东海水体中POC的分布特征

Distributive characteristics of POC in sea water in East China Sea

本文研究1994年春、秋季东海陆架海区水体POC的分布特征。0和10m层的水平分布图呈现：近岸海区水体的POC含量最高，并往外海递减，黑潮区域是POC的低值区。在离岸通的深水海区受长江径流影响削弱，POC分布比较均匀。秋季POC等值线呈现与岸平行并往外海递减，这是受陆地径流、海区生物活动所控制。春季POC的分布呈现受水团推移的迹象，在PN线上的406－408－411站位附近海区出现POC高值区，与表层水叶绿素a高值区的位置相吻合。垂直分布图显示：近岸浅海水域由于上下水体混合均匀，水体POC分布比较一致。外海深水区域POC呈现表层高，并往底层衰减。接近底层的部分水体受底部沉积物再悬浮的影响，POC含量略有起伏。水深20或35m以深的水体POC含量（以碳计）在60～40μg／dm3间。海域的2个典型站位（111、410站）周日连续观测表明，春、秋季水体上部真光层的POC含量的最高值都出现在深夜24：00，而表层海水的叶绿素a都在傍晚18：00出现最高值。可见，水体POC的分布明显受海区物理、化学和生物活动的影响。

This paper discusses and analyses the distributive characteristics of particulate organiccarbon (POC) in the marzinal shelf East China Sea during spring and autumn in 1994. Thehorizontal distribution chart from 0 m and 10 m layers indicates the highest POC content incoastal water area and its tend to decrease offshore, POC is low in value in Kuroshio currentarea. POC distribution in the deep water area farther off the coast is comparatively even ow-ing to the weakening influence of Changjiang runoff. In autumn POC isopleth tends to be par-allel with the coast and decreases offshore,which is controlled by continental runoff and bio-logical activities. In spring POC distribution tends to be moved by the water masses:its highvalue appears in the water area near stations 406-408-411 on PN line, which is consistentwith the high-value-area of chlorophyll-a in surface. The vertical sectional distribution chartindicates comparatively consistent POC distribution in both surface and bottom water in theshallow waters along the coast because of the even mixture of surface and bottom water. POCvalue in offshore deep sea area is high in surface and decrease to bottom. POC content issomewhat not stable in some areas near the bottom for the influence of the resuspension ofsediment and it is at the range 0f 60～40μg/dm3 in deep water below 20m or 35m. The datacollected from the continuous diurnal monitoring of two typical stations (Stations 111 and410) in the East China Sea indicate that during spring and autumn POC content in the eu-photic zone usually reaches its highest value at midnight 24: 00,While chlorophyll-a in thesurface reaches its highest value at 18: 00. The delay of peak values are perhaps due to bio-logical activities. Therefore,the distribution of POC in sea water is obviously influenced byphysical,chemical and biological activities in the East China Sea.