In Situ Study Of Algae Removal By Oleamide,Fruits Of Macleaya Cordata,and Its Alkaloids

The main work of this thesis involvs in the inhibitory effect of several biological originated substances against cyanobactria, which can be divided into indoor and outdoor experiments, the main findings are summarized as follows:In the indoor section, the inhibitory effect of the leachate from fruits of Macleaya cordata (LFMC) against cyanobacteria were studied. The results showed that LFMC could inhibit the growth of Microcystis aeruginosa PCC 7806. The different concentrations of LFMC showed different inhibitory effects, and the inhibitory effects increased with the increase of LFMC in the medium. Extraction of total alkaloids from fruits of M. cordata was studied using methanol or ethanol or acetonitrile as extraction solvent and followed by ultrasonic. The average extraction rate was 23.7%,16.9%,7.0% for methanol, ethanol and acetonitrile, respectively. The inhibitory effects of total alkaloids extracted from fruits of M. cordata using these three different organic solvents against M. aeruginosa PCC 7806 were also studied. The results indicated that all the extracted total alkaloids exhibited inhibitory effects against M. aeruginosa PCC 7806, and the intensity of inhibition order is methanol leachate> acetonitrile leachate> ethanol leachate. Thus, the best extraction solvent is methanol, and we used methanol to extract the total alkaloids from M. cordata in the following experiment. The extracted total alkaloids were stored in -20 ?.The outdoor section was involved in field experiments of the inhibition of four biological originated substances, fruits of M. cordata, total alkaloids from M. cordata, sanguinarine, and oleic acid amide, against Microcystis based water blooms in situ. Each field experiment lasted one month. The results indicated that all these four kinds of biological originated substances could effectively remove cyanobacterial blooms at the early stage of field experiment, and this inhibitory effect against cyanobacterial bloom gradually weakened with the extension of the test of time. However, throughout the trial period of 31 d, the concentration of chlorophyll a in the waters received biological originated substances were lower than control, and water transparency was just the opposite with the concentration of chlorophyll a, Results showed that, for any kind of biological originated substance, its inhibitory effects against cyanobacterial bloom could maintain at least one month. Through determination of cyanotoxins, ammonia nitrogen, total phosphorus and COD in wtaer, we found that the physicochemical characteristics of the water were not significantly influenced by amendment of biological originated algicidal substance.