『Abstract
This paper presents a methodology to evaluate and map environmental
hazard and characterize environmental impact of heavy metals in
Guadiamar river margins (South of Spain) contaminated by the Aznalcollar(oの頭に´) mining spill. This methodology accounts
for uncertainties in the mapping of the probability of soil contamination
with different heavy metals and is based on a co-simulation technique
using direct sequential simulation of a multivariate set of variables.
Each variable is simulated based on primary data - the heavy metal
concentrations in the soil - and on secondary data, consisting
of a previously simulated map of one of the heavy metals. Using
several realizations of the simulated multivariate set, a “hazard”
index was calculated for each pixel of the study area, based on
the simultaneous proportions (joint probabilities) of different
levels of all metals. Finally, the intersection of the hazard
map, based on the joint dispersion of all contaminants, with the
environmental impact map for the different ecosystems, resulted
in environmental hazard maps for the river margins. The performances
of the multivariate sets of co-simulated variables were compared
considering two extreme alternatives: i) the soil is considered
in need of treatment if all 5 heavy metals simultaneously exceed
their concentration limit value at the same location; ii) the
soil is considered in need of treatment if at least one heavy
metal exceeds its concentration limit at the same location.
Keywords: Heavy metal contamination; Stochastic simulation; Risk
maps; Environmental impact maps; Geostatistics』
1. Introduction
2. The data set
3. Methodology
3.1. Heavy metals' spatial dispersion estimation
3.2. Heavy metals hazard maps
3.2.1. Co-simulation of heavy metals
3.2.2. Hazard maps evaluation
3.2.2.1. An alternative approach for scenario iv - compulsory
treatment
3.3. Environmental impact maps
4. Discussion and conclusions
Acknowledgements
References