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71.
Silvia Becagli Emiliano Castellano Omar Cerri Mark Curran Massimo Frezzotti Federica Marino Andrea Morganti Marco Proposito Mirko Severi Rita Traversi Roberto Udisti 《Atmospheric environment (Oxford, England : 1994)》2009,43(5):1051-1058
Firn core methanesulphonic acid (MSA) stratigraphy from Talos Dome (East Antarctica) was compared with anomalies of the satellite-measured sea ice extent (1973–1995) in the Ross Sea and Wilkes Land oceanic sector. In spite of the sparseness of sea ice data, the MSA maxima fit with many positive sea ice anomalies in the Ross Sea. This evidence suggests that marine biogenic activity enhanced by large sea ice cover is an important, but not exclusive, factor in controlling MSA concentration in snow precipitation at Talos Dome. Other than source intensity, differences in regional atmospheric transport mechanisms affect the arrival of MSA-rich aerosol at Talos Dome. To clarify the role of transport processes in bringing biogenic aerosol to Talos Dome, a spectral analysis was applied to the MSA, SOI (South Oscillation Index), and SAM (Southern Annular Mode) record. Synchronicity or phase shift between the chemical signature and atmospheric circulation modes were tested. The variations in the MSA profile have a periodicity of 6.9, 4.9, 3.5, and 2.9 years. The 6.9 and 2.9 year periodicities show a strong positive correlation and are synchronous with corresponding SOI periodicity. This variability could be related to an increase in MSA source intensity (by dimethylsulphide from phytoplanktonic activity) linked to the sea ice extent in the Ross Sea area, but also to an increased strength in transport processes. Both of these factors are correlated with La Niña events (SOI positive values). Furthermore, SAM positive values are related to an increased sea ice extent in the Ross Sea sector and show two main periodicities 3.3 and 3.8 years. These periodicities determine the MSA variability at 3.5 years. However, the effect of intensification of the polar vortex and the consequent reduction in transport process intensity, which reduce the delivery of air masses enriched in MSA from oceanic areas to Talos Dome, make the effect of the SAM on the MSA concentration at Talos Dome less active than the SOI. In this way, snow deposition at the Talos Dome records larger MSA concentration by the combined effects of increased source emissions and more efficient transport processes. The MSA record from Talos Dome can therefore be considered a reliable proxy of sea ice extent when the effect of changes in transport processes in this region of Antarctica is considered. Over the previous 140 years, these conditions occur with a periodicity of 6.9 years. 相似文献
72.
Cécile Fauvelot Francesca Bertozzi Federica Costantini Laura Airoldi Marco Abbiati 《Marine Biology》2009,156(11):2313-2323
Human-made structures are increasingly found in marine coastal habitats. The aim of the present study was to explore whether
urban coastal structures can affect the genetic variation of hard-bottom species. We conducted a population genetic analysis
on the limpet Patella caerulea sampled in both natural and artificial habitats along the Adriatic coast. Five microsatellite loci were used to test for
differences in genetic diversity and structure among samples. Three microsatellite loci showed strong Hardy–Weinberg disequilibrium
likely linked with the presence of null alleles. Genetic diversity was significantly higher in natural habitat than in artificial
habitat. A weak but significant differentiation over all limpet samples was observed, but not related to the type of habitat.
While the exact causes of the differences in genetic diversity deserve further investigation, these results clearly point
that the expansion of urban structures can lead to genetic diversity loss at regional scales. 相似文献
73.
Gravina Paola Sebastiani Bartolomeo Bruschi Federica Petroselli Chiara Moroni Beatrice Selvaggi Roberta Goretti Enzo Pallottini Matteo Ludovisi Alessandro Cappelletti David 《Environmental science and pollution research international》2022,29(57):85815-85828
Environmental Science and Pollution Research - In this study, the anthropogenic contamination in Trasimeno lake (Central Italy) was investigated using three sediment cores spanning over the last... 相似文献