Physico-chemical assessment of sediments of Tamarindo estuary and its tributaries, Guanacaste, Costa Rica

Sediments of Tamarindo estuary and its tributaries were evaluated in order to determine the effect of anthropogenic activities of the surrounding communities. The evaluation relied on texture, total phosphorus, organic matter, and heavy metal (Pb, Cu, Ni and Cr) analyses. The study spanned four sampling campaigns between October 2007 and April 2008, including four climatic seasons: rainy season, rainy-dry transition, dry season and dryrainy transition. Five sampling points were selected at Tamarindo estuary and three additional sites were set at Matapalo, Lomas and Lajas rivers. Ontario Ministry of the Environment regulation was used to evaluate sediment quality. It was determined that theanthropogenic activities of the surrounding communities exert a negative impact over the sediment quality; the pollution effect caused by such activities was rated as lower effect.

Variability of thermohaline properties in Pearl Lagoon, Nicaragua (ESP)

Several hydrographic surveys were carried out in Pearl Lagoon, Nicaragua between april 1995 and december 1997 under the DIPAL (Proyecto para el Desarrollo Integral de la Pesca Artesanal en la Región Autónoma del Atlántico Sur) project. Surface temperature, salinity, dissolved oxygen and turbidity have been measured in 88 hydrographic campaigns. The annual cycle shows maximum and minimum temperatures in May (29.4 °C) and December (25.6 °C) respectively, maximum salinity (25.6 °C) in April, one month before the thermal peak, and minimum salinities (2‰) between July and August, when the annual precipitation index attains its seasonal maximum in the study area. In the case of dissolved O2 the maximum values of oxygen saturation were observed between March and May (90%), when the water turbidity in the lagoon is at its lowest and freshwater contributions from the rivers attains its minimum value. During the rainy season, in the second half of the year, there is an important decrease in oxygen contents, mainly as a consequence of the degradation of organic matter of riverine origin.