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- Álvarez-Muñiz, Jaime, et al.
(author)
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The Giant Radio Array for Neutrino Detection (GRAND) : Science and design
- 2020
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In: Science China Physics, Mechanics & Astronomy. - : Springer Science and Business Media LLC. - 1674-7348 .- 1869-1927. ; 63:1
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Research review (peer-reviewed)abstract
- The Giant Radio Array for Neutrino Detection (GRAND) is a planned large-scale observatory of ultra-high-energy (UHE) cosmic particles, with energies exceeding 108 GeV. Its goal is to solve the long-standing mystery of the origin of UHE cosmic rays. To do this, GRAND will detect an unprecedented number of UHE cosmic rays and search for the undiscovered UHE neutrinos and gamma rays associated to them with unmatched sensitivity. GRAND will use large arrays of antennas to detect the radio emission coming from extensive air showers initiated by UHE particles in the atmosphere. Its design is modular: 20 separate, independent sub-arrays, each of 10000 radio antennas deployed over 10000 km(2). A staged construction plan will validate key detection techniques while achieving important science goals early. Here we present the science goals, detection strategy, preliminary design, performance goals, and construction plans for GRAND.
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| 2. |
- Engel, Fabian, et al.
(author)
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A simplified approach to detect a significant carbon dioxide reduction by phytoplankton in lakes and rivers on a regional and global scale
- 2020
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In: The Science of Nature. - : Springer Science and Business Media LLC. - 0028-1042 .- 1432-1904. ; 107:4
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Journal article (peer-reviewed)abstract
- Carbon dioxide (CO2) uptake by phytoplankton can significantly reduce the partial pressure of CO2 (pCO2) in lakes and rivers, and thereby CO2 emissions. Presently, it is not known in which inland waters on Earth a significant pCO2 reduction by phytoplankton is likely. Since detailed, comparable carbon budgets are currently not available for most inland waters, we modified a proxy to assess the pCO2 reduction by phytoplankton, originally developed for boreal lakes, for application on a global scale. Using data from 61 rivers and 125 lakes distributed over five continents, we show that a significant pCO2 reduction by phytoplankton is widespread across the temperate and sub-/tropical region, but absent in the cold regions on Earth. More specifically, we found that a significant pCO2 reduction by phytoplankton might occur in 24% of the lakes in the temperate region, and 39% of the lakes in the sub-/tropical region. We also showed that such a reduction might occur in 21% of the rivers in the temperate region, and 5% of the rivers in the sub-/tropical region. Our results indicate that CO2 uptake by phytoplankton is a relevant flux in regional and global carbon budgets. This highlights the need for more accurate approaches to quantify CO2 uptake by primary producers in inland waters, particularly in the temperate and sub-/tropical region.
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| 3. |
- Engel, Fabian
(author)
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The role of freshwater phytoplankton in the global carbon cycle
- 2020
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Doctoral thesis (other academic/artistic)abstract
- Water flowing through the landscape transports chemical substances including carbon. Along the way from upland soils to the ocean, carbon is transformed from organic carbon into inorganic carbon and vice versa. One such carbon transformation process is the uptake of carbon dioxide (CO2) from the water phase by phytoplankton. For some inland waters, it has been shown that phytoplankton can significantly reduce the amount of CO2 (measured as partial pressure of CO2, pCO2) in the water phase. However, the importance of this process for carbon budgets on a regional and global scale is not yet known.The aim of this thesis was to investigate the importance of CO2 uptake by phytoplankton for CO2 dynamics in lakes and rivers on a regional and global scale, and to explain its spatial variation. Conceptual models and the analysis of monitoring data together with statistical modeling and meta-analyses were used.Combining a conceptual lake model for carbon transformation with a mass balance approach showed that gross primary production in lakes is an important flux in the global dissolved inorganic carbon budget of inland waters. In a next step, a simple proxy to assess the phytoplankton influence on the pCO2 in individual lakes and rivers was tested and applied on a regional and global scale. The analysis showed that a significant pCO2 reduction by phytoplankton could be expected in about 20% to 40% of lakes in the temperate and sub-/tropical region. In 9% of the Swedish lakes analyzed, the proxy indicated a significant pCO2 reduction by phytoplankton during summer. The pCO2 can also be significantly reduced by phytoplankton in rivers, and such a reduction might occur in about 20% of the temperate rivers on Earth. In a temperate river that was studied in more detail, consecutive impoundments were found to stimulate phytoplankton production, which might be one explanation for a greater phytoplankton influence on the pCO2 in such systems.Taken together, these results suggest that CO2 uptake by phytoplankton is a significant flux in the global CO2 budget of inland waters. The importance of CO2 uptake by phytoplankton for CO2 dynamics in individual lakes and rivers was predictable by easily available water physico-chemical and biological variables and varied widely in relation to environmental conditions.
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