Chemometric analysis of ecological toxicants in petrochemical and industrial environments.

The application of chemometrics in the assessment of toxicants, such as heavy metals (HMs) and polycyclic aromatic hydrocarbons (PAHs) potentially derived from petrochemical activities in the microenvironment, is vital in providing safeguards for human health of children and adults residing around petrochemical industrial regions. Several multivariate statistical methods are used in geosciences and environmental protection studies to classify, identify and group prevalent pollutants with regard to exhibited trends. Chemometrics can be applied for toxicant source identification, estimation of contaminants contributions to the toxicity of sites of interest, the assessment of the integral risk index of an area and provision of mitigating measures that limit or eliminate the contaminants identified. In this study, the principal component analysis (PCA) was used for dimensionality reduction of both organic and inorganic substances data in the environment, which are potentially hazardous. The high molecular weight (HMW) PAHs correlated positively with stronger impact on the model than the lower molecular weight (LMW) PAHs, the total petroleum hydrocarbons (TPHs), PAHs and BTEX correlate positively in the F1 vs F2 plot indicating similar source contributions of these pollutants in the environmental material. Cu, Cr, Cd, Fe, Zn and Pb all show positive correlation in the same space indicating similar source of contamination. Analytical processes involving environmental assessment data obtained in the Niger Delta area of Nigeria, confirmed the usefulness of chemometrics for comprehensive ecological evaluation.

Potential risk effect from elevated levels of soil heavy metals on human health in the Niger delta.

An analysis of the soil quality in the Niger Delta Area (NDA) was carried out to determine the severity of soil contamination. The United States Environmental Protection Agency (US EPA) risk assessment model was used in determining the potential health risk due to lifetime exposure (by means of ingestion, dermal contact and inhalation) of the population to heavy metal contents in the soil. Substantial levels of contamination were found indicating elevated levels of heavy metals above background concentrations from controlled samples in the areas. Median topsoil metal concentrations (0-15cm) in the NDA measured in mg/kg were: Zn 58.3±37.0, Cd 1.3±1.0, Cr(VI) 13.2±5.5, Cu 28.3±31.5, Pb 895.1±423.9, Ni 42.7±20.3, Mn 201.8±77.5 and Fe 1303.5±2028.6. Pb, Ni, Zn, Cd, Cr(VI), Fe and Mn exceeded some guideline and standard values; while the comprehensive levels of total metals contamination exceeded the environmental action level for soils, which could potentially affect human health. The collective total risk (carcinogenic and non-carcinogenic) for minors and adults were established from the model using the slope factors and reference dose of the compounds respectively. The study has shown that soil contamination in the industrial and residential regions are similarly significant; while the risk assessment proved that based on the pollutants concentration in the soil, metals with the highest cancer risk values (Pb=2.62E-02 and Cr(VI)=1.52E-02) have the potential of affecting the health status of the residents, especially for children in the region. The chronic daily intake of the metals are of major concern as their cumulative effect could result to several health complications of children and adults in the region.