Summer job

Every summer vacation he sets aside six days to explore other rivers around China. The trip takes two weeks to prepare for. On average, he spends six hours a day on the water and packs food supplies of compressed biscuits, ham and bottled water. An empty water bottle doubles as a toilet.

Zhou says he always hopes to find a suitable bank to camp on but sometimes has to float through the night.

In 2012 in Luzhou, a port city on the Yangtze River, Sichuan province, he drifted all night but ran into trouble when a drop in temperature caused a fall in the canoe's air pressure. "It was so cold that night that the air in my canoe shrank and it almost sank. Fortunately, I found a place to land," he said.

Another problem on the river was the dams villagers had built to control water levels for farming purposes, which created eddies and erratic currents. "I didn't notice them and was washed into the water while avoiding a boat coming from the opposite direction," Zhou said. "It was a swift current and not easy to float to a river bank even in a life jacket. I floated downstream and managed to make land."

Despite the occasional dangers, Zhou said his environmental guardianship work gave him great pleasure.

When he was a child, he lived near the Liuyang River which then had a Grade II ranking, the second-highest level in China's five-tier water quality system. He grew up drinking the water and swimming and fishing in the river.

"After I went to university, the water quality went down to Grade V due to the discharge of sewage and industrial waste from factories," he said.

"I really couldn't stand seeing the pollution continuing anymore. So I set out to find the source and explored 235 kilometers of the waterway. I then understood the basic situation of the river."