Source: Xinhua Daily Telegraph
On August 5, workers drove an algae clearing boat to clear cyanobacteria on the lake surface. Photo by Yang Xiaoyuan
In response to Chaohu pollution, over the past year, Hefei City has adopted methods such as fighting with pictures and dynamic cancellation, clarifying the rectification time limit one by one, and vigorously promoting the rectification work.
"The disease comes like a mountain falling, and the disease goes like a thread pulling away." The management of Chaohu is a tough battle and a protracted battle. There is no shortcut to lightness and generalization, only comprehensive measures can be implemented and long-term efforts.
Xu Xiaogang closed the window tightly, but still couldn't stop the strong stench. Every year in July and August, this taste is so familiar.
41-year-old Xu Xiaogang lives in Tangxi Village on the shore of Chaohu Lake. He is a native of Chaohu Lake. Since he can remember, there have been cyanobacteria in Chaohu. Every summer, this green algae will gather in large quantities and emit a foul smell under the sun.
In recent years, with the establishment of Binhu New District , Xu Xiaogang's life has also undergone great changes.
In 2015, in order to protect Chaohu Lake, Xu Xiaogang and the villagers of Tangxi Village moved to the relocation building 10 kilometers away from the lake. The former Tangxi Village has become a scenic lake-ring and a green park.
stores have moved, the shoreline has been rectified, and Chaohu has become beautiful, but the blue-green algae still attacks on time every year and cannot be dispersed. Xu Xiaogang heard that last year, the central environmental protection inspection pointed out that Chaohu pollution control was not effective. Over the past year, the occupied wetlands have been restored, the parking lot has been demolished, and the construction site has also been shut down...
"I invested so much money, and the central and local governments have also attached so much importance to it. Why can't a small blue algae be cured?" He was confused.
Xu Xiaogang is not the only one who is confused.
influence: "It smells so bad that I don't want to come to work"
Standing at the mouth of the river of Paihe into the lake, a foul stench hits my face, and the lake is covered with a thick layer of blue algae, thick as green paint. The whitening part above is the dead and rotten cyanobacteria, which is the main source of the odor.
"At the same time, the south wind, the cyanobacteria are blown to the north shore. The higher the temperature, the more cyanobacteria, the more stinky it is." Xu Xiaogang told reporters.
Since the beginning of summer this year, the situation of cyanobacteria blooms in Chaohu has been relatively serious. As of the end of July, cyanobacteria blooms have occurred in Chaohu 29 times. The maximum water bouquet area reaches 130 square kilometers, accounting for 17.1% of the Chaohu water area.
In recent days, the blue-green algae blooms have triggered large-scale irritating odors at least twice, which has had an impact on the lives of residents around Chaohu Lake.
Xinhua Daily Telegraph reporters visited along the coast, Zhang Haoyu, a citizen living in Binhu New District, said that he often went out for a walk in other seasons. In the end of June, the smell of blue-green algae was like garbage for a month, and it could be smoked and spit out for dinner. In late July, Yang Shan, a property consultant of a Binhu real estate project, complained on his circle of friends: "The recent air and circle of friends are filled with the smell of blue-green algae, which is so smelly that I don't want to come to work."
Paihe is one of the main rivers entering Chaohu Lake. The mouth of Paihe River is at the lower wind estuary, and a large number of blue-green algae are gathered here. The reporter took a boat to the Chaohu Lake area from the mouth of the Pai River into the lake. The engine blew green waves all the way, and you could see the salvage boat operating in Chaohu Lake.
salvage worker Meng Fanzhou said that salvage began in May in previous years, and the weather was hotter this year, and it started salvage on April 15th. In recent months, the high incidence of cyanobacteria has been achieved. Salvagers work from 7 a.m. to 7 p.m. every day. When the cyanobacteria outbreak is severe, the stench makes him almost suffocated.
Gao Binyou, director of the Hefei Lake Ambient Office, explained that there are three main unfavorable objective factors for frequent cyanobacteria blooms this year: First, the number of high temperatures is continuous. The number of high temperatures in July reaches 17 days, which is higher than in previous years; Second, the overall rainfall is small, and there are many typhoons in showers. Short-term heavy rainfall will stir up the bottom mud of the lake and promote the improvement of nutrients in the water; Third, the wind speed this year is generally less than the threshold of 3.1 meters per second, which facilitates the accumulation of cyanobacteria.
satellite monitoring data shows that the frequency of cyanobacteria blooms and the maximum bloom area in the lake area this year are higher than the same period last year. In the first half of this year, the total nitrogen concentration in Chaohu Lake was basically the same as the same period last year, with the total phosphorus concentration increasing by 7.32%, and the average density of algae in the lake increased by 78.1% compared with the same period last year.
consultation: "Pollution is in the water, roots are on the shore"
As one of the oldest species on the earth, cyanobacteria have a history of 3 billion years. They are called the ancestors of earth's plants and have extremely strong vitality.
Zhu Qing tends to compare cyanobacteria research with climate research: cyanobacteria exist much longer than humans. Research requires long-term data of more than 50 or 100 years. The reference value of 10 years of data is very limited, let alone fluctuations in one or two years.
As the director of Chaohu Research Institute, Zhu Qing has been dealing with Chaohu blue algae for more than 20 years.
"Because the meteorological conditions are different every year, it is not scientific year-on-year. Even if the cyanobacteria does not break out in a certain year and the data is very good, it may not be successful in the governance. It may be just God's help." Zhu Qing said.
"The transportation of grain and fertilizer is busy day and night, and the members pick up indigo by the lake." In the 1960s, the "lake indigo" sung in the Chaohu folk song " Chaohu Good " is today's blue-green algae. At that time, Chaohu Lake was sparsely populated around it, mainly agricultural planting, and farmers would fish out the blue algae from the lake for compost.
resident Zhang Zhengyin, a resident of Daxu Town, lived by Chaohu Lake all his life. He clearly remembered that when he was a child, there was no road from the town to Hefei, and he had to walk for a whole day. Now, there is a direct subway from the city center to the shore of Chaohu Lake.
This is also a true portrayal of Hefei's development concept of "Big Lake City". Since the 21st century, with the rapid development of Binhu New District, the impact of human activities on Chaohu Lake has gradually increased, and the intuitive impact of Chaohu blue-algae on people has become increasingly significant.
"The distance between citizens and Chaohu has brought the attention to the issue of cyanobacteria in recent years, but the research on cyanobacteria for a long time has been almost blank. The data is vague, which has caused considerable challenges to current governance." Zhu Qing said.
In fact, the mechanism of the outbreak of cyanobacteria remains a mystery to date. Zhu Qing told Xinhua Daily Telegraph reporter that the reasons can only be summarized from experience and rules, but these key questions cannot be explained how cyanobacteria absorb nitrogen and phosphorus nutrients, how algae seeds survive the winter, and why they broke out overnight.
In recent years, Chaohu Lake has experienced a high incidence of water boom, and a set of data highlights the urgency of governance: the largest water boom area in 2015 was 321.8 square kilometers, accounting for 42.2% of the total lake area, the highest in the past eight years; in 2016, the largest water boom area was 237.6 square kilometers, accounting for 31.2% of the total lake area.
"Pollution is in the water, the root is on the shore." Many environmental protection experts said that the current pollution discharge from Chaohu Lake into the lake has far exceeded the water environmental capacity.
Nan Fei River and Shiwuli River are in poor V category for many years, "contributing" most of the pollutants entering the lake. The western half of Chaohu Lake flowing into these two rivers is the hardest hit area for eutrophication and cyanobacteria flooding in Chaohu Lake. "Large amount of pollution entering the lake" was also one of the prominent problems discovered by the central environmental protection inspection last year.
However, it is extremely difficult to manage the Nanfei River and Shiwuli River. One of the important reasons is that these two rivers pass through the urban area of Hefei. The scale of basin construction has increased sharply and the population has grown rapidly. The pollution accumulated by human production and life has far exceeded the carrying capacity of the river itself, and it has also increased the difficulty of analyzing pollution sources.
Gao Binyou said that the management of any big river and lake in the world is a long process. Lake Biwa in Japan is recognized as a model for successful cyanobacteria control. It has been 30 years since then, but it has not been able to completely curb the outbreak of cyanobacteria; the cyanobacteria control in Taihu and Dianchi Lake started earlier and invested more than Chaohu, and is still troubled by cyanobacteria.
"Chaohu is indeed sick now. The disease comes like a mountain falling, and the disease goes like a thread pulling out." Gao Binyou said.
rectification: Promoting at a high level, but there are still slow progress in projects
At the end of April last year, the Fourth Central Environmental Protection Inspection Team entered Anhui to carry out a one-month inspection work. In July of the same year, the inspection team pointed out in feedback that a large number of commercial real estate projects were illegally approved along Chaohu. After the promulgation of the Chaohu River Basin Water Pollution Prevention and Control Regulations, the relevant requirements of the regulations were not fully implemented, and a large number of illegal development and construction still existed. In addition, the inspection team also announced three major issues: destroying the lakeside wetlands, illegally occupying the lake surface, and large amount of pollution entering the lake.
In fact, with the development of cities, "competing for land with lakes" has led to the gradual disappearance of wetlands around the lake, which is also an important reason for aggravating the ecological deterioration of Chaohu Lake.
Kuang Wu, director of the Institute of Water Environment of Anhui Academy of Environmental Sciences, believes that "If Chaohu Lake is compared to humans, shallow wetlands are kidneys for lakes. Now that kidney failure is now, historical debts are formed, it will not take place overnight to recover."
Over the past year, Hefei City has adopted methods such as fighting on the map and dynamic cancellation to clarify the rectification time limit one by one, and vigorously promote the rectification work.
Construction projects of the Chaohu River Basin First-level Protection Area strengthen daily supervision and inspection to ensure the suspension of production and work; hundreds of ships to be dismantled are gone, and nearly 100,000 square meters of occupied lake surfaces and beaches have been restored, and the plants and trees have been lush; tourism projects along the lake have been closed, and the 2,000 acres of encroached lake surfaces have been returned; parking lots have been demolished, birds have flies, grass has grown tall, and the wetland environment has been swallowed It is slowly recovering its vitality...
As of now, Hefei City has completed 41 rectification tasks in four categories based on feedback from the central environmental protection inspection. In addition to the problems required by the central environmental protection inspection, Hefei City has also taken the initiative to plan and build lake-circling wetlands with the protection of estuary and tidal flat wetlands in the lake.
Although the rectification has achieved certain results, some projects are still lagging behind the rectification time limit, and some key engineering projects are progressing slowly. For example, the water quality management of Shiwuli River that should be completed before the end of the year The goal is difficult to achieve, and some sewage treatment plants have lagged the planning time limits for projects such as standard renovation; 25 rainwater and sewage mixed flows into the lake that have not been treated by the sewage treatment plants should be completed by the end of this year as required, but it is difficult to complete on schedule.
There is still the project that has not achieved the expected results after the implementation of the project. For example, Xiaomiao sewage treatment plant in the Paihe Basin has been completed and put into operation for 2 years, but the chemical oxygen demand of water inlet is only about 50 mg per liter.
In early July, the Anhui Provincial Ecological Environment Protection Conference announced The progress of the rectification of feedback from the Central Environmental Protection Inspection Team. The notice stated that Hefei City failed to effectively control the high incidence of Chaohu Lake; the water quality of Shiwuli River is still in Class V; the transformation of rainwater and sewage in the Nanfei River Basin has been slow, and sewage in the basin has not been effectively collected and processed.
Relevant person in charge of the Anhui Provincial Environmental Protection Department said that the notice objectively reflects the current problems. Scientific governance requires respect for laws and requires a long process. However, in the context of the unprecedented height of ecological civilization, the people's requirements and expectations are greater than in the past. Improvement, which forces local governments to face up to the problem and speed up the governance progress.
governance: Magnetic fishing ships have become a "cyanobacterial salvage tool"
In 2011, the administrative divisions of Hefei and surrounding areas were adjusted, and Chaohu became the Neihu of Hefei City, which truly kicked off the Chaohu Lake governance.
In Zhu Qing's view, "Entering the Lake into the City" changed the embarrassment of Chaohu Lake's "nine dragons governing the water" in the previous Chaohu Lake, effectively strengthened organizational leadership guarantees, and the top-level design of basin-based restoration of the entire lake It was implemented and achieved tangible results.
is to effectively control pollution, and on the basis of the launch of the comprehensive water environment management project in Chaohu River Basin, Hefei City has implemented the first to fourth phases of ecological protection and restoration around Chaohu Lake. At present, more than 18 billion yuan has been invested, and various technologies and funds have gathered to control pollution in Chaohu Lake.
The largest algae water separation station along Chaohu Lake has implemented mechanized cyanobacteria salvage, and the operation 24 hours a day still cannot meet the salvage needs. In the waters between Chaohu and Pai River, a large white ship is slowly moving forward. In, wherever you go, the thick green algae water was sucked into the hull from the bow of the ship, and the clear lake water flowed back into Chaohu Lake from the stern of the ship. This is the new "cyanobacteria salvage artifact" magnetic trap that was just put into use this year.
Xinhua Daily Telegraph reporter saw on the ship that eight pushing pumps at the bow of the ship pushed the algae water into the treatment tank, and the floating cyanobacteria condensed into large pieces of flocs here. Then, the cyanobacteria flocs with iron powder added were adsorbed in the cracks of the disk, and turned into algae mud after being pressed and filtered, collected and bagged, transported to the fertilizer factory for use as phosphorus fertilizer.
Magnetic Li Yiming, the head of the ship hunting R&D company, introduced that magnetic fishing ships are more flexible and mobile than algae water separation ports, and are a mobile operation platform that operates all-weather and all-water areas.
As of the end of July, Hefei City salvaged a total of 750,000 tons of algae slurry and produced 24,000 tons of algae slurry. The amount of algae slurry salvaged and the amount of algae slurry increased by 65% and 159% respectively compared with the same period last year. Among them, the salvaged volume of magnetic fishing ships accounted for half.
magnetic fishing ships are just a microcosm of the key projects and technical reserves of Chaohu Lake management in Hefei in recent years.
Beijing-Taiwan Expressway Early Rainwater Storage Project intercepts and treatment of initial rainwater and drought sewage within the Economic and Technological Development Zone of the Shiwuli River Basin, which can reduce the pollution load of the basin by 8%; Lake Cyanobacteria Emergency Technology Innovation Center combines monitoring technologies such as satellites, drones, and robots to form an integrated monitoring network of air-ground...
In terms of controlling pollution, Chaohu Lake has achieved remarkable results. Data shows that Chaohu's chemical oxygen demand and ammonia nitrogen emissions were 132,000 tons and 11,400 tons respectively at the end of the 12th Five-Year Plan, down 13.5% and 19.4% respectively compared with the early stages of the 12th Five-Year Plan. During this period, the total economic output of Chaohu River Basin increased by 53%. Currently, the total monthly industrial output value of Hefei is equivalent to the total annual output in 2005.
Zhang Bo, Director of the Water Environment Management Department of the Ministry of Ecology and Environment, believes that in the context of rapid economic and social development in the basin, the water pollution in Chaohu Lake has not aggravated and has gradually improved. As a developing region, this is commendable.
"The phased achievements of Chaohu Lake governance have been reflected, but the governance of big rivers and lakes is not a one-day achievement, and there is no need to slack off." Zhu Qing said that in the future, the Chaohu Lake basin will still be in a period of accelerated industrialization and urbanization. Urban population is rapidly gathering, and the pollution emission load will still operate at a high level. The pressure on pollution increase is very huge.
Gao Binyou said that there have been a lot of technical reserves and attempts to explore, but Chaohu is still an algae-type lake after all, and it still takes a long process to convert it into a grass-type lake.
Ask for advice: Eliminate blind spots and keep the ecological red line
More than Chaohu Lake management experts believe that governing Chaohu Lake is a tough battle and a protracted battle. There is no shortcut to lightness and generalization. Only comprehensive measures can be implemented and long-term efforts.
"Chaohu pollution treatment must be treated with both symptoms and root causes, walk with two legs, and use symptoms as the root cause to win time. To implement root causes, the most urgent task is to eliminate blind spots as soon as possible in order to make precise efforts." Gao Binyou said.
Internationally, the first step in the governance of rivers and lakes is to investigate, monitor and analyze pollution sources. Only in this way can we clarify "where to reduce, how much to reduce, when to reduce, and how to reduce". According to data, when the British control the Mersey River, it took five years to analyze the pollution source alone.
Professor Yuan Zengwei of the Department of Environment of Nanjing University led his team to conduct a two-year analysis of pollution sources in the Chaohu River Basin. However, due to the rapid development of cities and population, quantitative and incremental research are complicated and are still under study.
In addition to the analysis of pollution sources, mixed rain and sewage flow is also a blind spot problem that needs to be solved in the treatment of Chaohu ecology. "This year, a batch of sewage outlets that had never been found before were found in Nanfei River. The detection robot was almost lost and failed to successfully track the source." Zhu Qing told Xinhua Daily Telegraph reporter helplessly that the urban pipeline network was not divided into rain and sewage, and there were too many debts for misconnection, misconnection, blockage, and damage to the pipeline network.
Not only that, a survey by the environmental protection department showed that the initial rainwater COD (chemical oxygen demand) collected by the Hefei Municipal Pipe Network is as high as 800 to 1,000 mg per liter, which is more than 10 times the sewage discharge standard. These sewage from large stalls and car washes flow directly to Chaohu through the rainwater pipeline, which often becomes a blind spot for supervision and governance.
Gao Binyou said that it is necessary to strengthen scientific research on the mechanism of cyanobacteria and industrial exploration of resource recycling. These are two key issues at the front and end of comprehensive management of cyanobacteria. In addition, we must scientifically analyze the ecological environment capacity of Chaohu, insist on determining the city with water, and establish the upper line of resource utilization, ecological protection red line, and environmental quality bottom line.
Shi Xiaoli of Nanjing Institute of Geography and Lakes, Chinese Academy of Sciences said that it is necessary to build an automatic monitoring system for Chaohu River Basin and lake bodies, objectively evaluate the effectiveness of the governance project, promptly discover problems and make scientific decisions, and at the same time, build a blue-green algae bloom prediction and early warning system.
The "Main Plan for Green Development of Chaohu Comprehensive Governance" that is being compiled by Hefei City has initially established the phased goals of Chaohu governance and protection: by 2022, the ecological environment will improve, the water circulation will be healthy, and the goal of "healthy Chaohu" will be basically achieved; by 2035, Chaohu comprehensive governance will achieve a fundamental victory.
Zhu Qing said that when the Yangtze River and Huaihei Project is completed in 2022, the Yangtze River and Chaohu will be connected again, and the river and lake water exchange will greatly improve the water quality purification capacity of Chaohu Lake, and the comprehensive management of Chaohu Lake is expected to usher in a turning point. (Reporters Yang Dingmiao, Wang Haiyue)
