Characterization of groundwater exposed in sand mining pits and evaluation of its use in sunflower germination
Water quality, water resources, irrigation, Helianthus annuus L..
The world faces recurring water crises, making the use of alternative water sources a fundamental strategy for water sustainability. Concomitantly, intense sand mining, especially in the Seropédica-Itaguaí-RJ region, has generated extensive lagoons in abandoned pits, creating reservoirs with significant volume that lack a use. Therefore, this study proposes an approach for sustainable agriculture and energy transition. The overall objective is to evaluate the potential use of groundwater exposed in sand pits (GSP) for irrigation and cultivation of a bioenergy species, sunflower (Helianthus annuus L.). The study methodology is divided into two main stages. In the first, the physicochemical characterization of the GSP will be carried out, collected bimonthly in active and inactive pits. The samples will be analyzed to determine parameters such as pH, electrical conductivity, total dissolved solids, and the concentrations of macro and microelements, including heavy metals. Based on this data, the quality of the GSP (aquatic water) will be classified using indicators that consider its risks and potential for the soil and plant. The second stage consists of evaluating the viability of using GSP in the initial development of sunflower and lettuce (Lactuca sativa L.) seedlings, the latter being used as an indicator of phytotoxicity, through germination tests. Germination, Germination Speed Index, seedling morphometry, mass, and abnormal seedlings were evaluated using GSP from different pits and distilled water. The results demonstrated that, although the GSPs present hydrogeochemical restrictions mainly related to acidity and the presence of metals, these waters were able to sustain high germination performance and adequate initial seedling development. Thus, it is concluded that sand pit waters have potential for agricultural use, provided they are subjected to continuous hydrogeochemical monitoring and specific management.