China Daily | Updated: 2023-05-20 09:40

Researchers collect samples along the Yangtze River section in Chibi, Hubei province, to conduct biological assessment of the water quality and monitor aquatic life. [Photo/Xinhua]

In a research vessel laboratory, scientists are busy analyzing samples taken from the Yangtze River.

They are conducting the second annual spring health assessment program of China's longest waterway, organized by the Ministry of Ecology and Environment, which started in April.

Within two months, seven groups of researchers and scientists were allocated to take and analyze samples from 331 designated sites of the river's primary course, its major tributaries and lakes linked to the river to quantitatively describe the Yangtze's ecology and biotic condition.

As of May 9, 199 designated sites had finished sample collection, about 83 percent of the total sites, according to Hu Sheng, from the research team.

Xiong Shaokai prepares to board another boat to a sampling site. [Photo/Xinhua]

"Compared to last year's work, algae are included as bioindicators for organic pollution," Hu says, adding that periphytic algae are investigated in rivers and streams, while planktonic algae are collected in lakes.

Besides algae, chemical and physical parameters are also measured. With these results, scientists can conduct "a comprehensive physical examination" on the river, according to Zhang Jing, who is in charge of the sample collection team.

Examining benthic invertebrates (backboneless species that inhabit the bottom of bodies of water) needs the use of silt samplers, because rapid water flow washes sediment away.

A research boat with monitoring devices. [Photo/Xinhua]

After obtaining the samples, researchers separate aquatic life, such as algae and benthic invertebrates, from water or mud. For 25-year-old Xiong Shaokai, it is a task that needs patience and care.

"Inside a mud sample, there is a microworld and benthic invertebrate communities are an important indicator in water health assessment," Xiong says.

The benthic invertebrate community is sensitive to disturbance and is a valuable indicator of the overall health of estuarine ecosystems.

Stretching more than 6,300 kilometers, the Yangtze is a deeply significant waterway in the history, culture and development of the Chinese nation and the central government has intensified efforts to protect the river environment.

Adopted in late 2020, the Yangtze River Protection Law went into effect in March 2021.

Researchers separate and analyze aquatic life-forms from a river sample. They provide a clear indication of the biological health of the river and its environs. [Photo/Xinhua]

Measures were also rolled out to ramp up the treatment of wastewater in industrial parks along the river, as well as to enhance the management of tailings ponds (mixtures of water, sand, clay and residual bitumen left over from the process of separating oil from sand and clay) in mines and the phosphorus sector. To preserve Yangtze biodiversity, China started a 10-year fishing moratorium along the river, protecting more than 4,300 types of aquatic life.

According to the latest statistics from the Ministry of Ecology and Environment, the water quality of the river's primary course has remained Grade II since 2020.

Under the country's six-tier quality system for surface water, Grade III and above is classified as "fairly good".

A speedboat takes researchers to a designated sample site. [Photo/Xinhua]

Monitoring water quality and the speed of the river flow in Wuhan, Hubei province. [Photo/Xinhua]

Along the banks of the river's section in Chibi, researchers scoop up samples of benthic invertebrates. [Photo/Xinhua]