中文摘要：

于2006年12月（冬季枯水期）和2007年8月（夏季丰水期）对万泉河口进行现场调查,探讨了此热带河口营养盐的分布特征。结果表明：万泉河口营养盐浓度（NO3-N,NO2-N,NH4-N,PO4-P）低于中国温带和亚热带的较大河流（如长江和珠江）,但河水冲刷及化学风化作用强,具有高硅酸盐特征。NO3-N和SiO3-Si在河口区主要受海水稀释作用影响;NO2-N和NH4-N呈非保守变化;丰水期PO4-P在低盐度区（S〈2.5）出现添加;在河流及河口中,枯水期与丰水期高的N/P比值使磷酸盐可能成为浮游植物生长的潜在限制因子;采用陆-海相互作用计划（LOICZ）所推荐的模型计算万泉河口营养盐的收支,模拟结果指出万泉河口冬、夏季均表现为DIN、DSi的汇,冬季是DIP的汇,夏季则成为DIP的源。

英文摘要：

Two cruises were carried out in the Wanquan River Estuary respectively in December 2006（dry season in winter） and August 2007（wet season in summer） to study and discuss the nutrients distributions and variations of this tropical estuary.It is showed in the results that nutrients concentrations（NO3-N,NO2-N,NH4-N and PO4-P） in the Wanquan River Estuary are lower than those in the subtropic or temperate rivers in China（such as the Changjiang River or the Zhujiang River）,but the dissolved silicate concentration is much higher due to the strong erosion by river and chemical weathering.NO3-N and SiO3-Si are diluted in the estuary by seawater.NO2-N and NH4-N have their seasonal variations.In the low salinity area,PO4-P becomes higher in wet season than in dry season.N/P ratio is higher in either dry season or wet stason in the river and its estuary,and it means that PO4-P might become a potential factor to limit phytoplankton growth.By means of a model suggested in Program for Land-ocean Interaction in Coastal Zone（LOICZ）,the nutrient budget in the Wangquan River Estuary can be estimated.It is learnt from the estimation results that there are a DIN sink,and a DS： sink in the estuary in summer.There is a DIP source in winter,but there becomes a DIP sink in summer.