Caracterização morfopedológica como subsídio à análise de vulnerabilidade frente à contaminação

Abstract

The characteristics of the relief influence the distribution of soils along the slopes and may also interfere in the diffusion and mobilization processes of the contaminant through the soil, keeping it immobilized or under disponibility for plant absorption and transport untill water sources for animal and human consumption. The transport and sedimentation processes associated with the physico-chemical characteristics of the pedological cover, and the chemical agent, constitute the morphopedological vulnerability to a certain contaminant. In this context, this research aimed to evaluate the relief indicators and the most relevant soil attributes linked to their vulnerability face to a possible contamination by chemical products. For this research, the methodology included technical procedures from the altimetrical topographic survey, the elaboration of a digital elevation model, the discretization of topographic attributes, to the opening of trenches, collections and analysis of soil samples. The study area, located in the municipality of Ponta Grossa, corresponds to an agricultural portion under no-tillage system for more than forty years, surrounded by the industrial corridor (N), Highway PR151 and by residential quarters. It is a flat and elongated geomorphological form with SE-NW orientation, consisting of two strands with different forms, under similar conditions of soil use and management, climatic and lithological matrix, favoring a better understanding of the influence of relief on the processes soil formation, potential for leaching and hauling of particles and chemicals. Its characteristics of relief and lithology are considered representative for the municipality of Ponta Grossa. The studied topsequences constitute a transect perpendicular to the axis of the hill, covering two segments of slope; one west (Vc) and one east (Vr). The segment Vc is convex in plan, more striking in the upper portion, and with concave, convex and rectilinear segments in its lateral view. The Vr segment is predominantly convex-planar from top to bottom. The influence of the relief was evident in the distribution of soils and in the control of the hydrological processes, conditioned by the declivity and shape of the relief. Such influence was also observed in the results of the chemical analyzes of soil samples, as well as in the organic matter content and iron and aluminum oxide values. The lithological influence was evidenced by the high levels of clay in the soil, even in the youngest ones. The concave portions of the relief, where there is greater concentration of hydric flow with the formation of wetlands, tend to be the most vulnerable to diffuse contamination, however, further studies are necessary, especially aiming to quantify the potential of contaminants transport, by surface runoff, to the rivers. The modeling of topographic/morphopedological attributes was considered representative and an important tool for the analysis of vulnerability to the diffuse contamination.