A recent trend involving the online sale of water from a lake at a top university at the conclusion of China's national college entrance exam, or?gaokao, has stirred up controversy.

Listings for water and soil allegedly sourced from Peking University, one of the country's most prestigious universities, have surfaced on Xianyu, an online marketplace for secondhand goods.

"Lake water from Weiming Lake at Peking University sells for 99 RMB ($13.80) per 500ml," read one listing, while another offered "soil from the university campus" for 129 yuan for 900 grams. These items were marketed as unique campus souvenirs by sellers claiming to be students at the university.

One seller touted the benefits of the lake water, claiming it has "magical effects on plant growth".

"Keeping a bottle of Weiming Lake water at home can help regulate air humidity," they said. "Gazing at the water daily can boost morale, enhance intelligence and significantly increase emotional intelligence."

A seller told China Youth Daily that there are "quite a few" buyers for these unconventional products. "People buy the water hoping for success in their?gaokao?exams, while those purchasing the soil are usually planning to build new homes," the seller said.

On Tuesday, a staff member of Peking University's security department told Beijing News that selling water from the Weiming Lake is strictly prohibited. The university will reach out to the sellers to have the listings removed. It has also urged the public to report any such activity.

By Thursday, searches for these products on the platform came up empty.

Zhu Wei, an associate professor at China University of Political Science and Law, told China Youth Daily that the sellers are capitalizing on people's anxieties about academic achievement.

Besides, the claims that the lake water can enhance intelligence are misleading, similar to previous controversies over selling "bank soil" for attracting wealth, Zhu said.