35 P 17 Particulate aluminium and iron in rainwaters at Amsterdam Island (South Indian Ocean)

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Assessing the actual size distribution of atmospheric aerosols collected with a cascade impactor

International audienceA set of elemental mass-particle size distributions is obtained from a low volume cascade impactor whose characteristics are discussed. The data processing used [Puttock's data inversion fitting technique; Puttock, J. S. (1981) Atmos. Envir. 15, 1709], shows that bounce-off can severely affect the interpretation of data when the ambient aerosol presents a coarse mode of dust particles (D > 2 #m). This study proposes an improvement of the fitting method, for correcting experimental mass-particle size distributions for these particle bouncing effects when usual preventive procedures cannot be applied. The bounce-off contribution to the final filter of the impactor could be estimated by a microscopic examination and compared to the one predicted by the method developed in this work

14.P.12 Long-range atmospheric transport of aerosols to the Southern Indian Ocean (Amsterdam Island: 37° 48′ S 77° 34′ E)

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Evaluation of the Effect of Crop Rotations on Yield and Yield Components of Bread Wheat (Triticum aestivum L. cv. Darya)

Grain yield in wheat is influenced directly and indirectly by other plant characteristics. One of the main goals in wheat breeding programs is increase of grain yield. Considering the role of crop rotation in increasing grain yield, and in order to study the difference between crop rotations for wheat yield and yield components (Darya cultivar), an experiment was conducted with six rotation treatments (wheat-chickpea-wheat, wheat-cotton-wheat, wheat-watermelon-wheat, wheat-wheat-wheat, wheat-canola-wheat and wheat-sunflower-wheat), as a randomized complete blocks design with six replications, at Research Farm of Agricultural Research Station of Gonbad Kavous, Iran, during 2004 to 2008. Results showed that number of spikes per m-2, number of kernels per spike and mean kernel weight were important traits in all rotations. Also, selection of different traits could be changed depending on the experiment’s conditions, as in the wheat-wheat-wheat, wheat-watermelon-wheat and wheat-sunflower-wheat rotations the kernel weight, grain filling period and vegetative growth period are useful for indirect selection of breeding strategy while in wheat-canola-wheat and wheat-chickpea-wheat rotations the number of kernels per spike, number of spikes per m2, grain filling period and vegetative growth period are more important

Atmospheric input of trace metals to the western Mediterranean Sea: 1. Factors controlling the variability of atmospheric concentrations

The factors controlling the variability of atmospheric trace metal concentrations over the western Mediterranean Sea have been investigated using a combination of geochemical and meteorological approaches. Al, Br, Cd, Na, Pb and 210Po concentrations from bulk filters and cascade impactor samples collected during five cruises (1980–1983) have been used to characterize the aerosol sources: the marine source (Na), the aeolian soil mobilization (Al), the anthropic sources (Cd, Pb), and the volcanic source (210Po). It has been confirmed that Cd and Pb directly derive from anthropic sources. As shown by three‐dimensional air mass trajectory analyses, the variability of daily atmospheric concentrations reflects both changes in continental source strengths and in airflow patterns. Atmospheric concentrations appear to be higher during episodes of short‐range transport of continental material from riparian countries. It is suggested that such source regions can be precisely identified by a careful examination of both geochemical data and three‐dimensional trajectories. From our data set, southwestern Europe would be responsible for the largest Pb and Cd inputs to the western Mediterranean atmosphere (30–40%), but the inputs from North Africa are also likely to be significant (20–25%). However, it cannot be ascertained whether this conclusion is valid on a yearly time scale. Indeed, whereas our sample set is representative of the yearly airflow climatology, it has not been possible to assess the effect of seasonal (for Pb) or sporadic (for Al) changes in source strengths. This points out that over such a marine environment, continuous sampling programs are needed to assess the respective contributions of individual source regions to the atmospheric burden of particulate trace elements

The origin of particulate organic carbon in the marine atmosphere as indicated by its stable carbon isotopic composition

International audienceOrganic carbon concentration and isotopic composition were determined in samples of atmospheric particulate matter collected in 1979 at remote marine locations (Enewetak atoll, Sargasso See) during the SEAREX (Sea-Air Exchange) program field experiments. Atmospheric Particulate Organic Carbon (POC) concentrations were found to be in the range of 0.3 to 1.2Bg.m-B, in agreement with previous literature data. The major mass of POC was found on the smallest particles (r<O.5•m)

Multiparametric investigation of North Sea particulate matter. Preliminary results in the Skagerrak

During the Tramanor cruise, in July 1988, seawater and particle samples were collected along a vertical profile (530 m depth) located in the Skagerrak, a crossing-area for different water-masses and particle pools. A sampling strategy was developed to ensure the homogeneity of the different sets of subsamples subjected to analysis by closely-coupled complementary techniques: turbidimetry, granulometry, scanning electron microscope (SEM) observations, Tracor analyses, particulate organic carbon and nitrogen measurements, and neutron activation analysis (NAA). The Baltic outflow is found in the topmost 20 m water-column (salinity approximately equals 23.5; temperature approximately equals 18 degree C) overlying North Sea waters (salinity approximately equals 35; temperature approximately equals 6 degree C). Surface waters undergo a plankton bloom, dominated by Dinoflagellates and Coccolithophoridae. The former, characterized by high C/N ratios ( approximately equals 15; cellulosic thecae), play a significant role in the biological recycling of Zn. The latter accumulate over the halocline as typically observed in frontal structures. The detrital phase mainly consists of clay minerals. Manganese is highly enriched relative to shale-type material together with Fe, Co and Zn

Quantitative Remote Sensing of African Dust Transport to the Mediterranean

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Decadal variability of sea surface temperatures off North Iceland over the last 2000 years

International audienceOcean variability at decadal time-scales remains poorly described partly because of the scarcity of high temporal resolution marine records. Here, we present a reconstruction of Sea Surface Temperatures (SSTs) over the past twomillennia at unprecedented temporal resolution (2 to 5 years), from a marine core located off North Iceland. Alkenone paleothermometry was used to infer SST variability, and tephrochronology to build the age model. Spectral analyses of the SSTsignal indicate intermittent 20–25 year oscillations, with periods of strong and weak power, that are likely reflecting the ocean response to wind forcing, presumably the North Atlantic Oscillation (NAO). Warmer SSTs and paleo-magnetic proxy data, between 1000 and 1350 year A.D., overlapping theMedievalWarm Period (MWP), suggest enhanced heat transport across the Denmark Strait by the North Icelandic IrmingerCurrent (NIIC). This is in contrast with the subsequent period, which includes the Little IceAge (LIA), showing continuous cooling towards the 20th century.Reduced NIIC flow through theDenmark Strait likely resulting from higher freshwater and sea ice export from the Arctic would account for the observed colder conditions