2000~2010年大鹏湾颗粒有机物的年变化和年际变化

依据2000～2010年每月一次的调查资料,简要描述和讨论了大鹏湾中颗粒有机物(particulate organic matter,POM)质量浓度的时空分布,并结合叶绿素a(chlorophyll a,Chl-a)实测数据探讨POM的组成和滞留时间.结果表明,大鹏湾的水动力条件对POM的分布变化影响不大,POM质量浓度为(1.1±0.8)mg·L-1,与珠江口伶仃洋和大亚湾的差别不大,但比南海北部的高.在表层,POM与Chl-a之间存在显著正相关,浮游植物有机物(phytoplankton POM,PPOM)∶Chl-a比率为70 g·g-1左右,由此估算的大鹏湾PPOM质量浓度为(0.31±0.39)mg·L-1,约占POM的28%.由初级生产力(primary productivity,PP)和累计POM(integrated POM,IPOM)估算的大鹏湾中POM的滞留时间约为6.5 d,与东海南部沿岸陆架区POC的相近.11 a调查期间,PP的年际变化略呈下降趋势,而POM和IPOM的年际变化呈较明显的上升趋势,暗示难降解的碎屑POM在大鹏湾中逐渐积累.

Intra- and Inter-annual Variabilities of Particulate Organic Matter in the Mirs Bay from 2000 to 2010

Based on the data obtained from monthly cruises from 2000 to 2010, temporal and spatial distributions of the particulate organic matter (POM) in the Mirs Bay were briefly presented and discussed. The POM composition and residence time were approached by combining with the chlorophyll a (Chl-a) measurements. It has been shown that the hydrodynamics in the Mirs Bay only pose a weak impact on the POM distributions. The POM concentration was (1.1±0.8) mg·L^-1, which was not much different from those in both the Pearl River Estuary and the Daya Bay, but higher than that in the northern South China Sea. A notably positive correlation was found between the POM and Chl-a in the surface-water. The ratio of the phytoplankton POM (PPOM):Chl-a was about 70 g·g^-1, based on which the PPOM concentration was calculated to be (0.31±0.39) mg·L^-1, accounting for about 28% of the POM. The primary productivity (PP) and integrated POM (IPOM) were used for estimating the POM residence time, which was found to be about 6.5 days in the Mirs Bay, close to that for POC in the coastal continental shelf waters in the southern East China Sea. During the 11-year investigation, the PP inter-annual variability showed a decreasing trend, but both the POM and IPOM underwent a trend of increase, which suggested that the refractory detritus POM had been gradually acumulated in the Mirs Bay.