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Copyright of Hydrogeology Journal is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The paper evaluates the effect of future climate change (as per the CSIRO Mk3.5 A1FI future climate projection) on cotton yield in Southern Queensland and Northern NSW, eastern Australia by using of the biophysical simulation model APSIM (Agricultural Production Systems sIMulator). The simulations of cotton production show that changes in the influential meteorological parameters caused by climate change would lead to decreased future cotton yields without the effect of CO fertilisation. By 2050 the yields would decrease by 17 %. Including the effects of CO fertilisation ameliorates the effect of decreased water availability and yields increase by 5.9 % by 2030, but then decrease by 3.6 % in 2050. Importantly, it was necessary to increase irrigation amounts by almost 50 % to maintain adequate soil moisture levels. The effect of CO was found to have an important positive impact of the yield in spite of deleterious climate change. This implies that the physiological response of plants to climate change needs to be thoroughly understood to avoid making erroneous projections of yield and potentially stifling investment or increasing risk. [ABSTRACT FROM AUTHOR]

Termites are a highly uncertain component in the global source budgets of CH and CO. Large seasonal variations in termite mound fluxes of CH and CO have been reported in tropical savannas but the reason for this is largely unknown. This paper investigated the processes that govern these seasonal variations in CH and CO fluxes from the mounds of Microcerotermes nervosus Hill (Termitidae), a common termite species in Australian tropical savannas. Fluxes of CH and CO of termite mounds were 3.5-fold greater in the wet season as compared to the dry season and were a direct function of termite biomass. Termite biomass in mound samples was tenfold greater in the wet season compared to the dry season. When expressed per unit termite biomass, termite fluxes were only 1.2 (CH) and 1.4 (CO)-fold greater in the wet season as compared to the dry season and could not explain the large seasonal variations in mound fluxes of CH and CO. Seasonal variation in both gas diffusivity through mound walls and CH oxidation by mound material was negligible. These results highlight for the first time that seasonal termite population dynamics are the main driver for the observed seasonal differences in mound fluxes of CH and CO. These findings highlight the need to combine measurements of gas fluxes from termite mounds with detailed studies of termite population dynamics to reduce the uncertainty in quantifying seasonal variations in termite mound fluxes of CH and CO. [ABSTRACT FROM AUTHOR]

This paper introduces the micrometeorological field campaigns known as OASIS (Observations At Several Interacting Scales) and then summarizes several companion studies that have used the OASIS dataset. Instrumented towers, aircraft and atmospheric sondes were used for measurements over three paired sites (crops and pastures), approximately equi-spaced along an 88-km transect in south-eastern New South Wales, Australia, during the austral springs of 1994 and 1995. Measurements included standard meteorological data and the fluxes of solar and net radiation, sensible heat, water vapour and the greenhouse gases CO2, N2O, CH4. Descriptions of the site, and the spatial and temporal variations of climate fields and fluxes, are presented. There were strong contrasts in fluxes and surface conductances, evaporation ratios and water use efficiencies between the 1994 drought year and the normal rainfall year of 1995. Despite greater incoming solar radiation in 1994 associated with less cloud cover, net radiation was lower than in 1995 because of greater outgoing thermal radiation caused by higher surface temperatures. In 1994 daily sensible heat fluxes were about 50% higher and evaporation rates about half those for 1995. Rainfall in the three-month growing season prior to the field campaigns was the key determinant of leaf area index, surface conductances and the fluxes of sensible and latent heat and CO2. Antecedent rainfall distribution also controlled variation in fluxes and surface properties along the transect within each year. There was a net loss of CO2 to the atmosphere at the drier central sites in 1994, and a net uptake at the wetter north-eastern sites. Both sites recorded uptake of CO2 in 1995, but values were lower at the central site than at the north–east site due to the strong rainfall gradient along the transect in the three months prior to each field campaign. Differences in fluxes between crops and pastures at each site were smaller than between sites. [ABSTRACT FROM AUTHOR]

The Water Alternating Gas (WAG) process is a cyclic process of injecting alternating water followed by gas. The main purpose of WAG injection is to improve both macroscopic and microscopic sweep efficiency, maintaining nearly initial high pressure, slow down the gas breakthrough and reduced oil viscosity. WAG injection also decreases the residual oil saturation resulted from the flow of three phases and effects associated with relative permeability hysteresis. The study area is in the Cornea Field located in Browse Basin, Western Australia. This study is conducted because there is no investigation on WAG injection feasibility in this field. In this study, two-phase bounding imbibition and drainage relative permeability model (Stone 1 and Stone 2) along with two-phase hysteresis model (Land, Carlson or Killough) were used. From the result, Carlson two-phase hysteresis model with Stone 1 correlation shows more oil was recovered. Therefore, it is a feasible model to be used compared with other models. From sensitivity analysis, it shows that highest oil was recovered at WAG ratio 1:1. Since it is a miscible reservoir, 1:1 ratio is more efficient and it is insensitive to trapping. Also, oil production increased with the shortest WAG cycle time at 180 days due to minimum miscibility pressure reached. In addition, it is best to inject water as the first phase to be injected into the reservoir compared to CO 2 because water has high mobility ratio while CO 2 can result in early breakthrough in the reservoir. [ABSTRACT FROM AUTHOR]

We examined the two-phase hydro-mechanical coupled process for subsurface applications. First, we exclusively derived governing equations for capillary pressure of the wetting fluid and pressure of the non-wetting fluid as a primary variable to make use of the global finite element model in the two-phase flow system. For the coupling process based on the derivation, we developed a module to couple the two-phase flow and the mechanical deformation for numerical modeling. For the verification of the coupling module, we solved a benchmark problem, which has an analytical solution for a single-phase hydro-mechanical system. To compare the results with those produced with the same coupling scheme of an existing module, we addressed the same benchmark problem with TOUGH–FLAC. After verification, we demonstrated the module for the two-phase hydro-mechanical coupled application of CO 2 storage at the field scale, the Otway Basin, Australia. The formation of caprock and reservoir in lithology had a significant effect on the movement of the CO 2 plume, providing a predominant pathway. Based on the mechanical analysis at the core of the CO 2 plume, the amount of pore pressure increase during the CO 2 injection period did not lead to noticeable damage in the formation. [ABSTRACT FROM AUTHOR]

Future levels of climate change depend not only on carbon emissions but also on carbon uptake by the land and the ocean. Here we are using the Earth system model (ESM1) version of the Australian Community Climate and Earth System Simulator (ACCESS) to explore the potential and impact of removing carbon dioxide (CO2) from the atmosphere through the climate and carbon cycle reversibility experiment. This experiment builds on the standard Coupled Model Intercomparison Project (CMIP) experiment, increasing CO2 at 1% per year until 4xCO2 is reached. The atmospheric CO2 levels are then decreased at the same rate which brings the CO2 back to pre-industrial levels. We then continue to run the model with constant CO2 for another 350 years. Our analysis focuses on the response of the land carbon cycle. We find that carbon stores are largely reversible at the global scale over the timescale of changing CO2. However, carbon stores continue to decrease after CO2 returns to its initial value, and the land loses another 40 Pg of carbon (PgC) with the largest change in the tropics. It takes about 300 years beyond the period of changing CO2 for the carbon stores to recover. Interestingly, we saw strong regional variations in the strength of the land response to changing CO2. Australia showed the largest increase/decrease in biomass carbon (about 40%) and the largest variability in productivity, which was strongly correlated with rainfall. This highlights the importance of assessing the regional response to understanding the processes underlying the response and the sensitivity of these processes within each model. This understanding will benefit future multi-model analyses of this reversibility experiment. It also illustrates more generally the potential to use Earth system model experiments as part of the evaluation of proposed applications of carbon dioxide removal (CDR) technologies. As such, we recommend that these types of modelling experiments be included when mitigation policies are developed. [ABSTRACT FROM AUTHOR]

The response of the carbon and hydrological cycles of irrigated agro-ecosystems in semi-arid regions to changes in temperature and increasing levels of atmospheric carbon dioxide concentrations is unclear. Furthermore, the extent to which these systems contribute to the carbon cycle as net sources or sinks of carbon dioxide remains relatively unknown. In this study, eddy covariance methodologies were employed to quantify mass and energy exchange of maize, rice and wheat grown in an Australian semi-arid irrigation-dependent agricultural region. It was found that there was a distinct seasonal difference in the magnitude of energy balance components. The latent heat exchange observed during the summer growing season was almost twice that observed during winter. Irrigation management practices significantly influenced the distribution of turbulent fluxes. Over the permanently flooded rice crop, the energy balance was predominately driven by latent heat flux, which accounted for ~99 % of the energy balance. For the crops irrigated intermittently (i.e. maize and wheat), latent heat flux represented ~80 % of the energy balance. In addition, all three crops acted as a net carbon sink over the growing season. The rate of carbon assimilation was impacted by the nature of the photosynthetic pathway of the plant and seasonality. Maize, a C4 plant, exhibited the greatest capacity for carbon uptake (−1,327 g C/m) during the summer months, and winter wheat, a C3 plant, exhibited the least (−388 g C/m). [ABSTRACT FROM AUTHOR]

Copyright of Hydrogeology Journal is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

An incubation study determined the effect of one dry–rewetting (DRW) event on the turnover of carbon (C), phosphorus (P) and nitrogen (N). Thirty-two soils were collected from different climatic regions of southern Australia, varying in soil type, land use and agronomic management history. We hypothesised that respiration and nutrient pulses are related to soil physio-chemical properties. Respiration (CO2 release) was measured intensively for 90 h after rewetting. C mineralisation ( Cmin) model fitting was used to describe the amount of mineralisable C (Co90 h) and the proportional mineralisation rate ( k). Compared to constantly moist soils, 13 soils showed increases in both Co90 h and k, indicating that DRW increased the amount of mineralisable C and the rate at which C was mineralised over the 90-h period. In 17 soils, k was increased but not Co90 h, showing an increase in C mineralisation rate but no change in the amount of mineralisable C. Two soils showed a reduction in k with no change in Co90 h, possibly due to low C contents and small microbial biomass. Only one soil exhibited no change in either Co90 h or k. Multiple linear regression analysis indicated that the magnitude of the increase in mineralisable C in response to the DRW event (∆Co90 h = Co90 h DRW − Co90 h moist) was primarily explained by clay content (39%); however, inclusion of nine soil physio-chemical properties explained more of the variation in ∆Co90 h than any of the properties alone. Five of the nine physio-chemical variables present in the multiple-regression model were related to C content or composition. Pulses in available N and P were not related to ∆Co90 h. [ABSTRACT FROM AUTHOR]

Investigates the effects of climate change due to increasing atmospheric carbon dioxide on the major tributaries to the Swan River in Perth, Western Australia. General Circulation Models; 1000 year time series; Stochastic weather generator; Conceptual rainfall-runoff model.

This study investigated an incubation method which employed simultaneous measurement of CO production and O consumption rates to calculate the RQ (respiratory quotient; CO production rate: O consumption rate) of individual benthic marine invertebrates. Carbon dioxide production rates were calculated from changes in CO concentration determined using seawater pH. O consumption rates were calculated from changes in O concentration with a correction applied for O flux across the air/water interface due to gaseous exchange. Species examined were Triphyllozoon sp. cf. moniliferum (MacGillivray 1860), a bryozoan; Herdmania momus (Savigny), a solitary ascidian; Poneroplax albida (Blainville 1825), a chiton; and Haliotis roei (Gray 1826), an abalone. Six individuals of each were collected on 14 November 1985 from the limestone walls of a cave in a nearshore reef off Marmion, Western Australia. After acclimation for 6 h in experimental conditions, rates of CO production and O consumption were measured. A minimum period of 4 h was required to obtain consistent RQ values for each species. The standard error (SE) of the (calculated) RQ ratio was 14 to 33% of the mean in incubations of 4 h, and less than 14% in incubations of 4 to 12 h. The RQ is commonly used as an indicator of unknown catabolic substrates by comparing it with biochemically determined limits for known substrates. This study provides a strong argument against using the RQ of individual animals to draw any conclusions about catabolic substrates. Unexplained variation in the components of the RQ of an individual, measured over short time periods, and the potential involvement of stored reserves in catabolism, over longer time periods, obscure the relationship between the RQ of individual animals and the ratio's biochemically determined limits. [ABSTRACT FROM AUTHOR]