Biological origins and annual variations of earthy-musty off-flavours in the Xionghe Reservoir in China

Abstract

The annual variations in physicochemical parameters, algal abundance and odorous compounds in the Xionghe Reservoir were investigated, in order to identify the possible odorous compounds and their origins. From May 2007 to April 2008, the algal composition, cell number and earthy-musty odorous compounds both in the water and in the flesh of fish at Sites A, B and C were determined monthly. The physicochemical parameters such as total nitrogen (TN), total phosphorus (TP), dissolved oxygen (DO), pH, transparency, water temperature and chlorophyll a (chl a) were simultaneously determined. A statistical correlation was noted between the chl a and water temperature: 0.678 (P , 0.05) for Site A, 0.831 (P , 0.01) for Site B and 0.659 (P , 0.05) for Site C. Geosmin and 2-methylisoborneol (2-MIB)-in the reservoir were identified by gas chromatography-mass spectrometry (GC-MS). We observed that a large amount of Anabaena circinalis bloomed in surface water during the off-flavour episodes. In July 2007, we detected the highest concentration of geosmin (2.7 mg/L in the water, 0.27 mg/kg in the silver carp and 0.10 mg/kg in the crucian carp), while no 2-MIB was detected, which indicated that geosmin was mainly responsible for the off-flavour episodes in summer.

Contribution of Streptomyces in sediment to earthy odor in the overlying water in Xionghe Reservoir, China

“…Furthermore, at the same time, considerably higher concentrations of 2-MIB were also observed in the surface water than in the overlying water, which was attributed to a 2-MIB-producing Pseudanabaena sp. (Zhang et al, 2010). An abundant 2-MIB-producing Pseudanabaena sp.…”

“…Since 2004, there have been frequent odor events, which have seriously damaged the quality of drinking water and rendered the fish unmarketable for long periods, thereby significantly decreasing the economic value. A previous study has indicated that cyanobacteria are responsible for the occurrence of odorous compounds in the surface water (Zhang et al, 2010); however, the occurrence of earthyemusty compounds in the sediment remains unclear. The present study was undertaken to monitor the fluctuations in geosmin and 2-MIB concentration and their causative microorganisms in sediments and overlying water, with the aim of evaluating their contributions to water bodies.…”

2-Methylisoborneol production characteristics of Pseudanabaena sp. FACHB 1277 isolated from Xionghe Reservoir, China

“…Pseudanabaena sp. FACHB 1277 used in this study is a strong 2-MIB producer and was isolated from the Xionghe Reservoir, China, in May 2007 (Zhang et al 2010). We think that Pseudanabaena sp.…”

Microcystis aeruginosa/Pseudomonas pseudoalcaligenes interaction effects on off-flavors in algae/bacteria co-culture system under different temperatures

“…MIB and GEO are two earthy-muddy-musty smelling terpenoids, which account for the global majority of drinking water odor outbreaks, and are widespread in many eutrophic lakes (Zhang et al, 2010a). They are synthesized by a selected number of planktonic bloom-forming and benthic-littoral cyanobacteria as well as by some actinomyces, myxobacteria, and fungi and soil microbiota (Watson et al, 2008).…”

“…Growth and decay of these blooms caused off-flavor episode, and off-flavor episodes are becoming a worldwide problem in aquatic environments, especially in eutrophic lakes and reservoirs in China (Yu et al, 2009). Since 2005, episodes of strong earthy-musty off-flavors have occurred every year, which lead to off-flavor contamination of drinking water and aquaculture systems in the Xionghe Reservoir (Hubei, China) (Zhang et al, 2010a). It also has triggered a serious drinking water pollution incident when a dense cyanobacterial bloom occurred in Taihu Lake during the summer in 2007 (Chen et al, 2010;Yang et al, 2008).…”