The University of The Bahamas (UB) is the national public institution of higher education in the Commonwealth of The Bahamas with campuses throughout the archipelago. The main campus is located in the capital city of Nassau, on the island of New Providence.After more than thirty-five years of serving The Bahamas, first as a two-year institution, then as a four-year degree-granting College, the University of The Bahamas was chartered on November 10, 2016.
Dissolved organic matter (DOM) plays a key role in influencing the environmental behavior of heavy metals in lake ecosystems. Through mechanisms such as complexation, ion exchange, and physical adsorption, DOM regulates the speciation, transport, and bioavailability of heavy metals, thereby shaping their ecological risks and fate. Here, we provide a comprehensive review of the sources and molecular composition of lake DOM, with particular attention to humic substances, proteins, and polysaccharides, and highlight the importance of functional groups such as carboxyl group and phenolic hydroxyl group in metal binding. The mechanisms of DOM-heavy metal interactions are discussed in detail. These include σ-ligand bonding, which relies on the donation of lone pair electrons from O/N-containing functional groups to metal orbitals. Also covered are π–d electron interactions, often initiated by photoexcitation of aromatic moieties in DOM to facilitate electron transfer, and multi-site adsorption, a process governed by the combined effects of electrostatic attraction, hydrogen bonding, and the porous structure of DOM. Additionally, the effects of environmental factors (temperature, pH, and light) and biological factors (microbial activity and aquatic plant decomposition) on DOM-heavy metal dynamics are examined. Although substantial progress has been made, key challenges remain in understanding the microscale mechanisms, capturing real-time changes in natural waters, and assessing long-term ecological impacts. Future research should prioritize multi-scale approaches. This entails employing advanced techniques like Fourier-transform ion cyclotron resonance mass spectrometry to elucidate molecular mechanisms, while also advancing in situ monitoring technologies and establishing long-term observation networks to resolve real-time dynamics and assess cumulative ecological impacts. This review provides a theoretical basis for understanding DOM-heavy metal interactions and supports future efforts in ecological risk assessment and the sustainable management of lake environments.
Eutrophication is a major threat to freshwater ecosystems, leading to harmful algal blooms, biodiversity loss, and hypoxia. Excessive nutrient loading, primarily from nitrates and phosphates, is driven by fertilizer runoff, sewage discharge, and agricultural practices. Sediment microbial fuel cells (sMFCs) have emerged as a potential bioremediation strategy for nutrient removal while generating electricity. Although various studies have explored ways to enhance sMFC performance, limited research has examined the relationship between external resistance, electricity generation, and nutrient removal efficiency. This study demonstrated effective nutrient removal from overlying water, with 1200 Ω achieving the highest nitrate and phosphate removal efficiency at 59.0% and 32.2%, respectively. The impact of external resistances (510 Ω and 1200 Ω) on sMFC performance was evaluated, with the 1200 Ω configuration generating a maximum voltage of 466.7 mV and the 510 Ω configuration generating a maximum current of 0.56 mA. These findings show that external resistance plays a major role in both electrochemical performance and nutrient-removal efficiency. Higher external resistance consistently resulted in greater voltage output and improved removal of nitrate and phosphate. The findings also indicate that sMFCs can serve as a dual-purpose technology for nutrient removal and electricity generation. The power output may be sufficient to support small, eco-friendly biosensing devices in remote aquatic environments while mitigating eutrophication.
Arsenic (As) is a regulated environmental hazard that poses significant health risks to humans through rice (Oryza sativa L.) consumption. Iron (Fe) plaque on rice roots typically acts as a barrier, limiting As uptake by rice plants. After harvest, rice root debris (RS) containing both organic carbon (C) and As is left in the soil, potentially enhancing As release when paddy fields are re-flooded, although this has not been experimentally verified. In this study, we simulated the addition of RS with and without Fe plaque (RS+Fe and RS-Fe) into As-contaminated and uncontaminated paddy soils to investigate the post-harvest effect of Fe plaque on As dynamics. In As-contaminated soils, RS+Fe did not significantly alter porewater chemistry (pH, Eh, DOC, Fe, Mn, or As), whereas RS-Fe markedly (p<0.05) increased porewater DOC (29.5%), Fe (25.2%), and As (31.7%) during a 60-day microcosm incubation. The rise in DOC under RS-Fe conditions strongly stimulated Proteobacteria (199%), a group of dissimilatory Fe- and As-reducing bacteria, resulting in elevated As(III) (98.1%) and exchangeable As (26.8%) fractions. Conversely, in uncontaminated soils, both RS+Fe and RS-Fe treatments promoted As immobilization, increasing the proportion of As in the more stable carbonate-bound (68.4%) and Fe/Mn-bound (32.0%) fractions. Overall, these findings demonstrate a clear effect of Fe plaque in immobilizing As in re-flooded paddy soils, and reveals that Fe plaque could be a long-lasting As sink in rice monoculture.
The escalating severity of heavy metal pollution in agricultural soils has driven significant interest in carbon-based nanomaterials (CNMs) as an effective remediation strategy, given their remarkable adsorption capacity, environmental persistence, and eco-friendly characteristics. This paper systematically reviewed recent research on four representative CNMs, graphene (GNs), carbon nanotubes (CNTs), carbon dots (CDs), and nanobiochar (NBCs), in the remediation of heavy metal-polluted agricultural soils. The review focused on their synergistic adsorption mechanisms and their ability to improve soil physicochemical properties and micro-ecosystems, regulate crop molecular responses, and enhance crop resistance. Studies indicated that CNMs can improve the soil’s capacity to immobilize heavy metals by improving soil pH, organic carbon content, and cation exchange capacity, thereby indirectly supporting crop growth. Additionally, CNMs can stimulate the expression of antioxidant-related genes and metal transporter proteins, thereby enhancing crop resistance to heavy metal stress at the molecular level. This review also compares the heavy metal adsorption performance and gene-regulatory effects of different CNMs, emphasizing their potential to enhance crop adaptability. By integrating the dual perspectives of “pollution remediation” and “crop resistance enhancement”, this review proposes a multidimensional mechanism of CNMs action in the soil-microbe-crop system, and provides insights into future research directions aimed at advancing smart and sustainable agriculture.
The deterioration of soil health due to salinization, acidification, and heavy metal pollution represents a critical environmental challenge threatening sustainable agriculture and ecosystem functions worldwide. Conventional remediation strategies often face limitations in efficiency, cost, and long-term stability. Carbon-based nanomaterials (CNMs), including nanobiochar (NBCs), graphene (GNs), carbon nanotubes (CNTs), and carbon dots (CDs) have emerged as promising alternatives due to their distinctive surface characteristics and nanoscale effects. This systematic review critically examines the dual role of CNMs in improving key soil properties (e.g., pH, cation exchange capacity, organic carbon content, and porosity) while also addressing their concentration-dependent effects and potential ecological risks. We analyze the mechanisms underlying CNMs-soil interactions, highlighting material-specific and concentration-dependent behaviors as well as their environmental implications, including effects on microbial communities and long-term fate. Based on mechanistic comparison, integration, and risk–benefit evaluation, this review combines field and laboratory research to identify the most promising CNMs for field application. It further proposes a synergistic framework integrating multi‑omics and field studies to guide the design of eco-friendly CNMs composites and standardized application protocols. This work provides a comprehensive foundation for applying CNMs in sustainable soil management while emphasizing the importance of ensuring ecological safety.
