in a diverse range of dynamic freshwater systems.

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Section: ■ Experimental Sectionmentioning

confidence: 99%

“…DGT samplers were assembled as described previously. 21,22,34 The probes were stored in sealed plastic bags with 1−2 mL of deionized water prior to deployment.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

Section: ■ Experimental Sectionmentioning

confidence: 99%

Section: ■ Experimental Sectionmentioning

confidence: 99%

See 2 more Smart Citations

“Diffusive Gradients in Thin Films” Techniques Provide Representative Time-Weighted Average Measurements of Inorganic Nutrients in Dynamic Freshwater Systems

Huang

Bennett

Welsh

et al. 2016

Environ. Sci. Technol.

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“…Purolite A520E anion exchange resin was developed for freshwaters 15 The diffusive layer thickness (∆g) and sampling window area (A) are specific to the geometry 167 of the DGT device, but consistent amongst samplers.…”

mentioning

confidence: 99%

Development and Application of the Diffusive Gradients in Thin Films Technique for the Measurement of Nitrate in Soils

Cai

Davison

et al. 2016

Anal. Chem.

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The temperature and flow dependence of nitrate concentration and load estimates based on diffusive gradients in thin films

et al. 2022

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Concentrations determined using diffusive gradients in thin films (DGT) have been used to derive time‐averaged loads in streams and rivers. However, DGT provide time‐weighted average concentrations that assume the independence of concentration and flow. Additionally, dynamic and coordinated changes in temperature, flow, and concentration are potential sources of bias in concentration and load calculations. We modeled scenarios in which temperature and flow were correlated to varying degrees with concentration and evaluated the consequences for DGT concentration and load calculations. As the correlation between solution flow and concentration moved toward 1 and –1, the load determined by DGT either overestimated or underestimated the actual load by as much as 30%. In DGT‐based load estimates, the degree of potential bias should be assessed, and the concentration‐flow relation should be characterized. As the correlation of analyte concentration and temperature approached 1 and –1, the deviation of the concentration determined by DGT from the actual concentration increased. In most cases, this bias was < 2%; however, if the changes in concentration and temperature were large (∼10 mg L–1 and ∼10 °C), the bias exceeded 5%. Concentration and temperature are unlikely to be perfectly or strongly correlated or anti‐correlated in natural systems and thus should not affect the accuracy of DGT concentration calculations in most circumstances. The more solution temperature, flow, and concentration were uncorrelated, the closer DGT‐derived concentration and load were to the actual solution concentration and load.

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Development and evaluation of the diffusive gradients in thin films technique for measuring nitrate in freshwaters

Cited by 38 publications

References 46 publications

“Diffusive Gradients in Thin Films” Techniques Provide Representative Time-Weighted Average Measurements of Inorganic Nutrients in Dynamic Freshwater Systems

“Diffusive Gradients in Thin Films” Techniques Provide Representative Time-Weighted Average Measurements of Inorganic Nutrients in Dynamic Freshwater Systems

Development and Application of the Diffusive Gradients in Thin Films Technique for the Measurement of Nitrate in Soils

The temperature and flow dependence of nitrate concentration and load estimates based on diffusive gradients in thin films

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