Distribution and origin of lead in stream sediments from small agricultural catchments draining Miocene molassic deposits (SW France)

Total Pb concentrations and isotopic composition were determined in stream-bed sediments and bedrock from 29 small agricultural or forested catchments in the Gascogne area (SW France). The contribution of Pb from various natural and anthropogenic sources was investigated in this rural area which is very weakly impacted by industrial or urban emissions. Environmental parameters in catchments (importance of forest cover, organic matter and oxide content in sediments) were considered. A combination of geochemical (enrichment calculation, sequential extraction) and isotopic investigations was performed to constrain the origin of Pb and the distribution of anthropogenic Pb in sediments. Most of the sediments have low total Pb content compared to other agricultural regions more impacted by industrial or urban emissions. The results indicated a moderate but significant Pb enrichment, particularly for catchments draining forested areas. This enrichment was positively related to organic C content in sediment and catchment forest cover, whereas in entirely cultivated catchments it was related to Fe-oxide content. An average anthropogenic end-member was determined using Pb isotopes, and was supposed to be representative of background atmospheric Pb pollution, with a weak influence of Pb from recent gasoline and local fertiliser spreading. The amount of anthropogenic Pb (Pbanthr) in sediments estimated using a geochemical approach (mean 63.7 ± 20.4%) was higher than that estimated using an isotopic approach (mean 36.6 ± 17.8%), but the same trend was observed among the samples, except for low anthropogenic contributions. The distribution of Pbanthr in sediments from weakly forested catchments indicated a strong affinity for carbonates and Fe-oxides. Amorphous Fe-oxides became preferential trapping compounds as soon as Pb enrichment increased and carbonate content decreased. Finally, in cultivated catchments, organic C was not a main trapping component for Pbanthr in sediments

Trace elements in stream bed sediments from agricultural catchments (Gascogne region, S-W France): Where do they come from?

The Gascogne region (SW of France) is cultivated for more than 75% of the area. 83 samples of stream bed sediments were collected in three main Gascogne river basins (Gers, Save and Touch, left tributaries of the Garonne river) to evaluate the impact of agricultural practices on trace elements behavior. Eight potential harmful elements (PHE) (Cr, Co, Ni, Cu, Zn, As, Cd and Pb), four reference elements for normalization (Sc, Cs, Al and Fe) and four major elements (Mn, Ca, Mg and P) were considered. The average trace element concentrations in the fine fractions (b63 μm) are in the decreasing order: ZnNCrNNiNPbNCuNCoNAsNScNCsNCd. Geochemical investigations and an original approach combining regression analysis and chemical sequential extraction allowed to select the most adequate reference material (regional molasse)and reference element (Cs) for normalization procedure. The enrichment factor (EF) is generally lower than 2.5, particularly for Cr, Ni, Cu, As, Zn; however, 23% of the sampling stations are more contaminated (2.5bEFb4.5), particularly for Cd, Pb and Co. The PHE in the Gascogne river sediments are mainly originated from natural weathering processes; nevertheless, anthropogenic contribution could represent up to 34% of the total sediment content. For lead, geochemical and isotopic methods gave very similar anthropogenic contributions (24% and 22%, respectively). The enrichment of Cu, Pb, Zn, Co, As, Ni, Cr was mainly related to global and local atmospheric deposition of industrial emissions and gasoline combustion, and was associated to forested catchments. All PHE's are controlled by clay and oxi-hydroxides minerals. Cdwas the only PHE enriched downstreamcultivated catchments and this enrichmentwas linked to Ca and P. This indicates a major origin of Cd fromfertilizer inputs and a main control by carbonate mineral

Dynamique des éléments traces dans les eaux de surface des bassins versants agricoles de Gascogne

La Gascogne, située dans le Sud-Ouest de la France, est une région marquée par une forte activité agricole, avec plus de 75% de terres cultivées. Pour évaluer l'impact des pratiques agricoles sur la qualité des eaux de surface drainant cette région, 83 échantillons de sédiments de fond et 75 échantillons d'eau de rivières ont été prélevés. Les concentrations en éléments majeurs, traces (Cr, Co, Ni, Cu, Zn, As, Pb et Cd), terres rares (REE), COP et COD et le pH ont été mesurés. Les résultats obtenus montrent des concentrations en PHE (Potential Harmful Element) évoluant de 0,01 µg.l-1 (Cd) à 4,46 µg.l-1 (Zn), et de 0.11µg.g-1 (Cd) à 84.98 µg.g-1 (Zn), respectivement dans les eaux en phase dissoute et dans les sédiments de fond en phase particulaire. Les PHE de la phase dissoute sont contrôlés par les chlorures et la matière organique, notamment dans les zones où la contribution anthropique en chlorures et matière organique est significative. Ceux des sédiments de fond sont majoritairement liés aux oxydes de fer et aux aluminosilicates, à l'exception de Cd qui est associé aux carbonates. Tous ces PHE proviennent essentiellement des processus d'altération de la molasse. Toutefois, un enrichissement faible à modéré (facteur d'enrichissement, EF inférieur à 5) a été mis en évidence, notamment pour Cd, Co et Pb. L'enrichissement en Cd est marqué dans les bassins carbonatés à activités agricoles (probablement dû aux épandages de fertilisants phosphatés) engendrant une contribution à hauteur de 35% de sa concentration totale. Les autres PHE sont plutôt affectés par les dépôts atmosphériques dans les zones plus forestières, avec une contribution entre 2% (Cr) et 24% (Co) de la concentration totale. La contribution anthropique du Pb estimée par une approche isotopique (24%) est très proche de la valeur obtenue par l'approche géochimique (22%). Les 3 éléments les plus enrichis (Cd, Co, Pb), présentent également le plus grand potentiel de mobilité et de disponibilité biologique vis à vis des conditions physico-chimiques des rivières gasconnes. Finalement, les profils de concentrations en terres rares, ont permis notamment de montrer que la signature géochimique des sédiments de fond de ces rivières reflète bien celle des horizons de surface des sols, par lesquels la plupart des polluants transitent avant d'être érodés/lessivés vers les cours d'eau. ABSTRACT : The Gascogne region, located in the South West of France, is cultivated for more than 75% of the area. To evaluate the impact of agricultural practices on the river quality in this region, 83 samples of river bed sediments and 75 samples of river waters were collected. Major and trace elements (Cr, Co, Ni, Cu, Zn, As, Pb and Cd) concentrations, rare earth elements (REE), POC and DOC, pH were analyzed in these samples. The results show that PHE (Potential Harmful Elements) concentrations vary from 0,01 µg.l -1 (Cd) to 4,46 µg.l -1 (Zn) and from 0.11µg.g -1 (Cd) to 84.98 µg.g -1 (Zn) respectively, in the dissolved fraction of the river water and in the particulate fraction of the bed sediments. In the dissolved fraction, PHE are controlled by chloride and organic matter, particulary in the areas where the anthropogenic inputs of these compounds are significant. In the river bed sediments, particulate PHE are mainly associated to iron oxides and aluminosilicates, except Cd which is associated to carbonates. In the Gascogne rivers, PHE mainly originated from natural weathering processes; nevertheless, an anthropogenic contribution can be observed, particularly for Cd, Co and Pb, but the enrichment factor (EF) does not exceed 5. Cd enrichment is particularly important in carbonated cultivated catchment (probably in relation to phosphate fertilizer inputs), which contribute to 35% of the total concentration. The other PHE are more affected by atmospheric depositions in forested areas, which supply between 2% (Cr) and 24% (Co) of the total PHE concentration. Pb anthropogenic contribution (24%) estimated using Pb isotopes is close to the value obtained by geochemical approach (22%). Cd, Co and Pb are the most enriched elements and are the most mobile and available for organisms within the physico-chemical conditions of Gascogne rivers. Finally, REE concentration patterns allow to show that the geochemical signature of Gascogne river bed sediments reflects that of soil surface horizons, in which most of the pollutants are passing through before to be eroded/leached towards the river

Cartographie de la dynamique du couvert vegetal de la foret Classee d’Agbo 1 Cote d’Ivoire

Pour garantir l’utilisation durable et l’équilibre écologique de la forêt classée d’Agbo 1, il est important d’acquérir des informations sur la dynamique de la végétation. Ainsi la présente étude a pour objectif d’évaluer la dynamique spatio-temporelle de la forêt classée d’Agbo 1 (Côte d’Ivoire) à partir des images Landsat datant de 1987, 2002 et 2017. Une analyse diachronique des données satellitaires a été réalisée et l’approche de la classification dirigée par la méthode de maximum de vraisemblance à partir des compositions colorées de type 4/5/7 (TM et ETM+) et 5/6/7 (OLI) ont été retenues en vue de la discrimination des classes et l’élaboration des cartes d’occupation du sol de la forêt de 1987, 2002 et 2017. Cinq classes d’occupation du sol ont été discriminées. Les précisions globales et les coefficients Kappa obtenus pour les images classifiées sont respectivement de 90,70 % (0,89) ; 91,78% (0,90) et de 92,19 % (0,91) pour 1987, 2002 et 2017. La couverture forestière de cette forêt qui déjà, en 1987 ne représentaient que 50,64 % de la superficie totale cette forêt classée a régressé davantage jusqu’à 28,85 % de la superficie totale en 2017. Les taux moyens annuels calculés pour la période de 1987 à 2017 montrent une régression des forêts anciennes (-3,26) et des forêts secondaires (- 1,26). On observe parallèlement une progression des classes zone agricole (0,08) et (2,35).Mots-clés: Dynamique, Télédétection, Déforestation, Gestion durable, Forêt classée Agbo 1English Title: Mapping of vegetation cover dynamics of the Agbo 1 Forest (Côte d’Ivoire)English AbstractTo ensure the sustainable use and ecological balance of the Agbo 1 Forest, it is important to acquire information on vegetation dynamics. Thus, the objective of this study is to evaluate the spatio-temporal dynamics of the Agbo 1 forest (Ivory Coast) using Landsat images dating back to 1987, 2002 and 2017. A diachronic analysis of the satellite data was carried out and the maximum likelihood-directed classification approach from type 4/5/7 (TM and ETM +) and 5/6/7 (OLI) color compositions were selected for the discrimination of classes and development of forest land cover maps of 1987, 2002 and 2017. Five classes of land use were discriminated against. The overall accuracies and Kappa coefficients obtained for the classified images are respectively 90.70% (0.89); 91.78% (0.90) and 92.19% (0.91) for 1987, 2002 and 2017. The forest cover of this forest, which in 1987 represented only 50.64% of the total area of this forest. Forest decreased further to 28.85% of the total area in 2017. The annual average rates calculated for the period 1987 to 2017 show a regression of old-growth forests (-3.26) and secondary forests (-1.26). At the same time, there is an increase in agricultural classes (0.08) and (2.35).Keywords: Dynamic, Remote Sensing, Deforestation, Sustainable Management, Agbo Fores

Dosage De Quelques Composantes Biochimiques Des Feuilles De Lippia multiflora (Verbenacee) a Deux Stades De Developpement Et Qualite Des Infusions, En Fonction De La Dose D’uree

Les feuilles de Lippia multiflora (verbénacée) récoltées simultanément sur des plantes d’un mois et demi et des plantes d’un an, cultivées sur des parcelles ayant reçu différentes doses d’urée ont été analysées. Les résultats indiquent que les feuilles des jeunes plantes ont un taux d’humidité élevé que celles des plantes adultes, surtout quand elles sont séchées à l’ombre. Elles sont plus riches en protéines (12 - 13 % MS) et en sucres totaux (0,013 - 0,015 % MS) avec une infusion plus astringente, plus colorée et plus parfumée. Les feuilles des plantes adultes par contre sont riches en glucides (≈ 0,6 % MS), en cellulose (≈ 0,85 % MS), en cendre (12 - 15 % MS) avec un taux d’humidité assez bas. Leur infusion est moins astringente, claire et moins parfumée. L’analyse de ces résultats révèle que les feuilles prélevées au stade d’un mois et demi sont de meilleures qualités organoleptiques à cause de leur richesse en protéine, en sucre totaux et surtout l’astringence, l’amertume et le parfum de leur infusion qui sont des critères d’appréciation du thé. Cependant, ces dernières seront conservées moins longtemps du fait de leur taux d’humidité élevés favorable à la croissance microbienne. Par ailleurs, la dose d’urée n’a pas eu d’effet significatif sur la composition chimique des feuilles et des infusions.The leaves of Lippia multiflora (verbenaceae) harvested at the same time on plants of one and a half month and the plants of one year cultivated on plots having accepted different doses of urea were analyzed. The results show that the leaves of the young plants have a well brought up rate of humidity that those of the adults plants, especially when they are dried in shade. They are richer in proteins (12 - 13 %) and in complete sugars (0.013 - 0.015 %) with a more astringent, more coloured and more sweet- scented infusion. The leaves of the adults plants are on the contrary rich in carbohydrates (0.6 %), in cellulose (0.85 %) and ash (12 - 15 %) with a low rate of humidity. Their infusion is less astringent, clear and less sweet- scented. The analysis of these results reveals that leaves taken at the stage of one and a half month are better quality because of their wealth in protein, in total sugar and especially the astringency, bitterness and the perfume of their infusion which are criteria of evaluation of tea. However, these last will be less kept for a long time because of to their hight humidity favourable to microbic growth. Moreover, the dose of urea did not have significant effect on the chemical composition of leaves and infusion. Keywords: Lippia multiflora, leaves, brewing, biochemical components, ure

Effet de la densite sur les parametres dendrometriques D'Acacia auriculaeformis en association avec le cocotier (Cocos nucifera L.) sur sables quaternaires en C&#244te d'Ivoire

No Abstract

Paramètres influençant la distribution des éléments traces métalliques dans les affluents du fleuve Garonne (France)

The left-bank tributaries of the Garonne River, located in the South-West of France, cross catchments, is affected by significant agricultural activities. To evaluate the quality of the dissolved fraction, seventy-five(75) samples of river waters were collected. Several trace elements were analyzed in this aqueous phase. The average metal trace element concentrations, in this region, are in the decreasing order: Zn (4.46 μg.l-1), As (1.03 μg.l-1), Cu (0.79 μg.l-1) Ni (0.62 μg.l-1), Cr (0.30 μg.l-1), Co (0.23 μg.l-1), Pb (0.04 μg.l-1), and Cd (0.01 μg.l-1). These values are, for the majority, lower than those of waters of rivers in non-anthropized areas. The distribution of these elements is controlled by chloride and organic matter, particularly in the areas where the anthropogenic inputs of these compounds are significant. In less anthropized areas, the availability of these trace elements in the water column decreases when the pH and the alkalinity increase according to natural geochemical processes. These observations show the predominant action of anthropogenic activities on the mobility and the biological availability of metallic pollutants in the tributaries of the Garonne River

Sustaining control of Schistosomiasis mansoni in western Côte d'Ivoire : results from a SCORE study, one year after initial praziquantel administration

The Schistosomiasis Consortium for Operational Research and Evaluation (SCORE) has launched several large-scale trials to determine the best strategies for gaining and sustaining control of schistosomiasis and transitioning toward elimination. In Côte d'Ivoire, a 5-year cluster-randomized trial is being implemented in 75 schools to sustain the control of schistosomiasis mansoni. We report Schistosoma mansoni infection levels in children one year after the initial school-based treatment (SBT) with praziquantel and compare with baseline results to determine the effect of the intervention.; The baseline cross-sectional survey was conducted in late 2011/early 2012 and the first follow-up in May 2013. Three consecutive stool samples were collected from 9- to 12-year-old children in 75 schools at baseline and 50 schools at follow-up. Stool samples were subjected to duplicate Kato-Katz thick smears. Directly observed treatment (DOT) coverage of the SBT was assessed and the prevalence and intensity of S. mansoni infection compared between baseline and follow-up.; The S. mansoni prevalence in the 75 schools surveyed at baseline was 22.1% (95% confidence interval (CI): 19.5-24.4%). The DOT coverage was 84.2%. In the 50 schools surveyed at baseline and one year after treatment, the overall prevalence of S. mansoni infection decreased significantly from 19.7% (95% CI: 18.5-20.8%) to 12.8% (95% CI: 11.9-13.8%), while the arithmetic mean S. mansoni eggs per gram of stool (EPG) among infected children slightly increased from 92.2 EPG (95% CI: 79.2-105.3 EPG) to 109.3 EPG (95% CI: 82.7-135.9 EPG). In two of the 50 schools, the prevalence increased significantly, despite a DOT coverage of >75%.; One year after the initial SBT, the S. mansoni prevalence had decreased. Despite this positive trend, an increase was observed in some schools. Moreover, the infection intensity among S. mansoni-infected children was slightly higher at the 1-year follow-up compared to the baseline situation. Our results emphasize the heterogeneity of transmission dynamics and provide a benchmark for the future yearly follow-up surveys of this multi-year SCORE intervention study

Spatial distribution and period of activity of the forest elephant (Loxodonta africana cyclotis) at Taï National Park, south western Côte d'Ivoire

Objective: This study aims at determining the spatial distribution and  period of activities of the forest elephant (Loxodonta africana cyclotis) at Taï National Park (TNP) to contribute to its conservation.Methodology and results: Observations of elephants at different locations and time periods were recorded by using 87 camera traps with date and time-stamped settings. Cameras were installed following a systematic placement approach, and their geographic coordinates were recorded using a GPS. After 120 days of trapping, we observed a high concentration of activities in the southern areas of the park. For the period of activities, we noted that observations of unit individuals were recurrent during the day while those of elephant groups were more important at night.Conclusion and application of the results: The south of the park where  there is a large distribution of elephants would be more favourable to these animals. The small number and remoteness of large cities on the periphery of this area of the park could explain that pattern. The distribution and activity period information is useful for park surveillance by rangers. In addition, further studies are needed for a better explanation on the distribution pattern of elephants at TNP.Key words: Taï National Park, elephant, camera traps, distribution, activity period