Although research on microplastic (MP) pollution in freshwater has increased, much remains unknown about the fate and distribution of this pollutant in sediments. This review provides a global perspective on how research efforts and data collection are distributed, also exploring recent studies on factors that play a key role in MPs transport and influence MP distribution in freshwater sediments worldwide.
The role of human activities, precipitation and stormwater run-off, water flow, sediment grain size, and land use on the spatial and temporal distribution of MPs in sediments has been demonstrated, highlighting the complex interactions between these factors and MP pollution. MPs have been found in sediments of rivers, tributaries, and lakes, from urbanized to remote areas, with variations across regions, ecosystems, and temporal scales. To date, most studies are concentrated in Asia, with limited representativeness of other continents. In addition, limitations remain, as data variations between studies may result from different scales or analytical methods.
This review provides an overview of the spatiotemporal variation of MP pollution in freshwater sediments, highlighting knowledge gaps and challenges. Future research should aim to more geographically balanced studies, addressing both temporal and spatial aspects to better assess the long-term environmental and ecological impacts of MPs in freshwater systems.
Seagrass meadows, essential yet vulnerable marine ecosystems, display complex dual responses to eutrophication. These impacts are especially concerning in seagrass meadows due to the higher frequency and intensity of eutrophication. This review was aimed at summarizing stress responses and adaptive mechanisms of seagrass from the view of eutrophication.
Moderate nitrogen and phosphorus inputs initially enhance photosynthesis and biomass accumulation in nutrient-poor environments by increasing chlorophyll synthesis and photosynthetic efficiency. However, prolonged exposure leads to detrimental effects, including light attenuation from algal blooms, ammonium toxicity impairing electron transport rates, and competitive exclusion by fast-growing algae. Species-specific tolerance varies significantly: resilient seagrasses like Halodule wrightii upregulate antioxidant enzymes (e.g., superoxide dismutase and catalase) and accumulate non-enzymatic flavonoids to mitigate oxidative stress, while sensitive species such as Syringodium filiforme suffer metabolic imbalances and biomass loss. Adaptive mechanisms span multiple scales. At the molecular level, stress-responsive transcription factors (e.g., WRKY transcription factor gene and MYB proto-oncogene transcription factor gene) regulate antioxidant and carbon metabolism genes in Posidonia oceanica under nutrient excess. Physiologically, seagrasses reallocate carbon to belowground tissues under shading and suppress algal competitors via allelochemicals. Ecologically, herbivory-mediated algal control indirectly reduces oxidative stress. Despite these adaptations, chronic eutrophication degrades ecosystem services and destabilizes fishery habitats.
This review summarized the stress responses and adaptive mechanisms of seagrass under eutrophication. Future research must address climate–eutrophication synergies and leverage omics technologies to decode epigenetic resilience mechanisms. Such interdisciplinary efforts are critical to preserving seagrass meadows as blue carbon hubs and biodiversity refuges in rapidly changing coastal ecosystems.
As fossil fuel–related emissions gradually decline, agriculture has become a major source of reactive nitrogen (Nr) in regions such as China, the USA, and Europe, significantly contributing to air pollution, including particulate matter (PM) and surface ozone (O3), as well as climate change. Despite this, agriculture has historically been underrepresented in air quality management and climate policy. Without effective mitigation, agricultural Nr emissions are expected to rise, driven by growing food demand and climate change, further exacerbating their negative impacts on air quality and the climate. This review provides a process-level overview of the current understanding of agricultural Nr emissions and their effects on atmospheric chemistry, with a focus on the underlying mechanisms, and also highlights research gaps and proposes future research directions.
Agricultural Nr emissions are influenced by a variety of factors and released through multiple biotic and abiotic pathways, resulting in significant spatial and temporal variability. Our understanding of the underlying mechanisms driving agricultural Nr emissions remains incomplete, and current emission estimates are associated with substantial uncertainties. Agriculture contributes to ambient PM pollution primarily through ammonia (NH3) emissions and to surface O3 pollution via oxidized Nr species, including nitrous acid (HONO) and nitrogen oxides (NOx). Although the chemistry of PM and surface O3 is highly nonlinear, with sensitivities to their precursors varying widely, agricultural Nr is gradually becoming a key contributor, particularly in regions where fossil fuel emissions are declining, such as China, the USA, and Europe. Agricultural Nr is estimated to exert a net cooling effect, with warming contributions from nitrous oxide (N2O) emissions and cooling from aerosols generated by Nr, although this estimate remains highly uncertain.
Our understanding of the underlying mechanisms driving agricultural Nr emissions remains limited, particularly when it comes to episodic pulses during extreme weather events. A knowledge-guided machine learning approach that integrates ground and airborne observations with process-based agroecosystem models could offer new opportunities for more accurate emission estimations. Further research is essential to fully understand the role of both reduced and oxidized reactive nitrogen in influencing air quality and climate.
Harmful algal blooms (HABs) present a growing threat to seagrass ecosystems, significantly impacting their ecological functions and blue carbon potential. Understanding the complex interactions between HABs and seagrasses is crucial for developing adaptive management strategies to protect seagrass ecosystems.
Recent studies reveal that global HAB events have significantly expanded both geographically and in frequency over the past two decades. The geomorphological processes and depositional environments of seagrass meadows, along with the effects of climate change, act as contemporary drivers that influence algal invasion, presence, and retention within seagrass ecosystems. Emerging research demonstrates that macroalgal blooms can significantly accelerate seagrass carbon loss by enhancing decomposition rates and increasing greenhouse gas emissions from blue carbon stocks. Seagrass allelopathy and associated algicidal bacteria play crucial roles in natural HAB control. Advanced monitoring techniques combining artificial intelligence with remote sensing have achieved significant improvements in detecting and tracking HAB events and seagrass ecosystems.
This review provides a comprehensive analysis of HAB-seagrass interactions, documenting diverse types of HABs affecting seagrass beds, including macroalgal and microalgal blooms. We examine key environmental factors contributing to HABs in seagrass ecosystems, particularly eutrophication, global warming, and ocean acidification, and analyze their complex impact mechanisms, including light limitation, resource competition, biogeochemical alterations, and toxin effects. Natural defense mechanisms of seagrasses, particularly allelopathy and algicidal bacteria, offer potential solutions for HAB control. Effective protection of these valuable blue carbon resources requires integrated adaptive management strategies, combining advanced monitoring technologies, water quality improvement measures, and community-based conservation approaches.
Effective management of aquaculture wastewater is essential for maintaining ecosystem health, ensuring the safety of aquatic products, and protecting human health. Despite advancements in aquaculture practices and wastewater treatment technologies, a comprehensive review addressing the risks associated with various pollutants is lacking. This review aims to fill that gap by examining the risks and regeneration technologies related to aquaculture wastewater.
This systematic review analyzes the risk profiles of different pollutants in aquaculture wastewater, highlighting the complexity of these contaminants. It reviews the characteristics and mechanisms of physical, chemical, and biological regeneration technologies employed in wastewater treatment. The findings indicate that the sources, composition, and hazardous properties of key pollutants vary, and the existing reuse technologies provide differing treatment advantages.
The review identifies limitations in current treatment methods and proposes future research directions, emphasizing the need to investigate the synergistic effects of pollutants, particularly emerging contaminants. It also suggests establishing clear criteria for acceptable contaminant levels and optimizing integrated treatment approaches. These insights will enhance aquaculture wastewater management and contribute to the sustainable development of the aquaculture industry.
Microalgae exhibit immense potential for treating textile wet processing wastewater (TWPW), owing to efficient assimilation of pollutants while simultaneously generating valuable biomass for bio-based applications. This review investigates the integration of microalgae cultivation at different stages of textile wet processing (TWP) for TWPW treatment and resource recovery, addressing a key gap in literature, while emphasizing natural dye pigment production and sustainable biorefining potential within the circular bioeconomy principles.
The textile industry, valued at USD 1837.27 billion, poses significant environmental challenges, due to the generation of chemically complex wastewater mainly during TWP. However, conventional treatment methods for TWPW are often inefficient and resource-intensive, whereas microalgae-integrated bioremediation provides a sustainable alternative, by removing pollutants through biosorption, biodegradation, and bioaccumulation/biotransformation, achieving ~ 99% nutrient removal. Furthermore, as eco-friendly alternatives to synthetic dyes, microalgae-derived natural pigments, including chlorophylls, carotenoids, and phycocyanin, are capable of dyeing a variety of textiles, such as cotton, silk, wool, and synthetic fibers. Particularly, Chlorella and Spirulina exhibit promising dyeing potential, with ~ 87% of uptake efficiency and excellent colorfasness.
This review critically evaluates the feasibility of microalgae-integrated TWPW treatment, emphasizing the wastewater characteristics and the treatment potential of microalgae. Furthermore, the study evaluates the potential of microalgae pigment as a sustainable alternative to synthetic dyes and the valorization of residual biomass into low-value products, promoting a circular bioeconomy in the textile industry. Hence, the review concludes by highlighting the requirement for a paradigm shift in the current research to optimize industrial-scale TWPW bioremediation and the use of microalgae-derived pigments for textile dyeing.
Biogenic volatile organic compounds (BVOCs) play a significant role in the global carbon cycle and climate change. While significant advancements have been made in terrestrial BVOCs research, critical gaps persist in understanding marine BVOCs, particularly their emission, multiphase oxidation pathways, and climate feedback mechanisms.
Current atmospheric models underestimate the flux of marine VOCs. Recent studies have revealed isomerization pathways and heterogeneous reaction mechanisms, thereby revising the traditional theory dominated solely by gas-phase oxidation in atmospheric transformation of BVOCs. This advancement enables more accurate prediction of oxidation product distributions. These products can drive new particle formation at the tropopause, thereby influencing radiation balance and regulating climate through resultant feedback mechanisms.
This review systematically elaborates the sources and sinks of marine BVOCs, their atmospheric transformation mechanisms, and climate feedback, highlighting the critical role of marine biota in global climate regulation. The production and emission of marine BVOCs exhibit significant spatiotemporal heterogeneity, primarily regulated by marine internal processes including biological activities and chemical reactions. Upon entering the atmosphere via sea-air exchange, marine BVOCs undergo complex atmospheric oxidation processes to form aerosols (e.g., sulfur-containing aerosols, brown carbon) and reactive halogen species, thereby influencing the radiation balance and atmospheric oxidation capacity while exerting crucial feedback on global climate. This provides an overarching perspective for a more comprehensive understanding of the role of marine ecosystems in global climate regulation.
Outdoor air pollution, the scourge of modern urban living, has long been associated with an array of adverse health outcomes. While empirically supported strategies have already been prescribed for individuals to effectively lessen the impact of contaminated air on their physical health, much is still unknown about comparable solutions for mental wellbeing. The utility of an all-embracing framework that could offer a parsimonious elucidation of existing apparently-heterogeneous work is contended to be pivotal, and this narrative review will address this by reviewing recent main findings through the lens of evolutionary mismatch theory.
In general, recent evidence suggests that the evolutionary mismatch theorisation (which posits that air pollution–induced lifestyle changes could play an influential role in modifying mental wellbeing outcomes due to their evolutionarily unfamiliar nature) might be valid. More specifically, the air pollution–mental wellbeing link (tentatively) appears to have been influenced by (1) the evolutionarily mismatched curtailment of physical activities, (2) sunlight exposure, and (3) social contact, together with (4) the evolutionarily mismatched overexposure to upsetting information. The jury is still out for the proposed role of the evolutionarily mismatched reduction of greenery exposure, while the very limited evidence does not support the postulated influence of evolutionarily mismatched opportunities for comparisons with others via media.
Findings from this review (tentatively) propound that deleterious mental-wellbeing consequences due to urban air pollution could be mitigated if individuals maintain a more evolutionarily familiar lifestyle within the limits of their circumstances.
The various disease outbreaks have increased the consumption of antibiotics. Unfortunately, this condition can further increase the accumulation of antibiotics that can pollute the environment and even human health. Biodegradation is one method to reduce or even eliminate the accumulation of antibiotics. This review aims to discuss the sources of antibiotics in the environment, mechanisms of antibiotic biodegradation, factors affecting the biodegradation process, ecological risks, regulatory implications, current strategies that have been implemented, and innovative approaches to reduce antibiotic resistance and environmental contamination.
Recent studies have highlighted antibiotic resistance in aquatic and soil environments. This increases the threat of antibiotic-resistant bacterial populations. Biodegradation techniques such as biological wastewater treatment, wetlands, microbial degradation, and algal degradation have been able to show satisfactory performance. In particular, microbial consortia and genetic modification of bacteria, fungi, and microalgae can also provide synergistic metabolic pathways that enhance the efficiency of antibiotic degradation. In addition, biogenic nanoparticles and enzyme-assisted degradation methods, such as laccases, can be advanced innovative approaches for antibiotic biodegradation.
Antibiotic biodegradation has been a pivotal research focus due to increasing environmental pollution and the risk of antibiotic resistance. This topic is promising in decomposing antibiotics into compounds that are more tolerant of the environment. Although there has been progress in antibiotic biodegradation research, further studies should be conducted to overcome challenges such as the complexity of the compounds, antibiotic stability, antibiotic and gene resistance phenomena, and non-optimal environmental factors.
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