Michael G. Lawrence

University of Queensland , Brisbane, Queensland, Australia

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Publications (39)75.51 Total impact

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    ABSTRACT: The assessment of potential impacts of wastewater effluent discharges in freshwater systems requires an understanding of the likely degrees of dilution and potential zones of influence. In this study, four tracers commonly present in wastewater effluents were monitored to compare their relative effectiveness in determining areas in freshwater systems that are likely to be impacted by effluent discharges. The four tracers selected were the human pharmaceutical carbamazepine, anthropogenic gadolinium, fluorescent-dissolved organic matter (fDOM), and electrical conductivity (EC). The four tracers were monitored longitudinally in two distinct freshwater systems receiving wastewater effluents, where one site had a high level of effluent dilution (effluent <1 % of total flow) and the other site had a low level of effluent dilution (effluent ∼50 % of total flow). At both sites, the selected tracers exhibited a similar pattern of response intensity downstream of discharge points relative to undiluted wastewater effluent, although a number of anomalies were noted between the tracers. Both EC and fDOM are non-specific to human influences, and both had a high background response, relative to the highly sensitive carbamazepine and anthropogenic gadolinium responses, although the ease of measuring EC and fDOM would make them more adaptable in highly variable systems. However, the greater sensitivity and selectivity of carbamazepine and gadolinium would make their combination with EC and fDOM as tracers of wastewater effluent discharges highly desirable to overcome potential limitations of individual tracers.
    Environmental Monitoring and Assessment 06/2013; · 1.68 Impact Factor
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    ABSTRACT: Advanced water treatment of secondary treated effluent requires stringent quality control to achieve a water quality suitable for augmenting drinking water supplies. The removal of micropollutants such as pesticides, industrial chemicals, endocrine disrupting chemicals (EDC), pharmaceuticals, and personal care products (PPCP) is paramount. As the concentrations of individual contaminants are typically low, frequent analytical screening is both laborious and costly. We propose and validate an approach for continuous monitoring by applying passive sampling with Empore disks in vessels that were designed to slow down the water flow, and thus uptake kinetics, and ensure that the uptake is only marginally dependent on the chemicals' physicochemical properties over a relatively narrow molecular size range. This design not only assured integrative sampling over 27 days for a broad range of chemicals but also permitted the use of a suite of bioanalytical tools as sum parameters, representative of mixtures of chemicals with a common mode of toxic action. Bioassays proved to be more sensitive than chemical analysis to assess the removal of organic micropollutants by reverse osmosis, followed by UV/H₂O₂ treatment, as many individual compounds fell below the quantification limit of chemical analysis, yet still contributed to the observed mixture toxicity. Nonetheless in several cases, the responses in the bioassays were also below their quantification limits and therefore only three bioassays were evaluated here, representing nonspecific toxicity and two specific end points for estrogenicity and photosynthesis inhibition. Chemical analytical techniques were able to quantify 32 pesticides, 62 PCPPs, and 12 EDCs in reverse osmosis concentrate. However, these chemicals could explain only 1% of the nonspecific toxicity in the Microtox assay in the reverse osmosis concentrate and 0.0025% in the treated water. Likewise only 1% of the estrogenic effect in the E-SCREEN could be explained by the quantified EDCs after reverse osmosis. In comparison, >50% of the estrogenic effect can typically be explained in sewage. Herbicidal activity could be fully explained by chemical analysis as the sampling period coincided with an illegal discharge and two herbicides dominated the mixture effect. The mass balance of the reverse osmosis process matched theoretical expectations for both chemical analysis and bioanalytical tools. Overall the investigated treatment train removed >97% estrogenicity, >99% herbicidal activity, and >96% baseline toxicity, confirming the suitability of the treatment train for polishing water for indirect potable reuse. The product water was indistinguishable from local tap water in all three bioassays. This study demonstrates the suitability and robustness of passive sampling linked with bioanalytical tools for semicontinuous monitoring of advanced water treatment with respect to micropollutant removal.
    Environmental Science & Technology 06/2011; 45(12):5387-94. · 5.48 Impact Factor
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    ABSTRACT: Mangroves grow along coastal lines over a wide latitudinal range and therefore have great potential for recording high-resolution environmental information of tropical to sub-tropical regions. Such records can potentially be linked to tropical corals and temperate tree rings. We undertook carbon isotope, trace element and lead isotope analyses on a sample of a living mangrove (Rhizophora apiculata) of known age from Leizhou Peninsula (about 20ºN, 109-110ºE) from the northern coast of the South China Sea. The results show that the tree-rings are annual and their alpha-cellulose d13C values are significantly correlated with ring width, annual sea level, salinity and sea surface temperatures in the growth period, suggesting mangrove tree-rings may be used to characterize past sea level fluctuations (Yu et al, 2004, Geophysical Research Letters, 31, L11203, doi:10.1029/2004GL019450). The concentrations of most trace elements show weak declining trends from 1982 to 1999, punctuated by several high concentration spikes. The declining trends are positively correlated with ring width and negatively correlated with water use efficiency inferred from alpha-cellulose delta13C, suggesting a physiological control over metal-uptake in this species. The episodic metal concentration-peaks cannot be interpreted with lateral movement in the tree trunk or growth activities, and appear to be related to local environmental pollution events. Lead isotope compositions clearly document the importance of gasoline Pb as an atmospheric contaminant taken up by tree leaves. Moreover, shale-normalised rare earth element and yttrium (REE+Y) patterns are relatively flat and consistent across the growth period, with all patterns showing a positive Ce anomaly and elevated Y/Ho ratio. The positive Ce anomaly is observed regardless of the choice of normaliser, in contrast to previously reported REE patterns for terrestrial and marine plants (Yu et al. 2007, Nuclear Instruments & Methods in Physics Research-B, doi: 10.1016/j.nimb. 11.127). This study demonstrates the promising potential for the use of mangroves for monitoring environmental change.
    01/2011;
  • Y Zhou, J. X. Zhao, Y Zhu, Y Feng, M. G. Lawrence, Q. Chi, J Yan, Q Zhou
    01/2011;
  • 01/2011;
  • Ke-Fu Yu, Jian-xin Zhao, Michael G. Lawrence, Yuexing Feng
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    ABSTRACT: Growth hiatuses in massive corals are usually indicative of past ecological or environmental stresses. Among 37 fossil Porites colonies surveyed from the reef flat of Dadonghai fringing reef at Sanya, Hainan Island, northern South China Sea, seven of them were found to show clear evidence of past mortality, representing a population of -19%. Among these samples, two of them (SYO-13 and SYO-28) display clear growth hiatuses reflecting mortality followed by subsequent recruitment, and five others exhibit a well-preserved mortality surface and no subsequent recruitment. The growth hiatuses were dated using high-precision thermal ionisation mass spectrometry U-series techniques. The age results suggest all the dated corals formed and died in the mid Holocene. Multiple dates below the growth hiatuses suggest that SYO-13 and SYO-28 died at 6298--11 and 6929--19 a BP (i.e. years before AD 1950), respectively. Multiple dates above the growth hiatuses indicate that growth in SYO-13 and SYO-28 resumed at 6257--14 and 6898--20 a BP, respectively. The calculated durations of growth hiatuses are therefore 41--18 a for SYO-13 and 31--28 a for SYO-28, respectively, implying growth resumed within decades after the mortality events. U-series dating of four other samples with dead heads suggests that they died at 6035--53, 6059--23, 6127--22 and 6474--24 a BP, respectively. In addition, using solution inductively coupled plasma mass spectrometry (ICP-MS), monthly resolution Sr/Ca and Mg/Ca ratios were determined for the annual growth bands below and above the growth hiatuses for three of the dated samples. The Sr/Ca and Mg/Ca profiles indicate that the three corals probably died in different seasons (from spring to autumn), and the mortality appears to be unrelated to anomalous sea surface temperature-induced bleaching. 2010 John Wiley & Sons, Ltd.
    Journal of Quaternary Science 12/2010; 25(8):1284-1292. · 2.66 Impact Factor
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    ABSTRACT: This paper examines the fate of perfluorinated sulfonates (PFSAs) and carboxylic acids (PFCAs) in two water reclamation plants in Australia. Both facilities take treated water directly from WWTPs and treat it further to produce high quality recycled water. The first plant utilizes adsorption and filtration methods alongside ozonation, whilst the second uses membrane processes and advanced oxidation to produce purified recycled water. At both facilities perfluorooctane sulfonate (PFOS), perfluorohexane sulfonate (PFHxS), perfluorohexanoic acid (PFHxA) and perfluorooctanoic acid (PFOA) were the most frequently detected PFCs. Concentrations of PFOS and PFOA in influent (WWTP effluent) ranged up to 3.7 and 16 ng L⁻¹ respectively, and were reduced to 0.7 and 12 ng L⁻¹ in the finished water of the ozonation plant. Throughout this facility, concentrations of most of the detected perfluoroalkyl compounds (PFCs) remained relatively unchanged with each successive treatment step. PFOS was an exception to this, with some removal following coagulation and dissolved air flotation/sand filtration (DAFF). At the second plant, influent concentrations of PFOS and PFOA ranged up to 39 and 29 ng L⁻¹. All PFCs present were removed from the finished water by reverse osmosis (RO) to concentrations below detection and reporting limits (0.4-1.5 ng L⁻¹). At both plants the observed concentrations were in the low parts per trillion range, well below provisional health based drinking water guidelines suggested for PFOS and PFOA.
    Chemosphere 11/2010; 82(1):9-17. · 3.14 Impact Factor
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    ABSTRACT: White pottery is among the most significant finds from China's earliest state, Erlitou (c. 1900–1500 bc). Samples were primarily discovered in small numbers from elite tombs of a few sites, leading to the hypothesis that they were made at only a few locations and then circulated regionally as prestige items. To facilitate determining provenances, we compare the ICP–MS trace elements and TIMS Sr isotopes of whiteware with two soil samples from Nanwa, a possible manufacturing site, and with shards found at three other sites: Erlitou, Huizui and Nanzhai. The Nanwa shards demonstrate special elemental and Sr isotopic features. Considering the chemical observation and archaeological background together, we propose that Nanwa was a centre for whiteware production, although the two soil samples we collected there were probably not the exact materials used. Some whiteware pieces from Erlitou, Huizui and Nanzhai fall in the chemical field defined by Nanwa samples, indicating that they were possibly made at Nanwa. Many other samples from these three sites plot outside the Nanwa field, implying they were probably not Nanwa products. This study demonstrates that while chemical sourcing is very useful, firm archaeological context must remain the cornerstone of such research.
    Archaeometry 08/2010; 52(5):760 - 776. · 1.29 Impact Factor
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    ABSTRACT: The analysis of 87 peer-reviewed journal articles reveals that sampling for pharmaceuticals and personal care products (PPCPs) and illicit drugs in sewers and sewage treatment plant influents is mostly carried out according to existing tradition or standard laboratory protocols. Less than 5% of all studies explicitly consider internationally acknowledged guidelines or methods for the experimental design of monitoring campaigns. In the absence of a proper analysis of the system under investigation, the importance of short-term pollutant variations was typically not addressed. Therefore, due to relatively long sampling intervals, potentially inadequate sampling modes, or insufficient documentation, it remains unclear for the majority of reviewed studies whether observed variations can be attributed to "real" variations or if they simply reflect sampling artifacts. Based on results from previous and current work, the present paper demonstrates that sampling errors can lead to overinterpretation of measured data and ultimately, wrong conclusions. Depending on catchment size, sewer type, sampling setup, substance of interest, and accuracy of analytical method, avoidable sampling artifacts can range from "not significant" to "100% or more" for different compounds even within the same study. However, in most situations sampling errors can be reduced greatly, and sampling biases can be eliminated completely, by choosing an appropriate sampling mode and frequency. This is crucial, because proper sampling will help to maximize the value of measured data for the experimental assessment of the fate of PPCPs as well as for the formulation and validation of mathematical models. The trend from reporting presence or absence of a compound in "clean" water samples toward the quantification of PPCPs in raw wastewater requires not only sophisticated analytical methods but also adapted sampling methods. With increasing accuracy of chemical analyses, inappropriate sampling increasingly represents the major source of inaccuracy. A condensed step-by-step Sampling Guide is proposed as a starting point for future studies.
    Environmental Science & Technology 08/2010; 44(16):6024-35. · 5.48 Impact Factor
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    ABSTRACT: The aim of this study was to assess uncertainties associated with different sampling modes when evaluating loads of pharmaceuticals and personal care products (PPCPs) in sewers and influents to sewage treatment plants (STPs). The study demonstrates that sampling uncertainty can range from "not significant" to "far greater than the uncertainty due to chemical analysis", which is site- and compound-specific and depends on the (in)accuracy of the analytical method. Conventional sampling devices operated in common time- or flow-proportional sampling modes, and applying traditional sampling intervals of 30 min or longer can result in the collection of nonrepresentative samples. At the influent of a STP, wastewater may appear as a continuous stream, but it is actually composed of a number of intermittently discharged, individual wastewater packets from household appliances, industries, or subcatchments in pressurized sewer systems. The resulting heterogeneity can cause significant short-term variations of pollutant loads. We present different experimental results and a modeling approach showing that the magnitude of sampling uncertainty depends mainly on the number of pollutant peaks and the sampling frequency; sampling intervals of 5 min or shorter may be required to properly account for temporal PPCP variations in influents of STPs. A representative sample is a prerequisite for providing meaningful analytical results and cannot be compensated with a large number of samples, accurate chemical analysis, or sophisticated statistical evaluation. This study highlights that generalizing from one case to another is difficult and hence a careful systems analysis of the catchment under investigation, or precautionary choice for a sophisticated sampling mode, is necessary to prove reproducibility.
    Environmental Science & Technology 08/2010; 44(16):6289-96. · 5.48 Impact Factor
  • Michael Glen Lawrence, David Guimerà Bariel
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    ABSTRACT: The discharge of treated wastewater into natural water bodies occurs worldwide; if drinking water is then extracted downstream, there is potential for micropollutants that are not fully mineralized in the wastewater treatment process to enter municipal drinking water. In Australia, drinking water treatment is typically a mixture of basic technologies such as flocculation and slow sand filtration; technologies that are not specifically designed to remove micropollutants. However, there is little awareness in Australia of the potential risk that upstream wastewater discharges may impart to the security and quality of downstream drinking water supplies. We apply a direct inductively coupled plasma mass spectrometry technique to determine the discharge of anthropogenic gadolinium from a wastewater treatment plant in Toowoomba, Queensland, Australia, that discharges into the small (147 km(2)) catchment of Gowrie Creek. We then continue to measure the concentrations of this wastewater tracer as Gowrie Creek flows downstream into the Condomine River, and to a community 100 km away where drinking water is extracted. Using this tracer, we demonstrate that the community has a detectable wastewater contribution within their surface drinking water supply.
    Chemosphere 08/2010; 80(7):794-9. · 3.14 Impact Factor
  • Michael G Lawrence
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    ABSTRACT: Wastewater effluent is known to contain macro and micropollutants, which may be deleterious to environmental health. One such class of micropollutants is chelated gadolinium, which are used as MRI contrast agents. As these MRI contrast agents can be assumed to behave conservatively during estuarine mixing, it is possible to calculate how much wastewater is represented in any particular sample. In this study, the percentage contribution of wastewater at specific locations in Moreton Bay, Qld, were determined by calculating the additional anthropogenic gadolinium contribution to the total rare earth element concentrations. Wastewater contributions were measured at concentrations as low as 0.2%, demonstrating the applicability of this technique for wastewater effluent plume mapping.
    Marine pollution bulletin 07/2010; 60(7):1113-6. · 2.63 Impact Factor
  • Michael G Lawrence, Jurg Keller, Yvan Poussade
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    ABSTRACT: Stable gadolinium (Gd) complexes have been used as paramagnetic contrast agents for magnetic resonance imaging (MRI) for over 20 years, and have recently been identified as environmental contaminants. As the rare earth elements (REE), which include Gd, are able to be measured accurately at very low concentrations (e.g. Tb is measured at 7 fmol/kg in this study) using inductively coupled plasma mass spectrometry (ICP-MS), it is possible to determine the fate of this class of compounds during the production of purified recycled water from effluent. Coagulation and microfiltration have negligible removal, with the major removal step occurring across the reverse osmosis membrane where anthropogenic Gd (the amount of Gd attributable to MRI contrast agents) is reduced from 0.39 nmol/kg to 0.59 pmol/kg, a reduction of 99.85%. The RO concentrate has anthropogenic Gd concentrations of 2.6 nmol/kg, an increase in concentration in line with the design characteristics of the plant. The increased concentration in the RO concentrate may allow further development of anthropogenic Gd as a tracer of the fate of the RO concentrate in the environment.
    Water Science & Technology 01/2010; 61(3):685-92. · 1.10 Impact Factor
  • Michael G Lawrence, Christoph Ort
    Environmental Science and Technology 08/2009; 43(14):5547-8; author reply 5549-50. · 5.48 Impact Factor
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    ABSTRACT: Pharmaceutical residues in water are frequently analysed and discussed in connection with sewage treatment, ecotoxicity and, natural and drinking water quality. Among different localities hospitals are suspected, or implied, to be a major and highly variable source of pharmaceuticals that substantially contribute to the total wastewater load. In this study, the contribution of pharmaceuticals from a hospital to a sewage treatment plant (STP) serving around 45,000 inhabitants was evaluated. Approximately 200 hospital beds result in a hospital bed density of 4.4 beds per 1000 inhabitants, which is a typical value for developed world countries. Prior to sampling, a sound systems analysis was performed, and a sophisticated continuous flow-proportional sampling regime was applied. Hence, overall experimental uncertainty was reduced to a minimum, and measurements provide clear evidence that, for 28 of 59 investigated substances, over 85% of the pharmaceutical residue loads do not originate from the hospital when applying a conservative error estimation. Only for 2 substances, trimethoprim (18%) and roxithromycin (56%), was the maximum observed contribution of the hospital >15%. On average, the contribution of the hospital for the compounds detected in both, hospital effluent and sewage treatment plant influent was small and fairly constant. Five compounds were only detected in hospital wastewater, and 24 neither in the hospital wastewater nor in the total wastewater at the influent of the STP. For these compounds no experimental contribution could be calculated. For the compounds where audit data for both the national consumption and the specific hospital under investigation were available, a prediction of the fraction of pharmaceuticals originating from the hospital was performed. Three quarters of the compounds, classified with the existing audit data, were in the same "hospital contribution category" as determined by measurements. For most of the other compounds, plausible reasons could be identified to explain the observed deviations.
    Water Research 08/2009; 44(2):605-15. · 4.66 Impact Factor
  • Michael G Lawrence, Christoph Ort, Jurg Keller
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    ABSTRACT: The use of refractory gadolinium (Gd) complexes as paramagnetic contrast agents in magnetic resonance imaging has resulted in point source release of anthropogenic Gd (Gd(Anth)) into the environment, and presents opportunities to trace the fate of wastewater in natural environments. We demonstrate an inductively coupled plasma mass spectrometry (ICP-MS) technique that is capable of detecting Gd(Anth) at concentrations as low as 48 fM, approximately six orders of magnitude lower than most other micropollutants, without the need for preconcentration. Further, we establish the ubiquitous presence of Gd(Anth) in wastewater at eight separate wastewater treatment plants in Brisbane, Australia, over a 3-month time period. In contrast, there is no evidence of Gd(Anth) in tap water, or in four separate regional water supply dams in South East Queensland, Australia. It is, therefore, highly unlikely that other anthropogenic micropollutants sourced from urban wastewater would be present in the drinking water supply.
    Water Research 06/2009; 43(14):3534-40. · 4.66 Impact Factor
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    ABSTRACT: Two perfluoroalkyl chemicals (PFCs), perfluoroctanoic acid (PFOA) and perfluorooctanesulfonate (PFOS), have been detected widely at low levels in biota and humans. Secondary sewage treatment plants (STPs) do not effectively remove these compounds; hence STP effluents are recognized point sources to the aquatic environment. Here we sampled water from various stages of an advanced water treatment plant, utilizing microfiltration, reverse osmosis and advanced oxidation, and assessed the removal of 15 PFCs in the system. The plant studied takes effluent from several STPs, producing up to 66 ML/day of purified recycled water. Grab samples were collected at various stages of the treatment train. Analysis showed PFCs to be present in the influent at concentrations of 78.9 – 151.2 ng/L (Σ15PFCs), but almost completely removed by reverse osmosis. PFCs were detected above reporting limits at 4 of the 7 sampling points. This work provides a measure of PFCs in Australian recycled water, contributes data on the fate of these compounds in advanced water treatment, and illustrates their efficient removal by RO under operational conditions. Analytical variability appeared to be less than variability between sampling events, indicating in future composite samples or flow proportional sampling will improve data quality.
    01/2009;
  • Quaternary Research 05/2008; · 2.58 Impact Factor