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Soil organic carbon is essential to improve soil fertility and ecosystem functioning. Soil microorganisms contribute significantly to the carbon transformation and immobilisation processes. However, microorganisms are sensitive to environmental stresses such as heavy metals. Applying amendments, such as biochar, to contaminated soils can alleviate the metal toxicity and add carbon inputs. In this study, Cd and Pb spiked soils treated with macadamia nutshell biochar (5% w/w) were monitored during a 49days incubation period. Microbial phospholipid fatty acids (PLFAs) were extracted and analysed as biomarkers in order to identify the microbial community composition. Soil properties, metal bioavailability, microbial respiration, and microbial biomass carbon were measured after the incubation period. Microbial carbon use efficiency (CUE) was calculated from the ratio of carbon incorporated into microbial biomass to the carbon mineralised. Total PLFA concentration decreased to a greater extent in metal contaminated soils than uncontaminated soils. Microbial CUE also decreased due to metal toxicity. However, biochar addition alleviated the metal toxicity, and increased total PLFA concentration. Both microbial respiration and biomass carbon increased due to biochar application, and CUE was significantly (p<0.01) higher in biochar treated soils than untreated soils. Heavy metals reduced the microbial carbon sequestration in contaminated soils by negatively influencing the CUE. The improvement of CUE through biochar addition in the contaminated soils could be attributed to the decrease in metal bioavailability, thereby mitigating the biotoxicity to soil microorganisms.

Since the late Miocene, plants using the C4 photosynthetic pathway have increased to become major components of many tropical and subtropical ecosystems. However, the drivers for this expansion remain under debate, in part because of the varied histories of C4 vegetation on different continents. Australia hosts the highest dominance of C4 vegetation of all continents, but little is known about the history of C4 vegetation there. Carbon isotope ratios of plant waxes from scientific ocean drilling sediments off north‐western Australia reveal the onset of Australian C4 expansion at ~3.5 Ma, later than in many other regions. Pollen analysis from the same sediments reveals increasingly open C3‐dominated biomes preceding the shift to open C4‐dominated biomes by several million years. We hypothesize that the development of a summer monsoon climate beginning in the late Pliocene promoted a highly seasonal precipitation regime favorable to the expansion of C4 vegetation.

The most successful chronostratigraphic correlation methods enlist multiple proxies such as biostratigraphy and chemostratigraphy to constrain the timing of globally important bio-and geo-events. Here we present the first regional, high-resolution shelly fossil biostratigraphy integrated with  13 C chemostratigraphy (and corresponding  18 O data) from the lower Cambrian of South Australia. The global ZHUCE, SHICE, positive excursions II and III and the CARE are captured in lower Cambrian successions from the Arrowie and Stansbury basins. The South Australian shelly fossil biostratigraphy has a consistent relationship with the δ 13 C results, bolstering interpretation, identification and correlation of the excursions. Positive excursion II straddles the boundary between the Kulparina rostrata and Micrina etheridgei zones, and the CARE straddles the boundary between the M. etheridgei and Dailyatia odyssei zones, peaking in the lower parts of the latter zone. New 3 CA-TIMS zircon dates from the upper Hawker Group and Billy Creek Formation provide calibration points for the upper D. odyssei Zone and corresponding chemostratigraphic curve, embedding the lower Cambrian successions from South Australia into a global chronostratigraphic context. This multi-proxy investigation demonstrates the power of integrated multi-proxy methods for global correlation of regional biostratigraphic schemes, facilitating robust global correlation of lower Cambrian successions from South Australia with coeval terranes on other Cambrian palaeocontinents, including South and North China, Siberia, Laurentia, Avalonia and West Gondwana.

Microplastics (MPs) are ubiquitous in the environment and are infiltrating the food chain, causing potential risks to living beings. However, current methods of MP removal from an aqueous environment are limited by low efficiency. Advanced oxidation processes (AOPs) are emerging techniques for MP purification. Herein, a hydrothermal coupled Fenton system is developed for decomposition of ultrahigh-molecular-weight polyethylene, achieving 95.9% weight loss in 16 h and 75.6% mineralization efficiency in 12 h. The high effectiveness is attributed to the synergy of hydrothermal hydrolysis, proton-rich environment, and massive production of hydroxyl radicals. The system is also efficient to remediate different petroleum-based plastics and maintains high efficiency in practical water bodies. Characterizations revealed a two-stage degradation process: chain unfolding/stretching and oxidation, giving rise to the formation of carbonyl groups and decreased crystallinity of MPs during the hydrothermal treatment. The chain stretching stage is pivotal to the whole treatment because it remarkably facilitates subsequent chain cleavage and Fenton oxidation. This study provides a new approach to removing MPs in water bodies and new insights into MP degradation by the AOP technology.

[1] Volcanoes discharge a range of inorganic major gas species (e.g., H 2 O, CO 2 , SO 2 , and CO) not only during eruptions but also during quiescent phases through fumarolic and diffuse degassing in their craters and on their flanks. The emission of organic trace gases from volcanoes is similarly not expected to be restricted to discrete fumarolic gas discharges alone. To test this hypothesis, we have sampled soil gas emissions for organic compounds and determined CO 2 fluxes along a profile extending from the vegetated base of the active La Fossa cone (Vulcano Island, Italy) over the unvegetated volcanic flank and up into the crater rim and base and then continuing over fumarolic areas. The results indicate that the majority of volatile organic compounds in the soil gas show significant increases in concentration toward the crater and fumaroles and that diffuse emissions contribute significantly to the volcanic halocarbon source strength. Emissions of the halocarbon CFC-11 (CCl 3 F) correlate well with soil CO 2 fluxes measured on site (R 2 = 0.89, slope = 1.42 ± 0.1) and both increase toward the crater and fumaroles. Other ozone-depleting substances were found in concentrations significantly above those found in field and system blanks, including CH 3 Br, CH 3 Cl, CH 3 I, C 2 H 5 Br, and chlorinated benzenes. Abundances ranged from upper pptv to ppmv; for example, the maximum observed CFC-11 concentrations were 1200 pptv in diffuse emissions and 3700 pptv in dry fumarolic gas (average dry air is 268 pptv). On the basis of these results the natural volcanic source strength of halocarbon emissions to the atmosphere requires reevaluation, and in some cases, correction to higher values. Global average fumarolic and diffuse halocarbon source strengths were estimated and scaled to known global volcanic fumarolic and diffuse CO 2 flux data. Among these were CFC-11 (8.56 ± 4.7 Â 10 À6 Tg y À1 ), CH 3 Br (0.98 ± 0.47 Â 10 À6 Tg y À1 ), CHCl 3 (94.9 ± 27.6 Â 10 À6 Tg y À1 ), and CCl 4 (3.41 ± 1.0 Â 10 À6 Tg y À1 ).

Asphaltites, long known to strand along the coastline of southern Australia and as distantly as New Zealand and Macquarie Island, are widely regarded as artefacts of submarine oil seepage. Their remarkably uniform composition suggests a common source: marine shale containing sulfur-rich Type II kerogen, probably deposited during an Early Cretaceous oceanic anoxic event (OAE). Suitable hydrocarbon kitchens may exist in the offshore Bight and Otway basins. The physical character of the asphaltites, including laminations and flow structures, and their degree of alteration, which is not the result of biodegradation or extensive water washing, suggest an origin from subsurface tar mats subsequently exposed by the incision of submarine canyons, with the possible formation of asphaltic volcanoes. API gravities of 4-18° impart quasi-neutral buoyancy, implying many asphaltites were submerged drifters prior to stranding, their degree of weathering reflecting, at least in part, the residence 2 time in the marine environment. For any individual asphaltite specimen, this will depend on the proximity of the seafloor seep to the stranding site, an important consideration when attempting to locate their point of origin. This study investigates the hydrocarbon biomarker signatures and n-alkane δ 13 C profiles of asphaltite specimens from stranding sites on the Eyre Peninsula (n = 2), Kangaroo Island (n = 4) and the Limestone Coast (n = 3), South Australia, and the south island of New Zealand (n = 2). Sub-samples of the interior and weathered surface of each specimen were analysed. No distinction could be made between strandings based on their source-dependent molecular and isotopic signatures, confirming their common origin. Comparison of the interior and exterior sub-samples revealed subtle although consistent differences. Given their degree of degradation and isotopic variance, these Australasian asphaltites seem to be products of low intensity seeps in the Ceduna Sub-basin of the Bight Basin and/or Morum Sub-basin of the Otway Basin.