Study On The Outer Tidal Flat And Water Ecological Restoration Of Pudong Airport In The Yangtze Estuary

The Yangtze river estuary area is flat,and the silt in the water is easily silted up by the geographical characteristics.Therefore,the reclamation and promotion of the Yangtze river estuary area have a long history and far-reaching influence on the project.The reclamation area of pudong airport is the reclamation land for the airport runway project of pudong airport.In order to reduce the impact of reclamation on the surrounding environment,especially on the Jiu Duansha Island conservation area,the ecological restoration work after reclamation was carried out outside the reclamation area.From September 2016 to January 2019,a series of investigations and studies were conducted on the ecological restoration area and surrounding waters of the beach outside pudong airport.This paper analyzes the change of water content of sediment in the beach restoration area,the change of species and density of algae attached to benthos and electric pole reef in the beach restoration area,and probes into the restoration effect of electric pole reef restoration technology on the ecological restoration area of the beach.The environmental factors and the diversity of plankton in the water around the ecological restoration area were investigated and compared with the data before restoration.The research results are as follows:(1)In the restoration area of electric pole reef,small water bodies are formed at the base of electric pole reef under the action of tides and waves.Analysis of inner diameter,outside diameter,water depth and the pole reef correlation hight and the volume of water on the ground,the results show that the length of pole reef on the ground and the corresponding water volume has a certain correlation(p = 0.035),pole reef the ground height and the size of water body were positively correlated.The repair time of electric pole reef has a certain influence on the water content of sediments in the repair area.The water content in the area with the repair time of 180 d is higher than that in the area with the repair time of 90 d.The water content at 0m of the region with a long restoration time was 48.41%,while that at 0m of the region with a short restoration time was 40.73%.The water content beyond 1m in the region with a longer restoration time was basically higher than 44%,while the water content in the region with a shorter restoration time was lower than 38%.Under the action of electric pole reef restoration area,the grain size of nearshore sediments is smaller than that of far shore sediments,and the nearshore water content is higher than that of far shore sediments.The mean water content in the nearshore was 50.56%,while the water content in the far shore was only 41.72% at the position 0m away from the pole reef,and the water content in other points was less than 40%.The specific surface area of particle size in the nearshore beach was 0.933m2/g,and that in the far shore was 0.891m2/g.The proportion of clay with strong water holding capacity less than 2 m in the tidal flat is also different,the content in the nearshore beach is 8.39%,and the content in the far shore is 7.54%.(2)The investigation results of benthic organisms in the restoration area of electric pole reef showed that the density of benthic organisms increased from 236.8 56.7 ind./m2 before restoration to 312.7 52.8ind./m2.Shannon-wienner index increased from H=1.52 before restoration(before May 2017)to H=1.57 after restoration(after May 2017).(3)A total of 28 species of algae were collected from the electric pole reef in the restoration area near the beach outside pudong airport of the Yangtze river estuary,including 23 species of diatoms and 5 species of cyanobacteria.Mastogloia.Sp quantity highest,accounting for 38.75% of the total number of adherent algae;Next was Navicula.sp,which accounted for 19.59% of the total number of algae.Oscillatoria.sp represents about 13.83 percent of the total number of attached algae.(4)According to the implementation process and measures of the overall restoration project,this study investigated and analyzed the basic situation of plankton quality and plankton in the waters outside pudong airport in 2014-2015 and 2018-2019.A total of 23 species of phytoplankton were collected from 4 phytoplankton phytoplankton in the waters outside pudong airport in the first stage,and 8 phytoplankton species were collected from 8 phytoplankton in the second stage.First stage investigation of ribs of phytoplankton dominant species for algae(Skeletonema costatum)(53.8%),with a slot linear algae(Margaret spellings ulcata)(11.12%),Cyclotella meneghiniana(6.7%),limnetic round sieve algal(Coscinodiscus lacustris grub)(3.05%)and radiation round sieve algal(Coscinodiscus radiatus)(2.88%).Second stage survey frame of phytoplankton dominant species of algae(Skeletonema costatum)(25.12%),implicit algal species undefined(Cryptomomas sp.)(18.29%),oval chlorella(C.e llipsoidea)(7.51%),speech to the little ring algae(Cyclotella meneghiniana)(5.7%),with a slot linear algae(Margaret spellings ulcata)(3.3%),naked algae species undefined(Euglena Sp.)(3.3%)and Ankistrodesmus sp.(2.95%).Shannon wiener index,Margale and Peilou evenness index,richness index,according to the results of the second phase 2018-2019 of phytoplankton community of shannon wiener index,evenness and richness(` H = 1.78,Dm = 1.12,J = 0.85)were higher than in the first phase of 2014-2015(H ` = 1.31,Dm = 0.95,J = 0.71).Similarity clustering analysis was carried out on 36 groups of data collected at 9 sites at two different sampling times.The results showed that when the similarity was greater than 25%,all the data analyzed could be divided into 6 groups,among which the first group and the fifth group were the sampling results of the first stage before restoration,and the sixth group was the sampling results of the second stage.It can also be seen from the MDS figure that the Stress coefficient is 0.17,indicating that the community similarity in the water area outside pudong airport is different.(5)A total of 25 species of zooplankton were detected in the two-stage investigation in the waters outside pudong airport,among which 17 species of zooplankton,15 species of copepods and 2 species of cladoceras were detected in the first stage.In the second stage,22 species of zooplankton were detected.The dominant species of zooplankton investigated in the first stage were Limnoithona etraspina(dominance =0.33),Sinocalanus dorrii(dominance =0.13)and Schmackeria poplesia(dominance =0.11).The dominant zooplankton species investigated in the second stage were Calanus sinicus(dominance =0.42),Schmackeria poplesia(dominance =0.21),Tortanus vermiculus(dominance =0.1)and Labidocera euchaeta(dominance =0.06).The dominant species in the two stages is Schmackeria poplesia.The changes of zooplankton density in the waters outside pudong airport in the two stages were analyzed,and the results were shown in figure 3-5.The density of zooplankton in the first stage was significantly lower than that in the second stage.In the first stage,the density of zooplankton was 0.22 0.085 ind./L in November 2014 and 0.48 0.13 ind./L in January 2015.In the second stage,the density of zooplankton was 1.07 0.29 ind./L in November 2018.The results of the survey in January 2019 showed that the density of zooplankton was 0.69 0.16 ind./L.The results of clustering and MDS analysis showed that there were some differences between the two stages of zooplankton community composition.MDS figure shows that under the premise of Stress=0.15,there is a certain difference between the zooplankton communities of the two stages.(6)According to the CCA sequence diagram results of plankton and environmental factors,the plankton density was negatively correlated with total suspended particulate matter(TSS),dissolved phosphate(DIP),total nitrogen(TN)and turbidity.The results can be analyzed as whole,the ecological restoration of the outer tidal flat of pudong airport has a certain impact on the improvement of the tidal flat and the surrounding water environment.