State Oceanic Administration announced Thursday that nearly 147,000 square kilometers of China's sea was below the clean water standard in 2009, up 7.3 percent from the previous year.

The country's marine environment, particularly the coastal waters in Liaodong Bay, Bohai Bay, Hangzhou Bay, the mouths of the Yangtze River and Pearl River, was not good, according to the Administration's bulletin.

The offshore eco-systems have kept deteriorating because of environment pollution, habitat loss, biological invasion and low bio-diversity, and around 76 percent out of 21 offshore eco-systems under monitoring were reported "sub-healthy" or unhealthy in 2009, it said.

The data also showed 73.7 percent of 457 sewage outlets went over their pollutant discharge limits, with those in Zhejiang, Jiangsu and Guangxi the worst.

Also, the total pollutants carried into sea by rivers increased considerably in 2009 compared to the previous year, it said.