Bo Wang

The cathode of the microbial electrochemical systems (MESs) can continuously provide electrons to drive microbial or electrode-based reduction reactions for pollutant degradation. Cathode material is a key factor influencing the efficiency of MESs in wastewater treatment. Carbon-based materials have attracted widespread attention due to their property tunability and low toxicity. This review focuses on enhancing the performance of MESs for wastewater treatment through the modification of carbon-based cathodes. It summarizes common modification strategies for carbon-based cathode materials and evaluates their application performance in both abiotic and biotic cathode systems. The results indicate that the modification of carbon-based cathodes significantly improves the wastewater treatment efficiency of MESs. Moreover, this review discusses the current limitations, noting that most studies remain at the laboratory stage, and proposes future research directions for practical implementation. Overall, carbon‑based cathode modification is a promising strategy to advance MESs toward practical wastewater treatment and resource recovery.

Coastal ecosystems are critical biogeochemical reactors and biodiversity reservoirs, yet the mechanisms governing the community connectivity and stability of their foundational microbiomes remain poorly understood, particularly in anthropogenically influenced coastal oceans. Here, we systematically analyzed prokaryotic and microeukaryotic communities along both vertical and horizontal gradients in the Bohai-Yellow Sea, a model anthropogenically influenced and multi-stressed coastal ocean. We found that horizontal gradients, primarily driven by distance to coastline and latitudinal transitions, surpassed vertical gradients as the principal force governing microbial community assembly, connectivity, and stability. These horizontal factors overwhelmingly shaped microbial diversity, niche breadth, and biogeographic patterns, with prokaryotes displaying broader environmental adaptability and stronger cross-regional dispersal potential than microeukaryotes. Consequently, prokaryotes maintained higher spatial connectivity than microeukaryotes across both dimensions. This prokaryotic connectivity advantage was most pronounced within intermediate water masses. In contrast, vertical connectivity weakened with intensified water column stratification from the well-mixed Bohai Sea to the hydrographically complex South Yellow Sea. Horizontal gradients directly steered microbial co-occurrence network properties, driving a depth-dependent decline in network complexity and stability. This regional disparity was further underscored by distinct stability trade-offs: the semi-enclosed Bohai Sea fostered robust, modular networks, whereas the Yellow Sea systems formed highly connected but less modular, and thus more vulnerable, network architectures. Our findings reveal a dominant horizontal connectivity mode in coastal microbiomes, establishing a mechanistic link between large-scale environmental gradients and microbial network stability. This is a crucial advance for predicting ecological responses to anthropogenic and climate perturbations in vulnerable coastal zones. IMPORTANCE: Coastal microbial communities drive global biogeochemical cycles, yet the principles governing their large-scale connectivity and microbial network stability remain elusive, particularly in anthropogenic disturbances regions. Focusing on the Bohai-Yellow Sea system, we establish that horizontal transport processes, modulated by land-sea exchange and latitudinal gradients, override vertical stratification as the dominant force structuring microbial assembly and interaction networks. We demonstrate that prokaryotes possess a stronger horizontal dispersal advantage than microeukaryotes, sustaining higher connectivity through intermediate water layers. This horizontal connectivity governs microbial network stability. Networks shift from robust, prokaryote-driven modular architectures in shallow coastal waters to fragile, microeukaryote-dominated patterns in deeper, stratified regions. These findings define a “horizontal connectivity mode” as a central organizing principle for coastal microbiomes, moving beyond descriptive biogeography to provide a mechanistic framework for predicting community resilience to anthropogenic and climate forcing.

The symbiotic microbiome constitutes a consortium that has been persistently domesticated by a specific algal species, fostering a close and enduring association with the host. The majority of microbial taxa remain uncharacterized. These unknown microbes, often referred to as “microbial dark matter (MDM)”, have important ecological contributions. Given the challenges in discerning symbiotic microbes in natural environments, herein, ecological characteristics of MDM and known taxa within symbiotic communities were investigated in a simulated bloom process using Alexandrium pacificum without antibiotic treatment. Specifically, increased diversification was observed in MDM along the bloom process. Higher trophic interaction and less vulnerability of the molecular network were found in MDM taxa. The “bridge” role of MDM species was better than that of known taxa, as shown by higher betweenness centralization. Deterministic processes dominated in MDM taxa, which promote phylogenic diversity of such groups to some extent. The findings highlight that MDM taxa play an important role in sustaining community stability and functioning. This study broadens our understanding of the ecological contribution of MDM under disturbances from dinoflagellate blooms, providing essential theoretical insights and empirical data to inform the management of coastal toxic blooms.

The small amount of organic impurities in the pre-treated saline wastewater will affect the original solubility of the saline wastewater, which is one of the key issues that restrict the evaporation of saline wastewater with near-zero discharge under the working condition. We have investigated the solid-liquid phase equilibrium relationship under typical organic impurities in falling film evaporation tubes with different parameters. Results show the phase diagram of Na⁺, Mg²⁺//Cl^--H₂O in the presence of organic impurities belongs to the phase diagram of a simple system. The phase diagram contains a co-saturation point, two single-variable curves and four crystallization zones. In addition, the overall change in the solubility of the ternary system of Na⁺, Mg²⁺//Cl^--H₂O under organic impurities was not significant with the increase in temperature. However, the solubility of MgCl₂ was more affected by temperature and increased by 5.67% when the temperature increased from 303.15 K to 373.15 K. This study provides a theoretical basis for rational control of salt scaling in the evaporation process of coal chemical industry. It is important to ensure the efficient operation of the evaporator, realize the recycling of inorganic salt products, and ultimately achieve the goal of 'near-zero discharge'.

With the rapid development of nanotechnology, nanomaterials have been widely utilized in many industries and daily life applications due to their unique properties. However, their potential release and the human health/environmental consequences have raised public concern greatly. In this study, we compared the toxic effects of AgNPs and AgNO₃ on Skeletonema costatum in 10, 100, and 500 μg·L⁻¹ Ag treatments. In all the AgNP exposure experiments, cell membrane damage and growth inhibition occurred. However, the cellular damage only obviously appears on exposure to a high concentration of AgNO₃. The antioxidant enzyme (SOD and CAT) activities and lipid peroxidation in Skeletonema costatum were also induced significantly in the AgNP treatments. In addition, the percentage of Ag release in seawater increased with the increase in AgNP concentrations (13%, 32% for 100 and 500 μg·L⁻¹ AgNPs). Thus, the biotoxic effects of AgNPs were found to be due to a combination of the solubilization of particles into toxic metal ions and the nature of the nanoparticles. It was worth noting that the induction of oxidative stress and damage to the cell membrane comprised the dominant mechanism of toxicity for AgNPs. Therefore, the behavior of nanometals in seawater affects the biotoxic effect on the phytoplankton. These results shed light on the biological toxicity of nanometals and their possible toxicity mechanism.

Freshwater components in the Southern Ocean, whether sea ice meltwater or meteoric water, influence the growth of phytoplankton by affecting water stability and supplying dissolved iron (DFe). In addition, melting sea ice stimulates phytoplankton blooms by providing ice algae. In this study, sea ice meltwater and meteoric water in the Amundsen Sea (AS) were differentiated by their stable oxygen isotopic compositions (δ¹⁸O), while the phytoplankton carbon fixation rate (CFR) and iron uptake rate (FeUR) values were determined using the ¹⁴C and ⁵⁵Fe tracer assays, respectively. Our results showed that FeUR exhibits a significant positive response only to sea ice meltwater, suggesting that DFe and algae provided by sea ice melting may be the main cause. In addition, the CFR had a slightly positive response to the freshwater input and a stronger correlation with the phytoplankton biomass, suggesting that the freshwater input may have enhanced the CFR through the algae released from sea ice melting. The FeUR normalized to the phytoplankton biomass was significantly positively correlated with the mixed layer depth, suggesting that water stability regulates the phytoplankton growth and the resulting Fe demand. A higher Fe demand per unit of carbon fixation during sea ice formation leads to a higher Fe/C ratio in phytoplankton. Although no significant correlations were observed between the FeUR, CFR, and meteoric water, meteoric water may have an effect on larger phytoplankton sensitive to Fe deficiencies. The results of culture experiments with DFe addition showed that the added Fe significantly enhanced the Fe uptake, carbon fixation, and Fe/C ratio of the cells, especially for micro-phytoplankton. The more pronounced response of micro-phytoplankton means that the meteoric water input may affect the efficiency of carbon export. Our study provides the first measurements of phytoplankton Fe quotas in the AS in austral late summer and early autumn, providing insights into how meteoric water and sea ice meltwater affect seasonal changes in Antarctic ecosystems.