Abstract:
To understand the transformation mechanism of sediment organic nitrogen and its impact on the eutrophication of the Bay, the characteristics of spatial distribution of dissolved organic nitrogen (DON), dissolved free amino acids (DFAA) and key enzyme activities were studied in the surface sediment of Daya bay.The results showed the average content of DON in Daya bay sediment was 50.56×10
-6, and the proportion of DON to total dissolved nitrogen (TDN) and total nitrogen (TN) were 64.52% and 3.58%, respectively, indicating that DON was a major component of TDN.The average concentration of DFAA was 8.48×10
-6, and the proportion of DFAA to DON was 20.34%, suggesting that considerable amount of DON in the Daya bay sediment was labile organic compounds.DON and DFAA were significantly related (
p < 0.01) with the total nitrogen, total phosphorus, organic matter in the sediment, and their high values were observed along the bay coast and in cage farming zones, while low values were found in central region.The protease, urease activity were 61.64 mg/kg/d and 86.12 mg/kg/d, respectively.Protease activity was closely related to the DFAA, while urease activity was closely related to DON and DFAA.Our results also suggested, that the urease activity could reflect the degree of secondary pollution caused by organic nitrogen release in sediment.