The use of magnetic susceptibility measurements to determine pollution of agricultural soils in road proximity

This research work presents a study on the application of magnetic susceptibility measurements and geochemical analysis for mapping or assessing heavy metal pollution in the agricultural soil in road proximity. The research work was also done to check any runoff of heavy metals pollution to the Owabi dam which serves as the main water sources to catchment areas and the whole of Kumasi Metropolis. This research work was conducted along the asphalt road closed to Amamfrom Community in the southern part of Ghana. The study revealed that magnetic susceptibility measurements can be used as a proxy and fastest method of determining heavy metal pollution in agricultural soils. The results showed three most important trends: 1) the samples collected near the road have higher values of magnetic susceptibility and mean heavy metals content than those collected far from the road exhaust; 2) some of the sample areas undisturbed by erosion and weathering have significant magnetic susceptibility and heavy metals contents; 3) some of the sample areas washed away by erosion are believed to be deposited in Owabi Dam due to their low ground reliefs. Therefore, future research should concentrate on Owabi Dam which may be polluted by the runoff from these heavy metals.Key words: Magnetic susceptibility, heavy metal, pollution, road proximity

Application of Electromagnetic and Electrical Resistivity Methods for Borehole Siting in Low-Grade Metavolcanic and Metasedimentary Rocks, Sunyani West, Ghana

This paper employs the electromagnetic (EM) and the electrical resistivity methods for siting boreholes for communities in the Sunyani-West district of Ghana, a terrane comprising a mixture of granites and low-grade metavolcanic and metasedimentary rocks. These communities which depend on groundwater for livelihood have over the past few decades been hit by drastic seasonal irregularities in rainfall, making it imperative to seek an alternative source of potable water (preferably groundwater). Measurements to locate sites for boreholes were made by employing the Geonics EM-34 conductivity meter. In addition, co-located measurements were made with the ABEM SAS 1000C Terrameter in the Schlumberger electrode array configuration. Results of the measurements showed that each community could have at least two borehole sites with a high potential for groundwater extraction. The overburden of selected sites varied for the communities and ranged from 40 to 67 m. However, recommended drilling depths at these sites were 60 m for Adwinsa community, 70 m for Akurakan community and 60 m for Nana Ameyaw community. Test boreholes sunk at respective depths of 45 m, 55 m and 68 m in Adwinsa, Nana Ameyaw and Akurakan had yields of 12 m3/h (200 l/min), 24 m3/h (400 l/min) and 1.14 m3/h (19 l/min) respectively. In all three communities the aquifer was intercepted in phyllite bedrocks. Keywords: aquifer, groundwater potential, borehole, electrical resistivity, vertical electrical sounding, conductivity DOI: 10.7176/JEES/10-10-05 Publication date:October 31st 202

Precipitation variability and trends in Ghana: An intercomparison of observational and reanalysis products

Inter-annual variability and trends of annual/seasonal precipitation totals in Ghana are analyzed considering different gridded observational (gauge- and/or satellite-based) and reanalysis products. A quality-controlled dataset formed by fourteen gauges from the Ghana Meteorological Agency (GMet) is used as reference for the period 1961?2010. Firstly, a good agreement is found between GMet and all the observational products in terms of variability, with better results for the gauge-based products?correlations in the range of 0.7?1.0 and nearly null biases?than for the satellite-gauge merged and satellite-derived products. In contrast, reanalyses exhibit a very poor performance, with correlations below 0.4 and large biases in most of the cases. Secondly, a Mann-Kendall trend analysis is carried out. In most cases, GMet data reveal the existence of predominant decreasing (increasing) trends for the first (second) half of the period of study, 1961?1985 (1986?2010). Again, observational products are shown to reproduce well the observed trends?with worst results for purely satellite-derived data?whereas reanalyses lead in general to unrealistic stronger than observed trends, with contradictory results (opposite signs for different reanalyses) in some cases. Similar inconsistencies are also found when analyzing trends of extreme precipitation indicators. Therefore, this study provides a warning concerning the use of reanalysis data as pseudo-observations in Ghana.This study was supported by the EU project QWeCI (Quantifying Weather and Climate Impacts on health in developing countries), funded by the European Commission Seventh Framework Research Programme under the grant agreement 243964

Soil and water pollution studies from a waste site deposit in Bantama, Kumasi, Ghana using magnetic susceptibility measurements

The magnetic susceptibility of soil and water samples from around the Uadara barracks waste site deposit in Bantama, a suburb of Kumasi was measured with the aim of investigating the potential threat of pollution to the soil, streams, fish ponds and other water sources at the site around the Armed Forces Senior High School campus which shares the same premises with the barracks. The studied soil samples were picked from the near surface (~ 10 cm depth) along pro-files taken from the waste site towards the stream and the ponds. Again, water samples were picked along the stream and from ten (10) ponds aligned along the stream. Laboratory measure-ments of the magnetic susceptibility were done using the Bartington MS2 metre and the MS2B dual frequency sensor for the soil samples, and the MS2G sensor for the water samples. The soil samples from the site registered an average magnetic susceptibility of 180.04 x 10-5 SI whereas the water samples recorded an average of –2.3 x 10-6SI showing a significant increment in com-parison with the standard water magnetic susceptibility of –9.04 x 10-6 SI. Thus, notwithstanding the lithology of the area studied, the presence of heavy metals and other chemical waste materi-als form the Uadara barracks garbage deposit site were found to greatly pollute the soil and par-ticularly the water bodies around the Armed Forces Senior High School

Assessing the Effects of Anthropogenic Land Use on Soil Infiltration Rate in a Tropical West African Watershed (Ouriyori, Benin)

Soil infiltration at a watershed scale is important for understanding and predicting the hydrological process in soil-water-plant systems. This study investigated the effects of land use (LU) conversion on the infiltration rate in the Ouriyori watershed. To that end, in situ infiltration was carried out over the watershed under thirty-six pairs of adjacent cropland-fallow plots using the hood infiltrometer. Saturated hydraulic conductivity (Ks), soil properties, and soil classes were further compared. Results showed a high variability of Ks following the LU classes with a coefficient of variation greater than 60%. After data log transformation, the mean values of Ks showed high infiltration and ranged between 2.59 and 2.42 cm d-1, respectively, for fallow land and cropland. Thus, Ks was relatively lower in cropland compared to fallow land. Hence, the low infiltration recorded in croplands indicated the degradative impacts of unceasing tillage operations for crop production without crop residue incorporation into the soil during tillage. There was no significant difference in bulk density and soil texture in both types of land use. Considering soil classes, the highest infiltration rate was found in Ferric Luvisol and the lowest rate in Dystric Gleysol, meaning that the high infiltration observed in Ferric Luvisol was due to the abundance of soil macropores. Change in natural vegetation to croplands induced a low infiltration rate and macropore connectivity. Moreover, fallow lands tend to provide water storage capacity through the improvement of mesopores, while soil compaction through agricultural activities reduces soil porosity and therefore soil infiltration. In addition, the paired Student's t-Test performed on the transformed data was statistically significant, indicating a difference between Ks under cropland and Ks under fallow land. To improve soil and water conservation for crop production as well as for sustainable rural populations' livelihoods in the watershed, occasional fallowing may be observed to dampen infiltration hindering soil surface conditions