长江口海域悬浮颗粒有机物的稳定氮同位素分布及其生物地球化学意义

Distribution in the stable nitrogen isotope of the suspended particulate organic matter in the Yangtze River(Changjiang) estuary,China and its biogeochemistry implications

对2006年2，5，8，11月份长江口海域表层水体中的悬浮颗粒物（SPM）进行稳定氮同位素分析，根据不同季节、不同区域内其伊。N值的变化研究水体中氮的迁移、转化等生物地球化学过程，揭示其环境行为，从而对该海域的氮循环机制进行探索。研究发现：该海域悬浮颗粒有机物的稳定氮同位素组成（δ^15Np）分布范围较宽，在0．6‰～8．2‰之间，具有明显的时空分布特点，反映了不同程度的陆源输入和氮的生物地球化学过程的影响。口门内，表层水体中δ^15Np的变化主要受长江径流的陆源输入影响，生物地球化学作用影响较弱；最大浑浊带，水体中的悬浮颗粒有机氮受微生物的降解活动影响明显，各季节均存在不同程度的颗粒物分解作用；外海区，陆源输入减弱，悬浮颗粒物的伊。Np值主要受微藻的同化吸收作用以及一定程度的颗粒物分解作用影响。

In this paper, δ^15N of suspended particulate matters （SPM） in surface water was studied during four seasons of 2006 in the Yangtze River estuary. Based on the variations of δ^15N in different seasons and geographical regions, the biogeochemical processing of nitrogen transformation was studied and its environ- mental implications were also revealed. In this paper, the mechanism of nitrogen cycle was explored in the Yangtze River estuary. The results show that δ^15N of SPM was in a wide range of 0. 6‰ and 8. 2‰, varying with seasons and geographic regions. The temporal and spatial variation reflected different influences of terrigenous inputs and nitrogen biogeoehemical processing. In the inner estuary, δ^15 N was affected mainly by riverine inputs from the Yangtze River. In the turbidity maximum zone, SPOM was affected by microbial degradation obviously, indicating the control of the decomposition processing of SPOM in δ^15N during four seasons. In the adjacent marine area, the influence of terrigenous inputs weakened and δ^15N was controlled by inorganic nitrogen assimilation by phytoplankton and the decomposition of SPOM.