Mercury waste from artisanal and small-scale gold mining facilities: a risk to farm ecosystems-a case study of Obuasi, Ghana

Rhizosphere microbiome of plants used in phytoremediation of mine tailing dams

Rhizospheric microbial communities improve the effectiveness of hyperaccumulators in the phytoremediation of heavy metals. However, limited access to tailing dams and inadequate assessment of plants' phytoremediation potential limit the characterization of native accumulators, hindering the effectiveness of local remediation efforts. This study evaluates the heavy metal sequestration potentials of Pennisetum purpureum, Leucaena leucocephala, and Pteris vittata and their associated rhizospheric microbial communities at the Marlu and Pompora tailing dams in Ghana. The results indicate shoot hyperaccumulation of Cd (334.5 ± 6.3 mg/kg) and Fe (10,647.0 ± 12.6 mg/kg) in P. purpureum and L. leucocephala, respectively. Analysis of rhizospheric bacterial communities revealed the impact of heavy metal contamination on bacterial community composition, associating Fe and Cd hyperaccumulation with Bacillus, Arthrobacter, and Sphingomonas species. This study reports the hyperaccumulation potentials of L. leucocephala and P. purpureum enhanced by associated rhizosphere bacterial communities, suggesting their potential application as an environmentally friendly remediation process of heavy metals contaminated lands.

Risks to Human Health from Mercury in Gold Mining in the Coastal Region of Ecuador

Artisanal and small-scale gold mining (ASGM) plays a crucial role in global gold production. However, the adoption of poor mining practices or the use of mercury (Hg) in gold recovery processes has generated serious environmental contamination events. The focus of this study is assessing the concentration of Hg in surface waters within the coastal region of Ecuador. The results are used to conduct a human health risk assessment applying deterministic and probabilistic methods, specifically targeting groups vulnerable to exposure in affected mining environments. Between April and June 2022, 54 water samples were collected from rivers and streams adjacent to mining areas to determine Hg levels. In the health risk assessment, exposure routes through water ingestion and dermal contact were considered for both adults and children, following the model structures outlined by the U.S. Environmental Protection Agency. The results indicate elevated Hg concentrations in two of the five provinces studied, El Oro and Esmeraldas, where at least 88% and 75% of the samples, respectively, exceeded the maximum permissible limit (MPL) set by Ecuadorian regulations for the preservation of aquatic life. Furthermore, in El Oro province, 28% of the samples exceeded the MPL established for drinking water quality. The high concentrations of Hg could be related to illegal mining activity that uses Hg for gold recovery. Regarding the human health risk assessment, risk values above the safe exposure limit were estimated. Children were identified as the most vulnerable receptor. Therefore, there is an urgent need to establish effective regulations that guarantee the protection of river users in potentially contaminated areas. Finally, it is important to continue investigating the contamination caused by human practices in the coastal region.

Persistent organic pollutants and heavy metals in Ghanaian environment: a systematic review of food safety implications

Advances in industrial and technological innovations have led to significant socio-economic benefits, but with overwhelming negative impacts on the environment. These impacts include the infiltration of organic contaminants into soil, water, and air, posing a threat to the environment and public health. Polybrominated diphenyl ethers (PBDEs), heavy metals, and polycyclic aromatic hydrocarbons (PAHs) are increasingly released as waste, endangering the environment. In countries like Ghana, where regulations are weakly enforced, industrial waste is released uncontrollably, posing threats to public health, environmental integrity, and food systems. This study systematically evaluated existing literature on PBDEs, heavy metals, PAHs, and organic contaminant exposure in Ghana and proposes a roadmap for achieving food safety and protecting the environment and human health. The research identified high mobility of specific heavy metals and risks associated with PBDEs and PAHs in sediments, dumpsites, and various food items. Unregulated dumping of electronic waste with PBDEs raised environmental concerns. An integrated approach is needed to address the multifaceted impact of organic pollutants on public health and ecosystems. Urgent implementation of effective environmental management strategies and regulatory measures is crucial. The study proposed short- to mid-term priorities emphasising the need to foster collaboration and implementing global measures. The mid- to long-term strategy includes a national information surveillance system, local monitoring capacity development, and integrating land contamination controls with food safety legislation. These measures would mitigate risks, ensure sustainable practices, and improve overall food safety management in Ghana, serving as a model for regions facing similar challenges with diverse pollutants.

A 'turn-off' fluorescence sensor for selective Hg(II) based on phenothiazine derivative

Given how crucial it is to preserve a human-safe and sustainable environment, the rapid discovery of possibly lethal heavy metals such as Hg(II) has drawn much attention in recent years. A novel sensor, known as (E)-2-((10-octyl-10H-phenothiazin-3-yl)methylene)hydrazine-1-carbothioamide (PTZHC), was synthesized as a fluorescence 'on-off' sensor for Hg2+ ions. Coordination alters organic molecule electron densities, quenching the fluorescence intensity. PTZHC was described completely with the help of FTIR and 1 H-NMR spectrum studies. The Hg2+ ion was successfully detected using the PTZHC sensor even when there were other metal ions present. The limit of the detection was estimated to be 2.5 × 10-8  M and the Job's plot examination implied that PTZHC was bound to Hg2+ with a simple 1:1 stoichiometry in s CH3 CN/H2 O (9:1, v/v) suspension. To further cast light on the bridged effect on geometric and optoelectronic characteristics, time-dependent density functional theory (TD-DFT) at the B3LYP/6-31G(d) level and DFT were both examined.