Small microplastics as a main contributor to plastic mass balance in the North Atlantic subtropical gyre

Estimates of cumulative plastic inputs into the oceans are expressed in hundred million tons, whereas the total mass of microplastics afloat at sea is 3 orders of magnitude below this. This large gap is evidence of our ignorance about the fate of plastics, as well as transformations and sinks in the oceans. One of the current challenges consists of identifying and quantifying plastic particles at the microscale, the small microplastics (SMP, 25–1000 μm). The aim of the present study is to investigate SMP concentration in count and in mass at the sea surface in the North Atlantic subtropical gyre during the sea campaign Expedition 7th Continent. After isolation, SMP were characterized by micro-Fourier-transform infrared spectroscopy. Microplastic distribution was modeled by a wind-driven vertical mixing correction model taking into account individual particle properties (dimension, shape and density). We demonstrate that SMP buoyancy is significantly decreased compared to the large microplastics (LMP, 1–5 mm) and consequently more susceptible to vertical transport. The uncorrected LMP concentration in count was between 13 000 and 174 000 pieces km–2, and was between 5 and 170 times more abundant for SMP. With a wind-driven vertical mixing correction, we estimated that SMP were 300 to 70 000 times more abundant than LMP. When discussing this in terms of weight after correction, LMP concentrations were between 50 and 1000 g km–2, and SMP concentrations were between 5 and 14 000 g km–2

Anticyclonic eddies increase accumulation of microplastic in the North Atlantic subtropical gyre

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The Mars Climate Database (MCD version 5.3)

Our Global Circulation Model (GCM) simulates the atmospheric environment of Mars. It is developped at LMD (Laboratoire de Meteorologie Dynamique, Paris, France) in close collaboration with several teams in Europe (LATMOS, France, University of Oxford, The Open University, the Instituto de Astrofisica de Andalucia), and with the support of ESA (European Space Agency) and CNES (French Space Agency). GCM outputs are compiled to build a Mars Climate Database, a freely available tool useful for the scientific and engineering communities. The Mars Climate Database (MCD) has over the years been distributed to more than 350 teams around the world. The latest series of reference simulations have been compiled in version 5.3 of the MCD which was released in 2017. To summarize, MCD v5.3 provides: - Climatologies over a series of synthetic dust scenarios: standard (climatology) year, cold (ie: low dust), warm (ie: dusty atmosphere) and dust storm, all topped by various cases of Extreme UV solar inputs (low, mean or maximum). These scenarios have been derived from home-made, instrument-derived (TES, THEMIS, MCS, MERs), dust climatology of the last 8 Martian years. The MCD also provides simulation outputs (MY24-33) representative of these actual years. - Mean values and statistics of main meteorological variables (atmospheric temperature, density, pressure and winds), as well as surface pressure and temperature, CO2 ice cover, thermal and solar radiative fluxes, dust column opacity and mixing ratio, [H20] vapor and ice columns, concentrations of many species: [CO], [O2], [O], [N2], [H2], [O3], ... - A high resolution mode which combines high resolution (32 pixel/degree) MOLA topography records and Viking Lander 1 pressure records with raw lower resolution GCM results to yield, within the restriction of the procedure, high resolution values of atmospheric variables. - The possibility to reconstruct realistic conditions by combining the provided climatology with additional large scale and small scale perturbations schemes. At EGU, we will report on the latest improvements in the Mars Climate Database, with comparisons with available measurements from orbit (e.g.: TES, MCS, TGO) and landers (Viking, Phoenix, Curiosity)

The Mars Climate Database (MCD version 5.3)

21st EGU General Assembly, EGU2019, Proceedings from the conference held 7-12 April, 2019 in Vienna, Austria, id.7153Our Global Circulation Model (GCM) simulates the atmospheric environment of Mars. It is developped at LMD (Laboratoire de Meteorologie Dynamique, Paris, France) in close collaboration with several teams in Europe (LATMOS, France, University of Oxford, The Open University, the Instituto de Astrofisica de Andalucia), and with the support of ESA (European Space Agency) and CNES (French Space Agency). GCM outputs are compiled to build a Mars Climate Database, a freely available tool useful for the scientific and engineering communities. The Mars Climate Database (MCD) has over the years been distributed to more than 350 teams around the world. The latest series of reference simulations have been compiled in version 5.3 of the MCD which was released in 2017. To summarize, MCD v5.3 provides: - Climatologies over a series of synthetic dust scenarios: standard (climatology) year, cold (ie: low dust), warm (ie: dusty atmosphere) and dust storm, all topped by various cases of Extreme UV solar inputs (low, mean or maximum). These scenarios have been derived from home-made, instrument-derived (TES, THEMIS, MCS, MERs), dust climatology of the last 8 Martian years. The MCD also provides simulation outputs (MY24-33) representative of these actual years. - Mean values and statistics of main meteorological variables (atmospheric temperature, density, pressure and winds), as well as surface pressure and temperature, CO2 ice cover, thermal and solar radiative fluxes, dust column opacity and mixing ratio, [H20] vapor and ice columns, concentrations of many species: [CO], [O2], [O], [N2], [H2], [O3], ... - A high resolution mode which combines high resolution (32 pixel/degree) MOLA topography records and Viking Lander 1 pressure records with raw lower resolution GCM results to yield, within the restriction of the procedure, high resolution values of atmospheric variables. - The possibility to reconstruct realistic conditions by combining the provided climatology with additional large scale and small scale perturbations schemes. At EGU, we will report on the latest improvements in the Mars Climate Database, with comparisons with available measurements from orbit (e.g.: TES, MCS, TGO) and landers (Viking, Phoenix, Curiosity)

The Mars Climate Database (version 6)

EPSC-DPS Joint Meeting 2019, held 15-20 September 2019 in Geneva, Switzerland, id. EPSC-DPS2019-593-1.- © Author(s) 2019. CC Attribution 4.0 license. https://creativecommons.org/licenses/by/4.0/deed.e

Planetary Protection Knowledge Gaps and Enabling Science for Human Mars Missions

In the coming decade, as we prepare for the first mission to Mars with a human crew, we have a continuing obligation to protect the integrity of scientific investigations at Mars. In particular, it is unlikely that the search for life on Mars will be completed by the time the first crew systems arrive at the martian surface. Indeed, some consider the presence of astronauts to be an essential augmentation to the robotic search for evidence of life on the red planet. In addition, the environment of the Earth needs to be protected from the threat posed by the uncontrolled release of a putative martian life form into the terrestrial biosphere. Prevention of such harmful cross-contaminations between Mars and the Earth is the practice of planetary protection. At present, the knowledge of how to achieve these two goals (prevention of forward contamination from Earth and backward contamination from Mars) is well described for robotic systems. In contrast, for human missions there are only guidelines (Kminek et al. 2017a) but no engineering requirements, in part, because our knowledge of Mars (and of how contamination from crewed systems will interact with Mars) is incomplete. These gaps in our knowledge (as also described in NASA NID8715.129) need to be addressed through acquisition of new data during the next decade, if planetary protection measures are to be implemented successfully for human missions. This paper describes the technical issues and measurements needed