The third and fourth quarters are normally peak seasons for Chinese ports. This year, though, the busy season started in the first quarter, suggesting the nation's robust economic recovery is continuing.

"We have been quite busy in the last two or three months," said Guan Hui, who is in charge of unloading at Qiangang Company, a unit of Qingdao Port Corporation, as he supervised the discharge of 240,000 tonnes of iron ores from a bulk carrier while, just offshore, another three iron ore-laden ships waited for their turn to unload.

The scene at the ports this year is different from last year when China's foreign trade slumped as the global economic recession dragged the country' s economic growth down to a decade low of 6.1 percent.

In the first quarter this year, Qingdao Port, China's biggest port for crude oil and iron ores, recorded year-on-year 8.1 percent growth in throughput in the first quarter with 84.79 million tonnes. Container throughput was up 8.9 percent to 2.72 million twenty-foot equivalent units.

That growth brought delight to Qingdao Qianwan Container Terminal, whose three docks are for foreign trade by container -- but the brisk business conditions have brought their own challenges.

"In the first quarter of last year, foreign trade was quite slack. Most of the throughput was empty containers from imports," company official Guan Qian said.

"The company took great pains to find room to place these containers with about 160,000 empty ones at dock at peak time last year while in total there was more than 700,000 in the whole year," Guan said.

During the first quarter of the year, total throughput at Qianwan dock exceeded 2.7 million twenty-foot equivalent units, up 10 percent from a year ago.

"The biggest change is that 96 percent of exported and imported containers are full of goods," Guan said.

"There are fewer empty ones and more full ones, meaning the recovery of import and export is real," Guan said, adding the company now faces a shortage of empty containers as out of the 100,000 containers at dock, the number of empty ones is now below 30,000.