On October 29, Huizhou West Lake Scenic Scenic Spot was officially awarded the title of National 5A Scenic Spot, and became the second 5A Scenic Spot in Huizhou after the Luofu Mountain Scenic Spot.

Qi Dongsheng. Photo by Wang Changhui, reporter of Southern Daily

From the West Lake East Station of the Guanhui City Train, walk along the shore of Fenghu Lake, Lipu style, Lipu Pavilion, Zhongyuan Pavilion... Every step is the scenery, especially the lake water is clear, fish swimming with bait, birds slithering, and the water plants floating at the bottom of the lake are clearly visible.

On October 29, Huizhou West Lake Scenic Scenic Spot was officially awarded the title of National 5A Scenic Spot, and became the second 5A Scenic Spot in Huizhou after the Luofu Mountain Scenic Spot. Among them, the water quality of West Lake has improved year by year, the gradual restoration of water ecology and the steady improvement of the surrounding environment have made an indelible contribution.

In the third-floor living room of a small building not far from West Lake, Qi Dongsheng, general manager of Guangdong Qianqiu Weiye Environmental Service Co., Ltd. and director of Huizhou West Lake Ecological Restoration Research Institute, told reporters about his and his team's experience in participating in the water environment improvement of West Lake for more than ten years, and their efforts have been made to promote the "water to become clearer" in the entire Huizhou West Lake area.

●Southern Daily reporter Wang Biao

spent more than ten years to create a city natural oxygen bar

According to Qi Dongsheng's understanding, the ecological restoration of the water quality of Huizhou West Lake is to treat West Lake as a living body. By cleaning sludge, planting aquatic plants, stocking benthic animals and fish, biological cultivation and maintenance, the problem of water body eutrophication is solved, so as to achieve the effect of clear water and beautiful lakes.

"This technology is to rebuild a complete ecological chain and restore the self-purification ability of the water body." Qi Dongsheng introduced that aquatic plants are "natural purifiers" that can absorb and purify pollutants in the water body, prevent silt from sludge at the bottom of the lake, inhibit algae growth, and significantly improve the transparency of the lake water and the ornamental value of the lake. At the same time, through the regulation of West Lake fish, we will reduce the agitation of sediments and release of nutrients by fish activities, and build an underwater ecosystem with self-purification function to achieve the effect of ecological restoration.

West Lake reappears the scene of "clear water and green banks, fish swimming in shallow bottoms" for more than ten years.

The old neighbors living around West Lake clearly remember that more than ten years ago, the water quality of West Lake was very poor, and the water body was green and smelly, which basically belonged to eutrophication .

In 2004, the environmental protection department of Huizhou City took the lead in organizing domestic and foreign experts to "take the pulse consultation" for West Lake. According to the experience accumulated in research on various lakes at home and abroad, Dr. Liu Zhengwen, an international lake science expert, recommended the "pure traditional Chinese medicine" method for ecological restoration. He selected a water area of ​​nearly 11,000 square meters in front of Yuanmiaoguan and next to the West Lake Hotel as a demonstration area. The fish community structure regulation, benthic animal stockings, shore zone transformation projects, submerged plants project and adjustment and maintenance will be completed within one year. This practice was later called "full ecological self-purification water body construction system" by Qi Dongsheng. It is a leading position in the country's similar technologies. In just a few months, the water body can change from turbid and odor to clear and from inferior V water to Class III water that can be directly contacted by the skin.

The government has carried out two comprehensive dredgings in Nanhu near Huizhou No. 1 Middle School, but the effect is not good. After the "pure traditional Chinese medicine" method, the lake water of more than 200 acres became clear, and many surrounding residents were also very happy. The specially grown high-quality aquatic plants are equivalent to the underwater grassland of West Lake. The oxygen generated can not only meet the needs of fish, but the negative oxygen ion content on the lake is significantly higher than that of other areas, which is equivalent to the recovery of a natural oxygen bar in a few hundred acres in the city center.

Another difficulty in the process of West Lake water environment improvement is to break the misunderstanding of traditional water control. The first is to divert water to rinse the stagnant water into living water, which is theoretically valid, but because it does not fundamentally change the self-purification function of the water body, the water pollutants have only transferred from the urban area to the rivers, which has become a greater harm; the second is the water control "artifact" with various means of savannah drugs and microorganisms. In fact, many of these technologies have not yet left the laboratory, and there is not even a case of successful practice.

Nanfeng Lake is close to the old city and sewage flows in from time to time. The water quality is the worst in the West Lake waters. In addition, the water depth is 3.6 meters (the depth of flat lake is about 2 meters), making ecological restoration of water bodies more difficult.

"If you want to chew, you have to chew the 'hard bones'."Qi Dongsheng said. On December 12, 2015, the Nanfeng Lake ecological restoration project just started, and snowflakes actually floated in Huizhou, located in the south. The temperature drop, coupled with the snowfall, not only makes construction more difficult, but also affects the cultivation of aquatic plants. In order to basically complete the restoration on time before the Spring Festival, the workers worked in the snow and fought for more than 20 days in a row, completed aquatic plants planting in advance, and restored the water level to about 1 meter to promote aquatic plants growth. On the eve of the Spring Festival, the effect of the ecological restoration project in Nanfeng Lake began to appear, and the lake water became significantly clearer.

domesticated submerged plants and cleared Fushou Snail

every winter encounters a sudden change in temperature. A large number of tilapia in the West Lake die. The garden department staff and many residents around the West Lake go to salvage dead fish. Many dead fish that were not caught rotted and cause greater pollution to the water body.

In Qi Dongsheng's view, this is caused by the unreasonable underwater biome of West Lake. "The introduced fish species must conform to the local climate and hydrological environment of Huizhou, contribute to a benign ecological structure, and fish species must also be properly allocated. "Qi Dongsheng said that from planting aquatic plants to selectively stocking snail shells and fish fry, it is all for restoring the biodiversity of West Lake. The lake itself should be treated as a living organism and rebuilding a healthy ecological chain in the water.

In recent years, they have solved the problem of eutrophication of water by cleaning sludge, planting aquatic plants, raising benthic animals and fish, and biological cultivation and maintenance, so as to achieve the effect of clear water and beautiful lakes. Among them, the common submerged plants planted in the lake include wheel leaf black algae, goldfish algae, foxtail algae, Malay osmanthus, bitter grass, etc. The roots of these plants are deeply rooted in the underwater soil. "We collect these plants from the wild and then domesticated to adapt to the ecological environment of the inner lake. "Qi Dongsheng said that after domestication, these submerged plants still adhere to a lot of microorganisms. "Submerged plants mainly absorb organic pollutants in the water. After adding microorganisms, they can improve their absorption and purification capabilities. "

submerged plants absorb organic matter and continue to grow. They have to be harvested once or twice a year. The other part of submerged plants can be used as food for fish in the water, so fish are also an important part of this ecosystem.

Qi Dongsheng told reporters that there are three alien species that have brought great negative impacts in the construction of healthy water ecology in the southern region. One is the tilapia with strong reproduction. The other two are the Fushou snails that destroy the aquatic grass environment and the water hyacinth that causes large-scale hypoxia to occur in the water body. Among them, Fushou snails are a major "opponent" they encountered when restoring the water ecological environment of West Lake.

March to November each year is the breeding season for Fushou snails. Fushou snails will lay eggs on the walls of ponds or stems and leaves of aquatic plants that are tens of centimeters away from the water surface. Second generation young snails can hatch in just ten days. Interestingly, although Fushou snails mainly live in shallow water, their eggs cannot hatch normally once they enter the water. Workers took advantage of this and found that the pink Fushou snail eggs were directly removed into the water, which could reduce their large-scale reproduction.

Running in the wind and rain is just for the environmental protection

Due to geographical and climate reasons, Huizhou is often hit by typhoons and rainstorms. As an inner lake in the city, West Lake needs to bear certain flood storage functions. However, the influx of urban water, coupled with the surface runoff with urban garbage, will greatly increase the water pollution load and cause interference and damage to the lake water ecosystem.

On May 16, 2014, Huizhou suffered the largest torrential rain in 50 years. The water surface of West Lake rose rapidly, and it has even risen to some road surfaces along the lake, causing debris on the road surface to flow into the lake, including The waters that have been restored. Qi Dongsheng, who is on a business trip outside the country, hurriedly arranged personnel to remove the garbage on the lake, strengthen drainage and restore the water level to normal as soon as possible, and then disinfect it with microorganisms. After the heavy rain, the lake water was turbid - it was difficult for aquatic plants to survive without sunlight. Can the water ecosystem that has completed the restoration withstand such a test? Although the professors and consultants hired by the team gave affirmative answers, many people were still worried due to the lack of relevant experience in China. What is gratifying is that in just one week, the lake water reappeared through self-repair.Experts said that before trials were conducted in Taihu Lake and other places, similar aquatic plants can tolerate harsh environments without sunlight for up to 21 days. "So I am full of confidence in the self-purification ability of this ecosystem!" Qi Dongsheng said proudly.

For more than ten years, Qi Dongsheng would walk around the West Lake whenever he has time. He often walks 8 kilometers to the office next to the West Lake on weekends, checking whether the water quality of the three lakes is normal along the way.

In order to promote the comprehensive improvement of the water environment in West Lake, Qi Dongsheng has worked tirelessly to coordinate all parties and submitted a self-recommendation letter to Huizhou City leaders many times, elaborating on the ins and outs of the improvement of the water quality of West Lake in detail. "I have always been engaged in environmental protection and like Huizhou very much. Through years of technological innovation and practice, we have the confidence and ability to turn the water of West Lake into clear water and restore the scene of the people's "clear water and green banks, fish swim in shallow bottoms". This is also the environmental protection sentiment I have been in the industry for many years!"

According to Qi Dongsheng, after the "water from Huizhou West Lake" became clear, the company left a water quality protection hotline by the lake. At present, several citizens or tourists call to share the joy brought by the clear water of West Lake.

Today, Qi Dongsheng’s environmental protection career in Huizhou is no longer limited to Huizhou West Lake.

Not long ago, the "Application Research and Industrialization of Eutrophied Lake Ecological Restoration Technology" project jointly applied by Huizhou Institute of Environmental Science and Guangdong Qianqiu Weiye Environmental Services Co., Ltd. won the second prize of the 2018 Guangdong Provincial Environmental Protection Science and Technology Award. Qi Dongsheng told reporters that they have applied the technical achievements accumulated in Huizhou West Lake to several water environment improvement projects such as beautiful rural construction. In August this year, the Ministry of Water Resources conducted an acceptance technical assessment of the pilot project of Huizhou's water ecological civilization city construction, and conducted a special inspection of the Boluo Songshugang Village water environment comprehensive management project and the Huizhou West Lake ecological restoration project that it created. The expert group gave a high evaluation.