Propiedades físico-químicas y variabilidad espacial de un suelo afectado por el vertido minero, finca "Pagua", parroquia Río Bonito.

Abstract

The problems in agriculture are the loss of soil fertility caused by poor agricultural practices, in addition to anthropogenic sources, those chemical by-products of industrial activities. Given the need to know the variation behavior of some physical properties and spatial variability of the soil of the Pagua farm affected by the Rio 7 mining spill, the present investigation was carried out in El Guabo, Rio Bonito, "Pagua" property. For the design, a descriptive observational study was carried out, where 18 sampling points were established, each with two depths (0 - 15 cm, 15 - 30 cm), processing a total of 36 samples in 20.1 ha. The physical and chemical properties were determined in the laboratory of the Technical University of Machala and the heavy metal content of the samples were sent to the TerraProductos S.A. laboratory located in Cayambe, province of Pichincha. The data analysis was performed in different approaches, univariate (descriptive statistics) using IBM SPSS Statistical 25 and Microsoft Excel 2019 software, exploratory graphs such as box and whisker diagrams were used to visually appreciate the behavior of each variable. In the geostatistical analysis, ArcMap 10.3 software was used for the determination of semivariograms, for the selection of a model (spherical, Gaussian and exponential), the Nash coefficient and the coefficient of determination (R2) was close or equal to 1, and to obtain the lowest values of the root mean square error (RMSE), being the most accurate and efficient the spherical and exponential model. The parameters obtained from the semivariogram were used for interpolation by the kriging method in order to design spatial variability maps of heavy metal content. The results showed a moderate spatial dependence for Cd, As and Hg, a strong spatial dependence for Ni and Pb, and no heavy metals with a weak spatial dependence for the first 15 cm of the soil. The levels of As and Pb found varied between 0.013 to 0.022 mg.kg-1 and 0.40 to 0.49 mg.kg-1 respectively, indicating that the content of these metals is higher than the optimal range to not consider them contaminants.