300 ton-class environmental research ship

300-ton class environmental research ship is a class of naval auxiliary ship currently in service with the People's Liberation Army Navy (PLAN). The exact type of this class remain unknown as of 2015, because no official information has been released, despite the ships have already been in service around a decade. 300-ton class is the most commonly referred term when describe these ships In addition to the usual task of conducting regular environmental sampling, surveillance and research missions, these ships are also tasked with additional task of sewer transfer and treatment from other ships to prevent sewer onboard other ships from overflowing into the sea and thus causing pollution, and thus these ships also act as sewer vessels for vessel sewage discharging.

300-ton class environmental research ships in PLAN service are designated by a combination of two Chinese characters followed by two-digit number. The second Chinese character is Jiu (监), meaning surveillance in Chinese, because the primary duties these ships are tasked. The first Chinese character denotes which fleet the ship is service with, with East (Dong, 东) for East Sea Fleet (ESF), North (Bei, 北) for North Sea Fleet (NSF), and South (Nan, 南) for South Sea Fleet (SSF). However, the pennant numbers may have changed due to the change of Chinese naval ships naming convention.