Geochemistry, Mineralogy and Microbiology of Cobalt in Mining-Affected Environments

This is the final version. Available on open access from MDPI via the DOI in this recordData Availability Statement: Data sharing not applicable. No new data were created or analyzed in this study. Data sharing is not applicable to this article.Cobalt is recognised by the European Commission as a “Critical Raw Material” due to its irreplaceable functionality in many types of modern technology, combined with its current high-risk status associated with its supply. Despite such importance, there remain major knowledge gaps with regard to the geochemistry, mineralogy, and microbiology of cobalt-bearing environments, particularly those associated with ore deposits and subsequent mining operations. In such environments, high concentrations of Co (up to 34,400 mg/L in mine water, 14,165 mg/kg in tailings, 21,134 mg/kg in soils, and 18,434 mg/kg in stream sediments) have been documented. Co is contained in ore and mine waste in a wide variety of primary (e.g., cobaltite, carrolite, and erythrite) and secondary (e.g., erythrite, heterogenite) minerals. When exposed to low pH conditions, a number of such minerals are known to undergo dissolution, typically forming Co2+(aq). At circumneutral pH, such aqueous Co can then become immobilised by co-precipitation and/or sorption onto Fe and Mn(oxyhydr)oxides. This paper brings together contemporary knowledge on such Co cycling across different mining environments. Further research is required to gain a truly robust understanding of the Co-system in mining-affected environments. Key knowledge gaps include the mechanics and kinetics of secondary Co-bearing mineral environmental transformation, the extent at which such environmental cycling is facilitated by microbial activity, the nature of Co speciation across different Eh-pH conditions, and the environmental and human toxicity of Co.UK Foreign, Commonwealth & Development Office (FCDO

The effectiveness and complementarity of field days and small seed packs (SSPs) in delivering Dryland Cereal technologies: A survey of field day participants and agro-vets in Singida and Iramba districts of central Tanzania, Working Paper Series No. 61

This paper is about the result of a survey done in the 2014-2015 cropping season of field day participants and agro-vets who were facilitated to market SSPs and SFPs in Singida and Iramba districts of Tanzania. The objective of the survey was to determine whether there was any correlation between awareness creation and preferences reported during field days and the demand for technological inputs from the agro-vets. The results showed a strong complementarity between the dissemination of information on improved technologies during field days and the retailing of SSPs and SFPs in agro-vets. The field days help in creating awareness about the benefits and attributes of available improved sorghum and finger millet varieties and associated agronomic recommendations; while retailing of the SSPs and SFPs by the agro-vets not only helps promote the demand for improved technological inputs but also enhances their accessibility as SSPs and SFPs are more affordable to resource poor farmers. Therefore, having field days for awareness creation without improving accessibility of technological inputs through sale of SSPs and SFPs or vice versa is futile and does not lead to enhanced experimentation and adoption of improved technologies by target farmers..

Reconstructing Asian faunal introductions to eastern Africa from multi-proxy biomolecular and archaeological datasets

Human-mediated biological exchange has had global social and ecological impacts. In subS-aharan Africa, several domestic and commensal animals were introduced from Asia in the pre-modern period; however, the timing and nature of these introductions remain contentious. One model supports introduction to the eastern African coast after the mid-first millennium CE, while another posits introduction dating back to 3000 BCE. These distinct scenarios have implications for understanding the emergence of long-distance maritime connectivity, and the ecological and economic impacts of introduced species. Resolution of this longstanding debate requires new efforts, given the lack of well-dated fauna from high-precision excavations, and ambiguous osteomorphological identifications. We analysed faunal remains from 22 eastern African sites spanning a wide geographic and chronological range, and applied biomolecular techniques to confirm identifications of two Asian taxa: domestic chicken (Gallus gallus) and black rat (Rattus rattus). Our approach included ancient DNA (aDNA) analysis aided by BLAST-based bioinformatics, Zooarchaeology by Mass Spectrometry (ZooMS) collagen fingerprinting, and direct AMS (accelerator mass spectrometry) radiocarbon dating. Our results support a late, mid-first millennium CE introduction of these species. We discuss the implications of our findings for models of biological exchange, and emphasize the applicability of our approach to tropical areas with poor bone preservation