Evaluation of heavy metal content and potential ecological risks in soil samples from wild solid waste dumpsites in developing country under tropical conditions

Solid waste management constitutes a major concern and unresolved problem in most parts of the world, particularly in developing countries where solid waste is disposed in unregulated dumpsites in the public spaces. This practice can lead to contamination of environmental compartments such as soil, surface and groundwater which could negatively impact human health. In this study, surface soil samples were collected from 15 selected solid waste dumpsites in Kinshasa City (Democratic Republic of the Congo) to examine the heavy metal content and potential environmental risks. The results highlighted a high concentration of metals in soil samples compared to local background values and international threshold. The average concentration of metals in all soil samples followed generally the order: Zn>Pb > Cu >Cr> Co> Cd> As> Hg. The calculated pollution indexes including Geo-accumulation, Enrichment Factor, Contamination degree and Potential Ecological Risk, revealed polymetallic contamination dominated by several of these metals in which Zn, Cu, Pb and Hg were of greatest concern indicating high environmental risks. This work showed that illegal wild landfills represent a real danger for the environment and human health. Due to the toxicity of heavy metals, the measures to establish a monitoring program that address uncontrolled landfills and solid waste management and disposal are recommended to reduce the load of contaminants in soils which can reach surface and groundwater. On the other hand, the use of manures from these dumpsites for agricultural purposes should be discouraged because they may be easily absorbed at alarming levels by vegetables

Putting conservation efforts in Central Africa on the right track for interventions that last

Interventions in Africa designed to stop biodiversity decline have often failed because they were based on a top-down approach to management and focused on enforcing restrictive rules and imposing bans. They were equally misaligned with the values and needs of local actors. This paper presents an African perspective on the discourse regarding the bushmeat crisis and shows that bushmeat in Africa goes beyond being a source of livelihood, having a multifaceted use that must be considered when designing interventions. We show that current conservation initiatives often do not address the right issues, by neglecting nonmonetary dimensions of bushmeat use, inadequately planning interventions, failing to align wildlife laws with realities on the ground, and carrying out ineffective law enforcement characterized by poor governance and corruption. We recommend a revision of current legal frameworks to enhance local ownership, tenure rights, and the sustainable economic empowerment of local communities to reduce hunting. We also call for development of regionally led innovative programs that invest in nature-based solutions and payments for environmental services. Finally, we identify where more research is needed to understand why wildlife use in Africa is overlooked in national development policies and not considered in national accounting

Leachates draining from controlled municipal solid waste landfill: Detailed geochemical characterization and toxicity tests

Management of municipal solid wastes in many countries consists of waste disposal into landfill without treatment or selective collection of solid waste fractions including plastics, paper, glass, metals, electronic waste, and organic fraction leading to the unsolved problem of contamination of numerous ecosystems such as air, soil, surface, and ground water. Knowledge of leachate composition is critical in risk assessment of long-term impact of landfills on human health and the environment as well as for prevention of negative outcomes. The research presented in this paper investigates the seasonal variation of draining leachate composition and resulting toxicity as well as the contamination status of soil/sediment from lagoon basins receiving leachates from landfill in Mpasa, a suburb of Kinshasa in the Democratic Republic of the Congo. Samples were collected during the dry and rainy seasons and analyzed for pH, electrical conductivity, dissolved oxygen, soluble ions, toxic metals, and were then subjected to toxicity tests. Results highlight the significant seasonal difference in leachate physicochemical composition. Affected soil/sediment showed higher values for toxic metals than leachates, indicating the possibility of using lagoon system for the purification of landfill leachates, especially for organic matter and heavy metal sedimentation. However, the ecotoxicity tests demonstrated that leachates are still a significant source of toxicity for terrestrial and benthic organisms. Therefore, landfill leachates should not be discarded into the environment (soil or surface water) without prior treatment. Interest in the use of macrophytes in lagoon system is growing and toxic metal retention in lagoon basin receiving systems needs to be fully investigated in the future. This study presents useful tools for evaluating landfill leachate quality and risk in lagoon systems which can be applied to similar environmental compartments