TY - JOUR A1 - Funk, Roger A1 - Busse, Jaqueline A1 - Siegmund, Nicole A1 - Sommer, Michael A1 - Iturri, Laura Antonela A1 - Panebianco, Juan E. A1 - Avecilla, Fernando A1 - Buschiazzo, Daniel T1 - Phytoliths in particulate matter released by wind erosion on arable land in La Pampa, Argentina JF - Frontiers in environmental science N2 - Silicon (Si) is considered a beneficial element in plant nutrition, but its importance on ecosystems goes far beyond that. Various forms of silicon are found in soils, of which the phytogenic pool plays a decisive role due to its good availability. This Si returns to the soil through the decomposition of plant residues, where they then participate in the further cycle as biogenic amorphous silica (bASi) or so-called phytoliths. These have a high affinity for water, so that the water holding capacity and water availability of soils can be increased even by small amounts of ASi. Agricultural land is a considerable global dust source, and dust samples from arable land have shown in cloud formation experiments a several times higher ice nucleation activity than pure mineral dust. Here, particle sizes in the particulate matter fractions (PM) are important, which can travel long distances and reach high altitudes in the atmosphere. Based on this, the research question was whether phytoliths could be detected in PM samples from wind erosion events, what are the main particle sizes of phytoliths and whether an initial quantification was possible.Measurements of PM concentrations were carried out at a wind erosion measuring field in the province La Pampa, Argentina. PM were sampled during five erosion events with Environmental Dust Monitors (EDM). After counting and classifying all particles with diameters between 0.3 and 32 mu m in the EDMs, they are collected on filters. The filters were analyzed by Scanning Electron Microscopy and Energy Dispersive X-Ray analysis (SEM-EDX) to investigate single or ensembles of particles regarding composition and possible origins.The analyses showed up to 8.3 per cent being phytoliths in the emitted dust and up to 25 per cent of organic origin. Particles of organic origin are mostly in the coarse dust fraction, whereas phytoliths are predominately transported in the finer dust fractions. Since phytoliths are both an important source of Si as a plant nutrient and are also involved in soil C fixation, their losses from arable land via dust emissions should be considered and its specific influence on atmospheric processes should be studied in detail in the future. KW - dust KW - dust composition KW - particulate matter KW - scanning electron microscope KW - (SEM) analysis KW - phytolith Y1 - 2022 U6 - https://doi.org/10.3389/fenvs.2022.969898 SN - 2296-665X VL - 10 PB - Frontiers Media CY - Lausanne ER - TY - JOUR A1 - Ramachandran, Srikanthan A1 - Rupakheti, Maheswar A1 - Lawrence, Mark T1 - Black carbon dominates the aerosol absorption over the Indo-Gangetic Plain and the Himalayan foothills JF - Environment international : a journal of science, technology, health, monitoring and policy N2 - This study, based on new and high quality in situ observations, quantifies for the first time, the individual contributions of light-absorbing aerosols (black carbon (BC), brown carbon (BrC) and dust) to aerosol absorption over the Indo-Gangetic Plain (IGP) and the Himalayan foothill region, a relatively poorly studied region with several sensitive ecosystems of global importance, as well as highly vulnerable populations. The annual and seasonal average single scattering albedo (SSA) over Kathmandu is the lowest of all the locations. The SSA over Kathmandu is < 0.89 during all seasons, which confirms the dominance of light-absorbing carbonaceous aerosols from local and regional sources over Kathmandu. It is observed here that the SSA decreases with increasing elevation, confirming the dominance of light absorbing carbonaceous aerosols at higher elevations. In contrast, the SSA over the IGP does not exhibit a pronounced spatial variation. BC dominates (>= 75%) the aerosol absorption over the IGP and the Himalayan foothills throughout the year. Higher BC concentration at elevated locations in the Himalayas leads to lower SSA at elevated locations in the Himalayas. The contribution of dust to aerosol absorption is higher throughout the year over the IGP than over the Himalayan foothills. The aerosol absorption over South Asia is very high, exceeding available observations over East Asia, and also exceeds previous model estimates. This quantification will be valuable as observational constraints to help improve regional simulations of climate change, impacts on the glaciers and the hydrological cycle, and will help to direct the focus towards BC as the main contributor to aerosol-induced warming in the region. KW - atmospheric aerosols KW - characteristics KW - absorption KW - black carbon KW - brown KW - carbon KW - dust KW - Himalayas KW - IGP KW - South Asia Y1 - 2020 U6 - https://doi.org/10.1016/j.envint.2020.105814 SN - 0160-4120 SN - 1873-6750 VL - 142 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Marschall, Raphael A1 - Skorov, Yuri A1 - Zakharov, Vladimir A1 - Rezac, Ladislav A1 - Gerig, Selina-Barbara A1 - Christou, Chariton A1 - Dadzie, S. Kokou A1 - Migliorini, Alessandra A1 - Rinaldi, Giovanna A1 - Agarwal, Jessica A1 - Vincent, Jean-Baptiste A1 - Kappel, David T1 - Cometary comae-surface links the physics of gas and dust from the surface to a spacecraft JF - Space science reviews N2 - A comet is a highly dynamic object, undergoing a permanent state of change. These changes have to be carefully classified and considered according to their intrinsic temporal and spatial scales. The Rosetta mission has, through its contiguous in-situ and remote sensing coverage of comet 67P/Churyumov-Gerasimenko (hereafter 67P) over the time span of August 2014 to September 2016, monitored the emergence, culmination, and winding down of the gas and dust comae. This provided an unprecedented data set and has spurred a large effort to connect in-situ and remote sensing measurements to the surface. In this review, we address our current understanding of cometary activity and the challenges involved when linking comae data to the surface. We give the current state of research by describing what we know about the physical processes involved from the surface to a few tens of kilometres above it with respect to the gas and dust emission from cometary nuclei. Further, we describe how complex multidimensional cometary gas and dust models have developed from the Halley encounter of 1986 to today. This includes the study of inhomogeneous outgassing and determination of the gas and dust production rates. Additionally, the different approaches used and results obtained to link coma data to the surface will be discussed. We discuss forward and inversion models and we describe the limitations of the respective approaches. The current literature suggests that there does not seem to be a single uniform process behind cometary activity. Rather, activity seems to be the consequence of a variety of erosion processes, including the sublimation of both water ice and more volatile material, but possibly also more exotic processes such as fracture and cliff erosion under thermal and mechanical stress, sub-surface heat storage, and a complex interplay of these processes. Seasons and the nucleus shape are key factors for the distribution and temporal evolution of activity and imply that the heliocentric evolution of activity can be highly individual for every comet, and generalisations can be misleading. KW - comets KW - coma KW - gas KW - dust KW - dynamics KW - modelling KW - inversion Y1 - 2020 U6 - https://doi.org/10.1007/s11214-020-00744-0 SN - 0038-6308 SN - 1572-9672 VL - 216 IS - 8 PB - Springer CY - Dordrecht ER - TY - JOUR A1 - Ye, S. -Y. A1 - Kurth, William S. A1 - Hospodarsky, George B. A1 - Persoon, Ann M. A1 - Gurnett, Don A. A1 - Morooka, Michiko A1 - Wahlund, Jan-Erik A1 - Hsu, Hsiang-Wen A1 - Seiss, Martin A1 - Srama, Ralf T1 - Cassini RPWS dust observation near the Janus/Epimetheus orbit JF - Journal of geophysical research : Space physics N2 - During the Ring Grazing orbits near the end of Cassini mission, the spacecraft crossed the equatorial plane near the orbit of Janus/Epimetheus (similar to 2.5 Rs). This region is populated with dust particles that can be detected by the Radio and Plasma Wave Science (RPWS) instrument via an electric field antenna signal. Analysis of the voltage waveforms recorded on the RPWS antennas provides estimations of the density and size distribution of the dust particles. Measured RPWS profiles, fitted with Lorentzian functions, are shown to be mostly consistent with the Cosmic Dust Analyzer, the dedicated dust instrument on board Cassini. The thickness of the dusty ring varies between 600 and 1,000 km. The peak location shifts north and south within 100 km of the ring plane, likely a function of the precession phase of Janus orbit. KW - Saturn KW - dust KW - ring Y1 - 2018 U6 - https://doi.org/10.1029/2017JA025112 SN - 2169-9380 SN - 2169-9402 VL - 123 IS - 6 SP - 4952 EP - 4960 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Srama, Ralf A1 - Kempf, S. A1 - Moragas-Klostermeyer, Georg A1 - Helfert, S. A1 - Ahrens, T. J. A1 - Altobelli, N. A1 - Auer, S. A1 - Beckmann, U. A1 - Bradley, J. G. A1 - Burton, M. A1 - Dikarev, V. V. A1 - Economou, T. A1 - Fechtig, H. A1 - Green, S. F. A1 - Grande, M. A1 - Havnes, O. A1 - Hillierf, J.K. A1 - Horanyii, M. A1 - Igenbergsj, E. A1 - Jessberger, E. K. A1 - Johnson, T. V. A1 - Krüger, H. A1 - Matt, G. A1 - McBride, N. A1 - Mocker, A. A1 - Lamy, P. A1 - Linkert, D. A1 - Linkert, G. A1 - Lura, F. A1 - McDonnell, J.A.M. A1 - Möhlmann, D. A1 - Morfill, G. E. A1 - Postberg, F. A1 - Roy, M. A1 - Schwehm, G.H. A1 - Spahn, Frank A1 - Svestka, J. A1 - Tschernjawski, V. A1 - Tuzzolino, A. J. A1 - Wäsch, R. A1 - Grün, E. T1 - In situ dust measurements in the inner Saturnian system JF - Planetary and space science N2 - In July 2004 the Cassini–Huygens mission reached the Saturnian system and started its orbital tour. A total of 75 orbits will be carried out during the primary mission until August 2008. In these four years Cassini crosses the ring plane 150 times and spends approx. 400 h within Titan's orbit. The Cosmic Dust Analyser (CDA) onboard Cassini characterises the dust environment with its extended E ring and embedded moons. Here, we focus on the CDA results of the first year and we present the Dust Analyser (DA) data within Titan's orbit. This paper does investigate High Rate Detector data and dust composition measurements. The authors focus on the analysis of impact rates, which were strongly variable primarily due to changes of the spacecraft pointing. An overview is given about the ring plane crossings and the DA counter measurements. The DA dust impact rates are compared with the DA boresight configuration around all ring plane crossings between June 2004 and July 2005. Dust impacts were registered at altitudes as high as 100 000 km above the ring plane at distances from Saturn between 4 and 10 Saturn radii. In those regions the dust density of particles bigger than 0.5 can reach values of 0.001m-3. KW - Cassini KW - dust KW - CDA KW - E-ring KW - water ice Y1 - 2006 U6 - https://doi.org/10.1016/j.pss.2006.05.021 SN - 0032-0633 VL - 54 IS - 9-10 SP - 967 EP - 987 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Naafs, B. David A. A1 - Hefter, Jens A1 - Acton, Gary A1 - Haug, Gerald H. A1 - Martinez-Garcia, Alfredo A1 - Pancost, Richard A1 - Stein, Rüdiger T1 - Strengthening of North American dust sources during the late Pliocene (2.7 Ma) JF - Earth & planetary science letters N2 - Here we present orbitally-resolved records of terrestrial higher plant leaf wax input to the North Atlantic over the last 3.5 Ma, based on the accumulation of long-chain n-alkanes and n-alkanl-1-ols at IODP Site U1313. These lipids are a major component of dust, even in remote ocean areas, and have a predominantly aeolian origin in distal marine sediments. Our results demonstrate that around 2.7 million years ago (Ma), coinciding with the intensification of the Northern Hemisphere glaciation (NHG), the aeolian input of terrestrial material to the North Atlantic increased drastically. Since then, during every glacial the aeolian input of higher plant material was up to 30 times higher than during interglacials. The close correspondence between aeolian input to the North Atlantic and other dust records indicates a globally uniform response of dust sources to Quaternary climate variability, although the amplitude of variation differs among areas. We argue that the increased aeolian input at Site U1313 during glacials is predominantly related to the episodic appearance of continental ice sheets in North America and the associated strengthening of glaciogenic dust sources. Evolutional spectral analyses of the n-alkane records were therefore used to determine the dominant astronomical forcing in North American ice sheet advances. These results demonstrate that during the early Pleistocene North American ice sheet dynamics responded predominantly to variations in obliquity (41 ka), which argues against previous suggestions of precession-related variations in Northern Hemisphere ice sheets during the early Pleistocene. KW - aeolian input KW - dust KW - terrestrial higher plant waxes KW - Milankovitch KW - North Atlantic KW - Quaternary Y1 - 2012 U6 - https://doi.org/10.1016/j.epsl.2011.11.026 SN - 0012-821X SN - 1385-013X VL - 317 SP - 8 EP - 19 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Hayes, Christopher T. A1 - Anderson, Robert F. A1 - Fleisher, Martin Q. A1 - Serno, Sascha A1 - Winckler, Gisela A1 - Gersonde, Rainer T1 - Quantifying lithogenic inputs to the North Pacific Ocean using the long-lived thorium isotopes JF - Earth & planetary science letters N2 - Dissolved Th-232 is added to the ocean though the partial dissolution of lithogenic materials such as aerosol dust in the same way as other lithogenically sourced and more biologically important trace metals such as Fe. Oceanic Th-230, on the other hand, is sourced primarily from the highly predictable decay of dissolved U-234. The rate at which dissolved Th-232 is released by mineral dissolution can be constrained by a Th removal rate derived from Th-230:U-234 disequilibria, assuming steady-state. Calculated fluxes of dissolved Th-232 can in turn be used to estimate fluxes of other lithogenically sourced dissolved metals as well as the original lithogenic supplies, such as aerosol dust deposition, given the concentration and fractional solubility of Th (or other metals) in the lithogenic material. This method is applied to 7 water column profiles from the Innovative North Pacific Experiment (INOPEX) cruise of 2009 and 2 sites from the subtropical North Pacific. The structure of shallow depth profiles suggests rapid scavenging at the surface and at least partial regeneration of dissolved Th-232 at 100-200 m depth. This rapid cycling could involve colloidal Th generated during mineral dissolution, which may not be subject to the same removal rates as the more truly dissolved Th-230. An additional deep source of Th-232 was revealed in deep waters, most likely dissolution of seafloor sediments, and offers a constraint on dissolved trace element supply due to boundary exchange. (C) 2013 Elsevier B.V. All rights reserved. KW - dust KW - aerosols KW - thorium KW - boundary exchange KW - North Pacific Ocean KW - GEOTRACES compliant Y1 - 2013 U6 - https://doi.org/10.1016/j.epsl.2013.09.025 SN - 0012-821X SN - 1385-013X VL - 383 IS - 12 SP - 16 EP - 25 PB - Elsevier CY - Amsterdam ER -