Promoting the denitrification process by heavy metals in Liaohe Estuary sediment

• Published in: Marine pollution bulletin Vol. 203; p. 116408
• Main Authors: Hongxia, Ming, Shuaijun, Zan, Jiwen, Liu, Jie, Su, Kaijia, Ren, Jiannan, Lin, Quanrui, Chen, Yinyin, Shi, Tingting, Shi, Jingfeng, Fan
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.06.2024
• Subjects: Bacteria - metabolism; China; Denitrification; Denitrification rate; Denitrifying bacterial community; Denitrifying functional genes; Estuaries; Estuarine sediment; Geologic Sediments - chemistry; Heavy metals; High-throughput sequencing; Metals, Heavy - analysis; Nitrate Reductase - metabolism; Water Pollutants, Chemical - analysis; China; Denitrifying functional genes; Denitrifying bacterial community; High-throughput sequencing; Estuarine sediment; Heavy metals; Denitrification rate
• ISSN: 0025-326X; 1879-3363
• DOI: 10.1016/j.marpolbul.2024.116408

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. [Display omitted] •Denitrification rate increases with the increase of heavy metals (Cu2+, Zn2+, Cd2+).•Heavy metals positively related with nosZ, napA and norB genes in Liaohe Estuary, which may promote the aerobic denitrification process.•The dominant narG-denitrifying bacteria were tolerant to heavy metal pollution.