Promoting the denitrification process by heavy metals in Liaohe Estuary sediment
Ming Hongxia1, Zan Shuaijun2, Liu Jiwen3
1National Marine Environmental Monitoring Center, Dalian 116023, China; State Environmental Protection Key Laboratory of Coastal Ecosystem, Dalian 116023, China.
Marine Pollution Bulletin
|May 2, 2024
Summary
Heavy metals like copper, zinc, and chromium positively correlate with denitrification rates in estuarine sediments. This suggests heavy metals may enhance aerobic denitrification and offset high dissolved oxygen impacts.
Area of Science:
- Environmental Science
- Microbiology
- Biogeochemistry
Background:
- The role of heavy metal ions in estuarine biodenitrification is poorly understood.
- Biodenitrification is crucial for understanding nitrogen cycling in estuarine environments.
Purpose of the Study:
- To investigate the impact of heavy metal ions on denitrification rates and enzyme gene abundance in Liaohe Estuary sediments.
- To analyze the community structure of nirK denitrifying bacteria under heavy metal influence.
Main Methods:
- Quantified denitrification rates and the abundance of five key denitrifying enzyme genes (narG, nirK, napA, norB, nosZ).
- Analyzed the community structure of nirK denitrifying bacteria.
- Correlated heavy metal content with denitrification parameters and environmental factors.
Main Results:
- A significant positive correlation was observed between heavy metal content (Cu2+, Zn2+, Cr) and denitrification rate.
- Heavy metals also correlated positively with the abundance of napA and norB genes.
- Dominant denitrifying bacteria (Pseudomonas, Hydrogenophaga, Serratia) showed tolerance to heavy metal pollution.
- Sediment particle size, nitrate, nitrite, Zn2+, and Cd2+ were identified as key factors shaping the denitrifying community.
Conclusions:
- Heavy metals may enhance aerobic denitrification in estuarine sediments.
- Heavy metals could mitigate the negative effects of high dissolved oxygen on denitrification.
- Understanding these interactions is vital for estuarine nitrogen cycle management.
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