环境与分析毒理学

The major transport fuels in Kenya are gasoline and diesel. A complaint on adulteration of these fuels at the point of sale or during transportation is a common occurrence in the country. The present studies on analysis of petroleum adulteration does not give a scope of what is happening at the newly and upcoming petrol stations outside the capital of city. Purposeful sampling was carried out on investigating gasoline and diesel adulteration sold at selected fuel stations in in a case study of Kisii County, and whether these products are within the standards set by Kenya bureau of Standards (KEBs). Samples of gasoline and diesel were collected from selected five fuel stations and two laboratory testing methods of ASTM D86 (Distillation) and ASTM D1298 (Density determination) were conducted at Vivo Energy Company laboratory in Nairobi. Currently, the number of fuel stations selling Gasoline and diesel is enormous in Kisii region. They involve four major oil companies namely, Shell, Total, Kenol/Kobil, Oil Libya, and now KNOCK which dominate the market as well as locally owned ones. Therefore, the sampling method that was employed to select randomly five specific filling stations comprising of one major and four Minor companies representing the population with parameters of interest, for analysis in this study.

A Plantain harvested from Bodo community, Gokana L.G.A Rivers state were analyzed for heavy metals and Polycyclic Aromatic Hydrocarbons (PAHs) concentrations. Physicochemical properties of the agricultural soil used for the plantain cultivation showed the following: pH (5.7) while the control experiment was seen at 7.4. Soil conductivity of 721 and 398 were obtained for both the test and control experiments, respectively. Soil mineral contents: Potassium (6.88 mg/g), phosphorus (2.63 mg/g), Magnesium (12.42 mg/g), chloride ions (1021.21 mg/g). Heavy metal analysis of the soil showed a greater proportion of copper and iron in while Hg, As and Cd were below detectable limit in both tested samples. Pb was found relatively in lower concentrations of 24.12 mg/g in the test sample, 6.23 mg/g in the control experiment. Total Oxidizable Carbon Content (TOC) and Total Petroleum Hydrocarbon (TPH) content of the soil were observed at 104.12 and 2567 mg/g respectively in the tested sample. The control experiment showed TOC and TPH concentrations of 42.85 and 1094 mg/g. Heavy metal analysis of harvested plantain from Bodoh community showed the presence of the following: Lead (Pb), Iron (Fe) and Copper (Cu) in the following order: Cu>Fe>Pb in the test sample while in the control experiment, iron (Fe) was seen greater than copper (Cu). Heavy metals of mercury, cadmium and arsenic were below detectable limit at in both the harvested plantain from Bodo community and those of the control experiment, respectively. Bioaccumulation factor of all the heavy metals identified were <1. PAHs of Acenaphthalene, Acenaphthene, chrysene, pyrene and fluranthene were not detected in the control experiment while only chrysene was not detected in the test samples. Naphthalene,methyl naphthalene, acenaphthalene, acenaphthene, benzo (k) fluranthene and flourene were relatively high in concentration than pyrene and flouranthene in the test samples. Naphthalene, methylnaphthalene, flourene and benzo(k) flouranthene were only recorded in the control experiment. Acenaphthalene (0.034 mg/g) was seen as the highest PAHs in bioaccumulation in the test sample while flourene (0.005 mg/g) recorded the highest in the control experiment.

Morphometric and meristic features, metal accumulation and chemical composition of Sarotherodon melanotheron and its intestinal parasites were investigated in August, 2013. The Standard length of Sarotherodon melanotheron range between 13.10-21.50 cm with Mean ± SD of 16.15 ± 1.97, (p<0.001) and Head length range from 1.50-2.70 with Mean ± SD of 2.15 ± 0.28, (p<0.001). Heavy metal concentrations were determined in water, sediment, intestinal parasites, gills and liver of Sarotherodon melanotheron were analysed using Atomic Absorption Spectrophotometry to determine concentration of Pb and Zn. Metals in the water, sediment and parasites were above WHO level. The concentration of Lead and Zinc were higher in the sediment (Pb-18.82 and Zn-21.52) than the water (Pb-2.66 and Zn-15.41). The liver accumulated highest concentration of Lead and Zinc than the gill and parasite. The trend of lead accumulation was; gill (0.86)<parasite (0.98)<liver (3.54). This accumulation followed similar trend in zinc sampled, the mean concentrations for zinc; parasites; (Zn) (mg/l); 3.39, p<0.01, gill; (Zn)(mg/l); 0.72, p<0.01, liver; (Zn) (mg/l); 11.04, p<0.01. Fish parasites, particularly intestinal acanthocephalans and cestodes, accumulated heavy metals at concentrations significantly higher than those in fish tissues or the environment; hence, they could be used as bioindicators of heavy metal pollution. It is important to continue monitoring heavy metals concentration in waters, sediments and fish of Makoko lagoon so as to assess trends in heavy metal behavior in the area.

Background: Calabash chalk geophagia commonly consumed in Sub-Saharan countries such as Cameroon may be a source of potential harmful elements such as lead and mercury. We sought to determine its geochemical composition on representative sample collected in the central market of Douala and evaluate their acute toxicity profile using rat.

Methods: The geochemical analysis of three prototypes of Calabash chalk samples collected in the Douala central market, their main place of supply in the town, has been performed using the X-ray Fluorescence (XRF) and the inductively Coupled Plasma-Mass Spectrometry (ICPMS) for major and trace elements respectively. Acute toxicity was assessed according to Organisation for Economic Cooperation and Development (OECD) guidelines test No 423.

Results: The geochemistry displays the Al₂O₃ as their main major component with iron, titanium, cerium and zinc as metal and metalloid trace elements. No acute toxicity was found in rat after administration of 5000 mg/kg body weight.

Conclusion: Calabash chalk belong to the kaolinite family which had showed evidence for digestive pharmacologic propriety. Their acute consumption may be less toxic while toxicity profile of chronic consumption should be investigated.