Study On The Relationship Between Metal Enrichment And Eutrophication Of Phytoplankton From In Guizhou Plateau Reservoir

Hongfeng Reservoir,Baihua Reservoir and Aha Reservoir are located in Southwestern China Plateau where is widely developed in karst area.Compared with other reservoirs of the same latitude,its light,temperature conditions,eutrophication,rule of bloom occurrence and phytoplankton community structure are unique.With the economic development in decades,the heavy metal content in HF Reservoir,BH Reservoir and AH Reservoir is higher than in domestic.To study the spatial and temporal distribution characteristics of phytoplankton community structure and the relationship between phytoplankton metal enrichment and water eutrophication in Guizhou Plateau Reservoir,sampling survey was conducted monthly from October,2017 to September,2018.This article clarifies the dynamic changes of phytoplankton community structure in three reservoirs.Phytoplankton enrichment experiments were carried out in three Reservoir in January,April,July and October 2018 respectively for understanding the phytoplankton enrichment of metals.At the same time,in order to explore the relationship between phytoplankton-enriched metals and water eutrophication,an indoor simulation experiment was conducted in July 2018.The results showed that:82 kinds of phytoplankton 7 door(genus)were detected in HF Reservoir,79 kinds of phytoplankton 7 door(genus)in BH Reservoirs and 60 kinds of phytoplankton 7 door(genus)in AH Reservoir.The total number of green algae was the largest,followed by diatoms,cyanobacteria,cyanobacteria and dinoflagellates,while the total number of species of cryptophyta and chlorella was the least among the three reservoirs.During the investigation,HF Reservoir was a diatom-cyanobacteria-green algae type,BH Reservoir was a diatom-cyanobacteria-green-diatomaceous algae type,and AH reservoir was a diatom-cyanobacteria-green algae type.The common functional groups of the three reservoirs are: B,D,MP,X1,S1,J,P,Lo,F,and W1.The seasonal succession of the dominant functional groups of HF Reservoir is as follows: D+B+P→D+B+P+J+MP →B+P+D+Lo+MP+N S1+D→A+B+Lo+N,BH Reservoir is : B+D+P+W1→Lo+B+P→B+D +Lo→D+J+S1+X1,AH Reservoir is : B+D+P+WI →B+Lo+P→D+Lo+ P+MP+B→D+S1+B.RDA analysis of the relationship between functional groups and environmental factors showed that nutrients,transparency(SD)and dissolved oxygen(DO)were the main environmental factors affecting the three reservoir.The metal contents of 11 species of phytoplanktonin the three reservoirs showed obvious differences,among which the content of Ca accounting for the largest proportion,followed by Fe,four kinds of metals such as Mg,Mn,Zn and Cu for the third,and As,Ni,Pb,Cd and Hg for the least proportion.The order of metal content of 11 species of phytoplankton was: Ca>Fe>Mg>Mn>Zn>Cu>As>Ni>Pb>Cd>Hg.The order of metal content of phytoplankton in different sampling points of HF Reservoir is:SCH>JJW>HW>HYD>HH>DB,BH Reservoir is:GLSC>DB>MXH>HQ>YJZ,AH Reservoir is: ZCS>JZH>NJ>DHP.Metal content in phytoplankton in each layer: bottom layer >surface layer > middle layer.The results of cluster analysis and Pearson correlation analysis of phytoplankton metal content are inconsistent,indicating that the sources of phytoplankton metal content in the three reservoir are complex and need further study.The metal content of 11 species of phytoplankton in the three reservoirs has a strong correlation with the dominant algae species.The metal content of phytoplankton in HF Reservoir is negatively correlated with the biomass of the dominant algae species,while BH Reservoir and AH Reservoir is positively correlated.In a word,the metal content of phytoplankton in the reservoir is positively correlated with the biomass of dominant algae species.The enrichment of Cd,Hg,Ca,Mn and Fe in microcystis aeruginosa increased with the time,and the enrichment rate was the highest when metal was added for 5 min,and then decreased.Different concentrations of Cd,Fe,Hg,Ca and Mn were added,and the metal content in phytoplankton increased with the increase of the concentration of added metals.Therefore,the nutrients affect the enrichment of Cd,Fe,Hg,Ca and Mn by phytoplankton under different nutrient levels rather than the metal concentration.There was a negative correlation between Cd,Fe and eutrophication in Microcystis aeruginosa,a positive correlation between Ca,Mn and eutrophication and there was no significant correlation between Hg enrichment and eutrophication.The metal content of phytoplankton has an important relationship with eutrophication,but there is a complex relationship between reservoir eutrophication and phytoplankton metal enrichment.In conclusion,there is a coordination effect between eutrophication and phytoplankton enrichment of Hg,Pb,Cu,Ni,Fe,Mg and Ca.However,there is an antagonistic effect between eutrophication and phytoplankton enrichment of Cd and As.