| Aquatic plants,which are an important part of the wetland ecosystem,are of great significance in maintaining ecological balance.Volatile Organic Compounds refer to all organic compounds which have volatile and their vapor pressure was greater than or equal to10 Pa at 20 °C.Among them,volatile organic compounds derived from biology are called biogenic Volatile Organic Compounds(BVOCs).Plant BVOCs are major components of volatile organic compounds.However,current studies on plant-derived BVOCs emissions are mostly focused on terrestrial ecosystems.Until now,little known is about aquatic plant-derived BVOCs.In this study,the method of qualitative analysis of BVOCs from aquatic plants was confrimed.The BVOCs composition spectrums of 25 collected aquatic plants including different taxa and different life forms were measured by this confirmed method.And the differences of BVOCs between different aquatic species and different life forms were explored.The main results are as follows:(1)It is proved by pre-experimental comparison that the collection of aquatic plant source BVOCs by solid phase micro-extraction can meet the samples requirement for the experiment.BVOCs produced by aquatic plants can be accurately tested by gas chromatography-mass spectrometry,after optimizing the parameters of the extraction head,sample temperature and duration.This method is convenient and accurate for qualitative analysis of BVOCs from aquatic plants.(2)The full-scan chromatograms of 25 aquatic plants from 4 different life-type were obtained and the concentrate release time and the major organic compounds were analyzed by searching the NIST 05 database.Totally 73 kinds of main volatile organic compounds were detected in 25 aquatic plants,including aldehydes,ketones,and esters,etc.Among 73 kinds detected main volatile organic compounds,there were 21 kinds belonging to aldehydecompounds,16 kinds belonging to alcohol compounds,8 kinds belonging to ketone compounds,7 kinds belonging to ester compounds,7 kinds belonging to olefin compounds,5kinds belonging to alkane compounds,4 kinds belonging to aromatic hydrocarbon compounds,4 kinds belonging to furan compounds,and 1 kind belonging to ether compounds.Aldehydes,alcohols,ketones,esters and olefins accounted for 82% of total.From frequency of occurrence,the highest frequency is n-hexanal,which was detected in 23 plants;trans-2-hexenal,benzaldehyde,β-ionone and cis-2-pentene-1-Alcohols were also found in more than 10 plants.(3)The β-diversity analysis and cluster analysis of volatile organic compounds in different life-form aquatic plants indicated that the volatile organic compounds of aquatic plants belonging to the same life-form type were more similar,such as Nelumbo nucifera,Pontederia cordata,Trapa bispinosa,Eichhornia crassipes,and Salvinia natans,etc.The similarities of volatile organic compounds in Elodeanuttallii,Najasminor,Najasmarina,Hydrillaverticillata,Myriophyllum aquaticum,and Myriophyllum spicatum were all reached to more than 0.40.For phylogeny,the similarity of volatile organic compounds in aquatic plants from the same family is higher.For example,the similarity of Najas marina and N.minor was 0.58;theβ-diversity coefficient of Myriophyllum spicatum and M.aquaticum were 0.30,and the similarity of Potamogeton malaianus and P.maackianus were 0.25.Exotic species have higher independence compared with native species.For example,Egeria densa was an independent group in cluster analysis,and it has lower similarity with other aquatic plants,and there were significant differences in volatile organic components with most native species. |
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