Spatial and temporal variability of hydrographic parameters measured in the estuary of the Jaguaribe river (semi-arid region, Northeast, Brazil)

Abstract

The objective of this work is to characterize the spatial and temporal variability of hydrographic parameters collected in April/2007 and May/2008, at two stations (12 hr and 25 hr) in the estuary of the Jaguaribe river (Semi-arid region, Northeast, Brazil). The time series analyses of the hydrographic data collected at fixed stations during the usual rainy months in the region showed a strong annual variation of the measured parameters. In May/2008, waters with low salinity values (<4) have been observed at a station located in the mouth of the Jaguaribe river. In April/2007, the lowest salinity values were observed around 32 at the same location. The temperature, suspended sediment concentration and turbidity time series values are controlled by the tide dynamic at stations located in the estuary mouth and in the mixture zone, showing highest values during low tide conditions and lowest values during high tide conditions. In April/2007, dissolved oxygen values tend to increase with the increase of salinity, whereas in May/2008, the values tend to increase with the decrease of salinity. The values of chlorophyll-a collected in May/2008 in the mixture zone showed an increase in comparison with April/2007.