Abstract:

 Distributions of various inorganic nitrogenous species in the seawater of the Dapeng Bay are analyzed based on the
data obtained from 106 cruises by the Environmental Protection Department of the Government of Hongkong Special Admin-
istrative Region from 1999 to 2007 and 10 cruises by the South China Sea Sub-administration of the State Oceanic Admini-
stration from 1998 to 2007. The results show that ammonia nitrogen contents were higher in the western Tolo Harbour and the
Sha Tau Kok Sea than in the other areas in the Dapeng Bay, due to the impact of continental discharges into the coastal zones
from Hongkong and Shenzhen. The average percentage contents of various components of dissolved inorganic nitrogen (DIN)
were in the order of ammonia nitrogen > nitrate > nitrite, and the multi-year average contents of ammonia nitrogen, nitrate, and
nitrite were 0.041, 0.019, and 0.007mg·L−1
, respectively, in the whole layer of seawater in Hongkong zone of the Dapeng Bay.
In summer, the content of nitrate was much higher in the bottom water than that of the surface water due to intrusion of high
salinity water from the open sea. The inter-annual variation trends of the cruise-average content of ammonia nitrogen de-
creased, and the nitrate and nitrite kept steady during the nine years.

Key words: Dapeng Bay, seawater, various inorganic nitrogenous species