Eduardo Chemas Hindi

A influência das atividades mineradoras na alteração do pH e da alcalinidade em águas fluviais: o exemplo do rio Capivari, região do carste paranaense

Mining activities causes many kinds of environmental impacts over environment. In this paper we describe the research developed in the Capivari watershed, in the Curitiba metropolitan region, Parana, Brazil. Alkalinity and pH changes in Capivari stream over 12 years were observed. The sampling program was performed in 387 sampling days series at 1986/1987, and another period covering 1,095 days from 1998 to 2000. Comparing these series, the pH average was higher in 0,5 unities and the alkalinity were 15% higher within this period of time. From 1980 to 2001, mining areas of metadolomites spread out to an average rate of 47,000 m2/year. Field evaluations carried out on the Capivari stream showed that in regions close to low water streams and closer to stone-pits, the pH level was higher and it became more alkaline as the electric conductivity increased. These data support the hypotheses that the expansion of mining areas would affect the pH and the alkalinity of the Capivari stream.

SISTEMA PARA INFILTRAÇÃO DAS ÁGUAS PLUVIAIS NO SOLO E SUBSOLO DA BACIA DE CURITIBA EM VIAS URBANIZADAS

The development of the cities, no matter how orderly it is, changes the environment. Where there used to be fields and forests, there are now buildings, paved streets, galleries of pluvial waters, etc. The covering of land with impermeable surfaces is one of the factors that changes the hidrological cycle, because it obstructs the water percolation to the underground and increases the runoff, which causes floods, erosions and sedimentations. The underground water flow is substantially altered because it is not recharged, therefore, it does not feed the rivers at dry seasons anymore causing a decrease of the river flow. In this context, we see the importance of the geological study of Curitiba region, in order to implement a system which can infiltrate the pluvial waters. The objective of this study so, is to create a system of pluvial water flow control on public streets in a small scale, through the installation of “gully pots” made up with a contention and infiltration system of these waters at two points with different litologic features, the Guabirotuba’s Formation and the Atuba Complex, in the insaturated layer of the soil and subsoil of Curitiba’s sedimentary basin. The system will allow for the softening of these environmental changes, refeeding the underground water, keeping the river level in dry seasons and will mitigate the consequences of the floods, erosions and sedimentations in intensive rain seasons.

IDENTIFICAÇÃO DA ZONA DE DISPERSÃO SALINA COM APLICAÇÃO DOS MÉTODOS ELÉTRICO E ELETROMAGNÉTICO NO DOMÍNIO DA FREQÜÊNCIA NO AQÜÍFERO COSTEIRO DE PLAYA PANAMÁ, COSTA RICA

In Costa Rica, only a few coastal aquifers have been studied with the employment of geophysical methods. No scientific investigation which uses simultaneously two different methods to analyze the hydrogeologic properties of coastal aquifers, particularly to define salt intrusion has been done before in the area of study.The aquifer of Playa Panama, localized on the Pacific Coast, in the northwest part of the country (picture 1), has a moderate hydric potential, to be used for tourist purposes. The Average monthly rainfall in the region is 1944 mm/year, the potencial evapotranpiration is of 1930 mm/year (table 1). The aquifer is composed of basaltic angular conglomerates, mainly eroded from the Nicoya Complex. The aquifer geometry was analyzed through the application of Vertical Electrical Soundings (VESs) using a Schlumberger array, and conductivity measurement in the frequency domain. The results were complemented with stratigraphic, hydrogeological and hydrochemical data and suggest a decreasing of the aquifer’s thickness towards the sea, and a non polluted condition. The saline dispersion zone was also studied with both techniques, together with an electric section obtained with Wenner array. Both methods showed a high sensitivity in the area corresponding to the salt intrusion (pictures 8,9), which occurs at a depth of 15 m in the sediments and at a distance not exceeding 65 m landward from the high tide line.

A IMPORTÂNCIA DO SISTEMA AQÜÍFERO SERRA GERAL PARA A CULTURA DA SOJA NO ESTADO DO PARANÁ

The lack or insufficient amount of rain fall during the blooming and growing periods of soybeans are one of the major factors that cause either complete loss or large reductions of harvest areas in the southern region of Brazil . Within the Parana State the soybeans agriculture covers an area of approximately 3,650,000 hectares (36,500 km 2 ), which is equivalent to nearly 18.3% of the State’s total geographical surface. Hence, these areas need a minimum of 30 mm per month of rain fall in order to maintain the sustainable activity in the long term, taking for instance the extensive loss of soybeans crop that took place in February 2005 due to the lack of rain. In order to flourish, soybeans needs 1 L.day -1 .m -2 . The yield of wells drilled into the Serra Geral Aquifer System (SASG) can vary from 21 a 35 m 3 .h -1 , with the exception of the ones drillled inside the Iguacu river basin, that show average yield of 5 m 3 .h -1 . In almost 90% of the wells, water can be found within less than 170 m deep. In wells which discharges vary from 25 m 3 .h -1 to 100 m 3 .h -1 , their capacity to irrigate an soybean crop, can cover an area of 600,000 m 2 and 2,400,000 m 2 , respectively. SASG waters presenta low to medium sodium risk and also a predominately low risk of salinity.