Fig. 5. Variation of Hg contents in surface water and column
water of the J. A. Alzate Reservoir. Mercury concentration in
water is rather homogeneous due to a resuspension process of
particular matter to which it is fixed.
sand, 17.7% lime and 64% clay. Scanning electron
microscope studies and X-ray diffraction
analysis of sedimentary samples gave the following
results: 15% of methalloysite and halloysite
with a grain size )2 mm; 4% of cristobalite
with a grain size between 2 and 135 mm;
58% of feldspars with a grain size between 5 and
75 mm; 7% of amphiboles with a grain size
between 2 and 175 mm; 2% of mica with a grain
size between 10 and 20 mm; 1% of other forms
like dickite and kaolinite; and 5% of amorphous
material with a grain size between 1 and 190 mm.
Additionally, feldspars altered to clay minerals
were observed.
Heavy metal contamination in water bodies is
regarded as a serious problem in Mexico, and
numerous studies have been undertaken. Similar
concentrations as the ones reported here have
been found in the State of Veracruz, River Blanco
Alvarez et al., 1986., River Papaloapan, Alvarado
Lagoon Rosales et al., 1986a,b., and River
Coatzacoalcos Botello and P´aez, 1986.. More