Li Yiru went to Puyang River again to look for bugs.
As a professor-level senior engineer of Zhejiang Environmental Technology Co., Ltd. and an expert in water management in the province, it seems that looking for bugs is a bit "not doing the right thing", but this time it is entrusted by reporters.
In the early morning of December 22, 2020, our group came to the Tongjiqiao Reservoir in the upper reaches of the Puyang River, which is the largest drinking water source protection area in Jinhua Pujiang County. The surface of the 5-square-kilometer lake is sparkling with turquoise waters and shimmering in the winter sun.
Before leaving, Li Xiangru told reporters about the target of this visit - EPT insects. EPT insects are a collective name for three types of aquatic insects, ephemera, stoneflies and stone moths (the abbreviation name EPT is taken from the Latin scientific names of the order to which the three belong: Ephemeroptera, the order Phectera to which stoneflies belong, and Trichoptera, to which stone moths belong). The larvae of these insects live in clear and clean water, and they cannot survive water pollution, so they are particularly suitable as the object of water quality monitoring and evaluation, and thus gain the reputation of the "Big Three" of water quality indicator organisms.
The more bugs in the water, the better the water quality, in the reporter's view, it is a new thing.
We took a speedboat to the center of the lake to take a sample. Li Yiru took out the water collector, plankton net, coagulant, etc. from the accompanying equipment, and began to conduct aquatic biological survey samples with several young investigators accompanying him.
They first used a water collector to sample at the bottom of the lake, in the lake, and on the surface of the lake, and then filtered it with a plankton net with a very small pore size, then added a potion to shake it and save it, and finally stored it in batches.
After half an hour, the water sample extraction is complete. "Strange, why haven't you seen a single insect?" The reporter was puzzled.
"For example, ephemerals, adult insects have only one day or a few days of life, and after mating, they fall into the water and drift away, so we are looking for eggs of EPT insects." Holding the railing of the bow of the ship with one hand, Li Xiangru said with a smile that these eggs need to be observed with a laboratory microscope and cannot be found by the naked eye.
So, are there EPT insects in the Puyang River? As early as a few months ago, Li Luru had the answer.
In July 2020, Pujiang County launched a survey of aquatic biodiversity in the Puyang River, and the trustee was Zhejiang Environmental Technology Co., Ltd. "It was an unexpected bonus." Li Said that during their investigation of aquatic insects, they accidentally found four-section ephemerals, flat ephemerals, microfloa, gaoxiang ephemerals and short-veined stone moths.
Where do these insects come from? The reporter specifically consulted Dr. Li Wenbing of the College of Life and Environmental Sciences of Hangzhou Normal University. He said the insects belong to EPT insects, have very low stain tolerance values, and only appear in clean waters.
Is this a kind of accident? Along with the reporter looking for bugs, Zhang Chungang, deputy director of the Pujiang Branch of the Jinhua Municipal Bureau of Ecology and Environment, also had the same doubts.
The Puyang River is the mother river of the Pujiang River, and the river runs through the city. Once, under the influence of the crystal processing industry, the ripples and blue waves were swallowed up by wastewater, and hundreds of "milk rivers", "garbage rivers" and "black and smelly rivers" appeared in the county, and the public satisfaction with the quality of the ecological environment ranked first in the province for 6 consecutive years.
Since the beginning of the "five-water co-governance", Pujiang has vigorously rectified the water ecological environment, and after several years of urban sewage interception and pipe interception, industrial pollution prevention, agricultural non-point source control, rural domestic sewage treatment and many other rectification actions, the water ecological environment in puyang river area has been significantly improved.
"Once the river passes through the main city and through the densest commercial and industrial areas, will the water quality be the same?" Zhang Chungang told Li Zhiru of his doubts.
"At that time, when doing the aquatic biodiversity survey, we also took into account, and at the same time, we also sampled the Sanjiangkou section in the middle reaches of the Puyang River and the Shangxian house section downstream, and found EPT insects, but the number was different." Li Xiangru said that this shows that the water quality of the entire Puyang River has been maintained at a certain level.
"EPT insects are just a windfall when we do the survey, in fact, there are more indicators representing the ecological and environmental quality of the Puyang River water body." Li Xiangru explained that dissolved oxygen content is an indispensable condition for aquatic biodiversity, and the dissolved oxygen of Puyang River reaches an average of 7.3mg/L, which is very suitable for the survival of fish, algae and plankton.
From physical and chemical indicators such as pH value and ammonia nitrogen to biological indicators represented by EPT insects, Puyang River water treatment is entering a new stage. In the past two years, the Provincial Department of Ecology and Environment has determined that the Puyang River will carry out a pilot project for the division of the ecological buffer zone of rivers and lakes, and pujiang will take ecological restoration as the focus of water management, further improve the river and lake ecosystem, and increase the capacity of the river ecological environment. "The aquatic biodiversity survey is only a 'bottom- and't-so- of the early water control effect, and in the future, we are also considering increasing the monitoring points of the EPT insect waters on the Puyang River in order to keep abreast of the changes in the water quality and water ecology of the Puyang River." Zhang Chungang said that during the "14th Five-Year Plan" period, Pujiang will put the restoration of the ecological buffer zone of the Puyang River in an important position, restore biological resources, protect biodiversity, and promote harmonious coexistence between man and nature.
A few days later, the reporter received a call from Li Liru, observed through the microscope, and found the EPT insects in the sample. (Jin Liang, Shen Chao, Lü Nanwei, Yan Shunhua, Chen Chenlei)