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Algal uptake of hydrophilic and hydrophobic dissolved organic nitrogen in the eutrophic lakes

Author:
Feng, Weiying, Liu, Shasha, Li, Cuicui, Li, Xiaofeng, Song, Fanhao, Wang, Beibei, Chen, Haiyan, Wu, Fengchang
Source:
Chemosphere 2019 v.214 pp. 295-302
ISSN:
0045-6535
Subject:
Microcystis flos-aquae, algae, aquatic ecosystems, bioavailability, biogeochemical cycles, dissolved organic nitrogen, eutrophication, fluorescence, hydrophilicity, hydrophobicity, lakes, nutrients, porous media, sediments
Abstract:
Dissolved organic nitrogen (DON) derived from sediments plays an active role in biogeochemical cycling of nutrients in aquatic ecosystems. Sediments from four eutrophic lakes were studied using three-dimensional fluorescence excitation-emission matrix (3DEEM) spectra and supelite XAD-8 macroporous resin separation to investigate the bioavailability of hydrophilic and hydrophobic DON to algae (Microcystis flos-aquae (Wittr.) Kirchner). The results showed that the average loss of DON was <6.0% after dividing DON into hydrophilic and hydrophobic components, demonstrating the utility of XAD-8 resin separation in the study of DON components from lake sediments. The 3DEEM analysis showed that hydrophobic and hydrophilic DON comprised humic- and protein-like materials, respectively. During the incubation period, the bioavailability of hydrophilic DON, which accounted for 59.3%–80.4% of total DON, stimulated algal growth, suggesting that hydrophilic DON was the primary source of organic nitrogen for algae. In contrast, hydrophobic DON increased algal density by only 31.8% of that observed for hydrophilic DON, and had a small (accounted for 20.0%–26.6% of total DON) effect on algal growth over the short-term. The significant differences in algal growth between the two types of DON suggested that they should be considered separately in the eutrophic lake restorations.
Agid:
6143745