Growth and physiological responses of submerged plant Vallisneria natans to water column ammonia nitrogen and sediment copper

Zhengjie Zhu; Siyuan Song; Pengshan Li; Nasreen Jeelani; Penghe Wang; Hezhong Yuan; Jinghan Zhang; Shuqing An; Xin Leng

doi:10.7717/peerj.1953

Growth and physiological responses of submerged plant Vallisneria natans to water column ammonia nitrogen and sediment copper

PeerJ. 2016 Apr 21:4:e1953. doi: 10.7717/peerj.1953. eCollection 2016.

Authors

Zhengjie Zhu¹, Siyuan Song¹, Pengshan Li¹, Nasreen Jeelani¹, Penghe Wang¹, Hezhong Yuan², Jinghan Zhang³, Shuqing An¹, Xin Leng¹

Affiliations

¹ School of Life Science and Institute of Wetland Ecology, Nanjing University, Nanjing Jiangsu, PR China; Nanjing University Ecology Research Institute of Changshu, Changshu Jiangsu, PR China.
² Nanjing University Ecology Research Institute of Changshu, Changshu Jiangsu, PR China; School of Environmental Science and Engineering, Nanjing University of Information Science and Technology, Nanjing Jiangsu, PR China.
³ Nanjing University Ecology Research Institute of Changshu , Changshu Jiangsu , PR China.

Abstract

Background. The decline of submerged plant populations due to high heavy metal (e.g., Cu) levels in sediments and ammonia nitrogen (ammonia-N) accumulation in the freshwater column has become a significant global problem. Previous studies have evaluated the effect of ammonia-N on submerged macrophytes, but few have focused on the influence of sediment Cu on submerged macrophytes and their combined effects. Methods. In this paper, we selected three levels of ammonia-N (0, 3, and 6 mg L(-1)) and sediment Cu (25.75 ± 6.02 as the control, 125.75 ± 6.02, and 225.75 ± 6.02 mg kg(-1)), to investigate the influence of sediment Cu and ammonia-N on submerged Vallisneria natans. We measured the relative growth rate (RGR), above- and below- ground biomass, chlorophyll, non-protein thiol (NP-SH), and free proline. Results and Discussion. The below-ground biomass of V. natans decreased with increasing Cu sediment levels, suggesting that excessive sediment Cu can result in significant damage to the root of V. natans. Similarly, the above-ground biomass significantly decreased with increasing ammonia-N concentrations, indicating that excessive water ammonia-N can cause significant toxicity to the leaf of V. natans. In addition, high ammonia-N levels place a greater stress on submerged plants than sediment Cu, which is indicated by the decline of RGR and chlorophyll, and the increase of (NP-SH) and free proline. Furthermore, high sediment Cu causes ammonia-N to impose greater injury on submerged plants, and higher sediment Cu levels (Cu ≥ 125.75 mg kg(-1)) led to the tolerant values of ammonia-N for V. natans decreasing from 6 to 3 mg L(-1). This study suggests that high sediment Cu restricts the growth of plants and intensifies ammonia-N damage to V. natans.

Keywords: Ammonia nitrogen; Sediment copper; Submerged plant; Vallisneria natans.

Grants and funding

This study was funded by the Major Science and Technology Program for Water Pollution Control and Treatment (2012ZX07204-004 & 2015ZX07204-002). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.