Lability of DOC transported by Alaskan rivers to the Arctic Ocean

Author Posting. © American Geophysical Union, 2008. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 35 (2008): L03402, doi:10.1029/2007GL032837.Arctic rivers transport huge quantities of dissolved organic carbon (DOC) to the Arctic Ocean. The prevailing paradigm is that DOC in arctic rivers is refractory and therefore of little significance for the biogeochemistry of the Arctic Ocean. We show that there is substantial seasonal variability in the lability of DOC transported by Alaskan rivers to the Arctic Ocean: little DOC is lost during incubations of samples collected during summer, but substantial losses (20–40%) occur during incubations of samples collected during the spring freshet when the majority of the annual DOC flux occurs. We speculate that restricting sampling to summer may have biased past studies. If so, then fluvial inputs of DOC to the Arctic Ocean may have a much larger influence on coastal ocean biogeochemistry than previously realized, and reconsideration of the role of terrigenous DOC on carbon, microbial, and food-web dynamics on the arctic shelf will be warranted.This material is based on work supported by the National Science Foundation under grant numbers OPP-0436106, OPP- 0519840, and EAR-0403962, and is a contribution to the Study of Environmental Arctic Change (SEARCH)

Vocabulari de botànica: català, castellà, francès, anglès

Vocabulari quadrilingüe català-castellà-francès-anglès que conté 1571 termes de botànica

A cytological study of four Sicilian Serapias

Cytological analysis of four Serapias L. (Orchidaceae), of which two are Sicilian endemics, is carried out. In particular, the endemic S. intermedia subsp. hyblaea shows a triploid chromosome complement with 2n = 3x = 54, representing natural nothotaxa arising from a hybridization process between supposed parental S. vomeracea (2n = 2x = 36) and Serapias lingua (2n = 4x = 72). For each of them the C-heterochromatin distribution, using Giemsa C-banding and karyotypes, was examined. The other endemic taxon (S. orientalis subsp. siciliensis) is characterized by a diploid chromosome number 2n = 2x = 36, of which the C-heterochromatin distribution is examined as well. The taxonomical relationships among these taxa are discussed in relation to the literature data