大亚湾沉积物中可溶性有机氮与蛋白酶和脲酶活性特征及其影响因素

Characteristics of dissolved organic nitrogen and key enzyme activities in the surface sediment of Daya bay and its influencing factors

  • 摘要: 为认知海湾沉积物有机氮转化机制及其对富营养化的影响,本文探讨了大亚湾表层沉积物可溶性有机氮(DON)、游离氨基酸(DFAA)含量及其关键酶活性的特征。结果表明,沉积物DON平均含量为50.56×10-6,分别占沉积物可溶性总氮(TDN)和总氮(TN)的64.52%和3.58%,DON是TDN的重要组成部分;DFAA平均含量为8.48×10-6,占DON的20.34%,表明大亚湾沉积物DON有较多易分解组分。DON和DFAA含量均与沉积物TN、总磷(TP)、有机质的含量密切相关,呈现出湾沿岸和海水养殖区较高,而湾中区域较低的分布趋势。蛋白酶和脲酶平均活性分别为61.64 mg/kg/d和86.12 mg/kg/d,蛋白酶主要与DFAA密切相关,而脲酶与DON、DFAA均密切相关,脲酶活性大小可以反映沉积物有机氮引起二次污染的风险程度。

     

    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.

     

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