| Cyanobacterial bloom occurs widely in eutrophic lakes.A large amount of particulate organic matter(POM)was introduced into the water body,thus the carbon(C),nitrogen(N)and phosphorus(P)cycles were also affected.In order to investigate the effect of cyanobacterial blooms on concentration of C,N,P in particulate organic matters,and the effect of the distribution and degradation of particulate organic matters on bacterial community structure.In this paper,Taihu and Chaohu as the research object.Association between the concentration of Chla,and the distribution of C,N,P element and its organic matters.,and The relationship between the concentration of C,N,P in particulate organic matter and the community structure of attached bacteria and free living bacteria were analyzed.In addition,A long-term(132 days)decomposition process of particulate organic matter(POM)derived from bloom-forming cyanobacteria was simulated under dark conditions in laboratory.The main results were as follows:1?The results showed that the characteristics of concentration of POC,PON and POP were high in winter and spring,low in summer and autumn in the Taihu lake and Chaohu lake.Correlation analysis showed that POM and Chla were significantly correlated.These results suggested that POM in the lakes mainly derived from cyanobacterial bloom.The order of nutrient concentration in Taihu lake was the North Taihu>Western Taihu>the middle South Taihu,that of Chaohu lake was Western Chaohu>Central Chaohu>Eastern Chaohu,and nutrient concentration of water had a regular:the nutrient concentration of water had a lower in summer or early autumn,and gradually increasing from winter and reaching the maximum in spring.2?Investigation of the relationships between particulate organic matter and the community structure of bacterial in cyanobacteria bloom serious area of Meiliang Bay,showed that attached bacteria were different with free living bacterial in water body.The attached bacteria mainly included Proteobacteria,Bacteroidetes,Firmicutes and Gemmatimonadetes.Free living bacterial mainly included Proteobacteria,Actinobacteria,Acidobacteria,Bacteroidetes,Verrucomicrobia,Planctomycetes,Chlorobi,Chloroflexi and Spirochaetae.The Shannon index of attached bacterial was between 0.78 and 2.49,lower than that of the free living bacterial(4.16?5.15).RDA analysis showed that PON,POC had more influence on the attached bacterial.Temperature and DO had more influence on the free living bacterial.It indicated that particulate organic matter was significantly affected the community structure of attached bacteria compared with that of free living bacteria.3?A long-term(132 days)degradation process of particulate organic matter(POM)derived from bloom-forming cyanobacteria was simulated under dark conditions in laboratory.The results showed that,The maximum release of POC in the three experimental groups A,AF and AS was 82.30%,81.90%and 63.14%;that of PON was 92.85%,91.68%and 73.27%;and that of POP was 93.50%,91.25%and 70.11%,respectively.The result indicated that AS experimental group had the lowest POM release,while the amount of POC release was less than PON and POP.These result illustrated that the existence of sediment can reduced the decomposition of cyanobacteria-derived organic matters.High-throughput sequencing results showed that the bacterial community structure changed significantly during the degradation process of cyanobacteria-derived organic matters.In the experiment group of A and AF,the proportion of Bacteroides and Proteobacteria declined,while the proportion of Nitrospira and Acidobacteria increased.However,bacterial community structure were relatively stable in experiment group of AS.It indicated that the cyanobacteria-derived organic matter would significantly influence the composition of bacterial communities in water,with little effect on the bacterial community structure in sediment.Thus the degradation of organic matter in the presence of sediment would be affected,which led to bury of organic matter in sediment. |
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