Environmental workers inspect pollution inside karst caves. (Photo/Zheng Yu)

Chongqing - Recently, Chongqing has launched a special investigation and cleanup of garbage and solid waste pollution in karst caves. The city tackles the issue through comprehensive inspections, digital monitoring, and pollution source management.

Karst caves are underground spaces formed by the dissolution and erosion of soluble carbonate rocks such as limestone, and they are a typical natural feature of the region. Statistics show that karst landscapes cover about 36% of Chongqing’s territory. These underground spaces maintain regional ecological balance and serve as an important ecological safety barrier.

Due to their unique geological conditions, caves in areas with weak infrastructure have long served as “hidden” dumping sites for household and industrial waste. Pollution in these caves can damage the internal ecosystem and contaminate groundwater, threatening residents’ drinking water and the wider environment.

To assess the situation, the Chongqing Municipal Ecology and Environment Bureau formed three professional inspection teams. “We use drones, underground robots, and other specialized equipment to conduct full inspections of key caves,” said Zhan Zhong, Deputy Director of the Bureau’s Solid Waste Division.

Meanwhile, districts and counties have mobilized village officials, grid workers, forest rangers, and NGOs for comprehensive inspections, while collecting tips from the public via WeChat, Douyin, and other social media platforms. So far, more than 7,000 caves have been inspected citywide, with 942 found to be polluted.

Building on the inspections, Chongqing uses digital technology to monitor the situations of pollution. For example, Heba Mouth sinkhole in Miaoyu Town, Wushan, had been polluted by nearby livestock. Local authorities implemented digital management through the county-level smart governance platform, achieving 24-hour AI alerts and visual supervision.

Currently, all cave-related digital data has been integrated into Chongqing’s ecological risk control and grassroots smart governance platforms, establishing regular maintenance and rapid response mechanisms.

Moreover, managing cave pollution is challenging, and source-level monitoring and treatment are more effective.

Zhan noted, most cave waste removal involves high-altitude work requiring specialized personnel. The narrow spaces make mechanical operations nearly impossible, and manual cleaning carries a risk of collapse. Stagnant air inside the caves can generate harmful gases like ammonia and hydrogen sulfide from old waste, posing high safety risks.

In response, Chongqing takes a proactive approach, focusing on monitoring pollution sources such as farms, residential areas, industrial sites, and agricultural zones within 1 kilometer of caves. The Bureau, together with relevant departments, strengthens rural solid waste management, optimizing farm layouts, and ensuring proper disposal of animal waste.

To date, the city has cleaned 750 polluted caves. Zhan said Chongqing aims to largely complete the cleanup of cave waste and solid waste pollution by August 2026, with the remaining difficult cases finished by the end of the year.