Investigations were conducted over a six-month period on leachate which continuously egresses from a “natural attenuation” landfill site into a fragile ecosystem in the Accra Metropolis, Ghana. Most physico-chemical, oxygen demand parameters and nutrient contents were within permissible limits but Total Dissolved Solids (1124 - 13200 mg/l), conductivity (7960 - 24890 µS/cm), Mn (0.12 - 0.94 mg/l), Ca²⁺ (160 - 356 mg/l) and, more especially chloride contents (1030 - 2967 mg/l) far exceeded respective World Health Organisation (WHO) limits for effluent discharge into the natural environment. Multivariate statistics using Principal Component Analysis (PCA) and Cluster Analysis (CA) suggest significant concentrations of Ca²⁺, Cl^-, and to a lesser extent Zn, Cd, Mn and PO₄<sup style="margin-left:-7px;">2-</sup> relative to the river water samples. Because the landfill was abandoned recently (in 2009), degradation and other breakdown processes of waste material may only have just began, suggesting that the uncontrolled and continuous discharge of chloride and some heavy metal-laden leachate could, in the long-term, substantially impact negatively on the Ramsar Densu wetland and surrounding water bodies, soil and nearby marine ecosystem

Manganiferous rocks in the Mankwadzi area in the southernmost portion of the Kibi-Winneba metavolcanic belt, one of several Mn occurrences in the Paleoproterozoic Birimian of Ghana, are hosted in hornblende schist and amphibolite. These rocks are, in places, intruded by hornblende dyke. In outcrop, the manganiferous rocks appear to be conformable with the host schist and amphibolite, are macroscopically dark, fine-grained and structurally massive to distinctly banded. Observed alternating light and dark occasionally macro-folded bands suggest post-depositional deformation of both light and dark bands. Microscopic observations revealed that the light bands are dominantly Si-rich and the dark bands mainly of opaque minerals. Whole rock analyses of the manganiferous rocks show high contents of MnO (16.75-27.4 wt%) suggesting that the opaque minerals are likely rich in Mn. The analyzed rock samples show moderate to strong enrichments in light rare earth elements compared to heavy rare earth elements. Whereas the manganiferous rocks show perceptibly negative Eu anomaly, host hornblende schist and hornblende dyke do not. Eu anomaly in amphibolite samples is, however, uncertain as the three samples analyzed gave positive, negative and no Eu anomalies. Based on the field characteristics, microscopic and geochemical features, we suggest that the Mn occurrence in the Mankwadzi area originated via sedimentary deposition and was later modified by metamorphism, hydrothermal and/or supergene processes similar to manganiferous occurrences at Nsuta and Tambao in the Birimian of West Africa.

Previous work on the manganese occurrence in the Mankwadzi area, Ghana, suggested that it resulted from localized hydrothermal or pyrometasomatic activity genetically related to dyke formation. This observation means that the Mankwadzi Mn occurrence could be genetically different from typical Birimian Mn mineralization which dominantly displays sedimentary protore and overlying, supergene-derived manganese oxides. We recently conducted field sampling, geophysical survey and petrographic analyses of the Mankwadzi Mn-bearing rocks. Our results suggest that the NNE-trending manganiferous zone, about 20–30 m wide and over 200 m long, is conformable with immediately enclosing hornblende schist. Samples of Mn rock from the manganiferous zone are generally massive to variably banded and occasionally show centimetre-scale macro-folding. Scanning electron microscope analyses revealed that bands dominated by Mn garnet often distinctly alternate with silica (chert) or siliciclastic layers. These converging lines of evidence, i.e. conformability of the manganiferous zone with enclosing rock, occurrence of distinct banding, inter-folding of manganese and silica (chert) or siliciclastic layers and alternating Mn garnet-rich and garnet-poor layers strongly suggest the Mankwadzi manganese occurrence is genetically similar to the stratiform Nsuta manganese deposit in Ghana and, more likely, to other Mn deposits in the Birimian of West Africa.