春、冬季长江口颗粒有机碳的时空分布及输运特征

根据2012年2月(冬季)、5月(春季)对长江口2个航次的调查数据,分析了春、冬季长江口颗粒有机碳(POC)的时空分布及影响因素,并探讨其输运特征.结果表明:2012年春季长江口POC的浓度为0.23~31.61mg/L,均值为2.55mg/L;冬季POC的浓度为0.16~5.82mg/L,均值1.42mg/L.春、冬季POC空间分布整体呈现近岸高远岸低、表层低底层高的特征,最高值均出现在口门附近.POC与悬浮物(TSM)呈极显著线性正相关,而与叶绿素a(Chl a)的相关性均较差,表明陆源输入对长江口POC的分布影响很大;POC/Chl a比值测算表明有机碎屑是调查水域POC的主要来源和存在形式,定量估算结果表明浮游植物生物量对春、冬季长江口POC的贡献分别仅1.26%和0.9%,且浮游植物对POC的贡献分别在TSM小于110mg/L和100mg/L时才能表现出来.春、冬季长江口TSM分别在大于117mg/L和335mg/L时,有机碳入海以颗粒态为主,反之则以溶解态为主.长江输送至河口的悬浮物中POC的百分含量(POC%)在春、冬季分别为0.9%和0.4%.春、冬季长江口最大浑浊带对POC的过滤效率分别达89%和69%,大量POC随泥沙在最大浑浊带发生了沉降.

Spatial-temporal distribution and transportation of particulate organic carbon in the Yangtze River Estuary in spring and winter 2012

Data were collected in two cruises in February and May 2012 in the Yangtze River Estuary, and the spatial- temporal distribution and transportation of particulate organic carbon (POC) and its affecting factors were analyzed. POC concentration in the estuary ranged 0.23~31.61mg/L in spring with average of 2.55mg/L, which was obviously higher than that in winter (0.16~5.82mg/L with average 1.42mg/L). Spatial distribution showed that POC concentration decreased seaward and the highest value occurred in the coastal zones and the mouth area, meanwhile POC concentration was higher in bottom layer than in the surface. POC was strongly and positively related to total suspended matter (TSM), but weakly to chlorophyll a (Chl a), which indicated that a large impact by terrestrial inputs on the POC distribution. POC/Chl a ratio revealed that organic detritus was the main source and carrier of POC. In addition, the contribution of phytoplankton biomass to POC could become explicit but very small for only 1.26% and 0.9% when TSM content was less than 110and 100mg/L in spring and winter, respectively. Organic carbon was transported into sea mainly in particulate form when TSM content was higher than 117 and 335mg/L in spring and winter, respectively, or otherwise in dissolved form. Only 0.9% or 0.4% of the POC was conveyed into the estuary in suspended matter, and 89% or 69% of POC would be filtrated by and deposited in the maximum turbidity zone in spring or winter, respectively.