Distribution And Dynamics Of Typical Odorous Compounds In Reservoirs For Drinking Water Supply In Guangdong Province

In recent years, off-flavor problems caused by algae-producing secondary metabolic compounds have attracted the worldwide attention, in which the musty and earthy odors originated from geosmin and 2-methylisoborneol (2-MIB) are the most common.Geosmin and 2-MIB are two typical semi-volatile organic compounds. They have very low odor threshold number in water, typically ng/L. In the experiments, heading solid phase micro-extraction (SPME) was used as preliminary treatment method, and accurate qualitative and quantitative gas chromatography-mass spectroscopy (GC-MS) determination method was used to determin the samples from reservoirs for dringking water supply in Guangdong Province. The concentrations of the two typical odorous compounds, geosmin and 2-MIB were determined, the species and abundance of blue-green algae, total nitrogen, total phosphorus, nitrate nitrogen, ammonia nitrogen, chlorophyll a, temperature and other environmental factors were investigated. The correlation between two compounds and abundance of blue-green algae and the environment factors were analyzed.The investigation of two typical odorous compounds in 33 reservoirs for drinking water supply during August and September showed that 2-MIB was detected in 22 reservoirs, and the concentrations of 2-MIB in 13 reservoirs were above 10 ng/L; geosmin was detected in 7 reservoirs, the concentrations of geosmin were above 10 ng/L. The main odorous compounds in reservoirs for drinking water supply in Guangdong were 2-MIB, the production of 2-MIB was correlated with filamentous cyanobacteria, while the concentrations of geosmin and 2-MIB and other environmental factors showed no significance.Shaoke Reservoir was intensely monitored. One-year investigation showed that geosmin was the main odor compound which could be detected throughout the year. The highest concentration was 858.835ng/L. The correlation analysis results showed that the sources of geosmin were Anabaena circinalis. There were positive correlativity between concentrations of geosmin and some environmental factors, including total phosphorus and total nitrogen. However, there was negative correlativity between concentrations of geosmin and ammonia nitrogen. 2-MIB was detected from August to November in 2009. There was no significant correlativity between the concentration of 2-MIB and either total abundance of blue-green algae or total abundance of filamentous blue-green algae, but a positive correlativity with the abundance of Cylindrospermopsis and Oscillatoria and the temperature, negative correlativity with the total nitrogen, nitrate nitrogen and N/P.