Qualite des eaux du Bandama-Blanc (Cote D’ivoire) et de ses affluents soumis a de fortes activites

La qualité écologique des eaux des localités soumises à l’exploitation artisanale et clandestine de l’or au niveau du Bandama-Blanc et de ses affluents a été étudiée entre le 01 et le 15 Avril 2015. Le prélèvement du phytoplancton a été réalisé à l’aide de la bouteille hydrologique et du filet à plancton, tandis que le périphyton a été récolté par les méthodes de grattage et d’expression respectivement sur cailloux, bois et feuilles immergés. Cent soixante (160) taxons composés de 84 taxons de Chlorophyta, 42 taxons d’Euglenophyta, 25 taxons de Cyanobacteria, 5 taxons de Dinophyta, 2 taxons de Chrysophyta, 1 taxon de Rhodophyta et 1 taxon de Xanthophyta ont été identifiés au niveau des sites d’échantillonnage. La densité des Cyanobacteria est élevée dans les sites soumis aux activités d’orpaillage, de pêche et d’élevage au niveau des eaux du barrage et de la carrière avec une contribution élevée de Microcystis aeruginosa. Les valeurs des indices de diversité ont montré que les eaux de la zone d’étude sont diversifiées avec un peuplement dominé par les espèces Microcystis aeruginosa et Peridinium cinctum. Une mésotrophie des sites d’échantillonnage de la zone d’étude a été révélée par les valeurs de l’indice B proposé par Nygaard (1949).Mots clés : Phytoplancton, périphyton, diversité, barrage, Côte d’IvoireEnglish Abstrarct Water quality of the Bandama-Blanc (Cote D'ivoire) and its tributaries subject to strong anthropogenic activities from the algal microfloraEcological waters quality of the localities subjected to artisanal and clandestine gold mining at the level of Bandama-Blanc and its tributaries was studied between 01 and 15 April 2015. Phytoplankton sampling was performed using the hydrologic bottle and plankton net, while periphyton was harvested by scraping and expression methods respectively on rocks, wood and floating leaves. The microalgae comprised 160 taxa, mainly Chlorophyta (84 taxa), Euglenophyta (42 taxa), Cyanobacteria (25 taxa), Dinophyta (5 taxa), Chrysophyta (2 taxa), Rhodophyta (1 taxa) and Xanthophyta (1 taxa). Highest Cyanobacteria densities was observed in the localities subjected to gold mining, fishing and rearing activities at the level of the Kossou dam and the quarry with a high contribution of the species Microcystis aeruginosa. Values of the diversity indices showed that the waters of the study area are diversified with a stand dominated by the species of Microcystis aeruginosa and Peridinium cinctum. Mesotrophy of the sampling sites in the study area was revealed by the Nygaard B index values (1949).Keys words : Phytoplankton, periphyton, diversity, dam, Côte d’Ivoir

Trends and seasonal variability in ammonia across major biomes in western and central Africa inferred from long-term series of ground-based and satellite measurements

Ammonia (NH3) is the most abundant alkaline component in the atmosphere. Changes in NH3 concentrations have important implications for atmospheric chemistry, air quality, and ecosystem integrity. We present a long-term ammonia (NH3) assessment in the western and central African regions within the framework of the International Network to study Deposition and Atmospheric chemistry in Africa (INDAAF) programme. We analyse seasonal variations and trends in NH3 concentrations and total column densities along an African ecosystem transect spanning dry savannas in Banizoumbou, Niger, and Katibougou, Mali; wet savannas in Djougou, Benin, and Lamto, Côte d'Ivoire; and forests in Bomassa, Republic of the Congo, and Zoétélé, Cameroon. We use a 21-year record of observations (1998–2018) from INDAAF passive samplers and an 11-year record of observations (2008–2018) of atmospheric vertical column densities from the Infrared Atmospheric Sounding Interferometer (IASI) to evaluate NH3 ground-based concentrations and total column densities, respectively. Climatic data (air temperature, rainfall amount, and leaf area index), as well as ammonia emission data of biomass combustion from the fourth version of the Global Fire Emissions Database (GFED4) and anthropogenic sources from the Community Emissions Data System (CEDS), were compared with total NH3 concentrations and total columns over the same periods. Annual mean ground-based NH3 concentrations are around 5.7–5.8 ppb in dry savannas, 3.5–4.7 ppb in wet savannas, and 3.4–5.6 ppb in forests. Annual IASI NH3 total column densities are 10.0–10.7 × 1015 molec. cm−2 in dry savanna, 16.0–20.9 × 1015 molec. cm−2 in wet savanna, and 12.4–13.8 × 1015 molec. cm−2 in forest stations. Non-parametric statistical Mann–Kendall trend tests applied to annual data show that ground-based NH3 concentrations increase at Bomassa (+2.56 % yr−1) but decrease at Zoétélé (−2.95 % yr−1) over the 21-year period. The 11-year period of IASI NH3 total column density measurements show yearly increasing trends at Katibougou (+3.46 % yr−1), Djougou (+2.24 % yr−1), and Zoétélé (+3.42 % yr−1). From the outcome of our investigation, we conclude that air temperature, leaf area index, and rainfall combined with biomass burning, agricultural, and residential activities are the key drivers of atmospheric NH3 in the INDAAF stations. The results also show that the drivers of trends are (1) agriculture in the dry savanna of Katibougou; (2) air temperature and agriculture in the wet savanna of Djougou and Lamto; and (3) leaf area index, air temperature, residential, and agriculture in the forest of Bomassa.</p

QTL detection by multi-parent linkage mapping in oil palm (Elaeis guineensis Jacq.)

A quantitative trait locus (QTL) analysis designed for a multi-parent population was carried out and tested in oil palm (Elaeis guineensis Jacq.), which is a diploid cross-fertilising perennial species. A new extension of the MCQTL package was especially designed for crosses between heterozygous parents. The algorithm, which is now available for any allogamous species, was used to perform and compare two types of QTL search for small size families, within-family analysis and across-family analysis, using data from a 2 × 2 complete factorial mating experiment involving four parents from three selected gene pools. A consensus genetic map of the factorial design was produced using 251 microsatellite loci, the locus of the Sh major gene controlling fruit shell presence, and an AFLP marker of that gene. A set of 76 QTLs involved in 24 quantitative phenotypic traits was identified. A comparison of the QTL detection results showed that the across-family analysis proved to be efficient due to the interconnected families, but the family size issue is just partially solved. The identification of QTL markers for small progeny numbers and for marker-assisted selection strategies is discussed

Comparative study of fatty acid composition, vitamin E and carotenoid contents of palm oils from four varieties of oil palm from Cote d'lvoire

BACKGROUND: Fatty acid, tocopherol, tocotrienol and carotene contents were assessed in four oil palm species from the National Centre of Agronomical Research of Cote d'lvoire, two of which were the basal Lame (HP1) and Deli (HP2) collections and two of which resulted from crossings between HP1 and HP2 varieties of Eleais guineensis, HP3 and HP4 being identified as the first and second cycle selection, respectively. RESULTS: Palm oil species were characterized by the richness in polyunsaturated fatty acids composition (48-60%) compared to saturated fatty acids (40-52%), especially the first variety, which was from the base collection, and the two hybrids ensuing from crossing. Total carotene content of those varieties was higher and accounted for 832-3575 mu g g(-1), and the beta-carotene level (580-2390 mu g g(-1)) was predominant. Total vitamin E content was 864-1124 mu g g(-1), with a notable higher content of tocotrienols, especially gamma-and alpha-tocotrienol, ranging from 400 to 515 mu g g(-1) and from 238 to 350 mu g g(-1), respectively. CONCLUSION: Crossing seemed to be useful in improving the performance and analytical characteristics of the base collection materials

Modelling the air–surface exchange of ammonia from the field to global scale

The Working Group addressed the current understanding and uncertainties in the processes controlling ammonia (NH3) bi-directional exchange, and in the application of numerical models to describe these processes