Pub Date : 2022-01-01DOI: 10.1525/elementa.2021.000103
B. Light, M. Smith, D. Perovich, M. Webster, M. Holland, F. Linhardt, Ian A. Raphael, D. Clemens-Sewall, Amy R. Macfarlane, P. Anhaus, D. Bailey
The magnitude, spectral composition, and variability of the Arctic sea ice surface albedo are key to understanding and numerically simulating Earth’s shortwave energy budget. Spectral and broadband albedos of Arctic sea ice were spatially and temporally sampled by on-ice observers along individual survey lines throughout the sunlit season (April–September, 2020) during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition. The seasonal evolution of albedo for the MOSAiC year was constructed from spatially averaged broadband albedo values for each line. Specific locations were identified as representative of individual ice surface types, including accumulated dry snow, melting snow, bare and melting ice, melting and refreezing ponded ice, and sediment-laden ice. The area-averaged seasonal progression of total albedo recorded during MOSAiC showed remarkable similarity to that recorded 22 years prior on multiyear sea ice during the Surface Heat Budget of the Arctic Ocean (SHEBA) expedition. In accord with these and other previous field efforts, the spectral albedo of relatively thick, snow-free, melting sea ice shows invariance across location, decade, and ice type. In particular, the albedo of snow-free, melting seasonal ice was indistinguishable from that of snow-free, melting second-year ice, suggesting that the highly scattering surface layer that forms on sea ice during the summer is robust and stabilizing. In contrast, the albedo of ponded ice was observed to be highly variable at visible wavelengths. Notable temporal changes in albedo were documented during melt and freeze onset, formation and deepening of melt ponds, and during melt evolution of sediment-laden ice. While model simulations show considerable agreement with the observed seasonal albedo progression, disparities suggest the need to improve how the albedo of both ponded ice and thin, melting ice are simulated.
{"title":"Arctic sea ice albedo: Spectral composition, spatial heterogeneity, and temporal evolution observed during the MOSAiC drift","authors":"B. Light, M. Smith, D. Perovich, M. Webster, M. Holland, F. Linhardt, Ian A. Raphael, D. Clemens-Sewall, Amy R. Macfarlane, P. Anhaus, D. Bailey","doi":"10.1525/elementa.2021.000103","DOIUrl":"https://doi.org/10.1525/elementa.2021.000103","url":null,"abstract":"The magnitude, spectral composition, and variability of the Arctic sea ice surface albedo are key to understanding and numerically simulating Earth’s shortwave energy budget. Spectral and broadband albedos of Arctic sea ice were spatially and temporally sampled by on-ice observers along individual survey lines throughout the sunlit season (April–September, 2020) during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition. The seasonal evolution of albedo for the MOSAiC year was constructed from spatially averaged broadband albedo values for each line. Specific locations were identified as representative of individual ice surface types, including accumulated dry snow, melting snow, bare and melting ice, melting and refreezing ponded ice, and sediment-laden ice. The area-averaged seasonal progression of total albedo recorded during MOSAiC showed remarkable similarity to that recorded 22 years prior on multiyear sea ice during the Surface Heat Budget of the Arctic Ocean (SHEBA) expedition. In accord with these and other previous field efforts, the spectral albedo of relatively thick, snow-free, melting sea ice shows invariance across location, decade, and ice type. In particular, the albedo of snow-free, melting seasonal ice was indistinguishable from that of snow-free, melting second-year ice, suggesting that the highly scattering surface layer that forms on sea ice during the summer is robust and stabilizing. In contrast, the albedo of ponded ice was observed to be highly variable at visible wavelengths. Notable temporal changes in albedo were documented during melt and freeze onset, formation and deepening of melt ponds, and during melt evolution of sediment-laden ice. While model simulations show considerable agreement with the observed seasonal albedo progression, disparities suggest the need to improve how the albedo of both ponded ice and thin, melting ice are simulated.","PeriodicalId":54279,"journal":{"name":"Elementa-Science of the Anthropocene","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66940423","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-01-01DOI: 10.1525/elementa.2021.00087
M. Brzezinski, D. Varela, B. Jenkins, K. Buck, Sile M. Kafrissen, Janice L. Jones
Diatoms are major contributors to marine primary productivity and carbon export due to their rapid growth in high-nutrient environments and their heavy silica ballast. Their contributions are highly modified in high-nutrient low-chlorophyll regions due to the decoupling of upper-ocean silicon and carbon cycling caused by low iron (Fe). The Si cycle and the role of diatoms in the biological carbon pump was examined at Ocean Station Papa (OSP) in the HNLC region of the northeastern subarctic Pacific during the NASA EXport Processes in the Ocean from RemoTe Sensing (EXPORTS) field study. Sampling occurred during the annual minimum in surface silicic acid (Si(OH)4) concentration. Biogenic silica (bSi) concentrations were low, being in the tens of nanomolar range, despite high Si(OH)4 concentrations of about 15 μM. On average, the >5.0-µm particle size fraction dominated Si dynamics, accounting for 65% of bSi stocks and 81% of Si uptake compared to the small fraction (0.6–5.0 μm). Limitation of Si uptake was detected in the small, but not the large, size fraction. Growth rate in small diatoms was limited by Fe, while their Si uptake was restricted by Si(OH)4 concentration, whereas larger diatoms were only growth-limited by Fe. About a third of bSi production was exported out of the upper 100 m. The contribution of diatoms to carbon export (9–13%) was about twice their contribution to primary productivity (3–7%). The combination of low bSi production, low diatom primary productivity and high bSi export efficiency at OSP was more similar to the dynamics in the subtropical gyres than to other high-nutrient low-chlorophyll regions.
{"title":"The upper ocean silicon cycle of the subarctic Pacific during the EXPORTS field campaign","authors":"M. Brzezinski, D. Varela, B. Jenkins, K. Buck, Sile M. Kafrissen, Janice L. Jones","doi":"10.1525/elementa.2021.00087","DOIUrl":"https://doi.org/10.1525/elementa.2021.00087","url":null,"abstract":"Diatoms are major contributors to marine primary productivity and carbon export due to their rapid growth in high-nutrient environments and their heavy silica ballast. Their contributions are highly modified in high-nutrient low-chlorophyll regions due to the decoupling of upper-ocean silicon and carbon cycling caused by low iron (Fe). The Si cycle and the role of diatoms in the biological carbon pump was examined at Ocean Station Papa (OSP) in the HNLC region of the northeastern subarctic Pacific during the NASA EXport Processes in the Ocean from RemoTe Sensing (EXPORTS) field study. Sampling occurred during the annual minimum in surface silicic acid (Si(OH)4) concentration. Biogenic silica (bSi) concentrations were low, being in the tens of nanomolar range, despite high Si(OH)4 concentrations of about 15 μM. On average, the >5.0-µm particle size fraction dominated Si dynamics, accounting for 65% of bSi stocks and 81% of Si uptake compared to the small fraction (0.6–5.0 μm). Limitation of Si uptake was detected in the small, but not the large, size fraction. Growth rate in small diatoms was limited by Fe, while their Si uptake was restricted by Si(OH)4 concentration, whereas larger diatoms were only growth-limited by Fe. About a third of bSi production was exported out of the upper 100 m. The contribution of diatoms to carbon export (9–13%) was about twice their contribution to primary productivity (3–7%). The combination of low bSi production, low diatom primary productivity and high bSi export efficiency at OSP was more similar to the dynamics in the subtropical gyres than to other high-nutrient low-chlorophyll regions.","PeriodicalId":54279,"journal":{"name":"Elementa-Science of the Anthropocene","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66942051","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-01-01DOI: 10.1525/elementa.2021.00095
Younki Cho, K. Smits, Nathaniel L. Steadman, Bridget A. Ulrich, Clay S. Bell, D. Zimmerle
Underground natural gas (NG) pipeline leakage can result in methane (CH4) buildup and migration through the soil. What is not well understood in such scenarios is how the soil conditions affect the gas migration behavior, particularly in regard to the relative contributions of specific soil properties such as soil moisture content. The objective of this study was to investigate the effects of soil properties on CH4 concentration and migration from leaking underground NG pipelines. Site characteristics such as surface cover and spatial dimensions, soil samples, and gas concentration data were collected from over 70 gas leakage sites across the United States using a standardized sampling method. Soil samples were collected from excavation sites that were 1.5′–5′ in depth. The collected soil samples were analyzed in the laboratory to measure the soil texture, permeability, and moisture. Statistical analysis was performed to evaluate the effects of soil properties on CH4 migration distance and concentration. Soil texture was consistent across geographic locations due to standardized pipeline backfill protocols, allowing for the analysis of gas concentration and transport data with respect to soil conditions. Soil moisture content was the dominant influence on the gas concentration and spreading distance. High soil moisture content was associated with reduced lateral diffusion and elevated concentrations near the leak point, whereas dry conditions were associated with reduced concentrations and greater spreading distance. Increasing soil moisture content reduced the lateral diffusion of CH4 into the soil due to water-induced tortuosity, resulting in elevated concentrations close to the leak point. Lateral migration of CH4 was suspected to be by diffusion, starting at 5 m from the leaks, while transport within the immediate vicinity of the leak was controlled by advection. These findings demonstrate a pronounced effect of soil moisture content and permeability on CH4 migration distance and concentration, providing key insight into the effects of soil conditions on NG migration and how to account for such effects in leak detection surveys.
{"title":"A closer look at underground natural gas pipeline leaks across the United States","authors":"Younki Cho, K. Smits, Nathaniel L. Steadman, Bridget A. Ulrich, Clay S. Bell, D. Zimmerle","doi":"10.1525/elementa.2021.00095","DOIUrl":"https://doi.org/10.1525/elementa.2021.00095","url":null,"abstract":"Underground natural gas (NG) pipeline leakage can result in methane (CH4) buildup and migration through the soil. What is not well understood in such scenarios is how the soil conditions affect the gas migration behavior, particularly in regard to the relative contributions of specific soil properties such as soil moisture content. The objective of this study was to investigate the effects of soil properties on CH4 concentration and migration from leaking underground NG pipelines. Site characteristics such as surface cover and spatial dimensions, soil samples, and gas concentration data were collected from over 70 gas leakage sites across the United States using a standardized sampling method. Soil samples were collected from excavation sites that were 1.5′–5′ in depth. The collected soil samples were analyzed in the laboratory to measure the soil texture, permeability, and moisture. Statistical analysis was performed to evaluate the effects of soil properties on CH4 migration distance and concentration. Soil texture was consistent across geographic locations due to standardized pipeline backfill protocols, allowing for the analysis of gas concentration and transport data with respect to soil conditions. Soil moisture content was the dominant influence on the gas concentration and spreading distance. High soil moisture content was associated with reduced lateral diffusion and elevated concentrations near the leak point, whereas dry conditions were associated with reduced concentrations and greater spreading distance. Increasing soil moisture content reduced the lateral diffusion of CH4 into the soil due to water-induced tortuosity, resulting in elevated concentrations close to the leak point. Lateral migration of CH4 was suspected to be by diffusion, starting at 5 m from the leaks, while transport within the immediate vicinity of the leak was controlled by advection. These findings demonstrate a pronounced effect of soil moisture content and permeability on CH4 migration distance and concentration, providing key insight into the effects of soil conditions on NG migration and how to account for such effects in leak detection surveys.","PeriodicalId":54279,"journal":{"name":"Elementa-Science of the Anthropocene","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66942557","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-01-01DOI: 10.1525/elementa.2021.000093
Leena Vilonen, J. Blair, P. Trivedi, L. Zeglin, Melinda D. Smith
The intensification of drought throughout the U.S. Great Plains has the potential to have large impacts on grassland functioning, as has been shown with dramatic losses of plant productivity annually. Yet, we have a poor understanding of how grassland functioning responds after drought ends. This study examined how belowground nutrient cycling responds after drought and whether legacy effects persist postdrought. We assessed the 2-year recovery of nutrient cycling processes following a 4-year experimental drought in a mesic grassland by comparing two different growing season drought treatments—chronic (each rainfall event reduced by 66%) and intense (all rain eliminated until 45% of annual rainfall was achieved)—to the control (ambient precipitation) treatment. At the beginning of the first growing season postdrought, we found that in situ soil CO2 efflux and laboratory-based soil microbial respiration were reduced by 42% and 22%, respectively, in the intense drought treatment compared to the control, but both measures had recovered by midseason (July) and remained similar to the control treatment in the second postdrought year. We also found that extractable soil ammonium and total inorganic N were elevated throughout the growing season in the first year after drought in the intense treatment. However, these differences in inorganic N pools did not persist during the growing season of the second year postdrought. The remaining measures of C and N cycling in both drought treatments showed no postdrought treatment effects. Thus, although we observed short-term legacy effects following the intense drought, C and N cycling returned to levels comparable to nondroughted grassland within a single growing season regardless of whether the drought was intense or chronic in nature. Overall, these results suggest that the key aspects of C and N cycling in mesic tallgrass prairie do not exhibit persistent legacies from 4 years of experimentally induced drought.
{"title":"Limited legacy effects of extreme multiyear drought on carbon and nitrogen cycling in a mesic grassland","authors":"Leena Vilonen, J. Blair, P. Trivedi, L. Zeglin, Melinda D. Smith","doi":"10.1525/elementa.2021.000093","DOIUrl":"https://doi.org/10.1525/elementa.2021.000093","url":null,"abstract":"The intensification of drought throughout the U.S. Great Plains has the potential to have large impacts on grassland functioning, as has been shown with dramatic losses of plant productivity annually. Yet, we have a poor understanding of how grassland functioning responds after drought ends. This study examined how belowground nutrient cycling responds after drought and whether legacy effects persist postdrought. We assessed the 2-year recovery of nutrient cycling processes following a 4-year experimental drought in a mesic grassland by comparing two different growing season drought treatments—chronic (each rainfall event reduced by 66%) and intense (all rain eliminated until 45% of annual rainfall was achieved)—to the control (ambient precipitation) treatment. At the beginning of the first growing season postdrought, we found that in situ soil CO2 efflux and laboratory-based soil microbial respiration were reduced by 42% and 22%, respectively, in the intense drought treatment compared to the control, but both measures had recovered by midseason (July) and remained similar to the control treatment in the second postdrought year. We also found that extractable soil ammonium and total inorganic N were elevated throughout the growing season in the first year after drought in the intense treatment. However, these differences in inorganic N pools did not persist during the growing season of the second year postdrought. The remaining measures of C and N cycling in both drought treatments showed no postdrought treatment effects. Thus, although we observed short-term legacy effects following the intense drought, C and N cycling returned to levels comparable to nondroughted grassland within a single growing season regardless of whether the drought was intense or chronic in nature. Overall, these results suggest that the key aspects of C and N cycling in mesic tallgrass prairie do not exhibit persistent legacies from 4 years of experimentally induced drought.","PeriodicalId":54279,"journal":{"name":"Elementa-Science of the Anthropocene","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66940365","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-01-01DOI: 10.1525/elementa.2021.00060
M. Shupe, M. Rex, B. Blomquist, P. Persson, J. Schmale, T. Uttal, D. Althausen, H. Angot, S. Archer, L. Bariteau, Ivo Beck, John Bilberry, S. Bucci, C. Buck, M. Boyer, Zoé Brasseur, I. Brooks, Radiance Calmer, J. Cassano, Vagner Castro, David Chu, D. Costa, C. Cox, J. Creamean, S. Crewell, S. Dahlke, E. Damm, G. de Boer, H. Deckelmann, K. Dethloff, M. Dütsch, K. Ebell, A. Ehrlich, Jody Ellis, R. Engelmann, A. Fong, M. Frey, Michael R. Gallagher, L. Ganzeveld, R. Gradinger, Jürgen Graeser, Vernon Greenamyer, H. Griesche, Steele Griffiths, Jonathan Hamilton, G. Heinemann, D. Helmig, A. Herber, C. Heuzé, J. Hofer, Todd Houchens, D. Howard, J. Inoue, H. Jacobi, Ralf Jaiser, T. Jokinen, O. Jourdan, Gina C. Jozef, Wessley King, A. Kirchgaessner, M. Klingebiel, M. Krassovski, T. Krumpen, A. Lampert, W. Landing, T. Laurila, D. Lawrence, M. Lonardi, B. Loose, C. Lüpkes, M. Maahn, A. Macke, W. Maslowski, C. Marsay, M. Maturilli, M. Mech, S. Morris, M. Moser, M. Nicolaus, Paul Ortega, J. Osborn, F. Pätzold, D. Perov
With the Arctic rapidly changing, the needs to observe, understand, and model the changes are essential. To support these needs, an annual cycle of observations of atmospheric properties, processes, and interactions were made while drifting with the sea ice across the central Arctic during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition from October 2019 to September 2020. An international team designed and implemented the comprehensive program to document and characterize all aspects of the Arctic atmospheric system in unprecedented detail, using a variety of approaches, and across multiple scales. These measurements were coordinated with other observational teams to explore cross-cutting and coupled interactions with the Arctic Ocean, sea ice, and ecosystem through a variety of physical and biogeochemical processes. This overview outlines the breadth and complexity of the atmospheric research program, which was organized into 4 subgroups: atmospheric state, clouds and precipitation, gases and aerosols, and energy budgets. Atmospheric variability over the annual cycle revealed important influences from a persistent large-scale winter circulation pattern, leading to some storms with pressure and winds that were outside the interquartile range of past conditions suggested by long-term reanalysis. Similarly, the MOSAiC location was warmer and wetter in summer than the reanalysis climatology, in part due to its close proximity to the sea ice edge. The comprehensiveness of the observational program for characterizing and analyzing atmospheric phenomena is demonstrated via a winter case study examining air mass transitions and a summer case study examining vertical atmospheric evolution. Overall, the MOSAiC atmospheric program successfully met its objectives and was the most comprehensive atmospheric measurement program to date conducted over the Arctic sea ice. The obtained data will support a broad range of coupled-system scientific research and provide an important foundation for advancing multiscale modeling capabilities in the Arctic.
{"title":"Overview of the MOSAiC expedition—Atmosphere","authors":"M. Shupe, M. Rex, B. Blomquist, P. Persson, J. Schmale, T. Uttal, D. Althausen, H. Angot, S. Archer, L. Bariteau, Ivo Beck, John Bilberry, S. Bucci, C. Buck, M. Boyer, Zoé Brasseur, I. Brooks, Radiance Calmer, J. Cassano, Vagner Castro, David Chu, D. Costa, C. Cox, J. Creamean, S. Crewell, S. Dahlke, E. Damm, G. de Boer, H. Deckelmann, K. Dethloff, M. Dütsch, K. Ebell, A. Ehrlich, Jody Ellis, R. Engelmann, A. Fong, M. Frey, Michael R. Gallagher, L. Ganzeveld, R. Gradinger, Jürgen Graeser, Vernon Greenamyer, H. Griesche, Steele Griffiths, Jonathan Hamilton, G. Heinemann, D. Helmig, A. Herber, C. Heuzé, J. Hofer, Todd Houchens, D. Howard, J. Inoue, H. Jacobi, Ralf Jaiser, T. Jokinen, O. Jourdan, Gina C. Jozef, Wessley King, A. Kirchgaessner, M. Klingebiel, M. Krassovski, T. Krumpen, A. Lampert, W. Landing, T. Laurila, D. Lawrence, M. Lonardi, B. Loose, C. Lüpkes, M. Maahn, A. Macke, W. Maslowski, C. Marsay, M. Maturilli, M. Mech, S. Morris, M. Moser, M. Nicolaus, Paul Ortega, J. Osborn, F. Pätzold, D. Perov","doi":"10.1525/elementa.2021.00060","DOIUrl":"https://doi.org/10.1525/elementa.2021.00060","url":null,"abstract":"With the Arctic rapidly changing, the needs to observe, understand, and model the changes are essential. To support these needs, an annual cycle of observations of atmospheric properties, processes, and interactions were made while drifting with the sea ice across the central Arctic during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition from October 2019 to September 2020. An international team designed and implemented the comprehensive program to document and characterize all aspects of the Arctic atmospheric system in unprecedented detail, using a variety of approaches, and across multiple scales. These measurements were coordinated with other observational teams to explore cross-cutting and coupled interactions with the Arctic Ocean, sea ice, and ecosystem through a variety of physical and biogeochemical processes. This overview outlines the breadth and complexity of the atmospheric research program, which was organized into 4 subgroups: atmospheric state, clouds and precipitation, gases and aerosols, and energy budgets. Atmospheric variability over the annual cycle revealed important influences from a persistent large-scale winter circulation pattern, leading to some storms with pressure and winds that were outside the interquartile range of past conditions suggested by long-term reanalysis. Similarly, the MOSAiC location was warmer and wetter in summer than the reanalysis climatology, in part due to its close proximity to the sea ice edge. The comprehensiveness of the observational program for characterizing and analyzing atmospheric phenomena is demonstrated via a winter case study examining air mass transitions and a summer case study examining vertical atmospheric evolution. Overall, the MOSAiC atmospheric program successfully met its objectives and was the most comprehensive atmospheric measurement program to date conducted over the Arctic sea ice. The obtained data will support a broad range of coupled-system scientific research and provide an important foundation for advancing multiscale modeling capabilities in the Arctic.","PeriodicalId":54279,"journal":{"name":"Elementa-Science of the Anthropocene","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66941269","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-01-01DOI: 10.1525/elementa.2021.00044
R. Seguel, L. Gallardo, M. Osses, N. Rojas, Thiago Nogueira, C. Menares, M. de Fátima Andrade, L. Belalcázar, Paula Carrasco, H. Eskes, Z. Fleming, N. Huneeus, S. Ibarra-Espinosa, E. Landulfo, M. Leiva, Sonia C. Mangones, F. Morais, G. A. Moreira, Nicolás Pantoja, Santiago Parraguez, Jhojan P. Rojas, R. Rondanelli, Izabel da Silva Andrade, R. Toro, Alexandre C. Yoshida
This study delves into the photochemical atmospheric changes reported globally during the pandemic by analyzing the change in emissions from mobile sources and the contribution of local meteorology to ozone (O3) and particle formation in Bogotá (Colombia), Santiago (Chile), and São Paulo (Brazil). The impact of mobility reductions (50%–80%) produced by the early coronavirus-imposed lockdown was assessed through high-resolution vehicular emission inventories, surface measurements, aerosol optical depth and size, and satellite observations of tropospheric nitrogen dioxide (NO2) columns. A generalized additive model (GAM) technique was also used to separate the local meteorology and urban patterns from other drivers relevant for O3 and NO2 formation. Volatile organic compounds, nitrogen oxides (NOx), and fine particulate matter (PM2.5) decreased significantly due to motorized trip reductions. In situ nitrogen oxide median surface mixing ratios declined by 70%, 67%, and 67% in Bogotá, Santiago, and São Paulo, respectively. NO2 column medians from satellite observations decreased by 40%, 35%, and 47%, respectively, which was consistent with the changes in mobility and surface mixing ratio reductions of 34%, 25%, and 34%. However, the ambient NO2 to NOx ratio increased, denoting a shift of the O3 formation regime that led to a 51%, 36%, and 30% increase in the median O3 surface mixing ratios in the 3 respective cities. O3 showed high sensitivity to slight temperature changes during the pandemic lockdown period analyzed. However, the GAM results indicate that O3 increases were mainly caused by emission changes. The lockdown led to an increase in the median of the maximum daily 8-h average O3 of between 56% and 90% in these cities.
{"title":"Photochemical sensitivity to emissions and local meteorology in Bogotá, Santiago, and São Paulo","authors":"R. Seguel, L. Gallardo, M. Osses, N. Rojas, Thiago Nogueira, C. Menares, M. de Fátima Andrade, L. Belalcázar, Paula Carrasco, H. Eskes, Z. Fleming, N. Huneeus, S. Ibarra-Espinosa, E. Landulfo, M. Leiva, Sonia C. Mangones, F. Morais, G. A. Moreira, Nicolás Pantoja, Santiago Parraguez, Jhojan P. Rojas, R. Rondanelli, Izabel da Silva Andrade, R. Toro, Alexandre C. Yoshida","doi":"10.1525/elementa.2021.00044","DOIUrl":"https://doi.org/10.1525/elementa.2021.00044","url":null,"abstract":"This study delves into the photochemical atmospheric changes reported globally during the pandemic by analyzing the change in emissions from mobile sources and the contribution of local meteorology to ozone (O3) and particle formation in Bogotá (Colombia), Santiago (Chile), and São Paulo (Brazil). The impact of mobility reductions (50%–80%) produced by the early coronavirus-imposed lockdown was assessed through high-resolution vehicular emission inventories, surface measurements, aerosol optical depth and size, and satellite observations of tropospheric nitrogen dioxide (NO2) columns. A generalized additive model (GAM) technique was also used to separate the local meteorology and urban patterns from other drivers relevant for O3 and NO2 formation. Volatile organic compounds, nitrogen oxides (NOx), and fine particulate matter (PM2.5) decreased significantly due to motorized trip reductions. In situ nitrogen oxide median surface mixing ratios declined by 70%, 67%, and 67% in Bogotá, Santiago, and São Paulo, respectively. NO2 column medians from satellite observations decreased by 40%, 35%, and 47%, respectively, which was consistent with the changes in mobility and surface mixing ratio reductions of 34%, 25%, and 34%. However, the ambient NO2 to NOx ratio increased, denoting a shift of the O3 formation regime that led to a 51%, 36%, and 30% increase in the median O3 surface mixing ratios in the 3 respective cities. O3 showed high sensitivity to slight temperature changes during the pandemic lockdown period analyzed. However, the GAM results indicate that O3 increases were mainly caused by emission changes. The lockdown led to an increase in the median of the maximum daily 8-h average O3 of between 56% and 90% in these cities.","PeriodicalId":54279,"journal":{"name":"Elementa-Science of the Anthropocene","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66941541","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-01-01DOI: 10.1525/elementa.2021.00070
E. Walker, I. Wiedmann, A. Nikolopoulos, J. Skarðhamar, E. M. Jones, A. Renner
Marine ecosystems, and particularly fjords, are experiencing an increasing level of human activity on a year-round basis, including the poorly studied winter period. To improve the knowledge base for environmentally sustainable management in all seasons, this study provides hydrographic and biological baseline data for the sub-Arctic fjord Kaldfjorden, Northern Norway (69.7° N, 18.7° E), between autumn 2017 and spring 2018. Field observations are integrated with results of a numerical ocean model simulation, illustrating how pelagic biomass, represented by chlorophyll a (Chl a), particulate organic carbon (POC), and zooplankton, is affected by stratification and circulation from October to May. We observed an unusually warm autumn that likely delayed the onset of cooling and may have supported the high abundances of holoplankton and meroplankton (5768 individuals m–3). With the onset of winter, the water column cooled and became vertically mixed, while suspended Chl a concentrations declined rapidly (< 0.12 mg Chl a m–3). In January and February, suspended POC concentrations and downward flux were elevated near the seafloor. The hydrodynamic model results indicate that the strongest currents at depth occurred in these months, potentially inducing resuspension events close to the seafloor. In spring (April), peak abundances of suspended biomass were observed (6.9–7.2 mg Chl a m–3 at 5–15 m; 9952 zooplankton ind. m–3 at 0–100 m), and field observations and model results suggest that zooplankton of Atlantic origin were probably advected into Kaldfjorden. During all investigated seasons, the model simulation suggests a complex circulation pattern, even in such a small fjord, which can have implications for environmental management of the fjord. We conclude that the pelagic system in Kaldfjorden changes continually from autumn to spring and that winter must be seen as a dynamic period, not a season where the fjord ecosystem is ‘at rest’.
海洋生态系统，特别是峡湾，全年都在经历越来越多的人类活动，包括对冬季的研究很少。为了完善四季环境可持续管理的知识库，本研究提供了2017年秋季至2018年春季挪威北部卡德约登亚北极峡湾(69.7°N, 18.7°E)的水文和生物基线数据。将野外观测结果与数值海洋模式模拟结果相结合，说明了10 - 5月分层和环流如何影响以叶绿素a (Chl a)、颗粒有机碳(POC)和浮游动物为代表的远洋生物量。我们观察到一个异常温暖的秋季，这可能推迟了降温的开始，并可能支持了整体浮游生物和浮游生物的高丰度(5768个m-3)。随着冬季的到来，水柱冷却并垂直混合，悬浮Chl a浓度迅速下降(< 0.12 mg Chl a m-3)。1月和2月，海底附近悬浮POC浓度和向下通量升高。水动力模型结果表明，这几个月发生了最强烈的深海洋流，可能会引起靠近海底的再悬浮事件。春季(4月)，悬浮物丰度最高(5 ~ 15 m, 6.9 ~ 7.2 mg Chl a m - 3;9952浮游动物(m - 3, 0-100 m)，野外观测和模式结果表明，来自大西洋的浮游动物可能平流到Kaldfjorden。在所有被调查的季节，模型模拟显示了一个复杂的环流模式，即使在这样一个小峡湾，这可能对峡湾的环境管理产生影响。我们的结论是，从秋天到春天，卡尔德约登的海洋系统不断变化，冬季必须被视为一个动态的时期，而不是峡湾生态系统“休息”的季节。
{"title":"Pelagic ecosystem dynamics between late autumn and the post spring bloom in a sub-Arctic fjord","authors":"E. Walker, I. Wiedmann, A. Nikolopoulos, J. Skarðhamar, E. M. Jones, A. Renner","doi":"10.1525/elementa.2021.00070","DOIUrl":"https://doi.org/10.1525/elementa.2021.00070","url":null,"abstract":"Marine ecosystems, and particularly fjords, are experiencing an increasing level of human activity on a year-round basis, including the poorly studied winter period. To improve the knowledge base for environmentally sustainable management in all seasons, this study provides hydrographic and biological baseline data for the sub-Arctic fjord Kaldfjorden, Northern Norway (69.7° N, 18.7° E), between autumn 2017 and spring 2018. Field observations are integrated with results of a numerical ocean model simulation, illustrating how pelagic biomass, represented by chlorophyll a (Chl a), particulate organic carbon (POC), and zooplankton, is affected by stratification and circulation from October to May. We observed an unusually warm autumn that likely delayed the onset of cooling and may have supported the high abundances of holoplankton and meroplankton (5768 individuals m–3). With the onset of winter, the water column cooled and became vertically mixed, while suspended Chl a concentrations declined rapidly (< 0.12 mg Chl a m–3). In January and February, suspended POC concentrations and downward flux were elevated near the seafloor. The hydrodynamic model results indicate that the strongest currents at depth occurred in these months, potentially inducing resuspension events close to the seafloor. In spring (April), peak abundances of suspended biomass were observed (6.9–7.2 mg Chl a m–3 at 5–15 m; 9952 zooplankton ind. m–3 at 0–100 m), and field observations and model results suggest that zooplankton of Atlantic origin were probably advected into Kaldfjorden. During all investigated seasons, the model simulation suggests a complex circulation pattern, even in such a small fjord, which can have implications for environmental management of the fjord. We conclude that the pelagic system in Kaldfjorden changes continually from autumn to spring and that winter must be seen as a dynamic period, not a season where the fjord ecosystem is ‘at rest’.","PeriodicalId":54279,"journal":{"name":"Elementa-Science of the Anthropocene","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66941949","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-01-01DOI: 10.1525/elementa.2021.00088
Jesse M Wilson, Natalia G. Erazo, Elizabeth J. Connors, E. J. Chamberlain, Samantha M. Clements, Melissa L. Carter, J. Smith, J. Bowman
Phytoplankton blooms create organic matter that stimulates entire marine ecosystems, including other components of the microbial community. How the ecosystem responds varies depending on the intensity, duration, and composition of the bloom. When the bloom has a direct or indirect negative impact on the ecosystem, it is termed a harmful algal bloom (HAB). HAB frequency is expected to increase in response to changing oceanic conditions and coastal nutrient supply. Characterizing the response of the bacterial and archaeal communities to HABs will improve our understanding of the ecological impacts of these phenomena. We utilized time series of chlorophyll a, phaeophytin, dissolved oxygen, flow cytometry cell counts, and microbial community structure (assessed via 16S rRNA gene sequences) maintained by several observing programs to investigate how the microbial community was affected by an exceptional bloom of Lingulodinium polyedra in coastal Southern California. These multi-year datasets allowed us to compare the microbial community response to past events, such as a smaller L. polyedra bloom the previous year. We demonstrated that the bacterial and archaeal response to the 2020 bloom was unique taxonomically, with many novel heterotrophs, and higher trophic state variance. The measured heterotrophic response to the bloom resulted in massive oxygen drawdown and may have impacted the length of the bloom and contributed to a secondary diatom bloom following the main HAB event. Taken together, these data illustrate how the massive 2020 L. polyedra bloom created unique ecological conditions for coastal Southern California.
{"title":"Substantial microbial community shifts in response to an exceptional harmful algal bloom in coastal Southern California","authors":"Jesse M Wilson, Natalia G. Erazo, Elizabeth J. Connors, E. J. Chamberlain, Samantha M. Clements, Melissa L. Carter, J. Smith, J. Bowman","doi":"10.1525/elementa.2021.00088","DOIUrl":"https://doi.org/10.1525/elementa.2021.00088","url":null,"abstract":"Phytoplankton blooms create organic matter that stimulates entire marine ecosystems, including other components of the microbial community. How the ecosystem responds varies depending on the intensity, duration, and composition of the bloom. When the bloom has a direct or indirect negative impact on the ecosystem, it is termed a harmful algal bloom (HAB). HAB frequency is expected to increase in response to changing oceanic conditions and coastal nutrient supply. Characterizing the response of the bacterial and archaeal communities to HABs will improve our understanding of the ecological impacts of these phenomena. We utilized time series of chlorophyll a, phaeophytin, dissolved oxygen, flow cytometry cell counts, and microbial community structure (assessed via 16S rRNA gene sequences) maintained by several observing programs to investigate how the microbial community was affected by an exceptional bloom of Lingulodinium polyedra in coastal Southern California. These multi-year datasets allowed us to compare the microbial community response to past events, such as a smaller L. polyedra bloom the previous year. We demonstrated that the bacterial and archaeal response to the 2020 bloom was unique taxonomically, with many novel heterotrophs, and higher trophic state variance. The measured heterotrophic response to the bloom resulted in massive oxygen drawdown and may have impacted the length of the bloom and contributed to a secondary diatom bloom following the main HAB event. Taken together, these data illustrate how the massive 2020 L. polyedra bloom created unique ecological conditions for coastal Southern California.","PeriodicalId":54279,"journal":{"name":"Elementa-Science of the Anthropocene","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66942238","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-01-01DOI: 10.1525/elementa.2021.00100
Hannah Wittman, D. James
Agroecological transitions aim to redesign the structure of contemporary global food systems to improve food security, ecosystem health, community development, worker livelihoods, and social and ecological justice. A fundamental principle of agroecology is the responsible governance of land. Yet land—as a concept, resource, and territory—is heavily contested through processes of colonization, enclosure, commodification, and financialization. The governance of land and natural resources is also intimately tied to questions of power and privilege—Who governs land? Who benefits, and who is excluded? These questions presuppose an ontological understanding of land that can also be contested: What is land, what purpose(s) does it serve, and for whom? In this article, we review key concepts at the intersection of land governance and agroecology. We take a case study approach to highlight how tensions around ontologies of land mediate agroecological futures in 2 settler-colonial contexts: Brazil and Canada. We then explore how land governance for agroecology might be experienced and understood across different land governance institutions—including relational and community commons, private property regimes, and new forms of hybrid land relations that challenge land privatization. We discuss how these land regimes influence people, landscapes, and agroecological outcomes and conclude with a consideration of the access, equity, and justice implications of different land governance approaches for sustainable food systems.
{"title":"Land governance for agroecology","authors":"Hannah Wittman, D. James","doi":"10.1525/elementa.2021.00100","DOIUrl":"https://doi.org/10.1525/elementa.2021.00100","url":null,"abstract":"Agroecological transitions aim to redesign the structure of contemporary global food systems to improve food security, ecosystem health, community development, worker livelihoods, and social and ecological justice. A fundamental principle of agroecology is the responsible governance of land. Yet land—as a concept, resource, and territory—is heavily contested through processes of colonization, enclosure, commodification, and financialization. The governance of land and natural resources is also intimately tied to questions of power and privilege—Who governs land? Who benefits, and who is excluded? These questions presuppose an ontological understanding of land that can also be contested: What is land, what purpose(s) does it serve, and for whom? In this article, we review key concepts at the intersection of land governance and agroecology. We take a case study approach to highlight how tensions around ontologies of land mediate agroecological futures in 2 settler-colonial contexts: Brazil and Canada. We then explore how land governance for agroecology might be experienced and understood across different land governance institutions—including relational and community commons, private property regimes, and new forms of hybrid land relations that challenge land privatization. We discuss how these land regimes influence people, landscapes, and agroecological outcomes and conclude with a consideration of the access, equity, and justice implications of different land governance approaches for sustainable food systems.","PeriodicalId":54279,"journal":{"name":"Elementa-Science of the Anthropocene","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66942374","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-01-01DOI: 10.1525/elementa.2021.00104
Miriam Seifert, C. Nissen, B. Rost, J. Hauck
Atmospheric and oceanic CO2 concentrations are rising at an unprecedented rate. Laboratory studies indicate a positive effect of rising CO2 on phytoplankton growth until an optimum is reached, after which the negative impact of accompanying acidification dominates. Here, we implemented carbonate system sensitivities of phytoplankton growth into our global biogeochemical model FESOM-REcoM and accounted explicitly for coccolithophores as the group most sensitive to CO2. In idealized simulations in which solely the atmospheric CO2 mixing ratio was modified, changes in competitive fitness and biomass are not only caused by the direct effects of CO2, but also by indirect effects via nutrient and light limitation as well as grazing. These cascading effects can both amplify or dampen phytoplankton responses to changing ocean pCO2 levels. For example, coccolithophore growth is negatively affected both directly by future pCO2 and indirectly by changes in light limitation, but these effects are compensated by a weakened nutrient limitation resulting from the decrease in small-phytoplankton biomass. In the Southern Ocean, future pCO2 decreases small-phytoplankton biomass and hereby the preferred prey of zooplankton, which reduces the grazing pressure on diatoms and allows them to proliferate more strongly. In simulations that encompass CO2-driven warming and acidification, our model reveals that recent observed changes in North Atlantic coccolithophore biomass are driven primarily by warming and not by CO2. Our results highlight that CO2 can change the effects of other environmental drivers on phytoplankton growth, and that cascading effects may play an important role in projections of future net primary production.
{"title":"Cascading effects augment the direct impact of CO2 on phytoplankton growth in a biogeochemical model","authors":"Miriam Seifert, C. Nissen, B. Rost, J. Hauck","doi":"10.1525/elementa.2021.00104","DOIUrl":"https://doi.org/10.1525/elementa.2021.00104","url":null,"abstract":"Atmospheric and oceanic CO2 concentrations are rising at an unprecedented rate. Laboratory studies indicate a positive effect of rising CO2 on phytoplankton growth until an optimum is reached, after which the negative impact of accompanying acidification dominates. Here, we implemented carbonate system sensitivities of phytoplankton growth into our global biogeochemical model FESOM-REcoM and accounted explicitly for coccolithophores as the group most sensitive to CO2. In idealized simulations in which solely the atmospheric CO2 mixing ratio was modified, changes in competitive fitness and biomass are not only caused by the direct effects of CO2, but also by indirect effects via nutrient and light limitation as well as grazing. These cascading effects can both amplify or dampen phytoplankton responses to changing ocean pCO2 levels. For example, coccolithophore growth is negatively affected both directly by future pCO2 and indirectly by changes in light limitation, but these effects are compensated by a weakened nutrient limitation resulting from the decrease in small-phytoplankton biomass. In the Southern Ocean, future pCO2 decreases small-phytoplankton biomass and hereby the preferred prey of zooplankton, which reduces the grazing pressure on diatoms and allows them to proliferate more strongly. In simulations that encompass CO2-driven warming and acidification, our model reveals that recent observed changes in North Atlantic coccolithophore biomass are driven primarily by warming and not by CO2. Our results highlight that CO2 can change the effects of other environmental drivers on phytoplankton growth, and that cascading effects may play an important role in projections of future net primary production.","PeriodicalId":54279,"journal":{"name":"Elementa-Science of the Anthropocene","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66942480","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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