Resumo

TOVILLA HERNANDEZ, Cristian  e  DE LA LANZA ESPINO, Guadalupe. Hidrological and nutrient balances in a costal wetland in Southern Pacific of Mexico. Hidrobiológica [online]. 2001, vol.11, n.2, pp.133-140. ISSN 0188-8897.

Coastal lagoons can export or import different amount of materials according to the geographical localization and fluvial and marine regimes associated to them. Taking this in account, water, salinity and nutrient balances (NO², NO₃, NH₄, PO₄) were measured in coastal wetland. The volume of fresh water that penetrated into the wetland was different in the two years (1991 and 1992), with a 0.87m³/s average. It was high in September (1.62m³/s) and low in April (0.37m³/s) with 31.4 × 10⁶ m³/yr. Marine water was more constant with an average per year of 1.72 m³/s and 28.5 × 10⁶/yr. This situation favored to oligohaline condition. Nitrates were the most abundant with a high input of 7.5 µM in June (16.8 µM) and low input of 1.6 mM in December. The exportation was twice the importation with an average of 14.5 µM. The ammonium and nitrites were second in place in exportation. The fluvial input of orthophosphates to wetland was less than to the sea exportation. The wetland received 33.7 tons of nutrients during the rainy season and 14.5 tons during the dry season. The lower amount caused by a diminishing river flow. The export of nutrients from the wetland was greater than the import, with 86.5 ton/yr vs 48.2 ton/yr respectively. The former meaning a great marine nutrient enrichment by consequence of the mangrove area.

Palavras-chave : Coastal wetland; hydrology and nutrient balances.

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