Effects of 15-Year-Old Plantation on Soil Conditions, Spontaneous Vegetation, and the Trace Metal Content in Wood Products at Kipushi Tailings Dam

peer reviewedPhytostabilization is a more appropriate way for rehabilitation of metal-polluted environments in the Copperbelt region. A 1.5-hectare tree planting trial had been installed on the tailings dam (TD) with the help of organic matter (OM) mixed to topsoil. Then, 15 years later, this study aimed to evaluate the performance of the tree plantation, in regard to soils and spontaneous vegetation. The Cu and Co concentration was higher in the reclaimed soil compared with the unreclaimed. Acacia auriculiformis, Acacia polyacantha, Albizia lebbeck, Pinus sylvestris, Psidium guajava, Senna siamea, Senna spectabilis, and Syzygium guineense responded well to the criteria of phytostabilization, whereas Leucaena leucocephala was very invasive. Metal concentration was manifold higher in charcoals than in woods (Zn: 3.8–39.8 mg kg−1 in wood versus 272–523 mg kg−1 in charcoal) with no differences between charcoals regardless of the origin. The tree implantation aided with amendments can meet the criteria of phytostabilization through good survival and regeneration in the heavily contaminated TD.13. Climate actio

Effet de l'amendement organique sur les caractéristiques physicochimiques des rejets et le développement racinaire des espèces d'arbres, quinze ans après la plantation.

peer reviewedAmong mine wastes, tailings are known to have the largest environmental impact, as they have high concentrations of trace elements and are susceptible to wind dispersal and water erosion. A tree plantation trial was installed at Kipushi tailing (DR Congo) in order to mitigate the contaminant dispersal in the surrounding areas. Fifteen years later, the present study was conducted for the purpose of investigating the macronutrient and metal content in amended holes and assessing the performance of tree species through root behavior in the tailings dams. Results show elevated available P, K, Ca, and Mg concentration in the surface and amended layers, which is higher than the unpolluted soil of the miombo woodland. Trace metals were manifold higher compared to the pedo-geochemical background of the region, with Cu and Co concentration tending to increase in the organic matter-rich layers, while Zn, Cd, Pb, and As remained higher in tailings. Compared to the tailing layer, roots grew well in the amended layers, but few roots ranging from very fine to big from all the surviving species were able to grow beyond the amended layers, indicating the possibility of tree survival on the tailings dams over many years. Acacia polyacantha and Psidium guajava are species that showed a higher quantity of roots in the unamended tailing layers. Leaves should be avoided for human or animal consumption, but as the concentration of Cu, Zn, and Co in guava was lower, there is no indication of hazards in case of their consumption. Therefore, the use of well-adapted tree species on the mix-up of the organic amendments with the uncontaminated topsoil seemed to be a good technique for the reclamation of larger polluted areas.11. Sustainable cities and communitie

Plantation agroforestière d'Acacia auriculiformis dans le Haut-Katanga. Guide technique

Agroforestry is a sustainable soil management method. It associates in time or space trees with crops and/or livestock. Thanks to this association, positive interactions are created between the different components of the system. For example, the introduction of nitrogen-fixing trees benefits food crops by playing the role of green manure. Agroforestry of trees in a crop plot also brings other benefits: - they facilitate the penetration of water into the soil, - they help fight erosion, - they draw nutrients from deep within the soil and make them available on the surface for crops, - they play the role of windbreaks, - they can provide shade in the dry season, - they can provide edible fruits, honey, timber, fuelwood, medicinal products, etc. Agroforestry is the focus of the "Agroforests for Kipushi Development" project, AFODEK, which was implemented between December 2012 and November 2017 with financial support from the European Union (DCI-FOOD/2012/294-526). Based on the experience of the Hanns Seidel Foundation in Mampu (Plateaux Batékés), three organizations, GRET, the Belgian non-profit organization Nature+ and the Centre Promotionnel du Paysannat, joined their efforts to develop an agroforestry perimeter of 2,000 hectares (ha) in an area of degraded savannahs with poor soil fertility. This technical document has been prepared by the AFODEK project to share the experience of the Kipushi agroforestry perimeter. It is intended primarily for a public of farmers or agricultural technicians. / L'agroforesterie est un mode de gestion durable des sols. Elle associe dans le temps ou dans l'espace des arbres avec des cultures et/ou l'élevage. Grâce à cette association, des interactions positives se créent entre les différentes composantes du système. Par exemple, l'introduction d'arbres fixateurs d'azote bénéficie aux cultures vivrières en jouant le rôle d'engrais vert. L'agroforesterie d'arbres dans une parcelle de culture apporte également d'autres avantages : - ils facilitent la pénétration de l'eau dans le sol, - ils permettent de lutter contre l'érosion, - ils puisent les éléments nutritifs en profondeur et les rendent disponibles en surface pour les cultures, - ils jouent le rôle de brise-vent, - ils peuvent apporter de l'ombrage en saison sèche, - ils peuvent fournir des fruits comestibles, du miel, du bois d'oeuvre, du bois de chauffe, des produits médicinaux, etc. L'agroforesterie est au coeur du projet "Agroforêts pour le développement de Kipushi", AFODEK, qui a été mis en oeuvre entre décembre 2012 et novembre 2017 grâce au soutien financier de l'Union européenne (DCI-FOOD/2012/294-526). S'appuyant sur l'expérience de la Fondation Hanns Seidel à Mampu (Plateaux Batékés), trois organismes, le GRET, l'asbl belge Nature+ et le Centre Promotionnel du Paysannat ont joint leurs efforts pour aménager un périmètre agroforestier de 2000 hectares (ha) dans une zone de savanes dégradées aux sols peu fertiles. Le présent document technique a été élaboré par le projet AFODEK en vue de partager l'expérience du périmètre agroforestier de Kipushi. Il s'adresse avant tout à un public d'agriculteurs ou de techniciens agricoles

Accumulation of Trace Metals in Fruits from Mango and Syzygium guineense Growing in Residential Households from a Contaminated District of Lubumbashi (DR Congo): Is Fruit Consumption at Risk?

peer reviewedCopper smelting has been a source of soil contamination with trace metals in Penga Penga (Lubumbashi). The residents are exposed to trace metal ingestion, and planting trees is challenging in such soil conditions. Nevertheless, planting trees in former household dumps or using various types of amendments has allowed the provisioning of fruits in a few residences. From the perspective of scaling up the process, a survey has been conducted with the aim of assessing the effectiveness of the planting processes on the trace metal content in fruits and leaves of Mangifera indica L. and Syzygium guineense (Willd) DC. Samples were collected from residential households in Penga Penga and Kalebuka (a non-polluted suburb). The bioconcentration factor (BCF) and the safe weekly consumption (SWC) were calculated for each species. The results showed higher values of total and soluble concentrations of Cu, Pb, and Zn in the rhizosphere of the two species in Penga Penga. Metal concentrations were higher in the fruits and leaves from Penga Penga, with 47% of samples above the FAO and WHO thresholds (vs. 18.5% in Kalebuka). The BCF values were below 1, demonstrating the effectiveness of the process in reducing the translocation of metals to leaves and fruits. Recommendations from the SWC limit Pb consumption to 9 kg for mango flesh and Cd consumption to 6.6 kg for S. guineense fruits in Penga Penga (vs. 78 kg and 68 kg in Kalebuka). Finally, the results of this study provide interesting lessons for the scaling up and technical itinerary of planting trees in Penga Penga

Combining the conservation of metallophytes with the phytostabilisation of polluted soils by trace elements - A review

peer reviewedLa conservation de la biodiversité est devenue un challenge social, politique et économique au niveau mondial. Etant donné que certaines régions du monde sont fortement soumises à l’anthropisation et à ses impacts, il est indispensable de modifier notre perception et notre réflexion en ce qui concerne la conservation de la biodiversité et la restauration écologique. Ce chapitre explore les possibilités existantes et les adapte pour associer la conservation des espèces végétales d’intérêt avec la phytoremédiation des sols pollués. Cette nouvelle stratégie semble encourageante pour conserver le lien entre la société et l’environnement. En utilisant la diversité végétale locale, il est possible de créer de nouvelles communautés végétales afin de réhabiliter des sols pollués par les éléments traces métalliques. Le cas de la ville de Lubumbashi et de la flore de l’Arc Cuprifère Katangais en est un exemple marquant qui a été récemment testé avec succès. Cependant, d’autres études sur les métallophytes sont essentielles pour les utiliser de manière appropriée

Revisiting copper and cobalt concentrations in supposed hyperaccumulators from SC Africa: influence of washing and metal concentrations in soil

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