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Rapid rates of urbanisation are placing growing demands on cities for accommodation and transportation, with increasing numbers of basements and tunnel networks being built to meet these rising demands. Such subsurface structures constitute continuous heat sources and sinks, particularly if maintained at comfortable temperatures. At the city-scale, there is limited understanding of the effect of heat exchange of underground infrastructures with their environments, in part due to limited availability of long-term underground temperature data. The effects of underground temperature changes due anthropogenic heat fluxes can be significant, impacting ventilation and cooling costs of underground spaces, efficiency of geo-energy systems, quality and quantity of groundwater flow, and the health and maintenance of underground structures. In this paper we explore the impact of anthropogenic subsurface structures on the thermal climate of the shallow subsurface by developing a heat transfer model of the city of Cardiff, UK, utilising a recently developed semi-3D modelling approach.

Understanding the subsurface is crucial in building a sustainable future, particularly for urban centers. Importantly, the thermal effects that anthropogenic infrastructure, such as buildings, tunnels, and ground heat exchangers, can have on this shared resource need to be well understood to avoid issues, such as overheating the ground, and to identify opportunities, such as extracting and utilizing excess heat. However, obtaining data for the subsurface can be costly, typically requiring the drilling of boreholes. Bayesian statistical methodologies can be used towards overcoming this, by inferring information about the ground by combining field data and numerical modeling, while quantifying associated uncertainties. This work utilizes data obtained in the city of Cardiff, UK, to evaluate the applicability of a Bayesian calibration (using GP surrogates) approach to measured data and associated challenges (previously not tested) and to obtain insights on the subsurface of the area. The importance of the data set size is analyzed, showing that more data are required in realistic (field data), compared to controlled conditions (numerically-generated data), highlighting the importance of identifying data points that contain the most information. Heterogeneity of the ground (i.e., input parameters), which can be particularly prominent in large-scale subsurface domains, is also investigated, showing that the calibration methodology can still yield reasonably accurate results under heterogeneous conditions. Finally, the impact of considering uncertainty in subsurface properties is demonstrated in an existing shallow geothermal system in the area, showing a higher than utilized ground capacity, and the potential for a larger scale system given sufficient demand.

The dissolved organic carbon (DOC) export from land to ocean via rivers is a significant term in the global C cycle, and has been modified in many areas by human activity. DOC exports from large global rivers are fairly well quantified, but those from smaller river systems, including those draining oceanic regions, are generally under-represented in global syntheses. Given that these regions typically have high runoff and high peat cover, they may exert a disproportionate influence on the global land–ocean DOC export. Here we describe a comprehensive new assessment of the annual riverine DOC export to estuaries across the island of Great Britain (GB), which spans the latitude range 50–60° N with strong spatial gradients of topography, soils, rainfall, land use and population density. DOC yields (export per unit area) were positively related to and best predicted by rainfall, peat extent and forest cover, but relatively insensitive to population density or agricultural development. Based on an empirical relationship with land use and rainfall we estimate that the DOC export from the GB land area to the freshwater-seawater interface was 1.15 Tg C year−1 in 2017. The average yield for GB rivers is 5.04 g C m−2 year−1, higher than most of the world’s major rivers, including those of the humid tropics and Arctic, supporting the conclusion that under-representation of smaller river systems draining peat-rich areas could lead to under-estimation of the global land–ocean DOC export. The main anthropogenic factor influencing the spatial distribution of GB DOC exports appears to be upland conifer plantation forestry, which is estimated to have raised the overall DOC export by 0.168 Tg C year−1. This is equivalent to 15% of the estimated current rate of net CO2 uptake by British forests. With the UK and many other countries seeking to expand plantation forest cover for climate change mitigation, this ‘leak in the ecosystem’ should be incorporated in future assessments of the CO2 sequestration potential of forest planting strategies.

Abstract Pyrite oxidation drives iron and sulfur availability across Earth’s subsurface and is partly microbially mediated. Subsurface microbial communities accelerate this process at circumneutral pH directly by weathering pyritic surfaces and indirectly by causing changes to the surrounding microenvironment, thereby further accelerating pyrite weathering. However, our understanding of community structure dynamics and associated biogeochemistry in Fe- and S-rich lithologies, e.g. pyritic coal, is limited. Here, we present the first comprehensive regional and seasonal genus-level survey of bacterial groundwater communities in a pyritic coal-based aquifer in the South Wales Coalfield (SWC), using 16S rRNA gene amplicon sequencing. Seasonal changes in community structure were limited, suggesting limited influence of surface processes on subsurface communities. Instead, hydrogeologically distinct mine water blocks (MWB) and coal rank largely explained bacterial community structure variation across sites. Fe(II)-oxidizing Betaproteobacteriales genera Gallionella and Sideroxydans dominated the bacterial communities across nine sites and seven MWBs, while three sites within a single MWB, were dominated by S-oxidizing Epsilonbacteraeota genera Sulfuricurvum and Sulfurovum. The cooccurrence of pairs of Fe(II)- and S-oxidizing bacterial genera suggests functional redundancy, which coupled with genus-specific morphologies and life strategies, indicates the importance of distinct environmental and ecological niches within the SWC groundwater at seasonal and regional scales. First spatio-temporal overview of South Wales Coalfield bacterial community structures reveals cooccurrence of Fe- and S-oxidizing bacterial pairs, suggesting hydrogeology and coal rank drive biogeochemistry in this pyritic coal-based aquifer.

Killer robots invoke scenes that belong in the realm of science fiction. However, weaponised artificial intelligence is making them a real possibility but perhaps not as sentient and evil as science fiction portrays. Weapons that possess autonomous features have been around for a number of decades in anti-material roles but their use in combat directed towards humans has now been documented for the first time. The advancement in artificial intelligence and robotics, especially in the civilian domain, has enabled the development of these weapons. However, how these weapons should be treated within the field of international law is still heavily debated. There are valid arguments to both the legality and illegality of these weapons in the current body of international law with no clear way forward. These weapons also pose complex ethical issues within the moral dimension of warfare, with views ranging from the argument that the development of these weapons is a moral imperative to the argument that they go completely against the morality of war and should be banned. Previous attempts at arms control have yielded successful results with a number of problematic weapons and similar results can be attempted in this instance with civil society leading the charge. This research explores all the dimensions related to the development and use of Lethal Autonomous Weapons Systems from a technological, legal, ethical, and regulatory perspective, concluding that the use of these weapons is likely to increase in the coming years, thus necessitating the urgent development of legal, ethical, and regulatory frameworks to adapt to this new reality.

Biographical material. Source: National Library of New Zealand Te Puna Matauranga o Aotearoa, licensed by the Department of Internal Affairs for re-use under the Creative Commons Attribution 3.0 New Zealand Licence.