Effects of gas flaring on blood parameters and respiratory system of laboratory mice, <Emphasis Type="Italic">Mus musculus</Emphasis>

In order to evaluate the potential harmful effects of gas flaring on mammals, albino mice, Mus musculus, were exposed to gas flares for 8 weeks under laboratory conditions. The effect of gas flaring on blood parameters includes a reduction in white blood cell counts among mice exposed to 8-h daily of gas flaring when compared to control mice. The red blood cells also showed varied abnormalities such as stacked erythrocytes (rouleaux formation), crenated (spicule) cells and teardrop cells (dacrocytes). The detection of the increasing level of eosinophils in the blood of mice exposed to gas flares was observed to be indicative of a degenerative disease condition and usefulness as a good marker of pollution for monitoring, and early detection of adverse effects of gas flares was recommended. Histopathological examination of the lungs of exposed mice revealed distortions in the segmental bronchus and alveoli of the respiratory organ, with interspersed brown pigments and polymorphonuclear cells, which were absent in the controls. The environmental implications including the health hazards posed by the exposure of mammals to gas flares in crude oil production areas were discussed.     

Monitoring of soil and groundwater contamination following a pipeline explosion and petroleum product spillage in Ijegun, Lagos Nigeria

In May 2008, an accidental damage of a Nigerian National Petroleum Corporation (NNPC) pipeline occurred in Ijegun area of Lagos, Nigeria, resulting in oil spillage and consequent contamination of the environment. The residual concentration of the total hydrocarbon (THC) and benzene, toluene, ethylbenzene, and xylene (BTEX) in the groundwater and soil was therefore investigated between March 2009 and July 2010. Results showed elevated THC mean levels in groundwater which were above the World Health Organization maximum admissible value of 0.1 mg/l. THC values as high as 757.97 mg/l in groundwater and 402.52 mg/l in soil were observed in March 2009. Pronounced seasonal variation in the concentration of THC in groundwater and soil samples show that there was significant (P?<?0.05) difference in the measured concentration of THC between each season (dry and wet), with the highest being in the dry season and between the years 2009 and 2010. Significant hydrocarbon contamination, 500 m beyond the explosion site and 25 months after the incident, was observed revealing the extent of the spillage of petroleum products. The highest concentrations of 16.65 μg/l (benzene), 2.08 μg/l (toluene), and 4864.79 μg/l (xylene) were found in stations within the 100 m buffer zone. Most of the samples of groundwater taken were above the target value of 0.2 μg/l set for BTEX compounds by the Environmental Guidelines and Standards for Petroleum Industry in Nigeria. The level of hydrocarbon in the impacted area calls for concern and remediation of the area is urgently needed to reduce further negative impact on the ecosystem.     

Relevance of joint action toxicity evaluations in setting realistic environmental safe limits of heavy metals

The evaluation of types of toxicological interactions existing between heavy metals, which are prominent in effluents of some industrial establishments in Lagos State, Nigeria and the Lagos lagoon sediment was carried out against benthic animals, Tympanotonus fuscatus, Clibanarius africanus and Sesarma huzardi of the Lagos lagoon. In order to determine the type of interactions existing between the metals, acute toxicity tests of the metal compounds when acting singly and in joint action studies, by adopting mixture ratios that depict (i) the proportions of the concentrations of the metal ions in the sediment of the Lagos lagoon and (ii) equitoxic mixtures, i.e. based on the 96 hLC(50) values of the metal compounds under single action studies were carried out in laboratory biotests. The joint action evaluations of the test metal mixtures, prepared on the basis of the proportion of the availability of the metals ions in lagoon sediment and equitoxic ratio against the test animals agreed mainly with the model of antagonism (reduction in toxicity) except for test mixtures prepared on the basis of equitoxic ratio and tested against T. fuscatus, where interactions between the test metals was in conformity with the model of synergism, indicating that the toxicity of the constituent metals in the mixture was enhanced. Furthermore, on the basis of classification of synergistic ratio model, the toxic effect of Pb compound which was the least toxic metal compound in the single action toxicity studies was found to be enhanced (synergised) in the presence of other metals when tested jointly. The significance of the results in setting water quality criteria aimed at protecting aquatic biota was discussed.     

Determination of types of interactions exhibited by binary mixtures of heavy metals tested against the hermit crab,Clibanarius africanus

Single and joint action toxicity of heavy metal compounds (ZnCO₃, CuSO₄ and CdSO₄) were carried out against the hermit crab, Clibanarius africanus in laboratory bioassays. On the basis of 96?h LC₅₀ values, CuSO₄ (96?h LC₅₀?=?0.03?mM) was found to be the most toxic followed by CdSO₄ and ZnCO₃ (96?h LC₅₀?=?0.24?mM) in decreasing order of toxicity. The evaluation of the metal compounds in mixtures of ZnCO₃–CuSO₄, ZnCO₃–CdSO₄ and CdSO₄–CuSO₄ in pre-defined molar ratios revealed that interactions between Zn–Cu and Zn–Cd test mixtures were in conformity with the models of antagonism (reduction in toxicity of constituent metals). The synergistic ratios (S.R.s) and relationship between observed/predicted 96?h LC₅₀ values (relative toxic unit, RTU) were consistently below 1, indicating antagonistic interactions. Analysis using isobolograms also indicated the interactions between the mixture components to be antagonistic. However, with regards to CdSO₄–CuSO₄ test mixtures, the interactions between these metals were mainly in conformity with the model of synergism. The S.R. and RTU values were largely above 1, indicating synergistic interactions. The importance of the joint action evaluations for the management and protection of aquatic ecosystems, particularly in the setting up of water quality criteria was discussed.     

Morphological and anatomical effects of crude oil on <Emphasis Type="Italic">Pistia stratiotes</Emphasis>

Fresh whole plants of Pistia stratiotes were exposed to varying doses of crude oil (0–100 ppm) for 28 days at normal temperature of 30 ± 2°C. Samples were taken weekly during this period for determination of changes in leaf area, root length, number of leaves, and number of sprouts. The cross-section of one terminal end of the major roots and cellular distribution of the meristematic region were also examined. The results show that crude oil was toxic to the plant at all concentrations in all investigated parameters for as low as 10 ppm. Association was also observed between crude oil toxicity and certain metals inherent in the crude oil such as manganese and lead. Cell shape disruptions, changes in mitotic indices, and the distortion of cellular anatomy and structure at the apical region also characterized the presence of crude oil in the environment of P. stratiotes. P. stratiotes may not be a good bio-accumulator of crude oil but may be used for the detection of pollution.     

Histopathology alterations and lipid peroxidation as biomarkers of hydrocarbon-induced stress in earthworm, Eudrilus eugeniae

This study investigated the biomarker responses of the earthworm, Eudrilus eugeniae, exposed to sublethal concentrations of benzene, toluene and xylene (BTX) for a time span of 28 days. Lipid peroxidation (LPO) and histopathological alterations were examined. Toxicological evaluations of BTX were carried out against E. eugeniae. On the basis of the 96-h LC₅₀ value, xylene (1.212 mg/kg) was found to be the most toxic followed by toluene (1.335 mg/kg) and benzene (1.896 mg/kg) was the least toxic. The exposure of earthworms to sublethal concentrations (1/10th and 1/100th of 96 h LC₅₀) of BTX premixed with the substrate (loamy and humus soil) induced pathological changes in the clitella such as severe lesion, necrosis and dark brown pigments. The result of the lipid peroxidation assay showed a significant increase in oxidative damage with LPO values ranging from 2.58–7.8 nM/g in exposed animals when compared to 0.07 nM/g in the control group. The findings from this study suggest the use of LPO and histopathology as useful biomarkers of exposure for early detection of petroleum related stress in terrestrial ecosystems     

Occurrence of chemical pollutants in major e-waste sites in West Africa and usefulness of cytotoxicity and induction of ethoxyresorufin-O-deethylase (EROD) in determining the effects of some detected brominated flame retardants and e-waste soil-derived extracts

Environmental Science and Pollution Research - We investigated the occurrence of chemical pollutants in major e-waste sites in West Africa and usefulness of cytotoxicity and induction of...     

Recovery assessment of a refined-oil impacted and fire ravaged mangrove ecosystem

An assessment of the diversity and abundance of macrobenthic community in a refined-oil (petrol) impacted and fire-ravaged mangrove ecosystem within the vicinity of a marine receipt terminal facility (Atlas Cove) serving as a distribution and pump station for refined products was carried out. The mangrove ecosystem was subjected to massive petrol spillage from a leaking pipeline and eventual fire outbreak. Following rehabilitation activities, a recovery assessment of the impacted ecosystem was carried out. The field surveys revealed that the petrol leakage and fire outbreak resulted in a near complete destruction of the mangrove ecosystem around the Atlas Cove depot, with macrobenthic species diversity index ranging between 0−0.4, compared to 0.78−0.87 in the control stations. The dominant early arrivals or colonizers of the impacted stations areas were Clibanarius africanus and Callinectes amnicola. Early signs of recovery of the impacted area were observed within about two and a half (2 1/2) to three (3) months, based on diversity and abundance indices respectively. The period of early signs of recovery also coincide with an observed reduction in the total hydrocarbon content (THC) levels in the sediment collected from the impacted stations by about nine folds from 3.67 mg/kg to 0.42 mg/kg within 3 months. Despite the apparent signs of recovery, the need for long-term monitoring of the impacted stations was discussed.     

Biological responses in edible crab, <Emphasis Type="Italic">Callinectes amnicola</Emphasis> that could serve as markers of heavy metals pollution

Responses of lagoon crab, Callinectes amnicola were explored as useful biological markers of heavy metal pollution. The toxicity level of the metals based on the 96-h LC50 values showed that copper with LC50 value of 0.018 mM was found to be two times more toxic than Lead (0.041 mM) against the lagoon crab, C. amnicola. The exposure of the lagoon crab to sublethal concentrations (1/100th and 1/10th of 96-h LC50 values) of Cu and Pb compound, respectively, resulted in the bioaccumulation of the test metals to varying degrees in the selected organs that were dependent on the type of metal and concentration of metal compound in the test media. The degree of metal (Cu and Pb) accumulation was generally in the following order: gills > muscle > heptopancrease. Exposure of the crabs to sublethal concentrations of the metals also caused pathological changes such as the disruption of the gill filaments and degeneration of glandular cells with multifocal areas of calcification in the hepatopancreas. A reduction in the weight of the exposed animals over a 14-day period of observation was also recorded. The significance of these results and the usefulness of the biological endpoints in monitoring programmes aimed at establishing the total environmental level of heavy metals in aquatic ecosystems were discussed.