The fertility and trace elements diagnosis of soils is important for agricultural and environmental purposes, because there is little data available on the Pantanal-Cerrado-Floresta Amazônica transitional areas. This work evaluated many parameters relative to the fertility, Fe, Mn, Zn, Cu and B bioavailability, and total content of As, Cd, Hg and Pb in soils of the Vale do Guaporé, in the south-western region of Mato Grosso. Soil samples were collected in depths of 0-0,2 and 0,20-0,40 m in native vegetation, pasture, annual crop and gold mineration areas. These samples were analyzed for fertility according to Embrapa methodologies and trace elements by the SW3051 methods; and the average results were compared with quality reference values (VRQ) of soils of São Paulo stipulated by the Company of Technology of Environment Sanitation (CETESB). The Pb contents in the majority of samples were below the VRQ. In relation to As, many samples showed contents above the VRQ: 45,8% in native vegetation areas; 60% in the gold mineration areas; 28% in annual crop areas; and 44% in the pasture areas. The Cd contents too were above the VRQ: 20,8; 50; 55,5; and 22% for native vegetation, gold mineration, annual crop and pasture areas. Similar behavior was observed for Hg, which presented 75; 65; and 67% for native vegetation; gold mineration; and annual crop and pasture areas, respectively, with mean contents above the VRQ. About pH, around 68% of the samples presented values between 6,1 and 7,0 and the values of base saturation (V) were high (60-80%) for 51,5% of the points sampled. However, the mean P content was short in the whole area. The comparison of As, Cd and Hg contents with the VRQ of soils showed that it is necessary to determine these values for the state of Mato Grosso, keeping in view that the total contents of these elements observed in native areas were superior to the VRQ.
Trace elements; Soil contamination; Organic matter; Gold mine
