『Abstract
The Visman method is an efficient tool in environmental geochemistry.
The present study concerns the application of the Visman method
in a pilot sampling exercise for the design and subsequent implementation
of a tactical campaign in geochemical soil prospection. The aim
of this study is to solve the problem of the support of the sampling
unit by planning for an optimum combination of the mass and number
of sampling increments. The areas selected for the pilot study
were in the traditional mining district of Linares (province of
Jaen（eの頭に´）, Southern Spain). The conclusions
drawn from this study have enabled, for the first time, a tactical
campaign to be carried out in this mining locality, over a surface
area of 126 km2 occupying virtually the whole of the
granite batholite. The large surface area, the different geological
substrates and the variety of human activities have given rise
to a large degree of geochemical variability. Aluminium and lead
were taken as reference elements to estimate the evolution of
the variance and the precision, with respect to the mass and number
of sampling increments. Three mapping units with a surface area
of 1 km2 were taken as representative of the geochemical
reality of the study area; in one of these, mining and metallurgic
activities took place, and in another, mining and mineral-extraction
activities, while in the third, lying outside the batholite, there
were no mining activities. The sampling programme for tactical
prospection (reconnaissance) was designed according to the Visman
method, on the basis of the variance and precision to be accepted,
the budget available and the objectives laid down. The elements
that presented a high degree of variability (i.e. a high distribution
variance) were identified as those related to former mining activities.
Keywords: Soils; Heavy metal distribution; sampling error; Variance;
Linares』
1. Introduction
2. Approach
3. Sampling design in the pilot campaign. Materials and methods
4. Interpretation of the results obtained by applying Visman's
formula
5. Design of the definitive sampling campaign (tactical campaign)
6. Conclusions
References