Soil water and fuel permeability of a Cambisol in southern Brazil and its spatial behavior: A case study

Abstract

The high demand for fuel derived from oil increases the risk of environmental hazard in agricultural fields caused by accidents with the operation of machines and spotting of fuel on the ground. When these accidents occur, a part of the spilled fuel infiltrates and redistributes in the soil according to the fuel's own physical properties. Most fuel products are light nonaqueous-phase liquids (NAPL) and contain compounds that are toxic and cause damage to the soil and to human health. The transport behavior of fuels in soils has been extensively studied but is lacking knowledge in specific soils with high clay content. This study aimed to evaluate the soil permeability (K) to the transport of water and fuels and their spatial variation in a Cambisol in southern Brazil. Furthermore, the question should be addressed whether Kwater may be used to estimate Kfuels based on the fluid viscosities. Moreover, a spatial variance analysis should evaluate the variability between replicate repacked samples at a particular location in comparison with spatial variability caused by soil texture and bulk density differences. Results showed that Kwater was, on average, 4.5 times smaller than Kgasoline and 1.25 times smaller than Kdiesel, that the correlation between measured and estimated Kfuels was moderately positive for the clayey soil investigated, and that a minimum set of three repacked parallel cores for each sampling location yields a local variance that is much smaller than the semivariance at any lag distance.