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Titolo:
THE IMPACT OF DESICCATION OF A FRESH-WATER MARSH (GARCINES NORD, CAMARGUE, FRANCE) ON SEDIMENT WATER VEGETATION INTERACTIONS .1. THE SEDIMENT CHEMISTRY
Autore:
DEGROOT CJ; VANWIJCK C;
Indirizzi:
STN BIOL TOUR VALAT,ASSOC LEIDEN CAMARGUE F-13200 ARLES FRANCE
Titolo Testata:
Hydrobiologia
fascicolo: 1, volume: 252, anno: 1993,
pagine: 83 - 94
SICI:
0018-8158(1993)252:1<83:TIODOA>2.0.ZU;2-S
Fonte:
ISI
Lingua:
ENG
Soggetto:
PHOSPHATE; SOIL;
Keywords:
FRESH-WATER MARSH; DRYING; SEDIMENT CHEMISTRY; PHOSPHATE; MINERALIZATION; DENITRIFICATION; WETLAND MANAGEMENT;
Tipo documento:
Article
Natura:
Periodico
Citazioni:
27
Recensione:
Indirizzi per estratti:
Citazione:
C.J. Degroot e C. Vanwijck, "THE IMPACT OF DESICCATION OF A FRESH-WATER MARSH (GARCINES NORD, CAMARGUE, FRANCE) ON SEDIMENT WATER VEGETATION INTERACTIONS .1. THE SEDIMENT CHEMISTRY", Hydrobiologia, 252(1), 1993, pp. 83-94

Abstract

The impact of desiccation on a marsh sediment was studied both in thelaboratory and in the field. Changes in the sediment chemistry of a homogenized sediment suspension during desiccation were studied in the laboratory. FeS was oxidized completely. A considerable mineralizationof organic phosphate took place, from both the acid soluble organic phosphate fraction and from the residual organic phosphate fraction, but no significant mineralization of organic matter was observed. The o-P formed during the mineralization was recovered partly in the Fe(OOH)almost-equal-to P fraction and partly in the CaCO3 almost-equal-to P fraction. An upward flux was found. During spring and summer 1990 the water inlet to a shallow permanent freshwater marsh with a surface of about 1.5 hectares was blocked, in order to desiccate the marsh by evaporation. The sediments initially consisted of a black anoxic organic top layer and a less organic anoxic gray layer. During the desiccationof the sediment a brown oxic surface layer was formed from the black layer and an increase of pH and Eh occurred. Subsequent rainfall made the Eh increase further but caused a decrease in pH indicating an increase in bacterial activity. A progressive oxidation of FeS was observed. An increase in Tot-P in the surface layer and a decrease in the gray and the black layer of the sediment occurred, probably due to a capillary upward flux. A mineralization of organic matter was observed in the two deeper layers. In the upper brown layer this mineralization was less evident, probably because it has been masked by the capillary movement. A net C loss of 40% was calculated to have occurred in the layer 0-40 cm. In the deeper layers a decrease in Tot-N was observed, whereas no important increase occurred in the top layer. Over a sedimentlayer of 40 cm a N loss of 50% was calculated. C- and N losses occurred simultaneously, suggesting the importance of mineralization as a source of inorg-N for denitrification. The chemical and physical changesin the sediment during desiccation affected layers down to 40 cm. This means that not only the top layer of a sediment but also deeper layers are active in systems of which part of the sediment dries occasionally. Fractionation of the surface sediment phosphate showed an increase of Fe(OOH) almost-equal-to P in the top layer due to the oxidation of FeS to Fe(OOH), enlarging the P-adsorption capacity of the sediment. A mineralization of about 50% of acid soluble organic phosphate occurred. After rainfall, a net increase in residual organic phosphate occurred presumably due to an increase of bacterial activity. Drying may therefor be utilized as a tool, in wetland management, to eliminate organic nitrogen and carbon from the sediment. In rice culture, it may beused to make part of the organic nitrogen available to the rice.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 26/09/20 alle ore 07:51:40