BAWLD-CH<sub>4</sub>: A Comprehensive Dataset of Methane Fluxes from Boreal and Arctic Ecosystems

Abstract. Methane (CH4) emissions from the Boreal and Arctic region are globally significant and highly sensitive to climate change. There is currently a wide range in estimates of high-latitude annual CH4 fluxes, where estimates based on land cover inventories and empirical CH4 flux data or process models (bottom-up approaches) generally are greater than atmospheric inversions (top-down approaches). A limitation of bottom-up approaches has been the lack of harmonization between inventories of site-level CH4 flux data and the land cover classes present in high-latitude spatial datasets. Here we present a comprehensive dataset of small-scale, surface CH4 flux data from 540 terrestrial sites (wetland and non-wetland) and 1247 aquatic sites (lakes and ponds), compiled from 189 studies. The Boreal-Arctic Wetland and Lake Methane Dataset (BAWLD-CH4) was constructed in parallel with a compatible land cover dataset, sharing the same land cover classes to enable refined bottom-up assessments. BAWLD-CH4 includes information on site-level CH4 fluxes, but also on study design (measurement method, timing, and frequency) and site characteristics (vegetation, climate, hydrology, soil, and sediment types, permafrost conditions, lake size and depth, and our determination of land cover class). The different land cover classes had distinct CH4 fluxes, resulting from definitions that were either based on or co-varied with key environmental controls. Fluxes of CH4 from terrestrial ecosystems were primarily influenced by water table position, soil temperature, and vegetation composition, while CH4 fluxes from aquatic ecosystems were primarily influenced by water temperature, lake size, and lake genesis. Models could explain more of the between-site variability in CH4 fluxes for terrestrial than aquatic ecosystems, likely due to both less precise assessments of lake CH4 fluxes and fewer consistently reported lake site characteristics. Analysis of BAWLD-CH4 identified both land cover classes and regions within the Boreal and Arctic domain where future studies should be focused, alongside methodological approaches. Overall, BAWLD-CH4 provides a comprehensive dataset of CH4 emissions from high-latitude ecosystems that are useful for identifying research opportunities, for comparison against new field data, and model parameterization or validation. BAWLD-CH4 can be downloaded from https://doi.org/10.18739/A27H1DN5S.

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Methane paradox in tropical lakes? Sedimentary fluxes rather than water column production in oxic waters sustain methanotrophy and emissions to the atmosphere

10.5194/bg-2020-142 ◽

2020 ◽

Author(s):

Cédric Morana ◽

Steven Bouillon ◽

Vimac Nolla-Ardèvol ◽

Fleur A. E. Roland ◽

William Okello ◽

...

Keyword(s):

Surface Waters ◽

Tropical Lakes ◽

Large Lakes ◽

Ch4 Flux ◽

Ch4 Emissions ◽

Isotope Tracer ◽

Ch4 Production ◽

Elevated Water ◽

Lake Size ◽

Sunlight Intensity

Abstract. Despite growing evidence that methane (CH4) formation could also occur in well-oxygenated surface freshwaters, its significance at the ecosystem scale is uncertain. Empirical models based on data gathered at high latitude predict that the contribution of oxic CH4 increases with lake size and should represent the majority of CH4 emissions in large lakes. However, such predictive models could not directly apply to tropical lakes which differ from their temperate counterparts in some fundamental characteristics, such as year-round elevated water temperature. We conducted stable isotope tracer experiments which revealed that oxic CH4 production is closely related to phytoplankton metabolism, and is a common feature in five contrasting African lakes. Nevertheless, methanotrophic activity in surface waters and CH4 emissions to the atmosphere were predominantly fuelled by CH4 generated in sediments and physically transported to the surface. Indeed, measured CH4 bubble dissolution flux and diffusive benthic CH4 flux were several orders of magnitude higher than CH4 production in surface waters. Microbial CH4 consumption dramatically decreased with increasing sunlight intensity, suggesting that the freshwater CH4 paradox might be also partly explained by photo-inhibition of CH4 oxidizers in the illuminated zone. Sunlight appeared as an overlooked but important factor determining the CH4 dynamics in surface waters, directly affecting its production by photoautotrophs and consumption by methanotrophs.

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Methane paradox in tropical lakes? Sedimentary fluxes rather than pelagic production in oxic conditions sustain methanotrophy and emissions to the atmosphere

Biogeosciences ◽

10.5194/bg-17-5209-2020 ◽

2020 ◽

Vol 17 (20) ◽

pp. 5209-5221

Author(s):

Cédric Morana ◽

Steven Bouillon ◽

Vimac Nolla-Ardèvol ◽

Fleur A. E. Roland ◽

William Okello ◽

...

Keyword(s):

Surface Waters ◽

Tropical Lakes ◽

Large Lakes ◽

Ch4 Flux ◽

Ch4 Emissions ◽

Isotope Tracer ◽

Ch4 Production ◽

Elevated Water ◽

Lake Size ◽

Sunlight Intensity

Abstract. Despite growing evidence that methane (CH4) formation could also occur in well-oxygenated surface fresh waters, its significance at the ecosystem scale is uncertain. Empirical models based on data gathered at high latitude predict that the contribution of oxic CH4 increases with lake size and should represent the majority of CH4 emissions in large lakes. However, such predictive models could not directly apply to tropical lakes, which differ from their temperate counterparts in some fundamental characteristics, such as year-round elevated water temperature. We conducted stable-isotope tracer experiments, which revealed that oxic CH4 production is closely related to phytoplankton metabolism and is a common feature in five contrasting African lakes. Nevertheless, methanotrophic activity in surface waters and CH4 emissions to the atmosphere were predominantly fuelled by CH4 generated in sediments and physically transported to the surface. Indeed, CH4 bubble dissolution flux and diffusive benthic CH4 flux were several orders of magnitude higher than CH4 production in surface waters. Microbial CH4 consumption dramatically decreased with increasing sunlight intensity, suggesting that the freshwater “CH4 paradox” might be also partly explained by photo-inhibition of CH4 oxidizers in the illuminated zone. Sunlight appeared as an overlooked but important factor determining the CH4 dynamics in surface waters, directly affecting its production by photoautotrophs and consumption by methanotrophs.

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Dispersal and Land Cover Contribute to Pseudorabies Virus Exposure in Invasive Wild Pigs

EcoHealth ◽

10.1007/s10393-020-01508-6 ◽

2021 ◽

Author(s):

Felipe A. Hernández ◽

Amanda N. Carr ◽

Michael P. Milleson ◽

Hunter R. Merrill ◽

Michael L. Avery ◽

...

Keyword(s):

Land Cover ◽

Disease Transmission ◽

Wildlife Conservation ◽

Pseudorabies Virus ◽

Spatial Scales ◽

Information Criterion ◽

Small Scale ◽

Wild Pigs ◽

Bacterial Agent ◽

Open Canopy

AbstractWe investigated the landscape epidemiology of a globally distributed mammal, the wild pig (Sus scrofa), in Florida (U.S.), where it is considered an invasive species and reservoir to pathogens that impact the health of people, domestic animals, and wildlife. Specifically, we tested the hypothesis that two commonly cited factors in disease transmission, connectivity among populations and abundant resources, would increase the likelihood of exposure to both pseudorabies virus (PrV) and Brucella spp. (bacterial agent of brucellosis) in wild pigs across the Kissimmee Valley of Florida. Using DNA from 348 wild pigs and sera from 320 individuals at 24 sites, we employed population genetic techniques to infer individual dispersal, and an Akaike information criterion framework to compare candidate logistic regression models that incorporated both dispersal and land cover composition. Our findings suggested that recent dispersal conferred higher odds of exposure to PrV, but not Brucella spp., among wild pigs throughout the Kissimmee Valley region. Odds of exposure also increased in association with agriculture and open canopy pine, prairie, and scrub habitats, likely because of highly localized resources within those land cover types. Because the effect of open canopy on PrV exposure reversed when agricultural cover was available, we suggest that small-scale resource distribution may be more important than overall resource abundance. Our results underscore the importance of studying and managing disease dynamics through multiple processes and spatial scales, particularly for non-native pathogens that threaten wildlife conservation, economy, and public health.

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Impact of recent artisanal small-scale gold mining in Senegal: Mercury and methylmercury contamination of terrestrial and aquatic ecosystems

The Science of The Total Environment ◽

10.1016/j.scitotenv.2019.03.108 ◽

2019 ◽

Vol 669 ◽

pp. 185-193 ◽

Cited By ~ 6

Author(s):

Birane Niane ◽

Stéphane Guédron ◽

Frédéric Feder ◽

Samuel Legros ◽

Papa Malick Ngom ◽

...

Keyword(s):

Aquatic Ecosystems ◽

Gold Mining ◽

Small Scale

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Small scale irregularities associated with a high latitude electron density gradient: scintillation and EISCAT observations

Journal of Atmospheric and Terrestrial Physics ◽

10.1016/0021-9169(88)90114-6 ◽

1988 ◽

Vol 50 (6) ◽

pp. 557-563 ◽

Cited By ~ 13

Author(s):

L. Kersley ◽

S.E. Pryse ◽

N.S. Wheadon

Keyword(s):

Density Gradient ◽

Electron Density ◽

High Latitude ◽

Small Scale ◽

Electron Density Gradient

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Small-scale characteristics of extremely high latitude aurora

Annales Geophysicae ◽

10.5194/angeo-27-3335-2009 ◽

2009 ◽

Vol 27 (9) ◽

pp. 3335-3347 ◽

Cited By ~ 8

Author(s):

J. A. Cumnock ◽

L. G. Blomberg ◽

A. Kullen ◽

T. Karlsson ◽

Keyword(s):

High Latitude ◽

Large Scale ◽

Small Scale ◽

Strong Correlations ◽

Polar Cap ◽

Plasma Flows ◽

Ionospheric Convection ◽

Local Closure ◽

Scale Characteristics

Abstract. We examine 14 cases of an interesting type of extremely high latitude aurora as identified in the precipitating particles measured by the DMSP F13 satellite. In particular we investigate structures within large-scale arcs for which the particle signatures are made up of a group of multiple distinct thin arcs. These cases are chosen without regard to IMF orientation and are part of a group of 87 events where DMSP F13 SSJ/4 measures emissions which occur near the noon-midnight meridian and are spatially separated from both the dawnside and duskside auroral ovals by wide regions with precipitating particles typical of the polar cap. For 73 of these events the high-latitude aurora consists of a continuous region of precipitating particles. We focus on the remaining 14 of these events where the particle signatures show multiple distinct thin arcs. These events occur during northward or weakly southward IMF conditions and follow a change in IMF By. Correlations are seen between the field-aligned currents and plasma flows associated with the arcs, implying local closure of the FACs. Strong correlations are seen only in the sunlit hemisphere. The convection associated with the multiple thin arcs is localized and has little influence on the large-scale convection. This also implies that the sunward flow along the arcs is unrelated to the overall ionospheric convection.

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Evaluation of anthropogenic CH<sub>4</sub> emissions over China using bottom-up inventories

10.5194/essd-2020-210 ◽

2020 ◽

Author(s):

Xiaohui Lin ◽

Wen Zhang ◽

Monica Crippa ◽

Shushi Peng ◽

Pengfei Han ◽

...

Keyword(s):

Waste Treatment ◽

Comprehensive Evaluation ◽

Energy Sector ◽

Atmospheric Methane ◽

Activity Data ◽

Bottom Up ◽

Average Growth ◽

Ch4 Emissions ◽

Source Contributions ◽

Change Mitigation

Abstract. Atmospheric methane (CH4) is a potent greenhouse gas that is strongly influenced by several human activities. China, as one of the major agricultural and energy production countries, e.g., rice cultivation, ruminant feeding and coal production, contributes considerably to the global anthropogenic CH4 emissions. Understanding the characteristics of China's CH4 emissions is necessary for interpreting source contributions and for further climate change mitigation. However, the scarcity of data from some sources or years and spatially explicit information pose great challenges to completing an analysis of CH4 emissions. This study provides a comprehensive evaluation of China's anthropogenic CH4 emissions by synthesizing most of the currently available data (12 inventories). The results show that anthropogenic CH4 emissions differ widely among inventories, with values ranging from 41.9–57.5 Tg CH4 yr−1 in 2010. The discrepancy primarily resulted from the energy sector (27.3–60.0 % of total emissions), followed by the agricultural (26.9–50.8 %), and waste treatment (8.1–21.2 %) sectors. Temporally, emissions among inventories stabilized in the 1990s, but increased significantly thereafter, with annual average growth rates (AAGRs) of 1.8–3.9 % during 2000–2010, but slower AAGRs of 0.5–2.2 % during 2011–2015. Spatially, the growth of CH4 emissions could be attributed mostly to an increase in emissions from the energy sector (mainly from coal mining) in the northern and central inland regions, followed by waste treatment in the southern and eastern regions. The availability of detailed activity data for sectors or subsectors and the use of region-specific emission factors play important roles in understanding source contributions, and reducing the uncertainty of bottom-up inventories.

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Using OpenStreetMap to Create Land Use and Land Cover Maps

Geospatial Intelligence ◽

10.4018/978-1-5225-8054-6.ch047 ◽

2019 ◽

pp. 1100-1123

Author(s):

Cidália Costa Fonte ◽

Joaquim António Patriarca ◽

Marco Minghini ◽

Vyron Antoniou ◽

Linda See ◽

...

Keyword(s):

Land Use ◽

Land Cover ◽

Level Of Detail ◽

Bottom Up ◽

Corine Land Cover ◽

Online System ◽

Urban Regions ◽

The World ◽

Future Work ◽

Land Cover Maps

OpenStreetMap (OSM) is a bottom up community-driven initiative to create a global map of the world. Yet the application of OSM to land use and land cover (LULC) mapping is still largely unexploited due to problems with inconsistencies in the data and harmonization of LULC nomenclatures with OSM. This chapter outlines an automated methodology for creating LULC maps using the nomenclature of two European LULC products: the Urban Atlas (UA) and CORINE Land Cover (CLC). The method is applied to two regions in London and Paris. The results show that LULC maps with a level of detail similar to UA can be obtained for the urban regions, but that OSM has limitations for conversion into the more detailed non-urban classes of the CLC nomenclature. Future work will concentrate on developing additional rules to improve the accuracy of the transformation and building an online system for processing the data.

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