Characterization of odorants in contrasting ecotypes of Lake Taihu: algae-dominated versus macrophyte-dominated zones

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CYANOBACTERIAL BLOOMS AND WATER ECOLOGICAL RESTORATION

Characterization of odorants in contrasting ecotypes of Lake Taihu: algae-dominated versus macrophyte-dominated zones Chuang Qi 1 & Jiaqi Fang 1 & Guoxiang Wang 1,2,3,4 & Hexiao Huang 1 & Zhuosen Wang 1 & Zejun Si 5 & Limin Zhang 1,2,3,4 Received: 1 August 2019 / Accepted: 27 January 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020

Abstract Globally, odorant incidents are occurring at an increasing frequency, magnitude, and duration under the dual influences of eutrophication and climate change. However, the contribution of multiple ecotypes to odorant production in the complicated and dynamic lake ecosystems remains unclear. In this study, the odorants and environmental conditions in algae-dominated zones (ADZs) and macrophyte-dominated zones (MDZs) in Lake Taihu were identified and characterized. Results showed that the ADZs were characterized by an abundance of pigments and nutrients and low DO levels, while the MDZs were featured as high TOC/TN ratios and high DO levels. Most odorants in ADZs and several in MDZs exceeded the odorant threshold content. The dominant odorants were dimethyl disulfide (DMDS) and dimethyl trisulfide (DMTS), β-ionone and β-cyclocitral in ADZs, which were associated with the accumulation and decomposition of algal detritus. For MDZs, the dominant odorants were 2-methylisoborneol (2-MIB) and geosmin, which were at least partially attributed to the massive addition of bait in a traditional aquaculture area. In addition, the odorant concentration in the water of ADZs was approximately 3 to 21 times higher than that in MDZs, while in the benthic sediment, the odorant concentration in ADZs was approximately 2 to 3 orders of magnitude higher than in MDZs. This study highlights the production and accumulation of nuisance odorants in the benthic sediment of ADZs, indicating a risk of diffusion from the sediment to the water column. This was supported by the correlation of odorants in the water column with that in the sediment. The results of this study will be helpful for the management of different ecotypes suffering from nuisance odorants problems. Keywords Odorants . Algal blooms . Macrophyte metabolites . Lake Taihu

Responsible editor: Philippe Garrigues

Introduction

* Guoxiang Wang [email protected]

Odorants have been a long-standing issue for water supply and aquaculture, with important implications for the integrity, esthetics, and safety of surface waters used for drinking and recreation (Watson et al. 2016; Watson et al. 2008; Yang et al. 2008). Recently, odorants produced by algae, actinomycetes, fungi, and sediment microorganisms in various aquatic environments have been widely reported (Lee et al. 2017; Peter et al. 2009; Watson and Jüttner 2017; Zaitlin and Watson 2006). Differences in the sources of odorants indicated that they respond differently to multiple ecotypes, as disparate primary producers might impact the associated metabolites (Fan and Peng 2016; Huang et al. 2018a). Algal metabolite-