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Treated Timber, Toxic Time-bomb: The Need for a Precautionary Approach to the Use of Copper Chrome Arsenate (CCA) as a Timber Preservative

Author/Creator: Lansbury, N., Beder, S.
Resource type: report
Date: 2005
Subject: arsenic, treated timber, health impacts, environmental impacts, waste disposal, regulation, children
Record contributed by: University of Wollongong

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http://ro.uow.edu.au/artspapers/41
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Timber preserved with Copper Chrome Arsenate (CCA) is ubiquitous in Australia. Wood, such as radiata pine, is treated with CCA to protect it from insects, rot and fungus. CCA-treated timber is commonly used on telegraph poles, decking, fencing, landscaping, vineyard stakes, picnic tables and in playgrounds. However the arsenic in CCA leaches out of CCA-treated timber and arsenic is toxic and can cause cancer in the long-term. There is a growing body of scientific evidence that timber treated with CCA poses a danger to both humans and the environment. As a result, authorities around the world are imposing tighter restrictions on its manufacture, use and disposal. This report investigates a range of concerns and issues surrounding its manufacture, use and disposal.

Publisher: Research Online

Format: application/pdf
Source: Faculty of Arts - Papers
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Timber preserved with Copper Chrome Arsenate (CCA) is ubiquitous in Australia. Wood, such as radiata pine, is treated with CCA to protect it from insects, rot and fungus. CCA-treated timber is commonly used on telegraph poles, decking, fencing, landscaping, ...
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Aspects of Management of Subterranean Termites in Queensland

Author/Creator: Peters, Brenton Charles Subject: subterranean termites, wood preservation, borates, bait technology, Coptotermes, Schedorhinotermes, field bioassay, softwood susceptibility, decay fungi, heat treatment
Record contributed by: Australasian Digital Theses Program, The University of Queensland

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i ABSTRACT I investigated aspects of the management of subterranean termites in the field by evaluating the protective values of preservative treated softwoods and evaluating the potential of softwoods conditioned by decay fungi or heat to produce termite monitoring and aggregating devices. As part of the investigation, it was necessary to: · develop assay techniques suitable for research into the natural resistance of timbers, the efficacy of wood preservatives and termite biology and foraging behaviour; and quantify variation in termite responses to untreated softwoods in various situations in the field using these techniques. Field bioassays were conducted with two Australian Coptotermes species to determine protection of pine sapwood afforded by borate compounds (Chapter 2). Coptotermes lacteus (Froggatt) was examined in winter and C. acinaciformis (Froggatt) in winter, spring and summer at two localities in Queensland. Hoop-(Araucaria cunninghamii Ait ex D. Don) and slash-pine (Pinus elliottii Engelm.)-sapwood blocks were placed in plastic containers and attached to termite mounds or infested trees. Termite response was determined by mass losses over five weeks and modelled. Coptotermes lacteus was relatively benign in winter and for 1.0 and 2.5% mass losses of hoop-pine sapwood, borate retentions of 0.20 and 0.06% mass/mass (m/m) boric acid equivalent (BAE), respectively, were derived. With C. acinaciformis, for 1.0 and 5.0% mass losses of hoop-pine sapwood, borate retentions ranged from 0.49 and 0.25% BAE, respectively, in winter to 0.76 and 0.47% BAE, respectively, in late summer. For 1.0 and 5.0% mass losses of slash-pine sapwood in summer, borate retentions of 0.58 and 0.14% BAE, respectively, were derived for C. acinaciformis. These results support conclusions from earlier laboratory studies conducted elsewhere. Prevention of damage by field populations of termites was not achieved. Marked intercolony variation in response to borate compounds was demonstrated, highlighting the usefulness of this rapid technique. The need for long-term field exposure trials to calibrate the lunch-box technique and to facilitate technology transfer to industry, is indicated. For comparison, termite response to white cypress (Callitris glaucophylla Thompson and Johnson), a naturally termite resistant timber, is also reported. A field bioassay was conducted to evaluate responses of C. acinaciformis to untreated southern-yellow-pine (Pinus spp.), hoop-pine and slash-pine blocks (Chapter 3). Sapwood blocks were placed in plastic containers and attached to trees infested with the termites during summer. Containers with a test block of each of the timber species were prepared. These and other containers were exposed to termites for 10 weeks. Termite feeding response (“voracity”) was assessed for all blocks by determining the mass of wood consumed. Termite voracity differed among trees. Variation in termite responses to individual hoop-pine feeder-blocks within a container was appreciable and consistent between containers. Variation in termite responses to the test blocks was appreciable, with hoop pine being significantly more susceptible to termite attack than either slash pine or southern yellow pine. Southern yellow pine is a generic name for five species of pine which are difficult to separate reliably. Therefore, caution should be exercised when using “southern yellow pine” to ensure that samples are at least from the same species of pine and preferably from the same length of timber. The sensitivity of both the bioassay and the statistical tests was demonstrated. Of particular interest was the similar level of termite response to the test timbers in the two sections of the experiment. The usefulness of feeder-blocks to initiate reliable attack rather than to promote sustained attack, is worth further attention. Sapwood stakes of Australian-grown hoop pine, slash pine, radiata pine and North American-grown southern yellow pine were exposed to subterranean termite attack in an in-ground bioassay (Chapter 4). Stakes in bait containers and bare stakes were attacked by C. acinaciformis and Schedorhinotermes intermedius (Brauer). Susceptibility of these timbers was evaluated with regard to potential for termite monitoring and aggregation. Variation between timbers and difference between termite species are described. The relevance of these data to suppressing foraging populations of subterranean termites, in Australia, using insect growth regulators, is discussed. Four field bioassays were conducted using two species of Australian subterranean termites, C acinaciformis and C. lacteus (Chapter 5). Hoop-pine blocks decayed using 14 fungi for four weeks and for 10 weeks were subsequently conditioned using dry heating, freezing or moist heating, and then exposed to termites. Blocks decayed by Gloeophyllum abietinum [Persoon: Fries] Murrill, Trametes lilacino-gilva (Berkeley) Wright & Deschamps, Schizophyllum commune Fries and Rigidoporus undatus (Persoon) Donk and subsequently oven dried, were attacked the most. Oven drying generally enhanced termite feeding responses in these two field bioassays. In a third bioassay, blocks of five softwood timber species conditioned with two high temperature regimes were exposed to C. acinaciformis. Slash pine was attacked the least. Mean mass losses for hoop pine, Caribbean pine (Pinus caribaea Morelet), radiata pine and the interspecific F1 hybrid between Caribbean and slash pine were not significantly different. For C. lacteus, slash and hoop-pine blocks were attacked the least while radiata pine was attacked the most. Additional heating at 105°C increased the susceptibility of most timber species. Relationships between heating duration and the consumption of hoop-pine-sapwood blocks were determined using results from a fourth bioassay. Heating the timber increased feeding responses for both termite species. The selective and rapid response of the termites highlights the usefulness of this field technique for multiple-choice bioassays. The cyclodiene termiticides were withdrawn from use, in Australia, as from 30 June 1995. Implications for the management of subterranean termites in Queensland are discussed. Community perceptions of the use of chemical pesticides and cost do not favour the widespread use of preservative treated timber in buildings. An integrated pest management approach to termite control is the likely direction for the future in Australia. A range of building techniques, regular inspections, and attention to factors that predispose existing buildings to termite attack can reduce the risk of damage from termites, but do not eliminate that risk. There will be an increased need for reliable preventative and remedial treatments involving bait technology. Much more work is needed on termite biology, foraging behaviour and bait toxicants before a baiting system can be confidently commercialised in Australia. Directions for research in Queensland are discussed.


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i ABSTRACT I investigated aspects of the management of subterranean termites in the field by evaluating the protective values of preservative treated softwoods and evaluating the potential of softwoods conditioned by decay fungi or heat to produce termite monitoring ...
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Novel Methods for the Removal of Colour from Pulp and Paper Mill Wastewater

Author/Creator: Wingate, Kathryn G.
Date: 2002
Subject: No Subjects
Record contributed by: Australasian Digital Theses Program

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Wastewater produced during pulp and paper manufacture is often highly coloured. Along with a decrease in the aesthetic appeal of the receiving water, the coloured material also reduces the penetration of the sunlight through the water which may decrease photosynthetic rates and affect aquatic productivity. As a result, there is strong pressure from environmental regulators for mills to reduce the colour of these wastewaters. Currently there is no sustainable colour removal technology available to remove this colour, predominantly due to economical restraints. The current study was undertaken with the aim of assessing novel and environmentally and economically sustainable technologies for the treatment of colour in pulp and paper mill wastewaters. A New Zealand softwood integrated bleached kraft mill was used for the technology assessment case studies. A synoptic survey of the mill was performed to locate the major sources of wastewater constituents and to select the most appropriate waste streams for application of these technologies. It was found that bleach plant wastewater was a significant source of colour (34% total mill load), dissolved organic carbon (DOC, 32%), and soluble chemical oxygen demand (sCOD, 25%), and was the predominant source of absorbable organic halides (AOX, ~100 %). Given these relative contributions, the concentrated flows arising from this source, and the relative case of retro-fitting a treatment process at full-scale, this wastewater was selected for remediation. The bleach plant wastewater is discharged in two waste streams, the acidic stream (pH 2) and the alkaline stream (pH 11). Two systems were investigated as colour removal tools; one chemical, the other biological. Both systems was chosen as suitable for the remediation of bleach plant wastewater (i.e. functioned in the required pH and temperature range), and because they were novel systems which had not been previously considered for removal of colour from wastewater. The first technology was an advanced oxidative process (AOP) which utilised macrocyclic tetraamide iron(III) complexes. These specially-designed complexes catalytically activate hydrogen peroxide and were developed by Collins et al., at Carnegie Mellon University. The activated complexes had previously been shown to be able to delignify and remove residual colour from kraft pulp. Preliminary trials indicated that these complexes would also have the potential to remove colour from pulp mill wastewaters. The second technology was an enzymatic treatment that utilised the enzyme cellobiose dehydrogenase (CDH). Although the broader purpose of these enzymes in biological systems has not been firmly established, previous studies have demonstrated that CDH reactions could reduce quinones. Quinones are highly coloured, lignin-related species produced during the bleaching of pulp that have been hypothesised to contribute a significant proportion of the colour found in bleached kraft mill wastewaters. It was therefore postulated that this enzyme could form the basis of a biological colour treatment for bleached kraft mill wastewaters, with particular focus on colour removal. Studies were undertaken to assess the effects of substrate concentrations, pH, temperature and time. As the AOP technology functioned best under alkaline conditions, it was selected to remediate the alkaline bleach plant waste stream. Optimal conditions were determined at pH 11,9 and 7. At pH 11 the optimal conditions were found to be an activator concentration of 2 µM (0.9 mg L-1), a hydrogen peroxide concentration of 26 mM (0.75 g L-1), 40ºC and 4 hours. As the pH decreased to 9, and then 7, more activator and peroxide was required to remove similar levels of colour from the alkaline waste stream. Under optimal conditions, the AOP was able to remove 47% of the colour from alkaline stage bleaching wastewaters. Additionally, using these conditions the AOP could remove 25% of the chlorinated organic material (as AOX), however it had no effect on the sCOD of the wastewater. For the enzymatic treatment two strains of enzyme were assessed. One strain, purified from the soft-rot fungus Humicola insolens,preferred alkaline conditions and was used to treat the alkaline stage bleaching wastewater, and the other strain, purified from the white-rot fungus Phanerochaete chrysosporium, preferred acid pH and was used to remediate the acid stage wastewater. Conditions required for the enzyme strain that preferred alkaline conditions were 0.01 IU of CDH, 7 mM (2.4 g L-1) of cellobiose, 40ºC and 4 days at pH 7. The enzyme was able to remove 41 % of the colour from the waste stream, however the enzyme treatment had no effect on the chlorinated organic content or the sCOD of the wastewater. Due to a limitation in acidophilic enzyme, optimal conditions were not fully characterised. However, it was found that using 0.1 IU of CDH,40ºC and 4 days at pH 4.5 resulted in a colour removal from the acid stage bleaching wastewater similar to that achieved for the enzyme strain that preferred alkaline conditions when treating the alkaline stage bleaching wastewater. An investigation of the structural changes in the wastewater organic material during treatment indicated that the AOP predominantly removed phenolic structures from the wastewater, in addition to structures containing aliphatic double bonds and carbonyl groups. In contrast, CDH solely reduced quinone structures. These findings were supported by studies using model compounds. With AOP treatment there were reaction rate differences for a range of phenolic model compounds with the most reactive compounds being vanillomandelic acid and catechol. Both technologies were able to remediate wastewater from other sources around the mill, such as the combined whole mill wastewater and the post-secondary treatment system wastewater. Removal efficiencies under optimal conditions were in the range 55 to 65%. In addition to the removal of colour from wastewater produced during pine processing, both technologies could also remediate wastewater produced during the processing of eucalypt, a hardwood. In this case treatment efficiencies were somewhat lower (33 and 27% for the AOP and enzyme technologies, respectively) possibly due to the difference in the nature of the chromophores in the hardwood wastewater. An environmental risk assessment of both technologies was undertaken. The results from this assessment indicated that the AOP treatment did not improve overall biological treatability of the wastewater. The enzyme treatment improved treatability of the wastewater by 92%. when measured as oxygen uptake of a microbial population. An investigation of the molecular weight distribution found the molecular weight distribution of the wastewater was not altered during treatment with the AOP, however it was altered during enzyme treatment with a preferential decrease in material > 30 000 Dalton. When wastewater which had been pre-treated with the AOP was subjected to biological treatment, the wastewater showed a small colour increase of approximately l5% whereas 96% of the colour removed during enzyme treatment reverted under model aerated lagoon conditions. This finding was consistent with other studies which showed that structures reduced by the enzyme (i.e. quinones) could be oxidised back into their original form. In comparison, the colour removed by the AOP did not revert, suggesting that chromophores altered by the AOP were unable to reform. MicrotoxTM studies showed that neither the AOP activator, nor the enzyme were toxic to the receiving environment. An economic study was carried out which found that although the activator is not yet commercially available, the AOP technology could be economically feasible as long as the price of the activator was reasonable. Inventors of the activator estimate that its actual cost would be between USD 100 and 500 per kilogram. Using a worst case scenario of USD 500 per kilogram. it was estimated that if the activator was installed for the remediation of the alkaline bleach plant wastewater at the case study mill it would cost 1% of the value of the bleached pulp production, and result in a 12 % colour reduction of final wastewater. The economic study found that the enzyme treatment was not feasible (cost relative to value of production was 8%) due to the high substrate concentrations required. Overall, the study found that the AOP was a promising colour removal technology for the remediation of the alkaline bleach plant waste stream. Pilot plant trials for wastewater remediation using the AOP technology are expected to commence in the near future.

Publisher: ResearchSpace@Auckland

Language: en
Rights: Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated.; http://researchspace.auckland.ac.nz/docs/uoa-docs/rights.htm; Copyright: The author
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Wastewater produced during pulp and paper manufacture is often highly coloured. Along with a decrease in the aesthetic appeal of the receiving water, the coloured material also reduces the penetration of the sunlight through the water which may decrease photosynthetic ...
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XYLOPHAGOUS INSECTS: DEVELOPMENTS IN FEEDING ASSAYS

Author/Creator: Peters, Brenton Charles Subject: Xylophagous insects, borers, Lyctus, termites, Coptotermes, Mastotermes, Schedorhinotermes, field-based feeding assays, preventative action, remedial treatment, bait toxicant, attraction, susceptibility, borate wood-preservatives
Record contributed by: Australasian Digital Theses Program, The University of Queensland

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Xylophagous borers and termites that damage "timber-in-service" cause millions of dollars loss annually throughout mainland Australia. I developed field-based feeding assays with practical relevance to preventative action and remedial treatment of infestations of xylophagous insects in the built environment. Essential to this work is facilitating a high termite risk by maintaining an environment conducive to sustained foraging by termites. Feeding assays conducted in low termite risk areas are unduly prolonged, with inherently erratic termite feeding responses. I successfully developed feeding assays with a high termite risk. To establish whether a physical barrier, retrofitted as a sleeve, could prevent termites from damaging wooden poles, eighty poles were established within Beerburrum State Forest, south-east Queensland, Australia. Poles within sets were interconnected with buried timber to facilitate a high risk to Coptotermes acinaciformis (Froggatt). Mesh sleeves to a depth of 1.5m did not prevent termite damage to the poles. Hoop pine Araucaria cunninghamii Ait. ex D.Don dowels ("dip-sticks") were useful termite monitoring devices on the poles. The depth of foraging by termites has implications for the effectiveness of retrofitted physical and chemical barriers in general. Timber quantity and quality has a pivotal influence on the aggregation of large numbers of feeding termites necessary for baiting work and for producing efficacy data of relevance to the protection of timber-in-service from termites. Seasonal variation in termite foraging was examined. Both C. acinaciformis and Coptotermes lacteus (Froggatt) were more active feeding in summer than in autumn. In general, mass loss followed mean ambient temperature. Suppression of C. acinaciformis feeding responses relative to C. lacteus during summer, particularly during January, is thought to be due to excessive temperatures in the containers attached to infested trees. Termite foraging behaviour and responses to both varying masses of softwood timbers and varying exposure times were investigated. The rate of mass loss was independent of the number of test specimens and appeared linear. Colonies regulate the number of foragers directly according to the mass of susceptible timber available. This phenomenon was exploited throughout the remainder of the thesis. Of particular significance was the considerable intra- and inter-specific variation in susceptibility of softwoods to C. acinaciformis and Mastotermes darwiniensis Froggatt. The sapwoods tested were susceptible, but the heartwoods were generally resistant to damage by termites. These data confirm that termites are discriminating feeders, and some more so than others. A novel methodology, developed to maintain an environment conducive to sustained foraging by termites during field-testing, is presented. Consistency in timber acceptance and susceptibility to termites is considered to be important in determining the frequency of inspection and the success of bait systems. I evaluate the termiticidal activity of the bait toxicants hexaflumuron and chlorfluazuron for the management of the subterranean termite C. acinaciformis in the field. The Sentricon Colony Elimination System with Baitube-devices containing 0.1% and 1% mass/mass (m/m) hexaflumuron bait toxicant in dry wood flour (Recruit) was successful in eliminating field colonies of C. acinaciformis. Similarly, the Exterra Termite Interception and Baiting System with cellulose-acetate powder containing either 0.05% m/m or 0.25% m/m chlorfluazuron (Requiem) eliminated C. acinaciformis. Indicators (including "dip-sticks") used to monitor colony health were reliable. By using C. acinaciformis, which builds mounds (epigeous nests) in northern Australia, I was able to avoid the use of multiple mark-release schemes to verify the effects of the bait toxicant on the termite colonies. Problems with multiple mark-release schemes, used elsewhere in the world, are discussed. I continued the focus on bait quality and placement by evaluating termite responses to two aspects of treated stakes, their attractiveness and their susceptibility. Three experiments were undertaken near Townsville and at Beerburrum, with Coptotermes and Schedorhinotermes. Whilst there were no significant differences in the rate of location and foraging, with respect to treatments, differences in foraging, with respect to C. acinaciformis and Schedorhinotermes seclusus (Hill) were significant. Coptotermes acinaciformis displayed greater foraging site tenacity than S. seclusus at Beerburrum. Increased consumption of bait, due to the addition of a phagostimulant, needs to be observed in the field before an increase in the efficacy of baits in a termite management program can be claimed. In Australia, softwood timbers are extensively used in building construction and are generally highly susceptible to damage by termites. I focussed on field feeding assays to test efficacy of borate-treated softwoods against termites and to define "adequate" protection thresholds. Laboratory and field data reported in the literature were confusing with regard to what constitutes "adequate" protection thresholds. The confusion was compounded by differences in termite species, timber species used and test methodology. Laboratory data indicated a borate loading of 0.5% m/m boric acid equivalent (BAE) would cause > 90% termite mortality and restrict mass loss in test specimens to 5%. Field data generally suggested that borate loadings in excess of 0.5% m/m BAE were required. The main contribution of the work to increasing our understanding of management options for termites in the built environment was in resolving the confusion between laboratory and field data for borate wood-preservatives. These apparently conflicting results were explained by the presence or absence of untreated feeder material in the test environment. In the absence of untreated feeder material, retention of 0.5% BAE provides adequate protection from Coptotermes sp., whereas in the presence of untreated feeder material, increased retentions are required. Furthermore, the retentions required increase with increased amounts of susceptible material. Some termites, Nasutitermes sp. and M. darwiniensis, for example, are borate-tolerant and borate wood-preservatives are not a viable management option. The lack of uniform standards for termite-test methodology and assessment criteria for efficacy across the world is recognized as a difficulty with research into the performance of wood preservatives with termites. The many variables in laboratory and field assays make "prescriptive" standards difficult to recommend. The use of "performance" standards to define efficacy criteria ("adequate" protection) is discussed. Whilst the majority of the work involves subterranean termites ("termites"), I examine the question of how to define a hardwood timber species as "not susceptible" to lyctine beetle damage. Aspects of the biology, behaviour and management of Lyctus brunneus (Stephens) are reviewed and a novel field sampling and testing protocol to establish lyctine susceptibility of timber species is presented. A sound understanding of the biology and behaviour of xylophagous insects in the field is essential to ensure that management options implemented in the built environment have a strong ecological basis. The success of this study in achieving stated aims, the need for further work and the implications for test methodologies in the field with practical relevance to infestations of xylophagous insects in the built environment are discussed.


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Xylophagous borers and termites that damage "timber-in-service" cause millions of dollars loss annually throughout mainland Australia. I developed field-based feeding assays with practical relevance to preventative action and remedial treatment ...
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Characterisation of aquatic natural organic matter by micro-scale sealed vessel pyrolysis

Author/Creator: Berwick, Lyndon J
Resource type: Thesis
Date: 2009
Subject: micro-scale sealed vessel (MSSV) pyrolysis, aquatic natural organis matter (NOM), potable water issues, structural characterisation, analytical capacity
Record contributed by: Curtin University of Technology

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The analytical capacity of MSSV pyrolysis has been used to extend the structural characterisation of aquatic natural organic matter (NOM). NOM can contribute to various potable water issues and is present in high concentrations (> 5 mg L-1) in many Australian source supplies. NOM can also impede the filtration performance of ultrafiltration or other membranes used in the increasingly popular practices of desalination and wastewater treatment. Characterisation studies that provide a detailed understanding of the origins, structural features and reactivity of NOM in source waters will help predict its impact on potable supplies and allow targeted treatment.

MSSV pyrolysis GC-MS analyses were conducted on XAD fractions of NOM from selected rivers, reservoirs, ground waters and biologically treated waste waters. The analytical sensitivity of the MSSV Py approach was demonstrated by the detection of high concentrations and complex distributions of pyrolysates. These included many additional products to those detected by corresponding flash pyrolysis GC-MS analysis, which is often limited by excessive degradation or poor chromatographic resolution of pyrolysates of high structural polarity. Nevertheless, flash pyrolysis did lead to several unique products from some samples, reflecting the complementary nature of the two methods.

Despite the high product concentrations detected by MSSV pyrolysis of NOM, primary structural fragments are prone to further alteration due to the confined nature and extended (e.g. 72 hr) application of the moderate thermal conditions (e.g. 300°C). This approach has not been widely applied to the characterisation of recent or immature OM. Consequently, the mechanistic formation of many NOM pyrolysates is poorly understood, seriously limiting interpretation of their source and significance. As articulated in CHAPTER 1, these issues are specifically addressed by the present research, which aims to extend the application of MSSV pyrolysis to the characterisation of NOM and related environmental organic materials rich in intact biochemical inputs. To gain a better understanding of product formation pathways, several samples, including soil leachates, the organic foulant of ultra filtration membranes and a suite of standards representing potential biochemical precursors of NOM were separately analysed by MSSV Py. The effect of thermal conditions on product distributions was also addressed by analysis of a small sub-set of the samples at several different temperatures (260 – 330°C for 72 hours).

The capacity of MSSV Py to convert functionalised biochemical precursors into hydrocarbon products more amenable to GC resolution was initially demonstrated by the conversion of bacterial hopanepolyols of several surface and ground water NOM fractions, a bacterial isolate and biomass growth from an ultrafiltration membrane into corresponding hopane biomarkers as described in CHAPTER 2. The significance and integrity of the hopane distribution of the MSSV data was assessed by analyses of the same samples by flash pyrolysis and the advanced analytical techniques of hydropyrolysis (HyPy) GC-MS and liquid chromatography (LC)-MS with atmospheric pressure chemical ionisation. Flash pyrolysis showed no evidence of hopanes.

In comparison to the distributions of intact biohopanoids detected by LC-MS, the microbial hopane biomarker signatures detected by MSSV Py and HyPy were generally consistent, although HyPy did produce higher concentrations of ββ−diastereoisomers and higher MW fragments indicating a lower degree of structural alteration. Hopane products were detected in very low concentrations in the NOM samples, hence bacterial contribution may be more conveniently detected with biological methods (e.g., microbial arrays, bacterial counts). Nevertheless, MSSV pyrolysis represents a simple, low cost analytical method able to confirm the occurrence of diagnostic bacterial biomarkers in complex environmental settings, such as source waters and surrounding catchments, and may be a useful screening method prior to more involved characterisation possible with LC-MS. Moreover, this application represents an elegant demonstration of the capacity of MSSV pyrolysis to provide new information concerning functionalised biological precursors which have historically proved difficult to analyse by GC(MS).

Additional source diagnostic molecular features detected by MSSV Py of the membrane biofoulant included sterane biomarkers of eukaryote triterpenoids (i.e. steroids), n-alkanes of fatty acids and C16-C19 phenylalkanes indicative of common surfactants used to clean the membranes. The vastly improved molecular characterisation of the polar lipid constituents of membrane foulants, including the identification of industrial chemicals used in cleaning processes, suggests that this analytical capacity might also be applicable to monitoring the fate of organic constituents through the entire potable water system, from source through treatment and distribution to tap.

Unlike the established bacterial hopanoid source of hopane biomarkers, the origins of most of the major products from MSSV pyrolysis of the NOM samples are not clear. Subsequent chapters were separately dedicated to a detailed investigation of several of the major product classes.

CHAPTER 3 focused on the alkyl aromatic pyrolysates of NOM. The multitude of potential precursors of alkyl substituted benzenes and polycyclic aromatics (e.g. naphthalenes, phenanthrenes) significantly limits their diagnostic potential, nevertheless they represented a major proportion (20 – 50 % of total GC amenable pyrolysate signal) of the MSSV, and to a lesser degree, the flash pyrolysates of the HPO fractions of several NOM samples. The more highly substituted alkyl aromatics (and heteroatom products) of potentially greater source diagnostic value were better preserved by MSSV Py. Distinctive distributions of alkyl aromatics were detected by MSSV Py of the HPO fractions of several surface waters and a lysimetric plate collected ground water. All samples showed high alkyl benzene (AB) concentrations, whilst the ground water showed higher alkyl naphthalene (AN) concentrations than the surface waters. Correlation of several isopropyl substituted benzenes indicative of plant resin terpenoids in a bark sample, suggested these may be a significant source of the alkyl aromatics products of NOM. Furthermore, several higher plant derived polycyclic aromatic terpenoid biomarkers (e.g. cadalene, eudalene, retene and dehydroabietins) were also identified in the NOM fractions. Allochthonous and autochthonous sourced terpenoids have been proposed to be significant precursors of aquatic NOM; however diagnostic flash pyrolysis information about these types of contributors is typically limited.

HPO fractions of two waste waters also showed consistently high concentration of alkyl aromatics, reflecting the general recalcitrance of their precursors to biological treatment. The distributions of these products differed from the natural surface and ground waters. Resistant aliphatic biomolecules derived from algal and bacterial biomass, susceptible to cyclisation and aromatization during MSSV Py, were tentatively assigned as the source of these distinctive pyrolysates.

MSSV pyrolysis proved particularly sensitive to detection of heteroatom containing products of the NOM samples, and O products (25 – 50 %) and S products (1 – 5 %) were the focus of CHAPTER 4. The alkyl (≤ C4) phenols (APs) of the HPO fractions of the humic rich Gartempe and Uruguay rivers accounted for ca. 40 % of the total product signal. Similarly high concentrations of APs were detected by MSSV Py of a lignin standard, demonstrating the laboratory simulated thermal transformation of methoxy phenolic structures into alkyl phenols. The high concentrations of APs and low concentrations of methoxyphenol biomarkers of lignin typically detected in NOM (e.g. by flash pyrolysis, 13C NMR) suggests that a similar structural change may also be diagenetically mediated. The detection of APs, therefore, may be a more sensitive indicator of lignin input than guiaicyl or syringyl based biomarkers. The polyphenol structural units of selected tannin standards did not survive MSSV Py treatment, so are not likely responsible for the AP MSSV pyrolysates of the NOM samples. The HPO fraction of the waste waters showed similarly high concentrations of APs and alkyl aromatics (as discussed in Chapter 3), suggesting these products are recalcitrant to biological treatment. The Naintré waste waters also contained additional higher MW C4-10 alkyl substituted phenols not detectable by flash pyrolysis. Several of these products were indicative of industrial chemicals of potential health concern.

The TPI and COL fractions showed significant concentrations of alkyl furans which along with cyclic ketones were present in much lower abundance than APs in the HPO fractions. These products were attributed to carbohydrate sources following correlation with mono- and polysaccharide standards including glucose, cellulose and chitin. Trace or low relative abundances of these products in the biologically treated wastewaters reflects their vulnerability to mineralization. The HPO fractions of the NOM samples also showed low concentrations of alkyl benzofurans, similar distributions of which were detected in the SRFA standard, suggesting these are more stable polysaccharide metabolites, but still prone to further biodegradation as evident by only trace concentrations detected in the waste waters.

Whilst MSSV provided increased access to several S-structural constituents of NOM, their relatively low concentrations and as yet undefined structural origins remain a challenge to source characterisation. Nevertheless, similar alkyl thiophene (AT) distributions were also generated from an S-containing amino acid standard. Notably higher concentrations of S-products in the waste waters may reflect additional anthropogenic sources (e.g. sewerage, industrial chemicals), which may also involve thermally catalysed reaction between H2S and humic substances, analogous to the interaction of inorganic S and functionalised lipids during sedimentary diagenesis.

CHAPTER 5 was concerned with the notably high concentrations of N products (3 - 50 %) detected by MSSV Py GC-MS of the NOM samples. These products included a large range of alkyl- pyrroles, pyridines, pyrazines and pyridinamines, as well as amine substituted mono-aromatics and condensed N-heterocyclics. They were consistently detected over a broader range of MSSV Py conditions. Many of these products, particularly those with increased alkyl substitution were not detected by flash pyrolysis; leading to an historic underestimation of their contribution to NOM. Highest concentrations of N-products were detected in the COL fraction of NOM. Similarly high concentrations and distributions were also detected from the organic material prone to foul ultrafiltration membranes, confirming the colloid rich nature of this material. The distinctive low MW N-heterocyclic products of the COL fractions were correlated with the N-products of the amino sugar standard, and to a lesser extent the protein standards. The occurrence in high concentrations of low MW heterocyclics also provides potentially rare evidence for the environmental occurrence of Maillard reactions. The interaction of sugars and amino acids via Maillard processes may be an important contributor to humic substances, although there is much doubt about whether this process is supported by ambient or near surface temperatures. As these reactions are more favourable at high temperatures they may be artefacts of the MSSV Py process. However, MSSV Py of mixtures of carbohydrate and amino acid standards showed no evidence for the production of additional low MW heterocyclics. The waste waters showed relatively high concentrations of alkyl carbazoles and β-carbolines, potentially derived from alkaloid precursors of plants, algae and bacteria, which have been implicated in toxic N-DBPs from potable water treatment.

To practically assess the analytical benefits of MSSV pyrolysis for NOM characterisation, it was used in combination with other established analytical methods to holistically characterise the NOM of the North Pine (NP) reservoir, a major source of the potable water supplies of Brisbane and SE Queensland. The NP water is of low colour and has moderate dissolved organic carbon (DOC; 5 mg L-1) levels, but is impacted by algae which periodically occur in bloom proportions. The hydrophobic (HPO; 65 % initial DOC) and transphilic (TPI; 12 %) fractions from XAD resin separation of the DOC both showed high (>1) H/C values, low UVabs characteristics and low aromatic-C measured by NMR, which are all indicative of a relatively low degree of aromaticity. However, MSSV Py of both fractions, in particular the HPO fraction, yielded prolific distributions of alkyl substituted aromatic hydrocarbon (i.e., benzenes, naphthalenes) and hydroaromatic (e.g. tetralins) products. These were attributed to aromatisation of aliphatic structural precursors, including terpenoids of algae and plants, which are usually difficult to detect by analytical pyrolysis. MSSV Py of both fractions also yielded high concentrations of alkyl phenols, which likely reflect contribution from non-methoxylated lignin units of catchment grasses, consistent with the vast forest cleared grassland regions of the NP catchment, but may also derive from algal biopolymers. None of the analytical methods used showed any significant evidence of dihydroxy or methoxy aromatic structures of wood lignin or tannin inputs.

MSSVpy of the TPI fraction showed very high abundances of N-products (e.g., alkyl pyrroles, pyridines, indoles) reflecting the structural significance of diagenetically altered proteins, most likely derived from algal biomass. In contrast, much fewer Nproducts were detected by flash Py. This demonstrates the analytical capacity of MSSV to access the significant N content of this fraction, which was quantitatively indicated by low C/N ratio, measured by elemental analysis, and high amide and amine signals by 13C NMR and FTIR spectroscopy.

Whilst MSSV generated much higher product concentrations than flash Py or TMAH thermochemolysis, the latter methods did include unique product information demonstrating the complementary nature of different pyrolysis methods. Overall, this case study demonstrates the significant contribution MSSV Py has made to characterising the structure and sources of the Brisbane source water, clearly distinguishing it from humic black waters such as the Gartempe, Arroyo Sanchez and Suwannee Rivers studied in preceding chapters.

This PhD project represents the first detailed study of the potential of using MSSV Py to assist the organic speciation and molecular characterisation of biochemically rich NOM. Important additional pyrolysis information can be released with this analytical method which represents an obvious complement to conventional flash pyrolysis techniques where chromatographic resolution of polar biochemicals can be limited. The full realization of this approach, however, will need much further development as briefly alluded to in the closing comments of CHAPTER 7. It is hoped that the present project makes a significant early step in the realization of this potential.

Publisher: Curtin University of Technology, Department of Applied Chemistry

Language: en
Rights: unrestricted
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CHAPTER 5 was concerned with the notably high concentrations of N products (3 - 50 %) detected by MSSV Py GC-MS of the NOM samples. These products included a large range of alkyl- pyrroles, pyridines, pyrazines and pyridinamines, as well as amine substituted ...
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