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

  • Date palm waste biochars alter a soil respiration, microbial biomass carbon, and heavy metal mobility in contaminated mined soil 2017-04-19

    Abstract

    A 30-day incubation experiment was conducted using a heavy metal-contaminated mined soil amended with date palm feedstock (FS) and its derivative biochars (BCs) at three pyrolysis temperatures of 300 (BC-300), 500 (BC-500), and 700 °C (BC-700) with different application rates (0.0, 5, 15, and 30 g kg−1) to investigate their short-term effects on soil respiration (CO2–C efflux), microbial biomass carbon (MBC), soil organic carbon (SOC), mobile fraction of heavy metals (Cd, Cu, Pb, Zn, Mn, and Fe), pH, and electrical conductivity (EC). The results showed that FS and BC-300 with increasing addition rate significantly reduced soil pH, whereas SOC, CO2–C efflux, and soil MBC were increased compared to the control. On the contrary, BC-500 and BC-700 increased soil pH at early stage of incubation and have small or no effects on SOC, CO2–C efflux, and MBC. Based on the results, the date palm biochars exhibited much lower cumulative CO2–C efflux than feedstock, even with low-temperature biochar, indicating that BCs have C sequestration potential. Applying BC-700 at 15 and 30 g kg−1 significantly reduced cumulative CO2–C efflux by 21.8 and 45.4% compared to the control, respectively. The incorporation of FS into contaminated soil significantly increased the mobile content of Cd and Mn, but decreased the mobile content of Cu. However, BC-300 significantly reduced the mobile content of Cd, Cu, Pb, and Zn. It could be concluded that low-temperature biochar could be used as a soil amendment for reducing heavy metal mobility in mining contaminated soil in addition to minimize soil CO2–C efflux.

  • Historical record of anthropogenic polycyclic aromatic hydrocarbons in a lake sediment from the southern Tibetan Plateau 2017-04-17

    Abstract

    High-altitude lake sediments can be used as natural archives to reconstruct the history of pollutants. In this work, the temporal distribution of polycyclic aromatic hydrocarbons (PAHs) was determined in a sediment core collected from the southern Tibetan Plateau (TP), which was dated by using the 210Pb dating method and validated with the 137Cs fallout peak. The concentrations of the anthropogenic PAHs (Σ8PAH) in the sediment core ranged from 0.83 to 12 ng/g dw, and the fluxes of the Σ8PAH were in the range of 2.1–27 g/cm2/year. The temporal variations in the concentration and input flux of anthropogenic PAHs were low with little variability before the 1950s, and then gradually increased from the 1950s to the 1980s, and an accelerated increase was observed after the early 1980s. The content of total organic carbon played an insignificant role in affecting the time trends of PAHs in the sediment core. Diagnostic concentration fractions of PAH components indicate PAHs in the lake sediment of the southern TP which are mainly from biomass burning and/or from long-range atmospheric transport.

  • Determination of the potential implementation impact of 2016 ministry of environmental protection generic assessment criteria for potentially contaminated sites in China 2017-04-12

    Abstract

    The Ministry of Environmental Protection of China issued a 3rd draft edition of risk-based Generic Assessment Criteria (the MEP-GAC) in March 2016. Since these will be the first authoritative GAC in China, their implementation is likely to have a significant impact on China’s growing contaminated land management sector. This study aims to determine the potential implementation impact of the MEP-GAC through an in-depth analysis of the management context, land use scenarios, health criteria values adopted and exposure pathways considered. The MEP-GAC have been proposed for two broad categories of land use scenarios for contaminated land risk assessment, and these two categories of land use scenarios need to be further delved, and a MEP-GAC for Chinese cultivated land scenario ought to be developed, to ensure human health protection of Chinese farmers. The MEP-GAC have adopted 10−6 as the acceptable lifetime cancer risk, given the widespread extent and severe level of land contamination in China, consideration should be given to the decision on excess lifetime cancer risk of 10−5. During risk assessment process in practice, it is better to review the 20% TDI against local circumstances to determine their suitability before adopting it. The MEP-GAC are based on a SOM value of 1%, for regions with particularly high SOM, it might be necessary to develop regional GAC, due to SOM’s significant impact on the GAC developed. An authoritative risk assessment model developed based on HJ25.3-2014 would help facilitate the DQRA process in practice. The MEP-GAC could better reflect the likely exposures of China’s citizens due to vapour inhalation by using characteristics of Chinese exposure scenarios, including China-generic building stock, as inputs into the Johnson and Ettinger model as opposed to adoption of the US EPA parameters. The MEP-GAC once implemented will set the trajectory for the development of the investigation, assessment and remediation of land contamination for years.