Effects Of Biochar On The Growth And Habitat Of Three Submerged Macrophytes

Both biochar and submerged macrophytes can absorb pollutants from water.However the effects of biochar on the growth of submerged macrophytes and the influence of the two parties on the water quality are still not very clear.In this study,a control experiments was carried out to investigate the effects of adding four amounts biochar(CK :0mg/g,T1:10mg/g,T2:20mg/g,T3:40mg/g)to sediment on water quality and growth of Vallisneria natans,Hydrilla verticillata,Ceratophyllum demersum).The following 6conclusions are drawn:(1)T1 treatment significantly increased the biomass of sedge,black algae and goldfish algae,with the promotion rates of 16.2%,15.3% and 18.8%,respectively;T3treatment significantly inhibited the growth of sedge,black algae and goldfish algae,with inhibition rates of 11.2%,15.0% and 17.8%,respectively;T2 treatment showed no significant difference in the growth of sedge,black algae and goldfish algae compared with CK treatment.(2)T1 treatment decreased the N:P ratio of submerged plants and changed the stress factors of submerged plants.The N:P ratio of T1 treatment decreased by 1.35,and the N stress of environment decreased,thus promoting the growth of submerged plants;T3treatment decreased by 5.22,and the submerged plants changed from N stress to P stress,thus inhibiting the growth of submerged plants.(3)The removal rates of TP and PO43-P were 15.7% and 13.6% respectively in T1 treatment group,and 19.4% and 14.2% in T3 treatment group,respectively.The removal of TN and NH4-N was promoted by adding biochar to sediment,and the removal rate was33.1% in T1 treatment group.And 41.5%.(4)The content of TOC,COND and pH value in water increased with the increase of biochar content in sediment,and T3 treatment group increased the most,the increasing rates were 24.6%,26.9% and 20.1% respectively;DO content and Cl-a content in water were mainly related to the growth of submerged plants,and the highest DO content phase was found in T1 treatment group at the end of the experiment.Compared with the control group,the content of Chl-a increased by 12.3%,and the lowest content of Chl-a decreased by 16.3% compared with the control group.(5)T1 treatment group can promote the increase of the total amount of microbial PLFAs in herbarium and goldfish bottom sediment,with the promotion rate of 33.9% and32.7%,respectively,and inhibit the increase of the total amount of microbial PLFAs in black algae bottom sediment.The T3 treatment group inhibited the increase of the total amount of PLFAs in the sediment plant sediment,and the inhibition rate of the PLFAs was23.3%,38.7% and 16.2%,respectively(6)The relative abundance and PLFAs biomass of arbuscular mycorrhizal fungi were increased by 17.6% and 27.6%,29.1%,28.6% and 13.7% respectively in T1 treatment group,while those of actinomycetes,Gram-positive bacteria,Gram-negative bacteria and fungi were increased by 27.6%,29.1%,28.6% and 13.7% compared with the control group.The biomass and relative abundance of PLFAs and eukaryotic microorganisms increased by 17.1% and 21.5% respectively compared with those in the control group.