Aerial photo taken on Oct. 9, 2019 shows the Lubei salt mine in Wudi County, east China's Shandong Province. Lubei salt mine has entered the harvest season recently. With 36,500 hectares of salt fields, Wudi County is one of the most important sea salt production bases in China. (Xinhua)

Aerial photo taken on Oct. 9, 2019 shows workers collecting salt at the Lubei salt mine in Wudi County, east China's Shandong Province. Lubei salt mine has entered the harvest season recently. With 36,500 hectares of salt fields, Wudi County is one of the most important sea salt production bases in China. (Xinhua)

Aerial photo taken on Oct. 9, 2019 shows the Lubei salt mine in Wudi County, east China's Shandong Province. Lubei salt mine has entered the harvest season recently. With 36,500 hectares of salt fields, Wudi County is one of the most important sea salt production bases in China. (Xinhua)

Aerial photo taken on Oct. 9, 2019 shows workers collecting salt at the Lubei salt mine in Wudi County, east China's Shandong Province. Lubei salt mine has entered the harvest season recently. With 36,500 hectares of salt fields, Wudi County is one of the most important sea salt production bases in China. (Xinhua)

Aerial photo taken on Oct. 9, 2019 shows workers collecting salt at the Lubei salt mine in Wudi County, east China's Shandong Province. Lubei salt mine has entered the harvest season recently. With 36,500 hectares of salt fields, Wudi County is one of the most important sea salt production bases in China. (Xinhua)

Aerial photo taken on Oct. 9, 2019 shows workers collecting salt at the Lubei salt mine in Wudi County, east China's Shandong Province. Lubei salt mine has entered the harvest season recently. With 36,500 hectares of salt fields, Wudi County is one of the most important sea salt production bases in China. (Xinhua)

Aerial photo taken on Oct. 9, 2019 shows the Lubei salt mine in Wudi County, east China's Shandong Province. Lubei salt mine has entered the harvest season recently. With 36,500 hectares of salt fields, Wudi County is one of the most important sea salt production bases in China. (Xinhua)