Natural isotopic composition of nitrogen as a tracer of origin for suspended organic matter in the Scheldt estuary     

André Mariotti  Christiane Lancelot  Gilles Billen 《Geochimica et cosmochimica acta》1984,48(3):549-555

The natural isotopic composition of suspended particulate organic nitrogen was determined in the Southern Bight of the North Sea and in the Scheldt estuary. These data show that δ¹⁵N constitutes a convenient tracer of the origin of the suspended matter.In the winter, in the absence of intensive primary production, the suspended organic matter of the Scheldt estuary is a mixture of two components: a continental detrital component characterized by a low δ value of 1.5%. and a marine component with a mean δ value of 8%..During the phytoplankton flowering period, lasting from early May to October, intensive primary production occurs throughout the estuary giving rise to a third source of organic matter. This material is characterized by high δ values reflecting the isotopic composition of ammonia, the nitrogenous nutrient assimilated by phytoplankton in the estuary.The nitrification process occuring in the mixing area of the Scheldt estuary leads to higher downstream δ values of ammonia (>20%.) which permits the distinction between estuarine from fresh-water phytoplankton. Simple isotopic budget calculations show that, both in the upstream part and in the downstream part, autochthonous phytoplanktonic material contributes a major part of the total suspended matter in the Scheldt estuary during summer.  相似文献   

Geochemical and biogeochemical observations on the biological communities associated with fluid venting in Nankai Trough and Japan Trench subduction zones   总被引：1，自引：0，他引：1  

J. Boulgue  E.L. Benedetti  D. Dron  A. Mariotti  R. Ltolle 《Earth and Planetary Science Letters》1987,83(1-4)

We have studied the compositions and structure of the lamellibranchiaCalyptogena sp associated with fluid venting in subduction zones off Japan. The gills of theCalyptogena are the habitat of symbiotic bacteria which develop owing to chemoautotrophy. They most probably assimilate hydrogen sulfide, methane and/or carbon dioxide and reduce nitrogen. The isotopic budget of methane uptake enables to establish the thermal diagenetic origin of the light hydrocarbons brought by the upwelling fluids. The microscopic examination of thin sections of the bacteria enables to establish that their membranes are compatible with uptake of inorganic nutrients and to establish relations with the metabolism of archeobacteria.  相似文献