New review warns of growing heavy metal threats in reservoirs, calls for smarter monitoring and greener cleanup solutions
Biochar Editorial Office, Shenyang Agricultural University
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Heavy metals in reservoirs: pollution characteristics, remediation technologies, and future prospects
view moreCredit: Song Cui, Chao Ma, Fuxiang Zhang, Zhaoyang Jia, Fengyang Pan, Dingwen Zhang, Hongliang Jia, Jingwei Wang, Zulin Zhang & Rupert Hough
Reservoirs are lifelines for drinking water, food production, and economic growth. But a new study warns that these crucial ecosystems are increasingly under threat from toxic heavy metals—and that urgent, innovative action is needed to safeguard both human health and the environment.
Researchers from Northeast Agricultural University, together with international collaborators, have published the most comprehensive review to date of heavy metal pollution in reservoirs, outlining its sources, risks, and promising solutions. The findings, published in Agricultural Ecology and Environment, reveal that heavy metals such as mercury, cadmium, and arsenic are accumulating at dangerous levels in reservoir waters and sediments, where they can persist for decades and move through food chains.
“Reservoirs are not only water storage systems, but also living ecosystems. Once heavy metals enter, they don’t just stay in the water—they accumulate in sediments and organisms, creating long-term risks for both ecosystems and people,” said lead author Dr. Song Cui.
The review identifies three main pathways of contamination: direct industrial and mining discharges, diffuse runoff from agriculture and other land uses, and internal release from sediments under changing environmental conditions. Once inside reservoirs, metals interact with complex physical and chemical processes, making them difficult to predict or remove. Fish from many reservoirs already exceed World Health Organization safety standards, posing dietary exposure risks for nearby communities.
To tackle this global challenge, the authors highlight recent progress in monitoring and remediation. Intelligent technologies, such as Internet of Things (IoT) sensor networks, artificial intelligence, and machine learning, are transforming heavy metal detection, enabling real-time monitoring and early warnings of pollution events.
On the remediation side, greener and more sustainable methods are emerging, including the use of nanotechnology, agricultural waste-based adsorbents, aquatic plants, and biochar. These eco-friendly approaches could replace traditional chemical methods, which are often costly and generate secondary pollution. However, the authors stress that scaling these technologies to real-world reservoirs remains a major challenge.
“Developing multifunctional, low-cost, and environmentally friendly solutions is essential if we want to prevent reservoirs from becoming long-term pollution traps,” said co-author Prof. Rupert Hough of the James Hutton Institute in Scotland.
The review also calls for greater international cooperation and the establishment of global risk management frameworks. With over 58,000 large dams worldwide, and many located in regions already facing water scarcity, the stakes are high. Climate change and growing industrial demand will likely worsen contamination risks unless proactive measures are taken.
“Our study shows that we need integrated strategies that combine advanced monitoring, innovative remediation, and coordinated governance,” added Dr. Cui. “Reservoirs are too important to fail—protecting them means protecting our future water security.”
The study offers a roadmap for policymakers, engineers, and environmental scientists to advance heavy metal pollution control and ensure the sustainability of reservoir ecosystems.
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Journal Reference: Cui S, Ma C, Zhang F, Jia Z, Pan F, et al. 2025. Heavy metals in reservoirs: pollution characteristics, remediation technologies, and future prospects. Agricultural Ecology and Environment 1: e003 https://www.maxapress.com/article/doi/10.48130/aee-0025-0003
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About Agricultural Ecology and Environment:
Agricultural Ecology and Environment is a multidisciplinary platform for communicating advances in fundamental and applied research on the agroecological environment, focusing on the interactions between agroecosystems and the environment. It is dedicated to advancing the understanding of the complex interactions between agricultural practices and ecological systems. The journal aims to provide a comprehensive and cutting-edge forum for researchers, practitioners, policymakers, and stakeholders from diverse fields such as agronomy, ecology, environmental science, soil science, and sustainable development.
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Method of Research
Literature review
Subject of Research
Not applicable
Article Title
Heavy metals in reservoirs: pollution characteristics, remediation technologies, and future prospects
Article Publication Date
27-Sep-2025
Biogas slurry boosts biochar’s climate benefits by reshaping soil microbes
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Biogas slurry strategy reshapes biochar-mediated greenhouse gas emissions via soil bacterial sub-communities
Credit: Xiaoyang Liang, Yongxing Wen, Chuanjuan Wang, Haitao Wang, Jiandong Wang & Xurong Mei
Adding biochar to farmland soils is widely promoted as a climate-friendly practice, but its impact on greenhouse gas emissions can vary. A new study finds that pairing biochar with biogas slurry, a nutrient-rich liquid fertilizer from biogas production, can reshape soil microbial communities and significantly alter emissions of carbon dioxide (CO₂), nitrous oxide (N₂O), and methane (CH₄).
Researchers from the Chinese Academy of Agricultural Sciences conducted controlled soil column experiments to test how different levels of biochar addition perform under two fertilization strategies: traditional chemical fertilizers and the biogas slurry strategy (BSS). They measured greenhouse gas emissions and tracked shifts in soil bacterial “sub-communities”—groups of microbes that play distinct roles in soil carbon and nitrogen cycling.
The team found that under conventional chemical fertilizer use, biochar consistently reduced CO₂ emissions by nearly one-third. However, it also increased emissions of CH₄ and N₂O, two potent greenhouse gases. When the fertilization strategy was switched to biogas slurry, CO₂ emissions dropped by about 15% and N₂O emissions fell by more than 70%. CH₄ emissions, however, rose sharply, highlighting a tradeoff. Interestingly, the impact of biochar depended on its application rate: while 4% and 6% biochar additions amplified the emission reductions seen with biogas slurry, a lower 2% dose reversed the effect.
“Our results show that the effectiveness of biochar in reducing greenhouse gas emissions depends strongly on the fertilization strategy used,” said corresponding author Dr. Jiandong Wang. “Biogas slurry not only changed the amount of gases released but also reshaped the microbial pathways that control those emissions.”
The study revealed that biogas slurry and biochar together enriched certain “rare” bacterial sub-communities, which proved surprisingly important in regulating emissions. These microbes altered how carbon and nitrogen were processed in soils, demonstrating what the researchers call a “priority effect”—where specific microbial groups take the lead in steering greenhouse gas outcomes.
The findings suggest that simply adding biochar is not a one-size-fits-all climate solution. Instead, its benefits depend on aligning application rates with local water and fertilizer practices. By combining biochar with organic fertilizers like biogas slurry, farmers could enhance carbon sequestration while lowering harmful N₂O emissions, though methane management remains a challenge.
“This research provides new scientific evidence for designing integrated soil management strategies,” said co-author Dr. Xurong Mei. “With careful optimization, biochar and biogas slurry together could help agriculture contribute to climate change mitigation and sustainable food production.”
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Journal Reference: Liang, X., Wen, Y., Wang, C. et al. Biogas slurry strategy reshapes biochar-mediated greenhouse gas emissions via soil bacterial sub-communities. Biochar 7, 92 (2025). https://doi.org/10.1007/s42773-025-00489-5
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About Biochar
Biochar is the first journal dedicated exclusively to biochar research, spanning agronomy, environmental science, and materials science. It publishes original studies on biochar production, processing, and applications—such as bioenergy, environmental remediation, soil enhancement, climate mitigation, water treatment, and sustainability analysis. The journal serves as an innovative and professional platform for global researchers to share advances in this rapidly expanding field.
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Journal
Biochar
Method of Research
Experimental study
Subject of Research
Not applicable
Article Title
Biogas slurry strategy reshapes biochar-mediated greenhouse gas emissions via soil bacterial sub-communities
