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Commercial papaya varieties grown in Australia vary greatly in taste and aroma. Previous profiling has identified undesirable 'off tastes' in existing varieties, discouraging a portion of the population from consuming papayas. Our focus on enhancing preferred flavours led to an exploration of the genetic mechanisms and biosynthesis pathways that underlie these desired taste profiles. To identify genes associated with consumer-preferred flavours, we conducted whole RNA sequencing and de novo genome assembly on papaya varieties RB1 (known for its sweet flavour and floral aroma) and 1B (less favoured due to its bitter taste and musty aroma) at both ripe and unripe stages. In total, 180,368 transcripts were generated, and 118 transcripts related to flavours were differentially expressed between the two varieties at the ripe stage. Five genes (cpBGH3B, cpPFP, cpSUS, cpGES and cpLIS) were validated through qPCR and significantly differentially expressed. These genes are suggested to play key roles in sucrose metabolism and aromatic compound production pathways, holding promise for future selective breeding strategies. Further exploration will involve assessing their potential across broader germplasm and various growth environments. [ABSTRACT FROM AUTHOR]

Mechanical thermal expression (MTE) was used for dewatering two lignites, Loy Yang (LY) from Australia and Shengli (SL) from China. The dewatering process was carried out with temperatures ranging from 24°C to 240°C. It was found that the moisture content of the MTE products decreased linearly with increasing temperature, and the residual moisture content was a function of compressibility. The MTE process was more effective for the low-rank LY lignite. The characterization of the lignite includes moisture content, C/H ratio, pore volume distribution from mercury intrusion porosimetry and, coal–water interaction from low-field nuclear magnetic resonance (LFNMR). Coal–water interaction only changed slightly with mechanical compression alone. Combined with heat mechanical effect found to compress the residual moisture into smaller pores. The coal–water interaction is stronger in the smaller pores, which makes dewatering progressively more difficult. The chemical characteristics were studied by solid-state 13C NMR, where no significant changes were apparent. Total organic carbon (TOC) analysis showed higher content of organics in the LY wastewater than in the SL wastewater. The chemical composition of the wastewater was analyzed by gas chromatography–mass spectrometry (GC-MS) and it was found that the majority of the compounds from LY and SL detected were acids, accounting for more than 50% of the organic compounds, followed by aromatic hydrocarbons, accounting for 27% in LY and 38% in SL wastewater. Lower levels of alkenes, alcohols, esters, and aliphatic hydrocarbons were also found in the wastewater. [ABSTRACT FROM AUTHOR]

Methane is an important energy resource internationally, and a large proportion of this methane is produced by microbial communities living in coal seams. Despite the value of this resource for human energy security, our understanding of the metabolic roles played by specific taxa during the biodegradation of coal to methane in situ is quite limited. In order to develop a greater understanding of microbial catabolism on coal, a community from a coal seam in the Surat Basin, Australia, was incubated on 10 different aromatic organic compounds: coronene, benzo[ a ]pyrene, pyrene, phenanthrene, naphthalene, ethylbenzene, phenol, benzoate, vanillate and syringate. Each of these aromatic compounds either occurs in coal or is a possible product of the coal biodegradation process. 16S rRNA sequencing revealed substantial changes to each community in response to each aromatic carbon substrate provided. Abundant taxa from these substrate-specific communities were identified and their probable catabolic roles proposed based on literature searches of related taxa. This study is the first to link specific coal seam taxa to aromatic substrates available in coal seam environments. Two conceptual models of the putative degradation pathways and key taxa responsible are proposed. [ABSTRACT FROM AUTHOR]

The occurrence and distribution of alkylphenanthrenes in upper Eocene–Oligocene sediments from Ocean Drilling Program Leg 189 (Sites 1168, 1170, 1171 and 1172) that were drilled off the coast of Tasmania have been examined by gas chromatography–mass spectrometry. Samples are thermally immature and contain predominantly terrigenous organic matter. Peculiar alkylphenanthrene distributions occur in four samples from Site 1168 at depths from 748 m to 762 m, with methylphenanthrene (MP) isomers showing complicated and irregular distributions. A dominance of 3-MP, 9-MP and 1-MP occurs in different samples, while 2-MP is systematically low in all the samples. Concentrations of alkylphenanthrenes and various other aromatic hydrocarbons generally increase with burial depth at Site 1168, likely indicating diagenetic formation. Commonly used source input and thermal maturity parameters derive inconsistent and confusing interpretations for all four sites. Maturity does not appear to be a decisive factor that influences the distributions of methylphenanthrene and dimethylphenanthrene (DMP) isomers and the degree of alkylation. The direct decomposition of retene to form an abnormal enrichment of 1-MP in one sample from Site 1168 is also difficult to envisage. The low 1,7-DMP/1,3- + 3,9- + 2,10- + 3,10-DMPs and ∑alkylphenanthrenes/∑alkylnaphthalenes ratios, coupled with the predominance of hopanoids over steroids, point to microbial input of 3-MP and 1-MP as a plausible interpretation in certain samples, while the dominance of 9-MP throughout the sedimentary column reflects local biomass input formed in the marine environment. Input of combustion-derived alkylphenanthrenes is unlikely to be the sole reason to cause unusually high phenanthrene/∑methylphenanthrenes ratios in the samples from the four sites. Oxidation during deposition and the immaturity of the sediments at an early diagenesis stage are likely to be an alternative interpretation. • Alkylphenanthrenes in immature sediments respond to source and environmental interactions. • Microbial interference can lead to unusual methylphenanthrene isomer distributions. • Maturity parameters from alkylphenanthrenes can be altered by microbial interference. • High P/ΣMP ratios (> 1.0) do not necessary reflect combustion/pyrogenic input. [ABSTRACT FROM AUTHOR]

• Perylene in Eocene marine sediments around Tasmanian Gateway has a terrigenous origin. • Concentration of perylene increases with depth, reflecting formation during diagenesis. • Preservation of precursors from oxidation is critical for the occurrence of perylene. • Perylene can be formed under dysoxic condition if its precursors can survive. Eocene to Lower Oligocene sediments were collected by Ocean Drilling Program Leg 189 at four sites in the Tasmanian Gateway, Australia, and geochemically characterised to investigate the occurrence and controlling factors of perylene. Perylene is enriched in samples from Site 1168, which is located closest to Tasmania, accounting for up to 53.4% of the total quantified aromatic hydrocarbons, with concentrations ranging from 15 ng/g dry weight sediment (dws) to 1700 ng/g dws. However, only trace amounts of perylene (<5 ng/g dws) are present in samples from the other three sites, except for two deep samples from Site 1171, which is furthest from Tasmania, with perylene concentrations of 15 ng/g dws and 95 ng/g dws. The concentrations of perylene increase with burial depth, suggesting its formation from diagenetic processes. Other molecular compositions, including land-plant-derived aromatic hydrocarbons, pyrogenic-related aromatic hydrocarbons and n -alkanes, indicate that the origin of perylene can be attributed to allochthonous organic material associated with terrigenous plants. Contributions from autochthonous organic matter and combustion cannot be validated. Detailed examination of the relationship between the concentrations of perylene and organic matter input and depositional conditions illustrate that both factors are important but not essential. The concentrations of perylene are positively correlated to pristane/phytane ratios, implying that perylene is probably formed under dysoxic rather than highly reducing conditions. Terrigenous-sourced organic matter was detected at all four sites, but perylene is only concentrated at the site closest to Tasmania. It is proposed that the preservation of the precursors of perylene is critical, as these are sensitive to destruction by oxidation. If the precursors of perylene are destroyed during transportation and early sedimentation, no perylene will be formed during diagenesis, no matter how strong the reducing conditions are. [ABSTRACT FROM AUTHOR]

Inhalation of petrol (gasoline) fumes has been prevalent in some Australian Indigenous communities since World War II, and has led to a continuing quest for an effective method of preventing the practice either by modifying the substance or by substituting nonharmful alternatives. This article traces the results of this search, beginning with the addition of ethyl mercaptan, then describing the substitution of aviation fuel for conventional vehicle fuel, and concluding with the staged introduction of Opal--a vehicle fuel containing low levels of aromatic hydrocarbons--throughout many communities from 2005. The article assesses the benefits and limitations of supply reduction methods. [ABSTRACT FROM AUTHOR]

Abstract: The present study aims to establish the factors controlling the stable carbon isotopic compositions (δ13C) of individual aromatic hydrocarbons analysed by compound specific isotope analysis (CSIA) in crude oils from western Australian petroleum basins of varying age and facies type. This paper reports δ13C values of individual aromatic hydrocarbons, like alkylbenzenes, alkylnaphthalenes, alkylphenanthrenes and methylated biphenyls. The main aims are to confirm the origin (source) and age of these oils based on CSIA of selected aromatic compounds and to understand why the Sofer plot is ineffective in establishing the source of western Australian petroleum systems. The bulk δ13C of saturated and aromatic hydrocarbon fractions of crude oils have been previously used to differentiate sources, however, many Australian crude oils are not classified correctly using this method. The oils were classified as marine by the δ13C values of individual aromatic compounds and as terrigenous based on the bulk δ13C data (Sofer plot). The oils where the δ13C values of 1,6-DMN and 1,2,5-TMN isomers are most negative are indicative of a marine source, whereas oils with a less negative values for the 1,6-DMN and 1,2,5-TMN isomers are derived from marine source rocks that contain a significant terrigenous component. Similarly, oils with the least negative δ13C values for the 1-MP and 1,9-DMP isomers reflect varying inputs of terrigenous organic matter to the their marine source rocks. Plots of P/DBT and Pr/Ph concentration ratios versus δ13C values of DMP, 1,6-DMN, 1,2,5-TMN, 1-MP and 1,9-MP are constructed to establish the relative amount of terrigenous organic matter contributing to the source rock of a series of marine oils. The ratios of P/DBT and Pr/Ph plotted against the δ13C values of the aromatic isomers (such as 1,6-DMN, 1,2,5-TMN, 1-MP and 1,9-MP) provide a novel and convenient way to discriminate crude oils derived from different source rocks that contain varying amounts of marine and terrigenous organic matter. [Copyright &y& Elsevier]

Abstract: Microscale sealed vessel pyrolysis (MSSVpy) with online gas chromatography mass spectrometry (GC–MS) was used with several other established and complementary analytical methods to robustly characterize the structure of aquatic natural organic matter (NOM) and to practically assess the analytical value of MSSVpy. The NOM used in the study was from North Pine (NP) reservoir, which is one of the major source waters supplying Brisbane, the capital city of the Australian state of Queensland. The reservoir has moderate dissolved organic carbon (DOC; 5mgL−1) levels and is impacted by algae which periodically occur in bloom proportions. The hydrophobic (HPO; 65% initial DOC) and transphilic (TPI; 12%) fractions showed H/C values >1, low UVabs and low aryl-C measured by NMR which are all indicative of low aromaticity. MSSVpy produced distinctly higher product concentrations than traditional flash pyrolysis and the molecular profile of the HPO and TPI fractions revealed by MSSVpy was correlated with the other analytical data to help establish their structural relevance. Prolific distributions of alkyl substituted aromatic (e.g., benzenes, naphthalenes) and hydroaromatic (e.g., tetralins) products detected in the HPO fraction were attributed to the aromatisation of terpanes and other aliphatic compounds from algal, and possibly also plant sources. Alkyl phenols also detected in HPO in high abundance, are probably from algal biopolymers, but may also reflect a contribution from non-methoxylated lignin units of catchment grasses. There was no analytical evidence of the dihydroxy or methoxy aromatic structures typical of wood lignin or tannin. N-organic pyrolysates (e.g., alkyl pyrroles, pyridines, indoles) of diagenetically altered proteins were concentrated in the TPI fraction. The quantitative importance of the N-organic moiety of the TPI fraction was corroborated by a low C/N ratio and distinctive amide and amine signals detected by 13C NMR and FTIR. This integrated study demonstrates that the qualitative speciation provided by MSSVpy can make a significant contribution to the structural characterisation and source recognition of aquatic NOM. [Copyright &y& Elsevier]

Diesel vehicles are an important source of emissions of air pollutants, particularly oxides of nitrogen (NO x ), particulate matter (PM), and toxic compounds with potential health impacts including volatile organic compounds (VOCs) such as benzene and aldehydes, and polycyclic aromatic hydrocarbons (PAHs). Current developments in engine design and fuel quality are expected to reduce these emissions in the future, but many vehicles exceed 10 years of age and may make a major contribution to urban pollutant concentrations and related health impacts for many years. In this study, emissions of a range of toxic compounds are reported using in-service vehicles which were tested using urban driving cycles developed for Australian conditions. Twelve vehicles were chosen from six vehicle weight classes and, in addition, two of these vehicles were driven through the urban drive cycle using a range of diesel fuel formulations. The fuels ranged in sulphur content from 24 to 1700ppm, and in total aromatics from 7.7 to 33mass%. Effects of vehicle type and fuel composition on emissions are reported. The results show that emissions of these toxic species were broadly comparable to those observed in previous dynamometer and tunnel studies. Emissions of VOCs and smaller PAHs such as naphthalene, which are derived largely from the combustion process, appear to be related, and show relatively little variability when compared with the variability in emissions of aldehydes and larger PAHs. In particular, aldehyde emissions are highly variable and may be related to engine operating conditions. Fuels of lower sulphur and aromatic content did not have a significant influence on emissions of VOCs and aldehydes, but tended to result in lower emissions of PAHs. The toxicity of vehicle exhaust, as determined by inhalation risk and toxic equivalency factor (TEF)-weighted PAH emissions, was reduced with fuels of lower aromatic content. [Copyright &y& Elsevier]

Abstract: Personal monitoring using passive samplers was conducted in Perth, Western Australia, to determine the concentrations of benzene to which residents were exposed during their daily activities. An additional aim of the study was to assess the contribution of different microenvironments to non-industrial exposure, and the extent to which lifestyle and behaviour influence personal exposure. Fifty participants were recruited and wore passive samplers over 24-h periods for 5 consecutive days (including weekends) in summer (November–March) and winter (June–September). The study commenced in June 2001 and was completed in April 2002. The mean benzene exposure of the participants in summer was 1.76 and 1.98μgm−3 in winter. Statistical analysis using a generalized linear mixed model revealed that refuelling and commuting were the most significant contributors to non-industrial exposure to benzene in summer and winter for Perth residents. [Copyright &y& Elsevier]

Terra preta is a fertile anthropogenic soil found in the Amazon basin. One of the most significant differences between the terra preta and surrounding soils is that terra preta is rich in aromatic carbons. Previous infrared investigations of terra preta were reported at energies above 1000 cm -1 where many other forms of carbon also have absorption lines. No measurements have been reported below 800 cm -1 , where many absorptions associated with aromatic carbons occur in the absence of aliphatic carbon lines. We employ Fourier transform infrared spectroscopy between 150 cm -1 and 500 cm -1 . A comparison was made between the spectra of terra preta , several pure aromatic compounds, organic fertilizers developed to replicate terra preta and several Australian soils, some of which containing char from bushfires. The spectra in the 150-500 cm -1 range were very similar between terra preta and the organic fertilizers, while they were very different for the natural soils. These findings indicate that the content of aromatic carbons in terra preta and organic fertilizers is different than in natural soils containing the bushfire chars, but also soils produced entirely by bacterial and fungal activities. This point to the importance of the preparation conditions of the biochars, which are essential ingredients of terra preta and organic fertilizers used in this study.

Twenty-seven hydrocarbon source rocks from the Proteacidites asperopolus , Malvacipollis diversus and Lygistepollenites balmei biozones, Palaeogene Latrobe Group in the Gippsland Basin were analysed using gas chromatography-mass spectrometry. Based on the molecular geochemistry of the aliphatic and aromatic fractions, together with bulk geochemical data (including Rock-Eval pyrolysis and total organic carbon contents), the thermal maturity, palaeoenvironments, and organic matter source of these Palaeogene samples were systematically evaluated. The results provide a useful comparison with those from Upper Cretaceous source rocks in the Gippsland Basin (Jiang and George, 2018, 2019). Similar to the Upper Cretaceous rocks, the aliphatic hydrocarbons in the Paleogene samples are mainly comprised of n- alkanes, isoprenoids, terpanes, hopanes and steranes. The aromatic hydrocarbons are dominated by naphthalene, phenanthrene, anthracene, fluorene, dibenzofuran, dibenzothiophene and their alkyl homologues. Other aromatic hydrocarbons detected include land plant-derived compounds (e.g. retene, methylretenes, cadalene, simonellite, etc), and combustion-derived compounds (e.g. chrysene, pyrene, picene, benzo[b]fluoranthene, benzo[a]anthracene, etc). These 4- to 6-ring polycyclic aromatic hydrocarbons are more abundant in the Paleogene samples compared to the Upper Cretaceous rocks. Biomarker and aromatic hydrocarbon distributions indicate that the Proteacidites asperopolus and Malvacipollis diversus samples are immature or are in the early stage of the oil generation window, while the Lygistepollenites balmei samples correspond to the low maturity to mature stage. The samples were all deposited under sub-oxic to oxic conditions in fresh water with low salinity, possibly in a lacustrine depositional environment. The organic matter inputs are from plankton/algae and higher land plants, but are dominated by organic matter with a terrigenous origin. • Palaeogene source rocks stay in a low mature-mature stage. • Both angiosperm and gymnosperm contribute to organic matter. • Source rocks deposited in a sub-oxic to oxic lacustrine environment with low salinity. • Abundant 4- to 6-ring polycyclic aromatic hydrocarbons are present. [ABSTRACT FROM AUTHOR]

Hydrocarbon fluid correlation studies often rely on compounds that are source-specific, but only represent a minor fraction of the bulk fluid (e.g. steranes). The correlation in the present study utilises compounds that represent a significant proportion of the bulk fluid, namely semi-volatile aromatics (SVA), and diamondoids. Comprehensive two dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC × GC-TOFMS) was used to analyse diamondoids and SVA in whole oil/condensate samples from the Browse Basin, North West Shelf, Australia. Together with aromatic maturity ratios and the stable carbon isotopic composition for selected diamondoids and alkylbenzenes, these analyses demonstrate that numerous accumulations within the Browse Basin contain hydrocarbons from mixed sources. The diamondoid and SVA data provides further information on the current hydrocarbon fluid discrimination, which is primarily based on saturated biomarker compositions. Results of this study reveal a complex fill history by identifying the presence of a high maturity fluid(s) in the biodegraded accumulations on the Yampi Shelf, i.e. in the greater Cornea field and at Gwydion-1. This high maturity fluid is most likely derived from the Lower–Middle Jurassic Plover Formation (J10–J20 supersequences) in the greater Cornea area and, in the case of Gwydion-1, additional hydrocarbons may also be derived from the Upper Jurassic Vulcan Formation (J30–K10 supersequences). Other accumulations that comprise mixtures include Mimia-1 and Concerto-1 ST1 Deep, located to the north of the Ichthys field, and could represent charge from several Jurassic source rocks. The most mature fluids analysed in this basin are family II Plover-sourced and reservoired condensates from Kronos-1, Dinichthys North-1 and Gorgonichthys-1, as demonstrated by their elevated concentrations of the methyladamantanes and methyldiamantanes. The Dinichthys North-1 and Gorgonichthys-1 condensates also show a significant enrichment in the δ13C compound-specific values of the di-, tri- and tetra-methylbenzenes, whereas the Kronos-1 condensate does not, suggesting derivation from different source kitchens. • Hydrocarbon fluid correlation in the Browse Basin, North West Shelf, Australia. • Diamondoids and aromatics complement and expand on biomarker assessments. • Condensates lacking biomarkers can be successfully typed with diamondoids and aromatics. • δ13C of methylbenzenes provide further information on fill history. [ABSTRACT FROM AUTHOR]

• Abundant 2- to 6-ring aromatic hydrocarbons were identified. • Several aromatic angiosperm/gymnosperm indices and higher plant parameters compared. • Ring-B aromatised triterpenes related to the arborane/fernane series were detected. Aromatic hydrocarbons extracted from Upper Cretaceous (Maastrichtian and Campanian) Latrobe Group coaly shales and shales from the Gippsland Basin were investigated by gas chromatography–mass spectrometry. A variety of 2-ring to 6-ring aromatic hydrocarbons were identified, including both higher-plant-derived and combustion-derived polycyclic aromatic hydrocarbons (PAHs). These aromatic compounds indicate that the Upper Cretaceous coaly shales and shales were deposited in a fluvial/deltaic environment with significant higher plant input and are at a relatively low thermal maturity stage. Higher plant parameters and angiosperm/gymnosperm indices based on aromatic components suggest that higher land plants, including both angiosperms and gymnosperms, were an important part of the palaeovegetation in the Upper Cretaceous. The aromatic angiosperm/gymnosperm index that includes chrysene- and picene-type PAHs is not as reliable for evaluation of relative angiosperm and gymnosperm contributions as the aliphatic indices due to input of combustion-derived PAHs and the complexity of burning conditions altering the relative contributions. However, combustion-derived PAHs and aromatic angiosperm/gymnosperm indices supplement the information from aliphatic hydrocarbons and provide further evidence to support the hypothesis that palaeoclimate cooled from the Campanian to the Maastrichtian. [ABSTRACT FROM AUTHOR]