Heavy metals’ availability and accumulation along the food chain pose public health risks. Water, sediment and plant samples were collected from selected sampling sites along Sosiani River, Uasin Gishu County, Kenya....Heavy metals’ availability and accumulation along the food chain pose public health risks. Water, sediment and plant samples were collected from selected sampling sites along Sosiani River, Uasin Gishu County, Kenya. The sediment and plant samples were dried in the oven at 50°C to constant weight and digested in a mixture of acids according to standard procedures. The water samples, sediments and plants digests were analyzed for selected heavy metals using Atomic Absorption Spectrophotometer (model AAS Variant 200). The site near the Moi Teaching and Referral Hospital (MTRH) had the highest total heavy metals concentration in water: Cu (0.18 ± 0.04 ppm);Pb (0.46 ± 0.09 ppm) and Zn (0.70 ± 0.22 ppm) and sediments: Cu (1.62 ± 0.14 ppm);Pb (1.27 ± 0.17 ppm) and Zn (6.73 ± 0.88 ppm) respectively. Fractionation of heavy metals in sediments showed low percentage solubility (Cu 9.3%;Pb 8.5%;Zn 4.2%). Concentration of zinc in studied plants was highest (3.60 ± 0.63 ppm), with a bioconcentration factor of 15.1 based on soluble zinc fraction. This indicates that conditions in the study area show preferential zinc metal uptake in plants and may lead to accumulation in exposed plants posing Zn exposure risks along the food chain. Suggestions are made for monitoring of heavy metals in food crops and aquatic organisms such as fish in the study area.展开更多
The study was conducted on the status of the quality of wastewater from the tailings dam of Central Africa Gold Limited in Bibiani, Ghana, to ascertain the level of contamination of the wastewater. The tailings dam st...The study was conducted on the status of the quality of wastewater from the tailings dam of Central Africa Gold Limited in Bibiani, Ghana, to ascertain the level of contamination of the wastewater. The tailings dam stores process effluent from the gold extraction plant. Wastewater samples taken from the tailings dam were analyzed for physico-chemical characteristics. Arsenic, iron and cyanide were identified as the major pollutants in the tailings dam wastewater with average concentrations of 4.5, 25.2 and 11.1 mg.L1, respectively. Arsenic, iron and free CN （cyanide） concentrations in the process effluent exceeded the Ghana EPA discharge limits of 0.2, 2 and 0.2 mg.Ll, respectively. High conductivity, total dissolved solids, sulphate and ammonium were found in the wastewater studied. The tailings dam serves as a natural reservoir that removes most of the total suspended solids and the turbidity, resulting in the improvement in the aesthetic appeal of the wastewater. Nonetheless, arsenic, iron and cyanide concentrations were still high and hence the wastewater cannot be discharged into the environment without prior treatment.展开更多
Schistosomiasis is a waterborne parasitic disease in sub-Saharan Africa,particularly common in rural populations living in impoverished conditions.With the scale-up of preventive chemotherapy,national campaigns will t...Schistosomiasis is a waterborne parasitic disease in sub-Saharan Africa,particularly common in rural populations living in impoverished conditions.With the scale-up of preventive chemotherapy,national campaigns will transition from morbidity-to transmission-focused interventions thus formal investigation of actual or expected declines in environmental transmission is needed as‘end game’scenarios arise.Surprisingly,there are no international or national guidelines to do so in sub-Saharan Africa.Our article therefore provides an introduction to key practicalities and pitfalls in the development of an appropriate environmental surveillance framework.In this context,we discuss how strategies need to be adapted and tailored to the local level to better guide and support future interventions through this transition.As detection of egg-patent infection in people becomes rare,careful sampling of schistosome larvae in freshwater and in aquatic snails with robust species-specific DNA assays will be required.Appropriate metrics,derived from observed prevalence(s)as compared with predetermined thresholds,could each provide a clearer insight into contamination-and exposure-related dynamics.Application could be twofold,first to certify areas currently free from schistosomiasis transmission or second to red-flag recalcitrant locations where extra effort or alternative interventions are needed.展开更多
文摘Heavy metals’ availability and accumulation along the food chain pose public health risks. Water, sediment and plant samples were collected from selected sampling sites along Sosiani River, Uasin Gishu County, Kenya. The sediment and plant samples were dried in the oven at 50°C to constant weight and digested in a mixture of acids according to standard procedures. The water samples, sediments and plants digests were analyzed for selected heavy metals using Atomic Absorption Spectrophotometer (model AAS Variant 200). The site near the Moi Teaching and Referral Hospital (MTRH) had the highest total heavy metals concentration in water: Cu (0.18 ± 0.04 ppm);Pb (0.46 ± 0.09 ppm) and Zn (0.70 ± 0.22 ppm) and sediments: Cu (1.62 ± 0.14 ppm);Pb (1.27 ± 0.17 ppm) and Zn (6.73 ± 0.88 ppm) respectively. Fractionation of heavy metals in sediments showed low percentage solubility (Cu 9.3%;Pb 8.5%;Zn 4.2%). Concentration of zinc in studied plants was highest (3.60 ± 0.63 ppm), with a bioconcentration factor of 15.1 based on soluble zinc fraction. This indicates that conditions in the study area show preferential zinc metal uptake in plants and may lead to accumulation in exposed plants posing Zn exposure risks along the food chain. Suggestions are made for monitoring of heavy metals in food crops and aquatic organisms such as fish in the study area.
文摘The study was conducted on the status of the quality of wastewater from the tailings dam of Central Africa Gold Limited in Bibiani, Ghana, to ascertain the level of contamination of the wastewater. The tailings dam stores process effluent from the gold extraction plant. Wastewater samples taken from the tailings dam were analyzed for physico-chemical characteristics. Arsenic, iron and cyanide were identified as the major pollutants in the tailings dam wastewater with average concentrations of 4.5, 25.2 and 11.1 mg.L1, respectively. Arsenic, iron and free CN （cyanide） concentrations in the process effluent exceeded the Ghana EPA discharge limits of 0.2, 2 and 0.2 mg.Ll, respectively. High conductivity, total dissolved solids, sulphate and ammonium were found in the wastewater studied. The tailings dam serves as a natural reservoir that removes most of the total suspended solids and the turbidity, resulting in the improvement in the aesthetic appeal of the wastewater. Nonetheless, arsenic, iron and cyanide concentrations were still high and hence the wastewater cannot be discharged into the environment without prior treatment.
基金The COUNTDOWN consortium receives funding from the Research and Evidence Division,Department for International Development,UK.
文摘Schistosomiasis is a waterborne parasitic disease in sub-Saharan Africa,particularly common in rural populations living in impoverished conditions.With the scale-up of preventive chemotherapy,national campaigns will transition from morbidity-to transmission-focused interventions thus formal investigation of actual or expected declines in environmental transmission is needed as‘end game’scenarios arise.Surprisingly,there are no international or national guidelines to do so in sub-Saharan Africa.Our article therefore provides an introduction to key practicalities and pitfalls in the development of an appropriate environmental surveillance framework.In this context,we discuss how strategies need to be adapted and tailored to the local level to better guide and support future interventions through this transition.As detection of egg-patent infection in people becomes rare,careful sampling of schistosome larvae in freshwater and in aquatic snails with robust species-specific DNA assays will be required.Appropriate metrics,derived from observed prevalence(s)as compared with predetermined thresholds,could each provide a clearer insight into contamination-and exposure-related dynamics.Application could be twofold,first to certify areas currently free from schistosomiasis transmission or second to red-flag recalcitrant locations where extra effort or alternative interventions are needed.
