珠江口柱状沉积物中氮的形态分布特征及来源探讨

对珠江口4个柱状沉积物中的氮进行测定,研究了氮的存在形态、含量及垂向分布特征,探讨了沉积物中有机质的来源和输入途径.结果表明:TN含量的变化范围为850.62～2 340.85mg/kg,平均值 1 502.73mg/kg.垂直分布表现为底层向表层逐渐增加的总趋势,且两端含量变化较缓、中间较大.有机氮含量的变化范围为655.42～2 029.86mg/kg,平均值 1 187.86mg/kg.垂直分布表现为2种分布类型:随深度减小型和两端含量高、中间低型.无机氮中铵氮含量较高,变化范围47.59～739.61mg/kg,平均值为271.69mg/kg.铵氮在沉积物中的含量随深度而增加.TOC/TN比值在5至17之间,明显反映出有机质是陆源和水生2种来源的混合输入.总氮和有机氮的沉积过程有明显的同步效应,而和铵氮之间的同步相关性较小,并且因站位不同差异很大.

Distribution Characteristics of Nitrogen and Its Source in Core Sediments from Pearl River Estuary

Based on the measurement of the concentration of nitrogen in four core sediments from Pear River Estuary,the forms and the depth-dependent changes characteristics of nitrogen were studied,and the possible sources of nitrogen in the sediments were discussed. The results indicate that the content of total nitrogen ranged from 850.62mg/kg to 2 340.85mg/kg,with mean content of 1 502.73mg/kg. There is a general tendency for an upward increase in core sediments,which is more evident in the middle than in two ends. Organic nitrogen had a range of content from 655.42mg/kg to 2 029.86mg/kg,with mean content of 1 187.86mg/kg. And the content of organic nitrogen decreases gradually with the increase of depth or lower in the middle than in two ends. The content of NH₄-N was relatively high,ranging from 47.59mg/kg to 739.61mg/kg,with mean content of 271.69mg/kg,and increases obviously with the increase of depth.The TOC/TN ratios were most between 5 and 17,which show organic matter is the mixture of aquatic and terrestrial sources. The total nitrogen has distinct synchronization phenomenon with the organic nitrogen in sedimentation course,but has little relativity with the NH₄-N. There is large difference of synchronization phenomenon between total nitrogen and NH_4-N at different sites.