Community Structure Characteristics And Environmental Analysis Of Phytoplankton And Periphyton In The Sediment-laden Weihe River And Its Tributaries From The Northern Foot Of The Qinling Mountains

The river ecosystem is one of the most important ecosystems in nature.However,the current river ecological environment has been severely damaged,and the remodeling of river life has a decisive role in protecting the ecological environment of the local area.This requires finding a breakthrough from the perspective of aquatic ecology,not only to understand the changing laws of the water environment,but also to clarify the construction mechanism of aquatic ecology.The Weihe River affects the social and economic development of Northwest China,and is an important watershed for maintaining regional ecological balance.In recent years,due to climate change and intensified human activities,the hydrology,water environment,and water ecology of the Weihe River Basin have undergone major changes.Therefore,it is urgent to protect the ecological environment of the Weihe River Basin.Based on field sampling and indoor analysis,this study conducted two investigations and analysis of the water environment background values of the mainstem of the heavy sediment-laden Weihe River and its typical tributary in the northern foot of the Qinling Mountains.This study provides an in-depth understanding of the community structure of phytoplankton and periphyton in the study area,clarifies the main environmental driving factors affecting the community structure of the two major biological groups in the study area,divides the phytoplankton and periphyton functional groups in the Weihe River Basin,and analyzes the effects of the environmental factors of the distribution characteristics of algae functional groups finally evaluated the water environment status and water ecological health level of the Weihe River Basin.(1)The study found that for the heavy sediment-laden Weihe River,environmental factors closely related to turbidity such as dissolved oxygen,electrical conductivity,and nutrients are the main environmental factors that affect the community structure of phytoplankton and periphyton in the mainstem of the Weihe River.The environmental factors affecting the community structure of the two major biological groups of tributaries are water temperature,flow velocity,pH and nutrients.Therefore,the sand content is the key factor causing the difference between the typical tributaries and mainstem of the Weihe River in the water environment and the aquatic ecology.(2)Using the concept of functional groups to divide the phytoplankton and periphyton in the Weihe River Basin,it was found that the main functional groups in the Weihe River Basin are A,D,P,MP and others which relates with water turbidity and scouring ability.Finally,the Qr index and Shannon-Wiener index were used to evaluate the water quality of the study area based on the two major biological groups.After summary analysis,it was concluded that the water quality of the typical tributaries of the Weihe River did not change significantly during the season,and the water quality of the mainstem of the Weihe River gradually improved.