Molecular characterization of macrophyte-derived dissolved organic matters and their implications for lakes

Authors: LIU, SHASHA - Chinese Research Academy Of Environmental Sciences; ZHAO, TIANHUI - Chinese Research Academy Of Environmental Sciences; ZHU, YUANRONG - Chinese Research Academy Of Environmental Sciences; QU, XIAOXIA - Chinese Research Academy Of Environmental Sciences; He, Zhongqi; GEISY, JOHN - University Of Saskatoon; MENG, WEI - Chinese Research Academy Of Environmental Sciences

Submitted to: Science of the Total Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/27/2017
Publication Date: 11/6/2017
Citation: Liu, S., Zhao, T., Zhu, Y., Qu, X., He, Z., Geisy, J.P., Meng, W. 2018. Molecular characterization of macrophyte-derived dissolved organic matters and their implications for lakes. Science of the Total Environment. 616-617:602-613.

Interpretive Summary: Dissolved organic matter (DOM) is a labile and reactive component of OM, and plays an important ecological role especially in aquatic systems. For better understanding of the quantities and features of DOM released by autochthonous macrophytes, in this study, one riparian species, three emergent macrophytes, one floating species and one submerged species from Lake Dianchi were collected for chemical characterization of their OM and DOM fractions. This work further evalauted the contribution of N, P in lake systems from macrophyte-derived OM and DOM and predicted the degradation of OM/DOM and possible environmental consequences based on their chemical composition deduced from 13C NMR data. An estimation of N and P accumulated and released by macrophytes in total N and P of the whole Lake Dianchi environment showed that N in the lake was mainly from eternal loading, while macrophyte is an important store and release source of P. Thus, to effectively control eutrophication in Lake Dianchi, macrophyte biomass should be a great concern in P regulation.

Technical Abstract: Chemical properties of whole organic matter (OM) and its dissolved organic matter (DOM) fraction from six dominant macrophytes in Lake Dianchi were comparatively characterized, and their environmental implications were discussed. Significant differences in chemical composition of the OM samples were observed between the species, and between leaf and shoot of the same species. 3D-EEM showed only a single fulvic-like fluorescence appeared in leaf biomass of emergent macrophytes. In contrast, protein-like peaks were observed in spectra of floating and submerged species, as well as the shoot DOM of emergent species. Solid state 13C NMR analysis demonstrated that the leaves had greater percent of the recalcitrant alkyl C and aromatic C, while the shoots were rich in the labile carbohydrates. Our observations suggested that the floating and submerged plants had stronger abilities not only in accumulating excess N and P but also in returning them to the lake. These data also provided new evidences on nutrient retranslocation from leaf biomass to shoot biomass during plant senescence, indicating a greater biodegradability of shoot OM and DOM. An estimation of N and P accumulated and released by macrophytes in total N and P of the whole Lake Dianchi environment showed that N in the lake was mainly from eternal loading, while macrophyte is an important store and release source of P. Thus, to effectively control eutrophication in Lake Dianchi, macrophyte biomass should be a great concern in P regulation.