about the size of each sink can account for the remaining anthropogenic N. Thus although anthropogenic N is clearly accwnulating on continents, we do not know rates of individual processes. We predict the anthropogenic N-fixation rate will increase by about 60 % by the year 2020, primarily due

temperature and precipitation rate, moisture source conditions, wind strength and aerosol fluxes of marine, volcanic, terrestrial, cosmogenic and anthropogenic origin. They are also unique with their entrapped air inclusions in providing direct records of past changes in atmospheric trace-gas composition

nally, synonymous and nonsynonymous substitution rates (Box 1) are defined in the context of comparing two DNA sequences, with d S and d N as the numbers of synonymous and nonsynonymous substitutions per site, respectively . Thus, the ratio v 5 d N /d S measures the difference between the two

across three regions in Alaska during the 2005 growing season, and determined the impacts on N-fixation rates, nodule biomass, and stand-level N-fixation inputs. The highest percentage of ramets colonized or dead with canker was found on Tanana River plots, suggesting the epidemic is most severe

. Anthropogenic sources of black carbon, although distributed globally, are most concentrated in the tropics where solar irradiance is highest. Black carbon is often transported over long distances, mixing with other aerosols along the way. The aerosol mix can form transcontinental plumes of atmospheric brown

Abstract. The anthropogenic era is generally thought to have begun 150 to 200 years ago, when the industrial revolution began producing CO2 and CH4 at rates sufficient to alter their compositions in the atmosphere. A different hypothesis is posed here: anthropogenic emissions of these gases first

of the global tropospheric O 3 burden from preindustrial times to present (80% and 50 % in the northern and southern hemispheres, respectively). Anthropogenic emissions of NO x and of CO and hydrocarbons make comparable contributions to the global O 3 increase (60 % and 40 % respectively), even though the local

for climate system properties (climate sensitivity, rate of deep-ocean heat uptake, and the net aerosol forcing strength) that include the effect on 20th century temperature changes of natural as well as anthropogenic forcings. The additional natural forcings, primarily the cooling by volcanic

Abstract-Determination of the naturally occurring radionuclides 232Th 23sTh “*Th and 2’sPb, and the anthropogenic radionuclides “‘Am 23g*2?‘u, ‘34Cs and r3’Cs in water samples collected across the Nansen Basin from the Barents Se: slope to the Gakkel Ridge provides tracers with which

to the size-dependent force of fishing mortality. Large-harvested populations initially produced the high-est catch but quickly evolved a lower yield than controls. Small-harvested popu-lations did the reverse. These shifts were caused by selection of genotypes with slower or faster rates of growth