Methane Mitigation:Methods to Reduce Emissions, on the Path to the Paris Agreement

The atmospheric methane burden is increasing rapidly, contrary to pathways compatible with the goals of the 2015 United Nations Framework Convention on Climate Change Paris Agreement. Urgent action is required to bring methane back to a pathway more in line with the Paris goals. Emission reduction from “tractable” (easier to mitigate) anthropogenic sources such as the fossil fuel industries and landfills is being much facilitated by technical advances in the past decade, which have radically improved our ability to locate, identify, quantify, and reduce emissions. Measures to reduce emissions from “intractable” (harder to mitigate) anthropogenic sources such as agriculture and biomass burning have received less attention and are also becoming more feasible, including removal from elevated-methane ambient air near to sources. The wider effort to use microbiological and dietary intervention to reduce emissions from cattle (and humans) is not addressed in detail in this essentially geophysical review. Though they cannot replace the need to reach “net-zero” emissions of CO2, significant reductions in the methane burden will ease the timescales needed to reach required CO2 reduction targets for any particular future temperature limit. There is no single magic bullet, but implementation of a wide array of mitigation and emission reduction strategies could substantially cut the global methane burden, at a cost that is relatively low compared to the parallel and necessary measures to reduce CO2, and thereby reduce the atmospheric methane burden back toward pathways consistent with the goals of the Paris Agreement

Carbon isotopic signature of coal-derived methane emissions to the atmosphere: from coalification to alteration

Currently, the atmospheric methane burden is rising rapidly, but the extent to which shifts in coal production contribute to this rise is not known. Coalbed methane emissions into the atmosphere are poorly characterised, and this study provides representative δ13CCH4 signatures of methane emissions from specific coalfields. Integrated methane emissions from both underground and opencast coal mines in the UK, Australia and Poland were sampled and isotopically characterised. Progression in coal rank and secondary biogenic production of methane due to incursion of water are suggested as the processes affecting the isotopic composition of coal-derived methane. An averaged value of −65 ‰ has been assigned to bituminous coal exploited in open cast mines and of −55 ‰ in deep mines, whereas values of −40 and −30 ‰ can be allocated to anthracite opencast and deep mines respectively. However, the isotopic signatures that are included in global atmospheric modelling of coal emissions should be region- or nation-specific, as greater detail is needed, given the wide global variation in coal type

Social anxiety symptoms in young children:Investigating the interplay of theory of mind and expressions of shyness

Children’s early onset of social anxiety may be associated with their social understanding, and their ability to express emotions adaptively. We examined whether social anxiety in 48-month-old children (N = 110; 54 boys) was related to: a) a lower level of theory of mind (ToM); b) a lower proclivity to express shyness in a positive way (adaptive); and c) a higher tendency to express shyness in a negative way (non-adaptive). In addition, we investigated to what extent children’s level of social anxiety was predicted by the interaction between ToM and expressions of shyness. Children’s positive and negative expressions of shyness were observed during a performance task. ToM was measured with a validated battery, and social anxiety was assessed using both parents’ reports on questionnaires. Socially anxious children had a lower level of ToM, and displayed more negative and less positive shy expressions. However, children with a lower level of ToM who expressed more positive shyness were less socially anxious. Additional results show that children who displayed shyness only in a negative manner were more socially anxious than children who expressed shyness only in a positive way and children who did not display any shyness. Moreover, children who displayed both positive and negative expressions of shyness were more socially anxious than children who displayed shyness only in a positive way. These findings highlight the importance of ToM development and socio-emotional strategies, and their interaction, on the early development of social anxiety

Groundwater Hydrographs in the Namoi and Gwydir Catchments: An Assessment of Groundwater Level Change

This report presents all groundwater hydrographs from the Namoi and Gwydir catchments.Change in the groundwater levels recorded throughout the Namoi and Gwydir catchments arepresented for two periods: 1985–2015 and 2006–2015.The period 1985–2015 was selected to show long-term change in groundwater levelsbecause from the mid 1980s there was widespread groundwater monitoring throughout the Namoiand Gwydir catchments. Prior to the 1980s, groundwater monitoring was mostly limited to the regionbetween Narrabri and Wee Waa.For the second period we selected 2006 as the starting reference year because this waswhen the Water Sharing Plans commenced in both catchments. The end reference year 2015 wasselected because the 2006–2015 winter-recovered water set provides the most extensive coveragewhen compared to the 2006–2016 or 2006–2017 available data. Maps of the shallow, intermediateand deep portions of the Namoi and Gwydir alluvium show how the groundwater levels throughoutthe catchments have responded since the “millennium drought” and since the introduction of theWater Sharing Plans in 2006

Baselining Lower Namoi Groundwater and Evaluating Pilliga CSG Developments

This report summarises the primary research outcomes and publications produced as part of CRDC project UNSW1601 Baselining Lower Namoi Groundwater and Evaluating Pilliga CSG Developments. There is considerable public apprehension about the expansion of coal seamgas (CSG) production in the Pilliga. To produce the gas from the Permian coal measures, large quantities of co-produced water will be extracted. This water is commonly of poor quality and once it is brought to the surface there are concerns about its treatment, disposal and subsequent use. There are also concerns about the depressurisation impacts on groundwater resources in the Great Artesian Basin and Lower Namoi Alluvium. This projectassessed potential impacts of CSG production in conjunction with ongoing groundwater withdrawals for irrigated agriculture on sustainable access to groundwater for the cotton industry, as well as stock and domestic users.Measurements of the methane content of groundwater undertaken in the USA have demonstrated that methane levels can be an early indicator of connectivity between coal seam gas developments and aquifers used as water supplies (Osborn et al. 2011). To date there are no extensive baseline measurements of methane concentration in the groundwater or the air in the Namoi Catchment that have been placed in the public domain. This projectestablished baseline methane concentrations in the Lower Namoi Alluvial Aquifer and ground-level atmosphere.Since the establishment of the water sharing plans there have been limited studies reviewing how groundwater levels have responded and whether the groundwater quality is being maintained or improved. To assess changes in water quality the hydrogeochemical data collected as part of this study were compared to historical data sets. Graphs of groundwater levels for all groundwater monitoring locations in the Namoi were produced, along with maps highlighting how the groundwater levels have changed for two periods 1985-2015 and 2006-2015.Throughout Australia there are thousands of abandoned legacy wells. These wells may act as pathways of hydraulic connectivity to enable the transfer of water and gas between the coal measures and overlying aquifers. In 2014 and 2016 as part of CRDC project UNSW1401 mobile surveys were undertaken to measure continuously the methane mole fraction in the ground-level atmosphere of the Condamine catchment. Those campaigns mapped the locations of two legacy wells that were leaking methane at concentrations above ignition potential. Those results demonstrated that the issue of legacy wells requires extensive further study, and that in any region where there is potential for legacy wells to exist surveys should be undertaken. To assess if there are any legacy wells of concern in the Lower Namoi three field campaigns were undertaken to measure the methane mole fraction (concentration) in the ground-level atmosphere. These surveys also created a baseline data set to enable future assessments of changing land use and industrial activities

A multi-tracer approach to constraining artesian groundwater discharge into an alluvial aquifer

Understanding pathways of recharge to alluvial aquifers is important for maintaining sustainable access to groundwater resources. Water balance modelling is often used to proportion recharge components and guide sustainable groundwater allocations. However, it is not common practice to use hydrochemical evidence to inform and constrain these models. Here we compare geochemical versus water balance model estimates of artesian discharge into an alluvial aquifer, and demonstrate why multi-tracer geochemical analyses should be used as a critical component of water budget assessments. We selected a site in Australia where the Great Artesian Basin (GAB), the largest artesian basin in the world, discharges into the Lower Namoi Alluvium (LNA), an extensively modelled aquifer, to convey the utility of our approach. Water stable isotopes (δ18O and δ2H) and the concentrations of Na+ and HCO3− suggest a continuum of mixing in the alluvial aquifer between the GAB (artesian component) and surface recharge, whilst isotopic tracers (3H, 14C, and 36Cl) indicate that the alluvial groundwater is a mixture of groundwaters with residence times of < 70 years and groundwater that is potentially hundreds of thousands of years old, which is consistent with that of the GAB. In addition, Cl− concentrations provide a means to calculate a percentage estimate of the artesian contribution to the alluvial groundwater. In some locations, an artesian contribution of up to 70 % is evident from the geochemical analyses, a finding that contrasts with previous regional-scale water balance modelling estimates that attributed 22 % of all inflow for the corresponding zone within the LNA to GAB discharge. Our results show that hydrochemical investigations need to be undertaken as part of developing the conceptual framework of a catchment water balance model, as they can improve our understanding of recharge pathways and better constrain artesian discharge to an alluvial aquifer

Hydrogeochemical, Microbial and Isotopic Composition of Groundwater from the Lower Namoi Alluvial Aquifer between Narrabri and Wee Waa (NSW) – Implications for Groundwater Management

Coal seam gas (CSG) exploration and production has expanded adjacent to the Lower Namoi Alluvium (LNA) since 2002, with tenements to Santos Limited in and around the Pilliga State Forest (Santos Limited 2015). The coal seams being targeted for production are the Bohena, Narrabri and Hokissons seams. CSG production generally requires the jointextraction of very large quantities of groundwater and thus there is significant community concern regarding the potential impacts of depressurisation and induced fluid and gas migration on both groundwater quality and quantity.The LNA has supplied groundwater for irrigated agriculture since the 1960s. These groundwater extractions have lowered the water table, changed groundwater flow paths and reduced the weight of water locally overlying the Great Artesian Basin (GAB). To rebalance extractions with natural aquifer recharge processes, there has been a staged reduction in groundwater withdrawals (commencing in 2006) with the aim of achieving sustainablegroundwater use (Lower Namoi Groundwater 2008).Future groundwater abstraction to support both irrigated agriculture and co-produced groundwater extractions associated with CSG production could potentially affect the sustainability of the groundwater resources in the LNA. Additionally, climate variability and change can impact the sustainability of groundwater resources in the LNA. There is also a societal desire to maintain and improve the health of groundwater dependent ecosystems.Analysing the groundwater chemistry provides insights on the impacts of past groundwater extractions, improves our understanding of recharge processes, and enables us to evaluate the conceptual hydrogeological models being used to guide the Water Sharing Plan and assessthe impacts of CSG production.The main objectives of this project are to: Collate baseline geochemical and, isotopic data of the groundwater, to providean assessment of the age of the groundwater; Measure the concentration of the methane (abbreviation; [CH4]) gas extracted from the groundwater, and analyse the isotopic chemistry of the methane content; Characterise the microbial communities in the water extracted from themonitoring wells and surrounding aquifer;Jointly interpret the CH4 chemistry in conjunction with the microbialcommunity results to provide an assessment of the source of CH4, and tocharacterise the processes acting upon the CH4; Improve our understanding of the hydraulic connection between the LNA and the GAB ; and Compare the hydrogeological processes inferred from the new data with the conceptual hydrogeological models used to guide the Lower Namoi Water Sharing Plan and the modelling used for the Santos Narrabri gas project environmental impact statement

Irrigation bore water in the Condamine Catchment: baselining groundwater quality and assessing pathways of hydraulic connectivity

The expansion of coal seam gas production adjacent to the irrigation farming districts in the Condamine Catchment has raised concerns about the impact of gas production on groundwater in adjoining aquifer systems. To assess the risk, and to be able to detect any future changes in groundwater properties, existing groundwater chemistry data sets need to be updated and expanded. Historically, the testing of groundwater chemistry in the Condamine Catchment has focused on the Queensland Government groundwater-monitoring network, but it is unlikely that these samples come from the same sand and gravel bodies from which the irrigation bores extract groundwater. We report the result of 20 groundwater samples collected from bores that supply irrigation water for cotton and other crops. These samples were collected in January 2014 at the end of the pumping season, when the aquifer system is at peak stress for the year. We compare the major ion chemistry recorded in the irrigation bores to that measured at selected sites from the QLD government groundwater-monitoring network and with historical results reported in the literature. A hydrochemical facies analysis of these data provides one assessment of the likelihood of hydraulic connectivity between the Walloon Coal Measures, other bordering Great Artesian Basin formations and the valley filling sediments of the Condamine Alluvium. The results highlight variation in groundwater chemistry within the Condamine Alluvium, particularly in the Cecil Plains and Dalby regions, where there are signs of water mixing. As a result, further research into the area to explain the baseline data sets would provide a better understanding of hydraulic connectivity and the potential effects of CSG on the groundwater

The use of the hydrogeochemistry and multivariate statistical methods as a tool for groundwater management. Condamine River Alluvial Aquifer (CRAA), Australia.

The alluvial aquifers of the Condamine River near Dalby have been increasingly used since the 1960s as a water resources to support Irrigated agriculture of mainly cotton and grain crops. Groundwater abstraction from the underlying Condamine River Alluvial Aquifer (CRAA) supplies 30% of the irrigation water (Dafny and Silburn, 2014). Over the past decade, Coal Seam Gas (CSG) exploration and production has expanded rapidly in the Queensland portion of the Surat Basin (SB), targeting the underlying Walloon Coal Measures (WCM), with tenements to multiple companies along the western flank of the Condamine Plain. To produce the gas, groundwater will be extracted in large quantities, depressurising the WCM. There is concern that the zone of depressurisation will impact the groundwater levels within the CRAA. In the last decade, great efforts have been made to improve hydrogeological conceptualization and modeling. The rapid expansion of CSG exploration and production in Australia has generated controversy within the public who are concerned about the impact on adjacent aquifers used to support irrigated agriculture, stock and domestic water supplies. The proximity of gas extraction to aquifers used for irrigation or domestic water supply is common to many CSG production sites globally. To address these concerns there has been increased research within the region to improve our understanding of aquifer connectivity and the regional water balance. To solve the uncertainties about the impact of CSG exploitation on the groundwater of the adjacent aquifers is necessary to have a robust conceptual model to understand the hydrological dynamics and hydrochemical processes. Most cases, spatial and temporal variability of groundwater chemistry is the result of mixing processes between different water sources. Understanding the mixing processes which take place between several groundwater inputs or groundwater with other water bodies is crucial for groundwater management. Mixing calculations have been successfully applied in many hydrogeological setting to improve the conceptual model and understanding the origins of groundwater compositions.The main aims of this work are to improve the knowledge of the hydrogeologic system in the Condamine alluvium and to investigate the possible impacts of CSG exploration and production to the Condamine Alluvium. To attain these objectives, this study applies a methodology based on multivariate statistical methods for computing the mixing ratios of different water sources (end-members) in several observation points to evaluate the potential impacts. This included the identification and chemical characterization of the recharge sources (end-members), the evaluation of the mixing proportions for each sample, the quantification of the geochemical processes undergone, and the evaluation of CSG exploitation effects. Mixing ratios are computed using MIX code developed by (Carrera et al., 2004). MIX code is based on the maximum likelihood algorithm to estimate the mixing ratios taking into account the uncertainty of the end-members and mixed samples.Building a robust conceptual model together with the application of multivariate statistical methods will serve as a useful tool for groundwater management