Wenner array resistivity and sp logging for ground water exploration in sawerpuram Teri deposits, Thoothukudi District, Tamil Nadu, India

A. Antony Ravindran, N. Ramanujam and P. Somasundaram

The aim of the study to identifyying a good site for groundwater exploration in teri deposits. In this rock types, groundwater occurs in secondary porosity developed due to weathering, faulting, fracturing in the subsurface formation. In such situations Wenner array with resistivity and SP logging is suitable method for groundwater exploration in the Teri deposits. Initially based topography, geomophological and hydrogeologial features, an area about 2km was segregate as a promising zone for groundwater exploration in the teri deposits of Sawerpuram, Thoothukudi District, Tamil Nadu, India. The Vertical Electrical Sounding was carried out using Wenner electrode configuration with help of equipment CRM 500. The interpretations were carried using Apparent Resistivity and SP logging techniques. The resistivity ranging from 100-120 Ohm.m indicates the freshwater zone in the study area.

Geophysical use of quarry dust (as admixture) as applied to soil stabilization and modification-a review

Onyelowe Ken C., Okafor F. O. and Nwachukwu D. G.

The availability of build able land is fast drifting away each day due to scarcity of lands with good natural bearing capacity. This leads to construction of buildings on poor soils which eventually lead to structural foundation failures. It has become very imperative to improve soils or the quality of grounds by the adoption of suitable improvement methods depending on the materials available. However, during soil or ground improvement, cost effectiveness is one of the major factors considered cardinal. Consequent upon this, there is a paramount need to adopt the use of admixtures during cement/soil improvement or stabilization. This necessitated the review on a very important admixture in geotechnical engineering and in cement stabilization of soils during pavement construction. However, quarry dust which is a waste product from aggregate production could replace some proportions of sand/soil. This admixture not only replaces some proportions of soil for cost effective soil improvement but according researches carried over the years on this waste product, improves the geophysical properties of the joint mixture; cement/soil/quarry dust. Since the introduction of quarry dust improves the engineering behavior of soils, this review work exposes those qualities and applications that make quarry dust a good replacement or admixture during soil improvement and for a more economic approach. The present review also gives researchers and geotechnical engineers a clue on the application of quarry dust and the limit for its usage.

Determination of hydrocarbon sources using n-alkane and PAH distribution indices in sediments from coastal areas of bonny river in Niger delta, Nigeria

Ebirien P. Fubara, Bassey O. Ekpo, Okon D. Ekpa and Hab L. Marynowski

Surface sediments from coastal areas of Bonny river in the Southeastern Niger Delta region of Nigeria were characterized for n-alkane and polycyclic aromatic hydrocarbon (PAH) compositions using gas chromatography-mass spectrometry (GC-MS) technique. The total n-alkane (TNA) concentrations in the study area ranged from 1.65-12.66 mg/kg dsw. The mean concentrations of n-alkanes C₁₆ - C₂₉ for the sediments ranged from 0.11- 10.31mg/kg dsw, with the highest mean value recorded for n-alkane C₁₇. CPI values ranged from 0.31 - 1.65, and a predominance of odd/even carbon n-alkanes with unimodal distributions were observed for the entire stations. Factor analyses reduced the data set into three principal components (PCs) confirming mixed inputs from biogenic (71.48%), anthropogenic (11.61%) and microbial/bacterial (7.90%) sources of n-alkanes. Twenty four (24) parent and alkylated homologous PAHs of dominant pyrogenic origin were detected in stations from the study area, with total PAH concentrations in the range of 2.13- 16.72mg/kg.

Assessment of surface water receiving sewage effluents for gardening irrigation purposes: a case study of Ona River in Ibadan southwest local government area of Oyo State, Nigeria

Adetayo Adewale Olusola

The analysis of chemical quality of Ona River in Ibadan Southwest Local Government (IBSWLG) area of Oyo State was undertaken in this study to assess its suitability for irrigation purposes by considering two major seasons in the ecological zone. In order to achieve the said objectives, fourty sampling points were selected along the stream at about 20m interval. The water samples collected were analyzed in the laboratory using methods of Ademoroti (1996). The result showed that despite the large content of sewage effluents characterized by some of the areas, the quality of the surface water remains within the safe limit for irrigation purposes; thus, Ona River water can be developed for all-year round crop production in the study area. However, the need to continuously monitor and assess surface water quality for irrigation is stressed.

Identification of 24-ethylcholestanes as molecular indicators of vascular plants source inputs in coastal sediments from Niger delta, Nigeria

Ebirien P. Fubara, Bassey O. Ekpo, Okon D. Ekpa and Hab L. Marynowski

The identification of aaa-24-ethylcholestane, 2a-methyl-24-ethylcholestane and 3β-Methyl-5a- stigmastane in extracts of sediments from the coastal areas of the Niger Delta of Nigeria was achieved by gas chromatography-mass spectrometry (GC-MS) technique. The concentrations of the 24-ethylcholestanes varied between 0.05 and 1.40 mgkg-1 in the entire study area. The distributions of the 24-ethylcholestanes, which are known to be diagenetic products of plant sterols (phytosterols) in our samples, suggest possible source inputs from vascular plants around the coastal vegetation of the Niger Delta environment.

Geochemistry of soil stabilization

Onyelowe Ken C. and Okoafor F. O.

This study was centered on elucidating the chemical reactions that bring about soil stabilization and modification during soil chemical stabilization without which there won’t be the achievement of an anticipated improved soil for most engineering works. In the course of the study, this research has been able to establish the reactions between soil and cement, bitumen, and the chloride compounds. It has been established that the chemical compounds found in soil; quartz, feldspar, dolomite, calcite, montmorillonite, kaolinite etc. react with the chemical constituents found in different identified chemical stabilizers. Cement for instance contains the calcium silicates, the calcium aluminates, and the calcium alumino ferrites that in turn react with the soil (clay) chemical compounds to form the matrix of soil used as either subgrade or subbase materials. From the work, it is observed that quicklime reacts in a deeper extent by dehydrating the soil. Through this process of dehydration, it becomes more useful by changing to hydrated lime. This is the stage where the main chemical reactions that led to soil stabilization starts. This research work will better place designers, constructors and researcher on the choice of soil chemical stabilizer and techniques and the extent of chemical reactions that take place during soil chemical stabilization.