The nitrogen reduction in eutrophic water column driven by Microcystis blooms
Yingshi Shen1, Yingying Huang1, Jun Hu2
1Shanghai Key Lab for Urban Ecological Processes and Eco-Restoration, School of Ecological and Environmental Sciences, East China Normal University, Dong Chuan Road 500, Shanghai, 200241, PR China.
Journal of Hazardous Materials
|November 17, 2019
Summary
Microcystis blooms significantly reduce water nitrogen through assimilation and denitrification. These blooms enhance nitrogen removal in surface waters and at sediment interfaces, clarifying nitrogen loss during blooms.
Area of Science:
- Environmental Microbiology
- Aquatic Ecology
- Biogeochemistry
Background:
- Dissolved inorganic nitrogen (DIN) depletion during blooms indicates nitrogen limitation.
- The fate of nitrogen during Microcystis blooms remains unclear.
- Microcystis blooms impact nitrogen cycling in aquatic ecosystems.
Purpose of the Study:
- To investigate the mechanisms and extent of nitrogen reduction by Microcystis blooms.
- To differentiate nitrogen loss pathways in various water layers.
- To provide field evidence for Microcystis-driven nitrogen removal.
Main Methods:
- Enclosure experiments and batch tests.
- Stable nitrogen isotope tracing.
- Analysis of nitrogen reduction in field-collected Microcystis aggregates.
Main Results:
- Microcystis blooms significantly reduce water nitrogen via assimilation (surface layer) and denitrification (sediment-water interface and water column).
- Microcystis enhances nitrate reduction efficiency at the sediment-water interface (76.5–84.7%).
- Denitrification is the dominant nitrate reduction pathway, exceeding DNRA (7.4–8.5 times).
- Microcystis aggregates effectively remove total nitrogen (TN) by 3.76–6.03 mg/L within two days.
Conclusions:
- Microcystis blooms play a crucial role in nitrogen reduction in aquatic systems.
- Distinct mechanisms drive nitrogen loss in different water compartments during blooms.
- Microcystis actively enhances nitrogen removal processes, particularly denitrification.
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