Impact of nitrogen pollution/deposition on extracellular enzyme activity, microbial abundance and carbon storage in coastal mangrove sediment.
This study applied different concentration of NaNO3solution to simulate the effect of inorganic nitrogen (N) deposition/pollution on carbon (C) storage in coastal mangrove sediment through observing the changes of enzyme activity and microbial abundance. Sediment collected from mangrove forest (MG) and intertidal zone (IZ) were incubated with different N rates (0 (control), 5 (low-N) and 20 (high-N) μg N g-1dry sediment, respectively). After incubation, the activities of phenol oxidase (PHO) and acid phosphatase (ACP) were enhanced, but β-glucosidase (GLU) and N-β-acetyl-glucosaminidase (NAG) activities were reduced by N addition. The altered enzymatic stoichiometries by N input implied that microbial phosphorus (P) limitation was increased, whereas C and N limitation were alleviated. Besides, N input decreased the bacterial abundance but increased fungal abundance in both types of sediment. The increased pH and soluble phenolics along with the exacerbated P limitation by N addition might explain these changes. Furthermore, sediment with N addition (except high-N treated MG sediment) showed a trend of C sequestration, which might be largely caused by the decrease of bacterial abundance and GLU activity. However, MG sediment with high-N suggested a trend of C loss, and the possible reason for this discrepancy might be the relatively higher increase of PHO and ACP activity. To better understand the influence of N deposition/pollution on C cycling, the long-term N effect on microorganisms, enzymes, and thus C storage should be paid more attention in the future.
College of Environmental Sciences, Sichuan Agricultural University, Huimin Road, Chengdu, 611130, People's Republic of China; Laboratory of Environmental Microbiology and Toxicology, School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong Special Administrative Region. Electronic address: luoling@sicau.edu.cn.
Ling
L
Luo
Laboratory of Environmental Microbiology and Toxicology, School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong Special Administrative Region.
Han
H
Meng
Laboratory of Environmental Microbiology and Toxicology, School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong Special Administrative Region.
Ruo-Nan
RN
Wu
Laboratory of Environmental Microbiology and Toxicology, School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong Special Administrative Region. Electronic address: jdgu@hku.hk.
Ji-Dong
JD
Gu
D000118:Acetylglucosaminidase / Q000737:chemistry; D000135:Acid Phosphatase / Q000737:chemistry; D001419:Bacteria; D057965:Carbon Sequestration; D004787:Environmental Pollution; D004798:Enzymes / Q000737:chemistry*; D005658:Fungi; D005843:Geography; D019015:Geologic Sediments / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D014442:Monophenol Monooxygenase / Q000737:chemistry; D009584:Nitrogen / Q000032:analysis* / Q000737:chemistry; D010758:Phosphorus / Q000737:chemistry*; D013696:Temperature; D014871:Water Microbiology; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000737:chemistry; D053833:Wetlands; D001617:beta-Glucosidase / Q000737:chemistry
D004798:Enzymes; D014874:Water Pollutants, Chemical; D010758:Phosphorus; D014442:Monophenol Monooxygenase; D000135:Acid Phosphatase; D001617:beta-Glucosidase; D000118:Acetylglucosaminidase; D009584:Nitrogen
Carbon storage; Enzymatic stoichiometry; Hydrolase; Nitrogen pollution; Phenol oxidase