File:ESPECIACIÓN QUÍMICA DE FÓSFORO EN SEDIMENTOS SUPERFICIALES DEL GOLFO DE PARIA Y EN LA COSTA ATLÁNTICA VENEZOLANA.pdf

The sequential extraction method SEDEX (sedimentary extraction) modificated by ANDERSON & DELANEY (2000) has been used to quantify separately four sedimentary phosphorus reservoirs in sediments of the gulf of Paria and the venezuelan atlantic coast: adsorbed or labile plus P-associated to oxides (F1), P-authigenic (F2), P-detrital (F3) and P-organic (F4). The marine and continental origin of the sediments was determined by separation of detrital apatite (continental) and carbonate fluorapatite (CFA) of marine origin. The total phosphorus concentrations are low within the gulf of Paria and the atlantic venezuelan coast in comparison with other coastal areas (2.38 mmol g-1 to 6.84 mmol g-1) and is mainly in detrital form (0.78 to 4.61 mmol g-1). In decreasing order the concentrations are: organic (0.56 a 2.47 mmol g-1), adsorbed or labile phosphorus plus associated oxides (0, 04 to 0. 56 m mol g-1) > autigenic phosphorus (0.04 to 0.31 m mol g-1) and (0.10 to 1.34 %). ANOVA statistical tests (P < 0.05) show discrepancies only in the concentrations of the adsorbed or labile phosphorus plus associated oxides fractions, values being lower in the gulf of Paria. The results suggests, that the principal sources are terrestrial lithogenic apatite from eroded material of the orogenic belts of the coastal Andes and Guayana shield and venezuelan and colombian plains which was then carried by waters of the Orinoco river and redistributed there. The organic material contribution of native origin and aloctonal is the second factor that controls the presence of phosphorus in the sediment. The marine contributions are noted towards the northeast end typified by the presence of carbonate fluoroapatite, indicating of transformation processes within the sediment.