• DOI:10.1038/s43017-019-0019-0
• Corpus ID: 211006052

River dam impacts on biogeochemical cycling

@article{Maavara2020RiverDI,
  title={River dam impacts on biogeochemical cycling},
  author={Taylor Maavara and Qiuwen Chen and Kimberly J Van Meter and Lee Eric Brown and Jianyun Zhang and Jinren Ni and Christiane Zarfl},
  journal={Nature Reviews Earth \& Environment},
  year={2020},
  volume={1},
  pages={103 - 116}
}

• T. Maavara, Qiuwen Chen, +4 authors C. Zarfl
• Published 1 February 2020
• Environmental Science
• Nature Reviews Earth & Environment

The increased use of hydropower is currently driving the greatest surge in global dam construction since the mid-20th century, meaning that most major rivers on Earth are now dammed. Dams impede the flow of essential nutrients, including carbon, phosphorus, nitrogen and silicon, along river networks, leading to enhanced nutrient transformation and elimination. Increased nutrient retention via sedimentation or gaseous elimination in dammed reservoirs influences downstream terrestrial and coastal environments. Reservoirs can also become hotspots for greenhouse gas emission, potentially impacting how ‘green’ hydropower is compared with fossil-fuel burning. In this Review, we discuss how damming changes nutrient biogeochemistry along river networks, as well as its broader environmental consequences. The influences of construction and management practices on nutrient elimination, the emission of greenhouse gases and potential remobilization of legacy nutrients are also examined. We further consider how regulating hydraulic residence time and environmental flows (or e-flows) can be used in planning and operation from dam conception to deconstruction. River damming can harness hydropower, control flooding and store water, but can also alter biogeochemistry in reservoirs and downstream environments. In this Review, the impacts of dams on nutrient cycling and greenhouse production are discussed, emphasizing the need to consider biogeochemical cycling at all stages of dam lifespan. Nutrient elimination in dam reservoirs modifies global biogeochemical cycles, with consequences to ecosystem structure and function along river networks. The global importance of reservoirs as greenhouse gas sources and/or sinks remains heavily debated. The reservoir hydraulic residence time can be used to develop simple relationships to predict nutrient eliminations, though small reservoirs can have large elimination efficiencies. Dam-management strategies impact nutrient cycling at all phases of a dam’s life cycle, including removal. Nutrient elimination in dam reservoirs modifies global biogeochemical cycles, with consequences to ecosystem structure and function along river networks. The global importance of reservoirs as greenhouse gas sources and/or sinks remains heavily debated. The reservoir hydraulic residence time can be used to develop simple relationships to predict nutrient eliminations, though small reservoirs can have large elimination efficiencies. Dam-management strategies impact nutrient cycling at all phases of a dam’s life cycle, including removal.