Anderson Luiz Ribeiro de Paiva

Origins and processes of groundwater salinization in the urban coastal aquifers of Recife (Pernambuco, Brazil): A multi-isotope approach

In the coastal multilayer aquifer system of a highly urbanized southern city (Recife, Brazil), where groundwaters are affected by salinization, a multi-isotope approach (Sr, B, O, H) was used to investigate the sources and processes of salinization. The high diversity of the geological bodies, built since the Atlantic opening during the Cretaceous, highly constrains the heterogeneity of the groundwater chemistry, e.g. Sr isotope ratios, and needs to be integrated to explain the salinization processes and groundwater pathways. A paleoseawater intrusion, most probably the 120 kyB.P. Pleistocene marine transgression, and cationic exchange are clearly evidenced in the most salinized parts of the Cabo and Beberibe aquifers. All (87)Sr/(86)Sr values are above the past and present-day seawater signatures, meaning that the Sr isotopic signature is altered due to additional Sr inputs from dilution with different freshwaters, and water-rock interactions. Only the Cabo aquifer presents a well-delimitated area of Na-HCO3 water typical of a freshening process. The two deep aquifers also display a broad range of B concentrations and B isotope ratios with values among the highest known to date (63-68.5‰). This suggests multiple sources and processes affecting B behavior, among which mixing with saline water, B sorption on clays and mixing with wastewater. The highly fractionated B isotopic values were explained by infiltration of relatively salty water with B interacting with clays, pointing out the major role played by (palaeo)-channels for the deep Beberibe aquifer recharge. Based on an increase of salinity at the end of the dry season, a present-day seawater intrusion is identified in the surficial Boa Viagem aquifer. Our conceptual model presents a comprehensive understanding of the major groundwater salinization pathways and processes, and should be of benefit for other southern Atlantic coastal aquifers to better address groundwater management issues.

Groundwater management in Recife

In developing countries, the rapid urbanization in the second half of the twentieth century provoked radical changes in the cities with serious water related problems, such as freshwater scarcity, sewage and drainage problems. This growth produced several impacts on groundwater resources such as land impermeabilization and change in groundwater recharge, excessive exploitation and groundwater pollution. These facts have demanded better planning and management, especially in areas with high dense population. In Brazil, water legislation has been approved by parliament, a water agency has been created and technical knowledge of water resources has improved. Management strategies incorporated several issues: planning, legislation, zoning, licensing, concession and controlling. Monitoring, hydrochemical analyses and groundwater modeling have been performed to obtain more information for better management towards sustainability.

Occurrence of Cryptosporidium spp., Giardia spp. and other pathogenic intestinal parasites in the Beberibe River in the State of Pernambuco, Brazil

INTRODUCTION Transmission of pathogenic protozoa and helminths by water is a serious public health problem. In this study, we analyzed the presence of these organisms in the Beberibe River in Pernambuco, Brazil. METHODS Parasite analysis was performed using the Hoffman, Pons, & Janer method followed by centrifugation and preparation of slides by staining with acetic acid and Lugols solution. Protozoan oocysts were isolated by the modified Ziehl Neelsen method. RESULTS Cryptosporidium spp., Giardia spp. and other parasites were found in the Beberibe River. CONCLUSIONS Sanitation companies must assess pathogenic intestinal parasites in water basins providing public water and subsequently develop improved treatment systems for removal of such parasites.

Vertical hydraulic gradient research in hyporheic zone of Beberibe river in Pernambuco State (Brazil)

The interaction between groundwater and surface water occurs naturally and is dependent on the dynamics in the hyporheic zone. The hyporheic zone is the interface between the surface water source and the phreatic aquifer and it’s a system that also influences the water quality. An important feature is the ability to flux in this zone. This work aimed to evaluate the vertical hydraulic gradient in the hyporheic zone at two points in Beberibe river, Olinda-PE, to understand the hyporheic environment characteristics and water flow dynamics in experimental area, in addition to identify the existence of hydraulic connection between surface water and groundwater. The experimental phase consisted of infiltration tests in riverbed with cylinder infiltrometer and vertical hydraulic gradients readings with differential piezometer, complemented with grain size information, for an assessment of the water budget between the river and the aquifer. Analyzing the behavior of the interaction over the period of 10 months, it was observed that the Beberibe river (middle course) contributes to the groundwater recharge in most of the time. The average infiltration rate was 1.02 mm/min in point 1 and 0.85 mm/min in point 2. It was concluded that there is a variability in flow direction, which often is top-down, but may undergo change in the stream showing upstream after long periods of rainfall. Another conclusion is that grain size distribution of bed sediment, that is predominantly sandy, influences hydraulic conductivity of hyporheic zone and influences consequently the vertical flow rates.