春季珠江口内营养盐剖面分布和沉积物-水界面交换通量的研究

2005年春季(4月)对珠江口内6个站位的营养盐剖面分布及沉积物-水界面的交换通量进行了全面研究。在获取该海域沉积物间隙水营养盐剖面资料的基础上,估算了沉积物-水界面营养盐的交换通量,并且与实验测定的沉积物-水界面交换通量进行了对比。研究结果表明,珠江口内间隙水营养盐在不同站位间含量差异明显,呈现出由河口向外海逐渐降低的分布趋势。对于大多数站位营养盐,交换实验得到的通量大于利用间隙水浓度梯度法估算的结果,交换实验具有更高的分辨率。应用交换实验测定的沉积物-水界面交换通量,体现了营养盐扩散和界面反应的综合作用结果。研究区域的NH4+,NO3-,NO2-,SiO44-和PO43-的交换通量分别为-1.318 4~0.985 4,-0.558 3~0.469 2,-1.518 8~0.143 8,-1.967 3~3.883 1和-0.246 4~0.093 9 mmol.d-1.m-2。

STUDY ON PROFILE DISTRIBUTION OF NUTRIENTS AND EXCHANGE FLUXES AT SEDIMENT-WATER INTERFACE IN INNER PEARL RIVER ESTUARY IN SPRING

The profile distribution of nutrients and exchange fluxes at the sediment-water interface were analyzed in the six sites of the inner Pearl River Estuary in April 2005.Based on the nutrient profiles of interstitial water from the aforementioned area,the nutrients exchange fluxes at the sediment-water interface were approximately calculated,which were compared with the experimental exchange fluxes at the sediment-water interface.It is shown that the contents of nutrients in interstitial water vary a lot?within the investigated sites,which decrease with the distance form the inner Pearl River Estuary.For most of the nutrients the measured fluxes by incubation experiments are overestimated relative to the calculated ones,which is probably due to the measured method with a higher resolution,and these are comprehensive results of nutrient diffusion and interface reaction.The exchange fluxes at the sediment-water interface of NH_4~+,NO_3~-,NO_2~-,SiO_4~(4-) and PO_4~(3-) are-1.3184～0.9854,(-0.5583)～0.4692,-1.5188～0.1438,-1.9673～3.8831 and-0.2464～0.0939 (mmol·)d~(-1)·m~(-2),respectively.