Investigating the effect of Eh and pH on binding forms of Co, Cu, and Pb in wetland sediments from Zambia.

This study investigated binding forms of cobalt (Co), copper (Cu), and lead (Pb) in 28 sediment samples from inlet to outlet of three Zambian wetlands receiving mining effluents. Use was made of a modified Tessier metal binding fractions procedure. Due to storage artefacts, the original aim of investigating the effects of redox potential (Eh) changes, starting from extremely low Eh, was suspended.

Distribution of the heavy metals Co, Cu, and Pb in sediments and Typha spp. And Phragmites mauritianus in three Zambian wetlands.

Zambia has been mining cobalt (Co), copper (Cu), and lead (Pb) for over a century, with discharges entering wetlands without investigations on the level of sediment pollution and how to solve it. This present study investigated: 1) the extent to which Co, Cu, and Pb that enter through mining wastewater were distributed in the sediment of three wetlands (Uchi, Mufulira, and Kabwe) in Zambia and 2) the accumulation and distribution of the heavy metals in two emergent wetland plants, Phragmites mauritianus, and Typha spp. in order to evaluate their potential for phytoremediation of metals.

Investigating Co, Cu, and Pb retention and remobilization after drying and rewetting treatments in greenhouse laboratory-scale constructed treatments with and without Typha angustifolia, and connected phytoremediation potential.

There is critical concern over heavy metals because they are biotoxins. The best management option is elimination or at least minimization of effluence into the environment, but in several regions, mining wastewater or acid mine drainage (AMD) effluence into natural wetlands has continued. The ability of wetlands to attenuate heavy metals in mining wastewater and AMD has led to natural wetlands being used as recipients of these effluents in many parts of the world.

Estimating Total Nitrogen and Phosphorus Losses in a Data-Poor Ethiopian Catchment.

Selecting a suitable model for a water quality study depends on the objectives, the characteristics of the study area, and the availability, appropriateness, and quality of data. In areas where in-stream chemical and hydrological data are limited but where estimates of nutrient loads are needed to guide management, it is necessary to apply more generalized models that make few assumptions about underlying processes. This paper presents the selection and application of a model to estimate total nitrogen (TN) and total phosphorus (TP) loads in two semiarid and adjacent catchments exposed to pollution risk in north-central Ethiopia.

Assessment of DDT, HCH and PAH contamination and associated ecotoxicological risks in surface sediments of coastal Tema Harbour (Ghana).

This study assessed DDTs, HCHs and PAHs contamination in sediments from the Tema Harbour (Ghana) and the associated ecotoxicological risks. The results showed widespread DDTs, HCHs and PAHs contamination in the harbour sediments with mean concentrations ranging from 6.0-12.

Occupational exposure to pesticides: blood cholinesterase activity in a farming community in Ghana.

A survey was undertaken to establish the extent of pesticide exposure in a farming community. Cholinesterase (ChE) activity in whole blood was used as a marker for assessing exposure to pesticides. Complete data were gathered for 63 farmers at Akumadan (exposed) and 58 control subjects at Tono, both prominent vegetable-farming communities in Ghana, by means of a questionnaire and blood cholinesterase analyses (acetylcholine assay).

The impact of agricultural runoff on the quality of two streams in vegetable farm areas in Ghana.

A study of two small streams at Akumadan and Tono, Ghana, was undertaken during the rain and dry season periods between February 2005 and January 2006 to investigate the impact of vegetable field runoff on their quality. In each stream we compared the concentration of current-use pesticides in one site immediately upstream of a vegetable field with a second site immediately downstream. Only trace concentrations of endosulfan and chlorpyrifos were detected at both sites in both streams in the dry season.

Dissipation of endosulfan in field-grown tomato (Lycopersicon esculentum) and cropped soil at Akumadan, Ghana.

The dissipation and persistence of endosulfan (6,7,8,9,10,10-hexachloro-1,5,5a,6,9,9a-hexahydro-6,9-methano-2,4,3-benzodioxathiepin 3-oxide) applied to field-grown tomato (Lycopersicon esculentum) were studied at a vegetable-growing location in Ghana. Plant tissue samples and cropped soil collected at 2 h-14 days and 8 h-112 days, respectively, after application, were analyzed by gas chromatography-electron capture detection (63Ni) to determine the content and dissipation rate of endosulfan isomers (alpha- and beta-endosulfan) and the major metabolite, endosulfan sulfate. After two foliar applications of commercial endosulfan at 500 g of active ingredient/hectare, the first-order reaction kinetic was confirmed to describe the dissipation of endosulfan residues in tomato foliage and cropped soil.

Accumulation of persistent organochlorine contaminants in milk and serum of farmers from Ghana.

In the present study, the concentrations of persistent organochlorine (OC) pesticides such as dichlorodiphenyltrichloroethane and its metabolites (DDTs), hexachlorocyclohexane isomers (HCHs), hexachlorobenzene (HCB) and dieldrin in pooled samples of human breast milk (n=109), and serum (n=115) from vegetable farmers in Ghana, during 2005, were determined. Gas chromatography with mass spectrometry was used to quantify residue levels on a lipid basis of the OCs. The pattern of OCs in human fluid showed that DDTs was consistently the prevalent OC in milk and blood.

Farmer perceptions and pesticide use practices in vegetable production in Ghana.

As an initial part of a programme aimed at promoting safe and sound agricultural practices in Ghana, a study was made of farmers' perceptions of pesticides for use and application in vegetable production, using a small survey of 137 farmers who applied pesticides. Field surveys, interviews, questionnaires and analytical games were used to obtain information on the type, scope and extent of use of pesticides, farmers' knowledge of pesticides, and their perceptions about the chemicals' potential for harm. Data from this sample of farmers were used to describe the status of use of pesticides in vegetable cultivation in Ghana.