Breakdown of Azadirachtin A in a Tropical Soil Amended with Neem Leaves and Animal Manures

A field investigation was conducted to assess the breakdown of azadirachtin A in a tropical coastal savanna soil amended with neem leaves （NL） combined with poultry manure （PM） or cow dung （CD） using gas chromatography. Samples in polythene bags 15 cm long and 4.8 cm in diameter were randomly placed to a depth of 14 cm in the soil, and azadirachtin A concentration was assessed on days 0, 14, 28, 42, 56, 70, and 84. Azadirachtin A degradation in the soil followed first-order reaction kinetics with different half-lives obtained for varying combinations of the amendments. Higher neem amendment levels of 100 g gave shorter half-lives of azadirachtin A than the lower levels of 50 g. Within the 50 g NL group the additions of the poultry manure and the cow dung gave significantly shorter （P 〈0.05） half-lives of azadirachtin A than the sole neem amendment, whereas in the 100 g NL group only additions of 10 g CD and 10 g PM were significantly less （P 〈 0.05） than the sole neem amendment. Different changes resulting from the kind and quantity of animal manure added were observed in the half-lives of azadirachtin A. The 100 g NL group had significantly higher （P 〈0.05） moisture content, which, coupled with the likely differeaces in microbial biomass, could be the major factor responsible for variations in the half-llfe of the compound. Therefore, the quantity of the neem leaves applied and the addition of animal manure affected the breakdown of azadirachtin A in the soil amended with neem leaves.

Adsorption Isotherm, Kinetic and Thermodynamic Modelling of <i>Bacillus subtilis</i>ATCC13952 Mediated Adsorption of Arsenic in Groundwaters of Selected Gold Mining Communities in the Wassa West Municipality of the Western Region of Ghana

This study investigated Bacillus subtilis ATCC13952 as an adsorbent for arsenic in groundwater. Batch experiments were used to determine the effect of contact time, adsorbent dose, arsenic (III) concentration, pH, and temperature on the process. The percentage of arsenic (III) removed was high at a contact time of four days, 3.0 mL of Bacillus subtilis ATCC13952, pH 8 and temperature of 35°C. The kinetics of the process showed the Elovich kinetics model as the best fit for the process. This indicates that arsenic removal was by chemisorption. The analysis of the nonlinear equilibrium isotherms and the error functions showed the Langmuir isotherm as best fit for the process. Mechanistic study of the process indicated bulk diffusion to be the rate-determining step. Thermodynamically, the process was favourable, spontaneous and feasible. When the community water samples were treated with the Bacillus subtilis ATCC13952 at the optimum contact time, adsorbent dose, pH and temperature, 99.96% - 99.97% of arsenic was removed across all sampling points within the studied communities. Hence, the results show that Bacillus subtilis ATCC13952 is an efficient adsorbent for arsenic in aqueous systems and the organism appears to hold the key to purging the environment of arsenic contamination.

The Cry of “Sumampa”: A River in Mampong Ashanti in Crisis

The Sumampa River in Mampong-Ashanti in Ghana is a very important river that supplies water to the water processing company for treatment for the whole community and its environs. In spite of its importance, the buffer area of the river has been encroached by settlers. Residential houses sited along the river have channeled their waste water into the river and several anthropogenic activities go on along the river. Therefore, this study was conducted to assess the effects of anthropogenic activities on the quality of the river. Water samples were collected from various parts of the river including the source and outflow for physico-chemical and microbial analyses. The results showed that, the water was highly turbid with high total dissolved solids at some points because of intense anthropogenic activities. High turbidity and total dissolved solids greatly influence the microbial load of the water. We therefore recommend that measures are put in place to protect the Sumampa River through the creation of a buffer zone by planting trees along the banks of the river. The trees could help detoxify the run-off water that flows into the river.

Soil Erosion around Foundations of Houses in Four Communities in Ghana

Soil erosion studies around houses in four communities in Ghana were carried out from August to November, 2010. Thirty houses were selected from each of the four communities for the study. Measurements of slope and the depth of exposed foundation of houses were done with the help of a string and a tape measure. Data were also obtained through questionnaire and interview of house owners. The Pearson’s correlation coefficient was used to measure some relationships among data. In the selection of site for building a house, higher percentage of the house owners considered no factor. The major cleaning activity around the surrounding of houses was noted to be sweeping with a broom. All the houses in the communities had their foundations exposed, 57% - 93% of the houses had exposed foundations up to a level within 51 - 100 cm which was classified as “Severely Exposed”. The extent of building foundation exposed by soil erosion was found to be positively correlated with the age of building and the slope of the land. Most of the respondents controlled soil erosion by blocking water ways with materials such as, sand heaps, stones and sacks filled with soil. Only 10% of the respondents from one of the communities planted grasses around their houses to control soil erosion. Communities need to be educated to plant grasses around their houses to beautify the surroundings and to control soil erosion.

Quality Assessment of River Offin along a Canopy Cover Gradient

The potential effect of canopy cover on the quality of River Offin which serves as drinking water for communities including Hwediem, Mprim and Boanim in the Mampong Municipality of the Ashanti region of Ghana was studied. These communities exemplify Ghanaian farming communities. Often, rural farmers do not have access to clean water. Using the part of the river serving these communities as a test case, we assessed the quality of water along a gradient of three different levels of canopy cover (closed, semi-closed and open canopy) where residents frequently access water. Physico-chemical tests showed that, the level of most of the physical and chemical properties of the water under all three different canopy covers was within the acceptable limits set by the World Health Organization. There was low turbidity where the canopy was closed resulting in relatively lower faecal coliforms. Total dissolved solids were also less where canopy cover was closed. Therefore, the general water quality could be potentially improved by planting trees along the river to form canopy.