Groundwater Vulnerability Assessment of the Tarkwa Mining Area Using SINTACS Approach and GIS

Groundwater vulnerability assessment to delineate areas that are susceptible to contamination from mining and anthropogenic activities has become an important element for resource management and landuse planning. In view of the extensive mining in the Tarkwa area, quality of groundwater has become an important issue. This study estimates aquifer vulnerability by applying the SINTACS model which uses seven environmental parameters to evaluate aquifer vulnerability and geographical information system (GIS) in the Tarkwa mining area. Sensitivity analysis has also been carried out to evaluate the relative importance of the model parameters for aquifer vulnerability. The SINTACS model results show that the intrusive rocks within the Tarkwaian and the Birimian rocks are dominated by very high vulnerability classes while the Banket Series is characterised by high vulnerability class. The Huni Sandstones have moderately high vulnerability. In addition, the Kawere Group and the Tarkwa Phyllites displayed medium vulnerability. Analysis from the variogram model shows that all parameters used in the SINTACS model have a strong spatial structure. From statistical analysis, depth to water parameter inflicted the highest impact on the vulnerability of the aquifer followed by effective infiltration, vadose zone media, soil media, aquifer media, topography and hydraulic conductivity in the order of decreasing impact. Sensitivity analysis indicated that the aquifer media, hydraulic characteristics and topography cause large variation in vulnerability index. Depth to water and effective infiltration were found to be more effective in assessing aquifer vulnerability. Keywords: Groundwater, Vulnerability, Tarkwa, SINTACS, GI

Combined Electrical Resistivity Imaging and Electromagnetic Survey for Groundwater Studies in the Tarkwa Mining Area, Ghana

The major source of potable water in Tarkwa is the Bonsa Treatment Plant sourced from the Bonsa River. The activities of illegal miners along the banks of the Bonsa River has resulted in pollution of the river. This has resulted in high treatment cost and irregular supply of water to the Tarkwa Township and surrounding communities that are fed by the Bonsa Treatment Plant. In view of the difficulty in getting frequent and regular potable supply of water, people have resorted to construction of boreholes and hand-dug wells. However, the success rates and borehole yields are low especially in the hydrogeologically difficult terrains in the Tarkwa area. The aim of this paper is to investigate the hydrogeological conditions of the Tarkwa area using both the Electrical Resistivity Imaging (ERI) and Electromagnetic (EM) geophysical techniques to determine the electrical resistivity and conductivity values that are related to groundwater accumulation, so that potential water-bearing zones can be identified. Results from electrical resistivity show that the general resistivity distribution in the Tarkwa area is between 32 Ωm and 100 000 Ωm. Water-bearing zones in the Huni Sandstone occur to a depth of 35 m with an average resistivity value of 400 Ωm, at a depth of 60 m and a resistivity of 600 Ωm in the Tarkwa Phyllite, at a depth of 55 m and a resistivity of 600 Ωm in the Banket Series and 50 m depth with resistivity value of 500 Ωm in the Kawere Conglomerate respectively. The electromagnetic conductivity values also show that the general conductivity distribution in the Tarkwa area is 3 – 32 S/m. The application of electrical resistivity and electromagnetic techniques separately gives success rate of 80 % and 65 % respectively. An improved success rate of 86 % is achieved combining the two techniques. Keywords: Electrical Resistivity Imaging, Electromagnetic Method, Groundwate

Carbon dioxide (CO2) utilizing strain database

Culling of excess carbon dioxide from our environment is one of the major challenges to scientific communities. Many physical, chemical and biological methods have been practiced to overcome this problem. The biological means of CO2 fixation using various microorganisms is gaining importance because database of their substantial role in reversing global warming. Carbon dioxide utilizing strain database (CSD) presents a comprehensive overview of microorganisms involved in biological fixation of carbon dioxide. As a part of this work, the wealth of information on CO2 utilizing strains was first collected and was then managed within four classes, that is, microorganisms, genus listing, mechanisms and literature. The first two classes consolidate information regarding the microbial genus and species, while the later two provide information regarding the CO2 fixing pathways and the taxonomic details of these organisms. The database also holds the current information about the issue. CSD can be used to gain information related to CO2 fixing microbes. It can also contribute to devising biological strategies for reducing carbon dioxide from the environment. It introduces an innovative idea of exploring the potential of these bacterial strains for reversing global warming. The CSD can be accessed at http://csd.igib.res.in.Key words: Carbon dioxide utilizing strain database (CSD), carbon dioxide, autotrophic microorganisms, global warming, biological fixation of CO2, CO2 fixing pathways

The Geometry and Structural Analysis of the Gold Deposits of Chirano Mine

The Chirano Mine gold deposit is a typical example of a structurally controlled deposit developed along the Kumasi Basin and the Sefwi Belt margin structure. The area has undergone various regimes of structural deformations. Consequently, all the Chirano deposits are intimately associated with shears and faults along a single continuous structural corridor known as the Chirano Shear Zone (CSZ). The CSZ geometry has been categorised into three major zones namely: (i) Laminated veins in shears, (ii) Breccia and (iii) Ductile to brittle ductile zones. The shear veins trend NE-SW and N-S, are laminated and occur in the sheared fabric close to the footwall. Penetrative foliated zones varying from a few centimeters to several meters constitute the ductile to brittle-ductile structures. Gold grades are much higher within this zone. Analysis of cataclasis intensity recorded in drill core confirms a semi brittle form of deformation within the mineralised domain. The CSZ has different orientations in dip and strike from the south of the mining lease to the north. The subtle changes in orientation are deposit dependent. The structure has a sinuous shape and tends to pinch and swell. The current geometry and the distribution of stratigraphy and orebodies at Chirano is a manifestation of the complex interplay of magmatic and hydrothermal events in the area.  Keywords: Ductile, Brittle-Ductile, Breccia, Chirano Shear Zone, Chirano Lode Horizo

Typhoid fever outbreak in the Democratic Republic of Congo: Case control and ecological study

During 2011 a large outbreak of typhoid fever affected an estimated 1430 people in Kikwit, Democratic Republic of Congo. The outbreak started in military camps in the city but then spread to the general population. This paper reports the results of an ecological analysis and a case-control study undertaken to examine water and other possible transmission pathways. Attack rates were determined for health areas and risk ratios were estimated with respect to spatial exposures. Approximately 15 months after the outbreak, demographic, environmental and exposure data were collected for 320 cases and 640 controls residing in the worst affected areas, using a structured interview questionnaire. Unadjusted and adjusted odds ratios were estimated. Complete data were available for 956 respondents. Residents of areas with water supplied via gravity on the mains network were at much greater risk of disease acquisition (risk ratio = 6.20, 95%CI 3.39-11.35) than residents of areas not supplied by this mains network. In the case control study, typhoid was found to be associated with ever using tap water from the municipal supply (OR = 4.29, 95% CI 2.20-8.38). Visible urine or faeces in the latrine was also associated with increased risk of typhoid and having chosen a water source because it is protected was negatively associated. Knowledge that washing hands can prevent typhoid fever, and stated habit of handwashing habits before cooking or after toileting was associated with increased risk of disease. However, observed associations between handwashing or plate-sharing with disease risk could very likely be due to recall bias. This outbreak of typhoid fever was strongly associated with drinking water from the municipal drinking water supply, based on the descriptive and analytic epidemiology and the finding of high levels of faecal contamination of drinking water. Future outbreaks of potentially waterborne disease need an integrated response that includes epidemiology and environmental microbiology during early stages of the outbreak

An analysis of the cloud environment over the Ross Sea and Ross Ice Shelf using CloudSat/CALIPSO satellite observations: the importance of synoptic forcing

We use the 2B-GEOPROF-LIDAR R04 (2BGL4) and R05 (2BGL5) products and the 2B-CLDCLASS-LIDAR R04 (2BCL4) product, all generated by combining CloudSat radar and CALIPSO lidar satellite measurements with auxiliary data, to examine the vertical distribution of cloud occurrence around the Ross Ice Shelf (RIS) and Ross Sea region. We find that the 2BGL4 product, used in previous studies in this region, displays a discontinuity at 8.2 km which is not observable in the other products. This artefact appears to correspond to a change in the horizontal and vertical resolution of the CALIPSO dataset used above this level. We then use the 2BCL4 product to examine the vertical distribution of cloud occurrence, phase, and type over the RIS and Ross Sea. In particular we examine how synoptic conditions in the region, derived using a previously developed synoptic classification, impact the cloud environment and the contrasting response in the two regions. We observe large differences between the cloud occurrence as a function of altitude for synoptic regimes relative to those for seasonal variations. A stronger variation in the occurrence of clear skies and multi-layer cloud and in all cloud type occurrences over both the Ross Sea and RIS is associated more with synoptic type than seasonal composites. In addition, anomalies from the mean joint histogram of cloud top height against thickness display significant differences over the Ross Sea and RIS sectors as a function of synoptic regime, but are near identical over these two regions when a seasonal analysis is completed. However, the frequency of particular phases of cloud, notably mixed phase and water, is much more strongly modulated by seasonal than synoptic regime compositing, which suggests that temperature is still the most important control on cloud phase in the region.</p

Responses of phytoplankton assemblages to iron availability and mixing water masses during the spring bloom in the Oyashio region, NW Pacific

Spring phytoplankton blooms play a major role in the carbon biogeochemical cycle of the Oyashio region, western subarctic Pacific, where the seasonal biological drawdown effect on seawater pCO 2 is one of the greatest among the world\u27s oceans. However, the bloom often terminates before depleting macronutrients, and the initiation and magnitude of the bloom is heterogeneous. We conducted a high resolution taxonomic and physiological assessment of phytoplankton in relation to the different physicochemical water masses of Coastal Oyashio Water (COW), Oyashio water (OYW), and modified Kuroshio water (MKW) in the Oyashio region from April to June 2007. Massive diatom blooms were found in April. Then, chlorophyll a concentration, cell abundance of diatom taxa, and the maximum photosystem II photochemical efficiency (F v /F m ) were positively correlated with the mixing ratios of COW, suggesting that the spring bloom in April was strongly affected by the intrusion of COW. In the OYW, intensive blooms occurred from the middle of May under low dissolved iron (DFe) concentration (\u3c 0.26 nM). Redundancy analysis showed that while diatom blooms accompanied by COW were related to DFe concentration, this was not the case in the OYW. These results indicated that diatoms in the OYW possess different iron adaptation strategies compared with diatoms in the water masses affected by COW. This led to the spatial heterogeneity of the Oyashio spring bloom. The results presented here demonstrate that water mass characterization with detailed assessments of phytoplankton taxonomy and physiological status can improve our understanding of marine ecosystems

Targeting quiescent leukemic stem cells using second generation autophagy inhibitors

In chronic myeloid leukemia (CML), tyrosine kinase inhibitor (TKI) treatment induces autophagy that promotes survival and TKI-resistance in leukemic stem cells (LSCs). In clinical studies hydroxychloroquine (HCQ), the only clinically approved autophagy inhibitor, does not consistently inhibit autophagy in cancer patients, so more potent autophagy inhibitors are needed. We generated a murine model of CML in which autophagic flux can be measured in bone marrow-located LSCs. In parallel, we use cell division tracing, phenotyping of primary CML cells, and a robust xenotransplantation model of human CML, to investigate the effect of Lys05, a highly potent lysosomotropic agent, and PIK-III, a selective inhibitor of VPS34, on the survival and function of LSCs. We demonstrate that long-term haematopoietic stem cells (LT-HSCs: Lin−Sca-1+c-kit+CD48−CD150+) isolated from leukemic mice have higher basal autophagy levels compared with non-leukemic LT-HSCs and more mature leukemic cells. Additionally, we present that while HCQ is ineffective, Lys05-mediated autophagy inhibition reduces LSCs quiescence and drives myeloid cell expansion. Furthermore, Lys05 and PIK-III reduced the number of primary CML LSCs and target xenografted LSCs when used in combination with TKI treatment, providing a strong rationale for clinical use of second generation autophagy inhibitors as a novel treatment for CML patients with LSC persistence