نتایج جستجو برای: anthropogenic source
تعداد نتایج: 440868 فیلتر نتایج به سال:
Land-use changes until the beginning of the 20(th) century made the terrestrial biosphere a net source of atmospheric carbon. Later, burning of fossil fuel surpassed land use changes as the major anthropogenic source of carbon. The terrestrial biosphere is at present suggested to be a carbon sink, but the distribution of excess anthropogenic carbon to the ocean and biosphere sinks is highly unc...
We use recent aircraft measurements of a comprehensive suite of anthropogenic halocarbons, carbon monoxide (CO), and related tracers to place new constraints on North American halocarbon emissions and quantify their global warming potential. Using a chemical transport model (GEOS-Chem) we find that the ensemble of observations are consistent with our prior best estimate of the U.S. anthropogeni...
Several potential dust sources, including generic sources of sparsely vegetated alluvium, playa deposits, and anthropogenic emissions, as well as the area around Owens Lake, California, affect the composition of modern dust in the southwestern United States. A comparison of geochemical analyses of modern and old (a few thousand years) dust with samples of potential local sources suggests that d...
Rivers are an important source of mercury (Hg) to marine ecosystems. Based on an analysis of compiled observations, we estimate global present-day Hg discharges from rivers to ocean margins are 27 ± 13 Mmol a(-1) (5500 ± 2700 Mg a(-1)), of which 28% reaches the open ocean and the rest is deposited to ocean margin sediments. Globally, the source of Hg to the open ocean from rivers amounts to 30%...
Climate Change has emerged as one of the grand global challenges facing humanity. The dominant anthropogenic greenhouse gas that seems to be contributing to the climate change problem, carbon dioxide (CO2), has a complex cycle through the atmosphere, oceans and biosphere. The combustion of fossil fuels (power production, transportation, etc.) remains the largest source of anthropogenic CO2 to t...
[1] Aerosol is an important source of uncertainty concerning the role of the atmosphere in climate forcing. In particular, major gaps exist with respect to its carbonaceous fraction in terms of composition, source apportionment (natural versus anthropogenic), change over the past, and radiative impact. The CARBOSOL project contributes to reduce these uncertainties. CARBOSOL combines a 2-year st...
Carbon monoxide is a colorless, odorless, non-irritating, and tasteless gas that is ubiquitous in the atmosphere. It arises from both natural and anthropogenic sources. It is produced as a primary pollutant during the incomplete combustion of fossil fuels and biomass. Carbon monoxide is also produced indirectly from the photochemical oxidation of methane and other volatile organic compounds (VO...
Owing to the methane (CH4) produced by rumen fermentation, ruminants are a source of greenhouse gas (GHG) and are perceived as a problem. We propose that with appropriate regenerative crop and grazing management, ruminants not only reduce overall GHG emissions, but also facilitate provision of essential ecosystem services, increase soil carbon (C) sequestration, and reduce environmental damage....
An investigation of atmospheric mercury was conducted in the urban coastal zone of the Gulf of Gdansk (Baltic Sea, Poland) in 2008. Rainwater samples were collected in bulk samplers and Hg concentration was determined using AAS method. Total mercury concentration ranged from 1.9 to 14.8 ng l(-1) (the mean was 8.3 ng l(-1) with standard deviation ±3.7), out of which about 34 % were water-soluble...
Future stratospheric ozone concentrations will be determined both by changes in the concentration of ozone depleting substances (ODSs) and by changes in stratospheric and tropospheric climate, including those caused by changes in anthropogenic greenhouse gases (GHGs). Since future economic development pathways and resultant emissions of GHGs are uncertain, anthropogenic climate change could be ...
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