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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。
In order to understand the mechanism of organic nitrogen transformation in sediment and its impact on eutrophication, the characteristics of soluble organic nitrogen (DON), free amino acids (DFAA) and their key enzyme activities in the surface sediments of the Daya Bay were studied. The results showed that the average content of DON was 50.56 × 10-6, which accounted for 64.52% and 3.58% of total dissolved nitrogen (TNN) and total nitrogen (TN), respectively, and DON was an important component of TDN. The average content of DFAA was 8.48 × 10-6, accounting for 20.34% of DON, indicating that there is more readily decomposed DON in Daya Bay sediments. The content of DON and DFAA are closely related to the contents of TN, TP, and organic matter in the sediments, showing a higher distribution in the littoral and mariculture areas and a lower distribution in the middle of the bay. The average activities of protease and urease were 61.64 mg / kg / d and 86.12 mg / kg / d, respectively. The protease was mainly related to DFAA, while the urease was closely related to DON and DFAA. The activity of urease could reflect the secondary The degree of risk of contamination.