Areal Footprint Research Articles

Mineral scaling and organic fouling in electrodialytic crystallization

The management of hypersaline brine is a critical challenge to achieving a circular water economy. Traditional brine treatment technologies mainly rely on thermal evaporation, which requires intensive energy, cost, and/or areal footprint. Electrodialytic crystallization (EDC) has been recently developed as a novel process that enables brine crystallization without evaporation. However, the potential effects of mineral scaling and organic fouling on the performance of EDC have not been revealed. In this study, we systematically investigated mineral scaling and organic fouling in EDC. We demonstrate that the ion transport and crystallization efficiencies of EDC are generally unaffected by a variety of mineral scalants and organic foulants, despite an increase of energy consumption in the presence of humic acid. Further, EDC is shown to be less susceptible to gypsum scaling than RO, mainly due to the difference in concentration polarization between these two membrane processes. To mitigate gypsum scaling in an assumptive EDC-RO treatment train towards zero liquid discharge (ZLD), polyacrylic acid (PAA) is employed as an antiscalant that prevents gypsum scaling in RO while not adversely affecting EDC performance at relatively low concentration. Our study unravels the behaviors of EDC when treating feedwater with high scaling and fouling potentials, providing valuable insights for understanding mineral scaling and organic fouling when applying an ED-based technology for hypersaline brine treatment towards ZLD.

An integrated assessment of erosion drivers facilitating gully expansion rates—A near century multi‐temporal analysis from South Africa

AbstractRural areas in the Eastern Cape Province of South Africa are severely affected by gully erosion, yet little is known about the rates at which these features are expanding. This study explores the areal extent, physical mechanisms, rates, and drivers of gully expansion with the aim of investigating how erosion rates fluctuate in response to temporal variations of drivers over the last century. Investigations involved the creation of an erosion inventory geo‐database, the identification of area‐specific physical expansion mechanisms, an assessment of static and dynamic drivers, and a multi‐temporal study of 25 gullies in the Mthatha area. Results show gully erosion affects 2.3% of the study area, with gullies exhibiting an average annual areal increase of 2.08%, a sidewall retreat rate of 0.2 m/y, and a headcut retreat of 1.03 m/y over an 82‐year period between 1938 and 2020. A multi‐temporal case study of the Ngwevana Gully showed average annual areal growth rates ranging from 3.9% between 1938 and 1948 to 0.7% between 2017 and 2020. Findings indicate that although gullies consistently expand their areal footprint, they do so at fluctuating rates. An assessment of erosion drivers reveals that temporal promotion or suppression of these erosion rates occurs in response to the complex and dynamic interactions of both natural mechanisms and anthropogenic activities. In Mthatha, the periods of increased rates of erosion are linked to large‐scale flooding events during drier climate cycles, which were further exacerbated by invasive dryland agricultural practices, inappropriate land use, haphazard infrastructure development, and rapid population increases facilitated by past Apartheid settlement laws.

Using Stochastic Point Pattern Analysis to Track Regional Orientations of Magmatism During the Transition to Cenozoic Extension and Rio Grande Rifting, Southern Rocky Mountains

AbstractThe southern Rocky Mountains in Colorado and northern New Mexico hosted intracontinental magmatism that developed during a tectonic transition from shortening (Laramide orogeny, ca. 75 to 40 Ma) through extension and rifting. We present a novel approach that uses stochastic weighted bootstrap simulations of a large set of new and historical geochronology data to better understand how regional anisotropies responsible for focusing magma emplacement evolved through time. This technique can detect subtle trends in directional distributions, including multi‐modal orientations, and can be filtered from regional to local scales. Our results indicate that magmatism followed first the northeast trend of the Colorado mineral belt between 75 and 40 Ma and deviated afterward. These deviations vary depending on the scale of the analysis. At the smallest scale we evaluated (<75 km), the orientation of magmatism from 45 to 30 Ma rotated counter‐clockwise before aligning with the north‐south trend of the modern Rio Grande rift. Larger, regional‐scale analyses indicate magma centers between 40 to 35 Ma and 25 to 20 Ma were dominantly oriented southwest‐northeast, whereas magmatism between 35 and 25 Ma had north‐south orientation. The large areal footprint of magmatism and shifting regional patterns suggest that ancient zones of weakness in the North American lithosphere accommodated magma flow at different moments in time, rather than controlled by a retreating interface of the Farallon and North American plates.

Green wall system coupled with slow sand filtration for efficient greywater management at households

AbstractGreen walls are gaining attention for greywater management in the imminent terrestrial space and land constraint scenario. They have been tested primarily with greywater from a single source such as showers, hand or wash basins, laundry, and kitchen or a mix of a couple of these sources but barely with mixed greywater from all these household activities. Here, a green wall system coupled with a slow sand filter (SSF) was tested for managing household greywater. It consisted of a set of five serial hydraulic flow-connected reactors and an SSF unit. Each reactor housed an Epipremnum aureum sapling embedded in the support bed matrix, consisting of cocopeat and granular activated charcoal. The system operated at 150 cm d−1 hydraulic loading rate (HLR) achieved 90 ± 0.7%, 85 ± 4.5%, 72.9 ± 4.4%, and 60.6 ± 5.1% removal efficiencies for turbidity, chemical oxygen demand (COD), total nitrogen (TN), and total phosphorous (TP), respectively. The system maintained similar treatment performance with varying greywater strength when COD and TN were below ~400 and ~15 mg L−1, respectively. The polished effluent produced by SSF operated at 187 cm d−1 HLR, with characteristics <5 mg L−1 COD, <2 NTU turbidity, <1 mg L−1 TN, ~0.5 mg L−1 TP, ~7.8 pH, and <100 MPN per 100 ml fecal coliforms, qualifies the standards for non-potable reuse applications. Along with reclaimed water reuse, green walls provide environmental benefits by fixing CO2 in plant biomass. Overall, the low-cost system offers efficient greywater management in an eco-friendly way with minimized resource consumption and areal footprint.

The city within the global: A framework for the simultaneous estimation of city emissions metrics

In line with national targets, sub-national governments – including cities – are introducing targets to reduce the emissions associated with economic activity within or associated with a particular geography. Cities are important drivers of not only emissions but also economic activity and are embedded into complex economic systems which reach beyond their boundaries, which can raise major issues in identifying whether a city is assisting in promoting sustainability across a wider spatial level. This paper sets out a methodology to downscale global Input Output tables to city-level and use these to calculate production- (territorial) and consumption-based carbon accounts at the city level simultaneously. Illustrating this for the case of Glasgow, Scotland, we show that the city's territorial emissions are significantly lower than its consumption-based carbon footprint (considering both the Areal and Personal Carbon Footprint), but that both metrics are sensitive to assumptions about the emissions intensity of individual sectors. Our results highlight the importance of data quality and accuracy, and the benefits of local knowledge, rather than the unquestioned use of national metrics.

Mechanism of lactose assimilation in microalgae for the bioremediation of dairy processing side-streams and co-production of valuable food products

Abstract This study investigated the mechanism of lactose assimilation in Nannochloropsis oceanica for dairy-wastewater bioremediation and co-production of valuable feed/food ingredients in a circular dairy system (β-galactosidase and omega-3 polyunsaturated fatty acids). Mixotrophic cultivation was found to be mandatory for lactose assimilation in N. oceanica, with biomass production in mixotrophic cultures reaching a fourfold increase over that under heterotrophic conditions. Under mixotrophic conditions, the microalgae were able to produce β-galactosidase enzyme to hydrolyse lactose, with maximum extracellular secretion recorded on day 8 of growth cycle at 41.47 ± 0.33 U gbiomass−1. No increase in the concentration of glucose or galactose was observed in the medium, confirming the ability of microalgae to indiscriminately absorb the resultant monosaccharides derived from lactose breakdown. Population analysis revealed that microalgae cells were able to maintain dominance in the mixotrophic culture, with bacteria accounting for < 12% of biomass. On the other hand, under heterotrophic conditions, native bacteria took over the culture (occupying over 95% of total biomass). The bacteria, however, were also unable to effectively assimilate lactose, resulting in limited biomass increase and negligible production of extracellular β-galactosidase. Results from the study indicate that N. oceanica can be effectively applied for onsite dairy wastewater treatment under strict mixotrophic conditions. This is commercially disadvantageous as it rules out the possibility of deploying heterotrophic fermentation with low-cost bioreactors and smaller areal footprint.

State spaces for agriculture: A meta-systematic design automation framework.

Agriculture is a designed system with the largest areal footprint of any human activity. In some cases, the designs within agriculture emerged over thousands of years, such as the use of rows for the spatial organization of crops. In other cases, designs were deliberately chosen and implemented over decades, as during the Green Revolution. Currently, much work in the agricultural sciences focuses on evaluating designs that could improve agriculture's sustainability. However, approaches to agricultural system design are diverse and fragmented, relying on individual intuition and discipline-specific methods to meet stakeholders' often semi-incompatible goals. This ad-hoc approach presents the risk that agricultural science will overlook nonobvious designs with large societal benefits. Here, we introduce a state space framework, a common approach from computer science, to address the problem of proposing and evaluating agricultural designs computationally. This approach overcomes limitations of current agricultural system design methods by enabling a general set of computational abstractions to explore and select from a very large agricultural design space, which can then be empirically tested.

Memristive Memory Enhancement by Device Miniaturization for Neuromorphic Computing

AbstractThe areal footprint of memristors is a key consideration in material‐based neuromorphic computing and large‐scale architecture integration. Electronic transport in the most widely investigated memristive devices is mediated by filaments, posing a challenge to their scalability in architecture implementation. Here, a compelling alternative memristive device is presented and it is demonstrated that areal downscaling leads to enhancement in the memristive memory window, while maintaining analog behavior, contrary to expectations. The device designs directly integrated on semiconducting Nb‐doped SrTiO3 (Nb:STO) allows leveraging electric field effects at edges, increasing the dynamic range in smaller devices. The findings are substantiated by studying the microscopic nature of switching using scanning transmission electron microscopy, in different resistive states, revealing an interfacial layer whose physical extent is influenced by applied electric fields. The ability of Nb:STO memristors to satisfy hardware and software requirements with downscaling, while significantly enhancing memristive functionalities, make them strong contenders for non‐von‐Neumann computing, beyond complementary metal–oxide–semiconductor.

Stretchable Liquid Metal Films with High Surface Area and Strain Invariant Resistance

AbstractThis paper reports soft and stretchable films of liquid metal particles (LMPs) that offer high surface area and high conductivity. Liquid metals (LM) based on gallium are compelling conductors for soft and stretchable devices, yet it is difficult to make electrodes of LM with high surface area due to the tendency of liquids to minimize their surface area. To form films of percolated particles with high surface area, LMPs are first created by sonicating LM in isopropanol with trace amounts of hydrochloric acid and 1,6‐hexane dithiol to decrease the amount of surface oxide on the LMPs. A film of these particles placed on a tacky substrate is initially insulating but percolate into conductive paths by straining the substrate. The resulting electrode has high conductivity (1.64 × 105 S m−1) and high surface area (1257% greater than a bulk LM film with the same areal footprint). Interestingly, these electrodes have nearly strain‐invariant resistance (R/R0 = 1.23 at 600% strain). The ability to create high surface area electrodes in such a simple manner may find use in sensing, capacitive storage, batteries, and energy‐harvesting devices.

Structural and functional spatial dynamics of microbial communities in aerated and non-aerated horizontal flow treatment wetlands

A multiphasic study using structural and functional analyses was employed to investigate the spatial dynamics of the microbial community within five horizontal subsurface flow treatment wetlands (TWs) of differing designs in Germany. The TWs differed in terms of the depth of media saturation, presence of plants (Phragmites australis), and aeration. In addition to influent and effluent water samples, internal samples were taken at different locations (12.5 %, 25 %, 50 %, and 75 % of the fractional distance along the flow path) within each system. 16S rRNA sequencing was used for the investigation of microbial community structure and was compared to microbial community function and enumeration data. The microbial community structure in the unaerated systems was similar, but different from the aerated TW profiles. Spatial positioning along the flow path explained the majority of microbial community dynamics/differences within this study. This was mainly attributed to the availability of nutrients closer to the inlet which also regulated the fixed biofilm/biomass densities. As the amount of fixed biofilm decreased from the inlet to the TW outlets, structural diversity increased, suggesting different microbial communities were present to handle the more easily utilized/degraded pollutants near the inlet vs. the more difficult to degrade and recalcitrant pollutants closer to the outlets. This study also confirmed that effluent water samples do not accurately describe the microbial communities responsible for water treatment inside a TW, highlighting the importance of using internal samples for investigating microbial communities in TWs. The results of this study reinforce an existing knowledge gap regarding the potential for TW design modifications which incorporate microbial community spatial dynamics (heterogeneity). It is suggested that utilizing step-feeding could allow for improved water treatment within the same areal footprint, and modifications enhancing co-metabolic processes could assist in improving the treatment of more difficult to degrade or recalcitrant compounds such as micropollutants.

Optimisation and performance prediction of photosynthetic biogas upgrading using a bubble column

Optimising biogas upgrading with microalgae in a combined bubble column-photobioreactor setup is at a low technology readiness. Most of the prior studies investigated the optimisation of the overall system and generated variable results. The approach employed here is to optimise the individual components of the system to achieve definitive conclusions and improve the integrated process performance. In this work, performance prediction and optimisation of the least optimised component of photosynthetic biogas upgrading, the bubble column, was conducted. The influence of liquid inlet pH and alkalinity, superficial gas velocity and liquid to gas flow rate (L/G) ratio were studied using the response surface methodology (RSM). Bubble column operations were sufficiently predicted via quadratic models for liquid inlet pH between 9.4 and 10.2; liquid inlet alkalinity between 1.3 g-inorganic carbon (IC)/L and 2.1 gIC/L; superficial gas velocities between 0.3 cm/s and 0.6 cm/s; and L/G ratios between 0.3 and 0.8. To ensure optimal operations while producing grid quality biomethane (CO2 < 2.5% and O2 < 1% by volume), the following tighter conditions were shown to be necessary: liquid inlet pH between 10 and 10.2; alkalinity between 1.7 gIC/L and 2.1 gIC/L; superficial gas velocities between 0.5 cm/s and 0.6 cm/s; and L/G ratio between 0.6 and 0.7. Based on these results, a perspective on the industrial-scale operation of the integrated bubble column photobioreactor system was developed by estimating the required number of bubble columns and the areal footprint of photobioreactors to upgrade 478 Nm3/hr of biogas (equivalent to a 1 MWe biogas plant).

Widespread exposure of marine parks, whales, and whale sharks to shipping

Context Shipping impacts are a major environmental concern that can affect the behaviour and health of marine mammals and fishes. The potential impacts of shipping within marine parks is rarely considered during the planning process. Aims We assessed the areal disturbance footprint of shipping around Australia, its overlap with marine parks, and known locations of megafauna, so as to identify areas of concern that warrant further investigation. Methods Automatic Identification System (AIS) shipping data from 2018 to 2021 were interpreted through a kernel-density distribution and compared with satellite data from ∼200 individuals of megafauna amalgamated from 2003 to 2018, and the locations of marine parks. Key results Over 18% of marine parks had shipping exposure in excess of 365 vessels per year. Around all of Australia, 39% of satellite-tag reports from whale shark and 36.7% of pygmy blue and humpback whale satellite-tag reports were in moderate shipping-exposure areas (&gt;90 ships per year). Shipping exposure significantly increased from 2018 despite the pandemic, including within marine parks. Conclusions These results highlight the wide-scale footprint of commercial shipping on marine ecosystems that may be increasing in intensity over time. Implications Consideration should be made for assessing and potentially limiting shipping impacts along migration routes and within marine parks.

Algal wastewater treatment integrated with carbon adsorption and ozonation for water reclamation: Multi-criteria comparison with conventional pathways

Our previous reports have documented a mixotrophic algal wastewater treatment (A-WWT) system integrated with downstream technologies for recovering net energy and fertilizers from domestic wastewater. In the current study, we explore the potential for reclaiming reuse-quality water via the A-WWT system by treating its effluent further by granular activated carbon (GAC) adsorption or/and ozonation (O3). Our study also includes a comparison of water reclamation capability of a pilot-scale A-WWT system against that of a full-scale conventional activated sludge (CAS) system, both fed with the same primary effluent and followed by GAC and O3. In this preliminary evaluation, aggregate chemical water quality data collected from the following 8 treatment trains are compared: T1) CAS + GAC; T2) CAS + O3; T3) CAS + GAC + O3; T4) CAS + O3 + GAC; T5) A-WWT + GAC; T6) A-WWT + O3; T7) A-WWT + GAC + O3; and T8) A-WWT + O3 + GAC. Based on aggregate water quality measures, ozonation followed by GAC adsorption achieved the lowest concentrations of organics (dissolved organic carbon, chemical oxygen demand, and UV absorbance) and nutrients (total nitrogen and total phosphorus), irrespective of the treatment provided by the CAS and A-WWT systems. Despite the higher footprint requirement, all four algal-based treatment trains (T5 to T8) ranked better than the CAS-based trains (T1 to T4) when compared on the basis of energy demand and energy recoverability. Following these findings, a multi-criteria evaluation of the 8 treatment trains was performed considering 16 criteria spanning energy demand, energy recoverability, disinfection capability, emissions, areal footprint, and complexity. The multi-criteria evaluation ranked the A-WWT system integrated with ozonation and GAC adsorption (T8) highest among the eight treatment trains considered here. This preliminary evaluation adds further credence to the A-WWT system and warrants a detailed Water quality-based evaluation of its effluent and follow-up treatment to reclaim reuse-quality water.

Sterically Stabilized Multilayer Graphene Nanoshells for Inkjet Printed Resistors

In the field of printed electronics, there is a pressing need for printable resistors, particularly ones where the resistance can be varied without changing the size of the resistor. This work presents ink synthesis and printing results for variable resistance, inkjet-printed patterns of a novel and sustainable carbon nanomaterial—multilayer graphene nanoshells. Dispersed multilayer graphene nanospheres are sterically stabilized by a surfactant (Triton X100), and no post-process is required to achieve the resistive functionality. A surface tension-based adsorption analysis technique is used to determine the optimal surfactant dosage, and a geometric model explains the conformation of adsorbed surfactant molecules. The energetic interparticle potentials between approaching particles are modeled to assess and compare the stability of sterically and electrostatically stabilized multilayer graphene nanoshells. The multilayer graphene nanoshell inks presented here show a promising new pathway toward sustainable and practical printed resistors that achieve variable resistances within a constant areal footprint without post-processing.

Making powder aerosol deposition accessible for small amounts: A novel and modular approach to produce dense ceramic films

AbstractPowder aerosol deposition is a promising technique to deposit dense ceramic films directly at room temperature. While previous developments pointed towards larger and more complex deposition devices, this work follows a different approach and proposes a simplified and miniaturized coating device (denoted as Micro‐PAD, µPAD). The aim is twofold: creating a smaller and flexible device consisting of an aerosol generation unit and a deposition chamber with a combined low areal footprint of 30 cm by 20 cm (that, e.g., easily fits in a glove box) as well as lowering the hurdle for other researchers to use the powder aerosol deposition. Therefore, we introduce a device mainly based on commercially available components/connectors as well as manual operated valves/flow meters. A key point is the elimination of moving components by just using a spot deposition that was enabled by using a circular de‐Laval‐type nozzle.The operational capability of µPAD is proven for the deposition of alumina films and compared to conventional PAD in terms of mechanical, crystalline, and optical film properties. Thick films with a bell‐shape‐like profile are deposited by µPAD, featuring a plateau in the center of the film with a diameter of 5 mm and a FWHM (full width at half maximum) diameter of about 10 mm. Alumina films produced by µPAD do not only match the properties of corresponding PAD films, but oftentimes outperform them. Here, µPAD films exhibit increased hardness and optical transmittance values, surpassing reference values of the conventional sprayed counterparts by at least 10%. Also, film integrity and adhesion to the substrate are slightly higher in case of µPAD. Reasons for the improved film properties are found by X‐ray diffraction, with a significantly higher fracturing of impacting particles during µPAD combined with improved film consolidation as observed by SEM. Furthermore, µPAD featured doubled to tripled the deposition rates and, markedly almost doubled the deposition efficiency.

Design and optimization of well-ordered microporous copper structure for high heat flux cooling applications

Capillary-driven boiling enables promising passive cooling structures and devices, and the use of highly-ordered microporous media promises efficient heat transfer at low superheat. Here we leverage the structural regularity of copper inverse opals (IO) to develop capillary structures with unprecedented fidelity, enabling a detailed study of the impacts of architectural design variables on boiling critical heat flux (CHF) as well as liquid and vapor transport properties. Fabrication of IO using a template-assisted electrodeposition method allows fine control of the microstructure and bulk geometry, producing structures with varying pore diameters (3.2 - 10.2 µm), heated area lateral dimensions (0.2 - 5.5 mm2), and structural thicknesses (10 - 40 µm). We demonstrate capillary fed copper IO structures capable of dissipating over 1 kW cm−2 in boiling with water as the working fluid. We identify two distinct transport regimes, namely, a capillary-limited regime where CHF increases as IO lateral dimension decreases, and a boiling-limited regime where further decrease in IO areal footprint does not significantly improve CHF. This yields an optimal length scale of porous media area and structural thickness that maximize the CHF of capillary-driven boiling due to hydrodynamic competition between capillary wicking of liquid replenishment and the viscous forces on vapor. This work makes progress both on the fundamentals of two-phase flow physics in porous media while providing fabrication and optimization details for practical capillary structures that will support the device design for applications ranging from energy conversion to electronics cooling.

Year-long performance assessment of an on-site pilot scale (100 L) photobioreactor on nutrient recovery and pathogen removal from urban wastewater using native microalgal consortium

The study was carried out as part of the Indo-Dutch collaboration project to ascertain the efficacy of the algal system for the treatment of urban wastewater. The study was done at Barapullah drain in New Delhi, using a pilot-scale (100 L) bubble column microalgae photobioreactor (PBR). The year-long study was intended to find the impact of seasonality coupled with varying hydraulic retention times (HRTs) on the PBR performance in terms of nutrient recovery, microbial contamination reduction, biomass productivity, and theoretical biomethane potential.To begin with, native microalgae consortium was enriched and cultivated in PBR directly on the Barapullah drain wastewater at the drain site. After achieving maximum recovery of nutrients in the batch mode, the PBR was operated in continuous mode at HRTs ranging from 1 to 3 days during summer, while 2–3 days during monsoon, autumn, and winter. The maximum and minimum biomass productivity obtained was 260 mg L−1 d−1 at the HRT of 1 day during summer and 77 mg L−1 d−1 at the HRT of 2 days during winter. At peak overall PBR performance at HRT of 2 days, the nutrient removal rate was 37.2 ± 6.2 mgCOD L−1 d−1, 39.3 ± 6 mgN L−1 d−1, and 4.7 ± 0.7 mgP L−1 d−1. Nearly 5 log removal of total and faecal coliform was obtained during summer and monsoon. However, the overall performance reduced during winters. The natural sedimentation of grown biomass achieved 81–95% of biomass settling at different HRTs. The areal footprint of the PBR is 1.42 m2 KLD−1, which was significantly lower than other pilot-scale microalgal wastewater treatment technologies. The obtained results at this lower HRT (2 days) even under non-optimized process parameters represent vital improvements over earlier reports with significantly higher HRTs. Results thus highlight the feasibility and scalability of the technology.

Thermal impacts of basaltic lava flows to buried infrastructure: workflow to determine the hazard

Lava flows can cause substantial physical damage to elements of the built environment. Often, lava flow impacts are assumed to be binary, i.e. cause complete damage if the lava flow and asset are in contact, or no damage if there is no direct contact. According to this paradigm, buried infrastructure would not be expected to sustain damage if a lava flow traverses the ground above. However, infrastructure managers (“stakeholders”) have expressed concern about potential lava flow damage to such assets. We present a workflow to assess the thermal hazard posed by lava flows to buried infrastructure. This workflow can be applied in a pre-defined scenario. The first step in this workflow is to select an appropriate lava flow model(s) and simulate the lava flow’s dimensions, or to measure an in situ lava flow’s dimensions. Next, stakeholders and the modellers collaborate to identify where the lava flow traverses buried network(s) of interest as well as the thermal operating conditions of these networks. Alternatively, instead of direct collaboration, this step could be done by overlaying the flow’s areal footprint on local infrastructure maps, and finding standard and maximum thermal operating conditions in the literature. After, the temperature of the lava flow at the intersection point(s) is modelled or extracted from the results of the first step. Fourth, the lava flow-substrate heat transfer is calculated. Finally, the heat transfer results are simplified based on the pre-identified thermal operating conditions. We illustrate how this workflow can be applied in an Auckland Volcanic Field (New Zealand) case study. Our case study demonstrates considerable heat is transferred from the hypothetical lava flow into the ground and that maximum operating temperatures for electric cables are exceeded within 1 week of the lava flow front’s arrival at the location of interest. An exceedance of maximum operating temperatures suggests that lava flows could cause thermal damage to buried infrastructure, although mitigation measures may be possible.

Reduced frequency and size of late-twenty-first-century snowstorms over North America

Understanding how snowstorms may change in the future is critical for estimating impacts on water resources and the Earth and socioeconomic systems that depend on them. Here we use snowstorms as a marker to assess the mesoscale fingerprint of climate change, providing a description of potential changes in winter weather event occurrence, character and variability in central and eastern North America under a high anthropogenic emissions pathway. Snowstorms are segmented and tracked using high-resolution, snow water equivalent output from dynamically downscaled simulations which, unlike global climate models, can resolve important mesoscale features such as banded snow. Significant decreases are found in the frequency and size of snowstorms in a pseudo-global warming simulation, including those events that produce the most extreme snowfall accumulations. Early and late boreal winter months show particularly robust proportional decreases in snowstorms and snow water equivalent accumulations. Predicting the impact of climate change on snowstorms is key for future water resource estimates. North American snowstorms are tracked in high-resolution warming simulations and exhibit robust decreases in storm count, snow water equivalent and areal footprint, particularly in shoulder seasons.

Greenhouse gas emission from the cold soils of Eurasia in natural settings and under human impact: Controls on spatial variability

The annual balance of biogenic greenhouse gases (GHGs; carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O)) in the atmosphere is well studied. However, the contributions of specific natural land sources and sinks remain unclear, and the effect of different human land use activities is understudied. A simple way to do this is to evaluate GHG soil emissions. For CO2, it usually comprises 60–75% of gross respiration in natural terrestrial ecosystems, while local human impact can increase this share to almost 100%. Permafrost-affected soils occupying 15% of the land surface mostly in the Eurasia and North America contain approximately 25% of the total terrestrial carbon. The biogenic GHG soil emissions from permafrost are 5% of the global total, which makes these soils extremely important in the warming world. Measurements of CO2, methane, and nitrous oxide, from eighteen locations in the Arctic and Siberian permafrost, across tundra, steppe, and north taiga domains of Russia and Svalbard, were conducted from August to September during 2014–2017 in 37 biotopes representing natural conditions and different types of human impact. We demonstrate that land use caused significant alteration in soil emission and net fluxes of GHGs compared to natural rates, regardless of the type and duration of human impact and the ecosystem type. The cumulative effect of land use factors very likely supported an additional net-source of CO2 into the atmosphere because of residual microbial respiration in soil after the destruction of vegetation and primary production under anthropogenic influence. Local drainage effects were more significant for methane emission. In general, land use factors enforced soil emission and net-sources of CO2 and N2O and weakened methane sources. Despite the extended heat supply, high aridity caused significantly lower emissions of methane and nitrous oxide in ultra-continental Siberian permafrost soils. However, these climatic features support higher soil CO2 emission rates, in spite of dryness, owing to the larger phytomass storage, presence of tree canopies, thicker active layer, and greater expressed soil fissuring. Furthermore, the “Birch effect” was much less expressed in ultra-continental permafrost soils than in permafrost-free European soils. Models and field observations demonstrated that the areal human footprint on soil CO2 fluxes could be comparable to the effect of climate change within a similar timeframe. Settlements and industrial areas in the tundra function as year-round net CO2 sources, mostly owing to the lack of vegetation cover. As a result, they could compensate for the natural C-balance on significantly larger areas of surrounding tundra.