Promoting the denitrification process by heavy metals in Liaohe Estuary sediment

Ming Hongxia; Zan Shuaijun; Liu Jiwen; Su Jie; Ren Kaijia; Lin Jiannan; Chen Quanrui; Shi Yinyin; Shi Tingting; Fan Jingfeng

doi:10.1016/j.marpolbul.2024.116408

Promoting the denitrification process by heavy metals in Liaohe Estuary sediment

Mar Pollut Bull. 2024 May 1:203:116408. doi: 10.1016/j.marpolbul.2024.116408. Online ahead of print.

Authors

Ming Hongxia¹, Zan Shuaijun², Liu Jiwen³, Su Jie¹, Ren Kaijia¹, Lin Jiannan⁴, Chen Quanrui⁵, Shi Yinyin¹, Shi Tingting¹, Fan Jingfeng⁶

Affiliations

¹ National Marine Environmental Monitoring Center, Dalian 116023, China; State Environmental Protection Key Laboratory of Coastal Ecosystem, Dalian 116023, China.
² Groundwater Provincial Engineering Research Center for Urban Water Recycling and Environmental Safety, Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China.
³ Ocean University of China, Qingdao 266100, China.
⁴ National Marine Environmental Monitoring Center, Dalian 116023, China; State Environmental Protection Key Laboratory of Coastal Ecosystem, Dalian 116023, China; College of Marine Ecology and Environment, Shanghai Ocean University, Shanghai, 201306, China.
⁵ State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Sciences, Xiamen University, Xiamen 361005, China.
⁶ Ecological Environment Monitoring and Scientistic Research Center, Taihu Basin & East China Sea Ecological Environment Supervision and Administration Bureau, Ministry of Ecology and Environment, Shanghai 200125, China; National Marine Environmental Monitoring Center, Dalian 116023, China; State Environmental Protection Key Laboratory of Coastal Ecosystem, Dalian 116023, China. Electronic address: jffan@nmemc.org.cn.

PMID: 38696947
DOI: 10.1016/j.marpolbul.2024.116408

Abstract

The impact of heavy metal ions on the biodenitrification process remains unknown, which is the key to understand the nitrogen cycle in estuarine areas. Here, denitrification rate and the abundance of five denitrifying enzyme genes (narG, nirK, napA, norB and nosZ) in Liaohe Estuary sediments were examined, and the community structure of nirK denitrifying bacteria was also analyzed. The results demonstrate a significant positive correlation between heavy metal content (Cu²⁺, Zn²⁺, and Cr) and the denitrification rate, and the abundance of napA/norB (periplasmic nitrate reductase and nitric-oxide reductase) in sediments. The dominant narG denitrifiers were Pseudomonas, Hydrogenophaga, and Serratia known to be tolerant to heavy metal pollution. Sediment particle size, NO₃^-, NO₂^-, Zn²⁺, and Cd²⁺ were the key factors influencing the denitrifying community structure. These findings suggest that heavy metals may enhance the aerobic denitrification process in sediments and mitigate the adverse effects of high dissolved oxygen levels.

Keywords: Denitrification rate; Denitrifying bacterial community; Denitrifying functional genes; Estuarine sediment; Heavy metals; High-throughput sequencing.