Mercury in the surface soil and cassava, Manihot esculenta (flesh, leaves and peel) near goldmines at Bogoso and Prestea, Ghana.

Mercury amalgamation is used indiscriminately in the recovery of gold by small-scale native gem winners in Ghana. Mercury is released into the environment in the form of wastewater, tailing and vapor from the roasting of amalgam to separate gold. The study looked at the levels of total mercury concentration in surface soil and cassava crop from farms located within the vicinities of Bogoso and Prestea Goldmines. The surface soil total mercury concentrations ranged between 125.29 and 352.52 µg/kg whiles cassava had between 66.60 and 195.47 µg/kg. The results showed proportionately more deposits at higher distances in 15-30 cm soil zone and less deposits at higher distances on leaves with relatively high uptake of the metal occurred at higher distances from the mines into the peels. These results suggest serious mercury pollution to the surface soil and the cassava crop but the speciation exercise showed that mercury is not in the free state, rather bound to hydroxides and organic compounds as complexes.

Quality of "sachet" waters in the Cape Coast municipality of Ghana.

To determine the quality of sachet water samples in the Cape Coast municipality of Ghana, random sampling procedures were used to collect 180 samples from 29 brands produced in the municipality from 1999 to 2004. For any particular year, each tested brand was sampled three times at intervals of not less than 2 weeks (usually monthly) between the months of March to June. Forty-five percent (45%) of the brands subjected to bacteriological examination contained coliform bacteria for one sampling period or another during the period of investigation. The coliform contamination seemed to be more prevalent with some particular brands. Three out of seven brands examined in 2004 also recorded the presence of E. coli. Exceedances were recorded for WHO drinking water quality guidelines for pH (6.25-7.93) in 2002 and for conductivity (67-306 microS cm(-1)) in 2002 and 2004. Total hardness values for all sachet water brands were less than 100 mg/l CaCO(3) and therefore below the WHO limit for potable water. None of the samples seems to pose any health dangers as far as the major cations; sodium (17.4-19.1 mg/l), potassium (5.7-6.2 mg/l), calcium (8.0-24.0 mg/l) and magnesium (19.9-50 mg/l) are concern. Apart from nitrite, for which some exceedances were recorded and phosphate which does not have an established WHO guideline, the measured major anions (i.e., chloride: 1.57-37.7 mg/l, sulfate: 0.33-44.33 mg/l and nitrates: 0.005-0.70 mg/l) were within the WHO drinking water guideline. No exceedances were also recorded for iron and lead. In general, the high quality claimed for sachet waters could not be confirmed based on the measured physico-chemical and bacteriological properties. The variable quality and in some cases, poor water quality observed, likely reflects the fact that the sachets are not always bagged under scrutinized sanitary conditions.