SEGH Articles

Application of geochemical signatures of shale in environmental pollution and human health assessment in South East Nigeria

15 June 2011
Therese Ntonzi Nganje describes her experience through a Commonwealth Scholarship scheme on connecting Nigerian and UK scientists.

This work contained activities during the period of my Commonwealth Scholarship Commission Fellowship (NGCF-2009-154) tenable held at the University of the West of Scotland October 2009- April 2010 under the supervision of Professor Andrew Hursthouse.

Areas underlain by shale rock in some parts of south-eastern Nigeria were investigated to ascertain the degree of environmental pollution by potential toxic trace element and the possible impact on human health.   A control area underlain by sandstone was also investigated as a known naturally low potentially toxic trace element area. Shales, especially the black variety, are natural geological sources of potentially toxic trace elements such as As, Cd, U, Mo, Cu, Ni, Hg among others, which are known to influence human health. The aim of this work was to primarily assess the effect of shale on the quality of the environment (soil, edible crop plants and water), evaluate the exposure pathways of the toxic trace elements and their implications on the health of humans. Samples of food, soil and drinking water were collected and transported under licence to the  

The water and soils and crop plants materials after the necessary treatment were digested with aqua regia in a hot block and were analyzed for both major and trace metals contents using Inductively Coupled Plasma Emission Spectrometry (ICP - OES) and Inductively Coupled Plasma Mass Spectrometry (ICP - MS) techniques. The anions in the water samples were determined by means of ion chromatography. Water physical parameters such as pH and conductivity were determined in-situ in the field. Also, soil parameters such as pH, total organic carton (TOC) as well as particle size were determined using standard methods.

The full results of the work are in various stages of preparation for publication and will include assessment to:

  • Allow comparison with existing global soil/plant/water data bases.
  • Establish the relationship between micronutrients and trace elements in soils and plants and possible implications to the health of humans in the area of study.
  • It is anticipated that this will provide a guide for policy analysis, environmental and health management decisions in the rapid urbanizing environment of Calabar and environs where my home University is located.

In addition, during my Fellowship, I was able to update and acquire new analytical skills and support to enable me to obtain a tenured position and scientific leadership in the area of Environmental Geochemistry at the University of Calabar (Nigeria). 

 

Activities included typical staff induction and orientation activities, advanced lecture courses in analytical techniques and measurement processes, seminars on environmental geochemistry - including iodine deficiency as well as research funding guidance. I also met many researchers, academics and technicians from Universities and regulatory organisations in the local area and had contact with other Commonwealth Fellows in the UK. I also had the opportunity to supervise UWS students in practical lab work.

All these activities were very relevant to my research at UWS as well as for my future career back in Nigeria as I am acquainted with the recent advances and analytical techniques in the area of environmental geochemistry and health of humans

My research stay in Scotland and UK has been very joyous, beneficial and successful as can be seen from the above report. The enabling environment to carry out this work to a successful completion was due to the receptive, friendly and accommodating people I met within and out of UWS.

 

I would like to thank Prof Andrew Hursthouse for accepting to host me, supervision and guidance, the University of the West of Scotland for access to facilities at the School of Science, the Commonwealth Scholarship Commission and British Council for funding and for their support prior to my visit and during the period of my fellowship and the authorities of the University of Calabar for the nomination and granting a study leave for me to take up the fellowship. The contributions of my head of department, Prof Aniekan Edet and colleague, Prof CS Okereke, SEGH and Dr Michael Watts of the British Geological Survey in UK for finding me a host institute are appreciated. The assistance provided in various aspects of the research work by Dr Simon Cuthbert, Dr John Hughes, Mr David Wallace, Mr Charlie McGuinnes, Ms Margaret Train and Natalie Dickson are also appreciated.

Finally my sincere and special thanks to Mr David Stirling for skills acquired and updated in the use of ICP-AES and ICP-MS and Mr Iain Mclellan for skills updated in the determination of some soil bulk parameters in soils.

Dr. Therese Ntonzi Nganje, University of Calabar, Nigeria

Keep up to date

Submit Content

Members can keep in touch with their colleagues through short news and events articles of interest to the SEGH community.

Science in the News

Latest on-line papers from the SEGH journal: Environmental Geochemistry and Health

  • Editorial 2018-12-11
  • Chemical fractionation of heavy metals in fine particulate matter and their health risk assessment through inhalation exposure pathway 2018-12-11

    Abstract

    Samples of PM2.5 were collected from an urban area close to a national highway in Agra, India and sequentially extracted into four different fractions: water soluble (F1), reducible (F2), oxidizable (F3) and residual fraction (F4) for chemical fractionation of arsenic (As), cadmium (Cd), cobalt (Co), chromium (Cr), nickel (Ni) and lead (Pb). The metals were analyzed by inductively coupled plasma optical emission spectroscopy in each fraction. The average mass concentration of PM2.5 was 93 ± 24 μg m−3.The total concentrations of Cr, Pb, Ni, Co, As and Cd in fine particle were 192 ± 54, 128 ± 25, 108 ± 34, 36 ± 6, 35 ± 5 and 8 ± 2 ng m−3, respectively. Results indicated that Cd and Co had the most bioavailability indexes. Risk Assessment Code and contamination factors were calculated to assess the environmental risk. The present study evaluated the potential Pb hazard to young children using the Integrated Exposure Uptake Biokinetic Model. From the model, the probability density of PbB (blood lead level) revealed that at the prevailing atmospheric concentration, 0.302 children are expected to have PbB concentrations exceeding 10 μg dL−1 and an estimated IQ (intelligence quotient) loss of 1.8 points. The predicted blood Pb levels belong to Group 3 (PbB < 5 μg dL−1). Based on the bioavailable fractions, carcinogenic and non-carcinogenic risks via inhalation exposure were assessed for infants, toddlers, children, males and females. The hazard index for potential toxic metals was 2.50, which was higher than the safe limit (1). However, the combined carcinogenic risk for infants, toddlers, children, males and females was marginally higher than the precautionary criterion (10−6).

  • Effects of steel slag and biochar amendments on CO 2 , CH 4 , and N 2 O flux, and rice productivity in a subtropical Chinese paddy field 2018-12-07

    Abstract

    Steel slag, a by-product of the steel industry, contains high amounts of active iron oxide and silica which can act as an oxidizing agent in agricultural soils. Biochar is a rich source of carbon, and the combined application of biochar and steel slag is assumed to have positive impacts on soil properties as well as plant growth, which are yet to be validated scientifically. We conducted a field experiment for two rice paddies (early and late paddy) to determine the individual and combined effects of steel slag and biochar amendments on CO2, CH4, and N2O emission, and rice productivity in a subtropical paddy field of China. The amendments did not significantly affect rice yield. It was observed that CO2 was the main greenhouse gas emitted from all treatments of both paddies. Steel slag decreased the cumulative CO2 flux in the late paddy. Biochar as well as steel slag + biochar treatment decreased the cumulative CO2 flux in the late paddy and for the complete year (early and late paddy), while steel slag + biochar treatment also decreased the cumulative CH4 flux in the early paddy. The biochar, and steel slag + biochar amendments decreased the global warming potential (GWP). Interestingly, the cumulative annual GWP was lower for the biochar (55,422 kg CO2-eq ha−1), and steel slag + biochar (53,965 kg CO2-eq ha−1) treatments than the control (68,962 kg CO2-eq ha−1). Total GWP per unit yield was lower for the combined application of steel slag + biochar (8951 kg CO2-eq Mg−1 yield) compared to the control (12,805 kg CO2-eq Mg−1 yield). This study suggested that the combined application of steel slag and biochar could be an effective long-term strategy to reduce greenhouse gases emission from paddies without any detrimental effect on the yield.