ORCID Profile
0000-0003-3954-3638
Current Organisation
James Cook University
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Publisher: Elsevier BV
Date: 03-2014
DOI: 10.1016/J.ENVPOL.2013.11.030
Abstract: Perfluorinated chemicals (PFCs) have been recognised as environmental pollutants that require monitoring. A modified polar organic chemical integrative s ler (POCIS) is able to quantify aqueous PFCs. However, with varying external water velocity, PFC s ling rates (Rs) may change, affecting accuracy of derived water concentrations. To facilitate field deployment of this s ler, two methods of in-situ calibration were investigated: performance reference compounds (PRCs) and passive flow monitors (PFMs). Increased Rs's (by factors of 1.2-1.9) with PFM loss rate (g d(-1)) were observed for some PFCs. Results indicate PFMs can be used to correct PFC specific Rs's for more reliable estimates of environmental concentrations with a precision of about 0.01 L d(-1). Empirical models presented provide an improved means for aquatic monitoring of PFCs. The PRC approach was unsuccessful, confirming concern as to its applicability with such s lers.
Publisher: Elsevier BV
Date: 05-2012
DOI: 10.1016/J.MARPOLBUL.2012.02.004
Abstract: Passive s ling techniques facilitate the time-integrated measurement of pollutant concentrations through the use of a selective receiving phase. Accurate quantification using passive s ling devices rely on the implementation of methods that will negate the effects of environmental factors (flow, temperature, etc.) or that will allow the calculation of the chemical specific rates of uptake (R(s)) into the passive s ler employed. We have applied an in situ calibration technique based on the dissolution of gypsum to measure the average water velocity to which a s ler has been exposed. We demonstrate that the loss of gypsum from the passive flow monitor (PFM) can be applied to predict changes in R(s) dependent on flow when using the absorbent SPMD (semipermeable membrane device) and PDMS (polydimethyl siloxan) passive s lers. The application of the PFM will enhance the accuracy of measurements made when calculating and reporting environmental pollutant concentrations using a passive s ling device.
Publisher: American Chemical Society (ACS)
Date: 03-03-2011
DOI: 10.1021/ES101645Z
Abstract: Passive s lers for phosphate were calibrated in the laboratory over a range of flow velocities (0-27 cm s(-1)) and ionic strengths (0-0.62 mol kg(-1)). The observed s ling rates were between 0.006 and 0.20 L d(-1). An empirical model allowed the estimation of these s ling rates with a precision of 8.5%. Passive flow monitors (PFMs), based on gypsum dissolution rates, were calibrated for the same range of flow velocities and ionic strength. Mass loss rates of the PFMs increased with increasing ionic strength. We demonstrate that this increase is quantitatively accounted for by the increased gypsum solubility at higher ionic strengths. We provide a calculation scheme for these solubilities for an environmentally relevant range of temperatures and salinities. The results imply that co-deployed PFMs can be used for estimating the flow effect on the in situ s ling rates of the phosphate s lers, and we expect that the same may hold for other passive s lers.
Publisher: Elsevier BV
Date: 05-2011
DOI: 10.1016/J.ENVPOL.2010.12.028
Abstract: Passive s lers are typically calibrated under constant flow and concentration conditions. This study assessed whether concentration and/or flow pulses could be integrated using a phosphate passive s ler (P-s ler). Assessment involved three 21-day experiments featuring a pulse in flow rate, a pulse of filterable reactive phosphate (FRP) concentration and a simultaneous concentration and flow pulse. FRP concentrations were also determined by parallel grab s ling and the P-s ler calibrated with passive flow monitors (PFMs) and direct measurement of flow rates. The mass lost from the PFM over the deployment periods predicted water velocity to within 5.1, 0.48 and 7.1% when exposed to a flow rate pulse (7.5-50 cm s(-1)), concentration pulse (5-100 μg P L(-1)), or both simultaneously. For the P-s ler, good agreement was observed between the grab and passive measurements of FRP concentration when exposed to a pulse in flow (6% overestimation) or concentration (2% underestimation).
Publisher: Wiley
Date: 14-10-2010
DOI: 10.1111/J.1751-1097.2010.00816.X
Abstract: Proper application of sunscreen is essential as an effective public health strategy for skin cancer prevention. Insufficient application is common among sunbathers, results in decreased sun protection and may therefore lead to increased UV damage of the skin. However, no objective measure of sunscreen application thickness (SAT) is currently available for field-based use. We present a method to detect SAT on human skin for determining the amount of sunscreen applied and thus enabling comparisons to manufacturer recommendations. Using a skin swabbing method and subsequent spectrophotometric analysis, we were able to determine SAT on human skin. A swabbing method was used to derive SAT on skin (in mg sunscreen per cm(2) of skin area) through the concentration-absorption relationship of sunscreen determined in laboratory experiments. Analysis differentiated SATs between 0.25 and 4 mg cm(-2) and showed a small but significant decrease in concentration over time postapplication. A field study was performed, in which the heterogeneity of sunscreen application could be investigated. The proposed method is a low cost, noninvasive method for the determination of SAT on skin and it can be used as a valid tool in field- and population-based studies.
Publisher: Royal Society of Chemistry (RSC)
Date: 2009
DOI: 10.1039/B809901D
Abstract: Monitoring of nutrients including phosphate in the aquatic environment remains a challenge. In the last decade passive s ling techniques have been developed that facilitates the time integrated monitoring of phosphate (P) through the use of an iron hydroxide (ferrihydrite) to sequester dissolved phosphate from solution. These methods rely on established techniques to negate the effects of flow (and associated turbulence) and control the rate at which chemicals accumulate within passive s lers. In this study we present a phosphate s ler within which a suspension of ferrihydrite is contained behind a commercially available membrane. Accumulation of dissolved phosphates into the P-s ler is governed by the rate at which ions are diffusing through the membrane and the water boundary layer (WBL). As the WBL changes subject to flow we have adopted an in situ calibration technique based on the dissolution of gypsum to predict the change in the rate of uptake dependent on flow. Here we demonstrate that the loss of gypsum from the passive flow monitor (PFM) can be used to predict the s ling rate (the volume of water extracted per day) for phosphate as a function of water velocity. The outcome of this study presents a new in-field tool for more accurate prediction of the effect of flow/turbulence on the uptake kinetics into passive s lers that is controlled by the diffusion of the chemical of interest through the stagnant water boundary layer.
Publisher: Elsevier BV
Date: 05-2011
DOI: 10.1016/J.CHEMOSPHERE.2011.02.089
Abstract: The use of the adsorbent styrene inylbenzene-reverse phase sulfonated (SDB-RPD) Empore disk in a chemcatcher type passive s ler is routinely applied in Australia when monitoring herbicides in aquatic environments. One key challenge in the use of passive s lers is mitigating the potentially confounding effects of varying flow conditions on chemical uptake by the passive s ler. Performance reference compounds (PRCs) may be applied to correct s ling rates (R(s)) for site specific changed in flow and temperature however evidence suggests the use of PRCs is unreliable when applied to adsorbent passive s lers. The use of the passive flow monitor (PFM) has been introduced for the assessment of site-specific changes in water flow. In the presented study we have demonstrated that the R(s) at which both atrazine and prometryn are accumulated within the SDB-RPD-Empore disk is dependent on the flow conditions. Further, the calibration of the measured R(s) for chemical uptake by the SDB-RPD-Empore disk to the mass lost from the PFM has shown that the PFM provides an accurate measure of R(s) for flow velocities from 0 to 16cms(-1). Notably, for flow rates >16cms(-1), a non linear increase in the R(s) of both herbicides was observed which indicates that the key resistance to uptake into the SDB-RPD Empore disk is associated with the diffusion through the overlying diffusion limiting membrane. Overall the greatest uncertainty remains at very low flow conditions, which are unlikely to often occur in surface waters. Validation of the PFM use has also been undertaken in a limited field study.
No related grants have been discovered for Dominique O'Brien.