As condições pedogeoquímicas da planície flúvio-marinha do Rio Apodi-Mossoró (RN) e a ocupação humana para atividades econômicas

Abstract

The fluvio-marine plains are related to continental and oceanic factors, giving rise to estuaries, environments where contact, mixing and dilution of sea water and river water occur. In the northern area of Rio Grande do Norte (RN), due to the geomorphological and climatic conditions, these plains are characterized as hypersaline environments, since the potential evapotranspiration exceeds the rainfall rates, characterizing the estuary as negative and providing the appearance of different environments adapted to salinity levels; however, they face constant occupation even in unfavorable circumstances for some activities. The objective of this research was to evaluate the pedogeneochemical conditions for the development of human activities in the fluvio-marine plain of the ApodiMossoró river (RN), located in the Brazilian semi-arid region. For this, soil samples were collected at different depths in environments of the upper estuarine course, the least occupied sector. Laboratory analyzes indicated high concentrations of Na+, Ca2+ and Mg2+; the results characterized the soil with sodic classification, salic character and moderately alkaline condition, circumstances caused by the influence of dry weather and progressive evaporation of seawater in the supratidal area. The granulometry of the sediments, however, indicated a predominance of finer particles such as silt and clay in the textural composition. To identify and monitor the potential for economic activities, the DPSIR structure (Demand-Pressure-State-Impact-Response) was used, which is capable of providing an analysis of the systemic relationships between anthropic and environmental actions. With this, bibliographic surveys and Control Listing (Check-List) were carried out to identify the main indicators that characterize the problem. The results revealed that the plain under study has the ability to meet the demands for food, energy and real estate space, through by shrimp farming, salt industry, fishing, livestock, agriculture, onshore oil activity and population growth; however, these pressures have impacts, being the more significant the loss of biodiversity and changes in the natural composition of the soil. To mitigate this damage and ensure sustainability, the main responses were inspection based on environmental standards and the implementation of environmental sanitation.