Jean-Pierre Schmit

Efficacy of essential oil of Ocimum basilicum L. and O. gratissimum L. applied as an insecticidal fumigant and powder to control Callosobruchus maculatus (Fab.) (Coleoptera: Bruchidae)

Essential oils from sweet basil, Ocimum basilicum, and African basil, O. gratissimum, (Labiatae) grown in Guinea were obtained by steam distillation. Following exposure of newly emerged adult beetles (Callosobruchus maculatus) to 12h of fumigation using pure essential oils at a dose of 25&mgr;l/vial, 80% mortality was recorded for O. basilicum, 70% for O. gratissimum and 0% in the control. A significant difference was observed between the responses of males and females with males exhibiting greater sensitivity. When 1g of aromatized powder was applied to adults, a 50% lethal concentration at 48h was found to be 65&mgr;l/g for O. basilicum and 116&mgr;l/g of O. gratissimum oils. The essential oils from the two plant species exhibited a significant effect both on the egg hatch rate and on the emergence of adults. The egg hatch rate was reduced to 3% with O. basilicum and 15% with O. gratissimum using an essential oil concentration of 30&mgr;l, whereas the egg hatch rate for the control was 95%. When compared with the control (97%), adult emergence dropped to 0% with O. basilicum and to 4% with O. gratissimum. Storage bioassays were run to assess the long-term effect of powders aromatized with essential oils of Ocimum. Complete protection was observed over 3 months starting at a dose of 400&mgr;l in the case of both oils. From a germination test, it was concluded that aromatized powders have no significant effect on the seed germination rate. After 5d, a rate of 88% germination was seen in seeds treated with aromatized powder and protected from insects, compared with 97% for untreated seeds that were not exposed to insects.

Effect of various essential oils on Callosobruchus maculatus (F.) (Coleoptera: Bruchidae)

Essential oils were extracted from four West African plant species [Tagetes minuta (Family Compositae), Hyptis suaveolens (Family Labiatae), white basil Ocimum canum (Family Labiatae), and sweet basil O. basilicum (Family Labiatae)] by steam distillation. The oil of the pepper Piper guineense (Family Piperaceae), was extracted from the fruits by hydro distillation and ethanol extraction. Mixed essential oil and total ethanol extract was used. Kaolin powder (clay) was mixed (aromatized) with these different oils. Cowpea weevils were reared on chickpeas and newly emerged males and females were deposited on uninfested seeds. Bioassays, i.e. fumigation with pure essential oils and aromatized kaolin powders, were carried out on adults and eggs. Twenty four hours after fumigation, 99 and 0% adult mortality were observed, respectively, as the result of treatments with Ocimum basilicum and the control. The application of powders aromatized with the same oils to weevil pairs resulted in a complete lack of oviposition, whereas 31, 56 and 76 eggs were laid in the controls after 24, 48 and 72 h, respectively. Application of aromatized powders did not have a significant effect on egg hatching (50 out of 110 with O. canum, 100 out of 115 with O. basilicum and 100 out of 130 in the control sample) but did have a significant impact on adult emergence: 0% for the two treatments compared with 100% in the controls. Our results suggest that plants of the genus Ocimum can be used as an alternative to synthetic insecticides.

Trace inorganic elements in rainfall in the Montreal Island

Abstract Using inductively coupled plasma-mass spectrometry (ICP-MS), 24 inorganic elements were analysed for about 65 station-events during the summer of 1989, at Montreal Island (Canada). Enrichment factors indicate that numerous elements are enriched as compared to the Earths crust, since only six elements (titanium, iron, rubidium, yttrium, zirconium, and cerium) can be considered natural. A comparison with results from a rural area indicates that most elements are affected by urbanization. For the majority of the elements, scavenging below the cloud (wash-out) seems to be a significant atmosphere cleansing mechanism, although one element, lead, appears to be rather governed by long-range transportation and rain-out (in-cloud scavenging). Correlation between elements indicates that some elements have similar behaviour, which can be partly explained by sorption phenomena or chemical bonding in the same compound.

Essential oil composition of Ocimum basilicum L., O. gratissimum L. and O. suave L. in the Republic of Guinea

Specimens of Ocimum basilicum L., O. grattisimum and O. sauve L. were collected at Coyah, Kindia and Faranah in the Republic of Guinea (voucher specimens were deposited in the herbarium of the Environmental Studies and Research Center (ERSC), University of Conakry-Guinea). Steam distillation of the specimens was done at ESRC. The essential oil obtained was analysed by GC and GC – MS, and had the following major constituents: linalool (69%), eugenol (10%), t-α-bergamotene (3%) and thymol (2%) for O. basilicum; thymol (46%), p-cymeme (12%) and γ-terpene+t-sabiene hydrate (17%) for O. gratissimum; and p-cymeme (59%), α-thujene (10%), myrcene (7%) and thymol (7%) for O. sauve. A list of compounds is given for each plant species. Copyright

Well water survey in two districts of Conakry (Republic of Guinea), and comparison with the piped city water

Analyses of water from wide-diameter open wells were carried out in two districts of Conakry (Republic of Guinea) during the dry season of 1994 (April-May) to evaluate its bacteriological and physico-chemical quality and to compare well water to the piped city water. Widespread well water contamination for nitrate and fecal bacteria was found throughout both districts. The other common water-quality parameters, as well as total organic carbon and halogens, oils and greases of general use, and 34 inorganic elements were within the standard norms for safe drinking water. Chromium and, to a lesser extent, lead and mercury could become a threat to health if the situation worsens. Although thorough hydrogeological studies are needed to determine contaminant pathways, insufficient well maintenance appears to be the main factor contributing to the bacteriological contamination, while the nitrate contamination seems more closely linked to infiltration of organic contaminants from the soil surface. Piped city water was found to comply with WHO norms for drinking water and its use should be strongly encouraged to reduce the incidence of water-borne diseases.

History of the atmospheric deposition of major and trace elements in the industrialized St. Lawrence Valley, Quebec, Canada.

The history of the atmospheric deposition of major and trace elements over southwestern Quebec, Canada, was reconstructed using multielemental analysis of lacustrine sediments sampled in a small and undisturbed lake located on top of a mountain in the heart of the industrialized St. Lawrence Valley. Acid leachable and residual elements were extracted from a 37-cm long core (1-cm resolution) using clean techniques and analyzed by inductively coupled plasma mass spectrometry. Organic matter and sulfur concentrations were high and played a major role in the low postdepositional diagenetic remobilization of many trace elements. Sulfur, manganese, iron, arsenic, molybdenum and barium displayed a high mobility making it exceedingly difficult to infer unambiguously time-dependent changes in atmospheric deposition for these elements. Atmospheric deposition rates for the less mobile elements (e.g., potassium, vanadium, chromium, cobalt, nickel, copper, zinc, rubidium, cadmium, tin, antimony, mercury, thallium, lead, and bismuth) increased regularly between 1942 and 1960–1975 in the Lake Hertel area and then stabilized for most of these elements, with the exception of nickel, copper, zinc and tin. Lead deposition rate was reduced by about 25% between 1982 and 1995, and a slight decreasing trend was also found for cobalt, mercury, and thallium during the same period. Present-day atmospheric deposition of metals directly on the lake surface represents a small percentage of the sedimentary deposition rates at this location. Deposition followed by surface runoff and outwash of terrestrial organic and inorganic matter most likely is the driving mechanism leading to the non-diagenetic enrichment of metals in Lake Hertel sediments.

Multi-element analysis of biological tissues by inductively coupled plasma mass spectrometry

Abstract A general method for the quasi-simultaneous determination of most of the elements present in biological tissues by inductively coupled plasma mass spectrometry is described. Its validity was assessed by the multi-element analysis of NBS SRM 1577a Bovine Liver and its sensitivity was established by spiking digested samples of fish muscle tissue with known amounts of elements (0.125, 0.250, 0.500, 1.00 and 10.00 ng ml −1 ). Spike recoveries of 0.124±0.002 ng ml −1 (five repeated determinations for each element in the multi-elemental determination mode) were obtained for eleven elements (Ag, Co, Cr, Li, Mn, Mo, Sb, Sr, Tl, V and Y), 0.241 ±0.008 ng ml −1 for eight elements (As, Ba, Cd, Hg, Pb, Sn, Zr and U), 0.487±0.015 ng ml −1 for seven elements (B, Cu, Ni, Rb, Se, Ti and W), 0.97±0.06 ng ml −1 for Al and Zn and 9.53±0.76 ng ml −1 for Bi, Fe, Sc, Si and I.

The cytotoxic effects of cadmium chloride and mercuric chloride mixtures in rat primary hepatocyte cultures

The toxic effects of Cd and Hg mixtures were studied using primary monolayer cultures of rat hepatocytes. Cytotoxicity was assessed by measuring the release of lactic dehydrogenase from the cells. Cytotoxic and non-cytotoxic metal levels were used. At the higher exposure concentrations (0.2 micrograms Cd.ml-1 and 2.0 micrograms Hg.ml-1), Cd was very toxic to hepatocytes whereas Hg was only marginally toxic. The combination of Cd and Hg was more toxic than predicted by summation of the individual metal toxicities. The incorporation of [35S]cysteine into protein of the cytosol and insoluble cell fraction was increased in response to Cd or Hg exposure and was directly related to cell 35S accumulation. Combinations of Cd and Hg significantly increased the proportion of total 35S which was incorporated in cell protein, an effect that was attributed to the accumulation of protein in the insoluble cell fraction. Cd uptake by hepatocytes was related to exposure concentration but was lower when Hg was also present in the incubation medium. Gel chromatography of the cytosol from Cd-exposed cells showed 3 Cd containing fractions which corresponded to the elution positions of high Mr proteins, metallothionein (MT) and low Mr molecules. When hepatocytes were exposed to Hg in combination with Cd, the MT-like fraction was no longer evident and Cd in the low Mr fraction was greatly reduced. Regardless of the presence or absence of Cd in the exposure medium, 98% of cytosol Hg in Hg-exposed cells was found to elute after the low Mr fraction, at a position equivalent to inorganic salts. This indicates that the enhanced cytotoxicity of Cd and Hg may be related to a decrease in the MT-like protein in the cytosol and not due to a direct competitive binding interaction in relation to the protein.

Estimation of the bulk atmospheric deposition of major and trace elements to a rural watershed

Despite the existence of many reports on the background deposition of contaminants in remote areas, very little is known about the total aerial inputs of major and trace elements to the entire surface of rural watersheds. In this work, the influence of the contribution from local nonpoint-sources of emission or resuspension (e.g. agricultural soil and road dust resuspension, direct emission from vehicle use, and small towns) on the background regional fluxes was evaluated in a small rural watershed of southern Quebec (Canada). A seasonal pattern was found for the background deposition of 28 major and trace elements, with spring and fall maxima as well as winter and midsummer minima mostly owing to agricultural practices and weather. The contribution from the Greater Montreal area, located 30 km to the west, was <5% of the background fluxes for all elements except Zn, Cu, Cd, and Mn. Although some of them do not constitute true inputs at the entire watershed level, a preliminary estimate of the local nonpoint-sources (e.g. agricultural soil resuspension, roads, small town) showed that the total aerial fluxes to the streams of the watershed could be considerably underestimated, owing mostly to agricultural soil resuspension source. Background-only deposition often represents a fraction of the total inputs to the waters of inhabited watersheds.

Multi-element analysis of biological tissues by inductively coupled plasma mass spectrometry: healthy sprague dawley rats

Abstract The normal inorganic contents of bone, brain, erythrocyte, heart, kidney cortex, kidney medulla, liver, lung, muscle and plasma from healthy Sprague Dawley rats were established by using a general method developed for inductively coupled plasma mass spectrometric multi-element determinations of most of the elements present in biological tissues. The most characteristic elemental pattern of each tissue was identified via a statistical multivariate analysis and a principal component analysis helped to elucidate the correlations between elements and tissues.