| 摘要: |
| 为了更好地了解长江流域城市化进程和三峡工程对长江口生态系统的影响及其响应,为长期观测提供参考,采用分光光度法对2003年5月19-26日采自长江口的水样中的溶解态无机氮、磷、硅进行了分析。结果表明,该海域营养盐的空间分布呈现出较好的规律性:SiO3-Si的浓度总体上沿长江径流入海方向递减,其在淡水端的浓度>100μmol/L,在离岸最远的海水端附近的浓度约为10μmol/L;NO3-N、NO2-N、NH4-N和PO4P沿长江径流入海方向的浓度分布则呈现出先增加后降低的特征,最高值出现在咸淡水交界面附近,分别为130.0、3.14、31.43和2.06μmol/L。南北方向上各种形态营养盐的浓度总体上呈现出北部海域表、底层之间差异大于南部海域的分布特征。连续观测数据显示,NO3-N、NO2-N、PO4-P和SiO3-Si的浓度均可能在4h的时间里发生较大幅度的波动。在混合水区,由于水深较浅,水体混合较容易,垂直方向上各元素的浓度平均值差异不大;在水深较深的海水区,随着水深的增加,NO3-N和NO2-N的浓度平均值总体上呈下降趋势,PO4-P则相反,SiO3-Si变化不大。采用营养状态质量法和潜在性富营养化标准对调查海域的营养状况进行了分析，结果均显示，调查海域在长江径流入海方向上由淡水区的高营养水平逐渐过渡到海水区的贫营养水平。由于长江口水体中个营养元素浓度时空变化显著，准确计算其入海通量难度很大，需要足够多的高时空分辨率的数据。 |
| 关键词: 营养盐 空间分布和日变化 营养状况 长江口 |
| DOI： |
| 分类号: |
| 基金项目:中国科学院“百人计划”项目,科人2003-202号;青岛市科技将才专项计划,04-3-JJ-03、05-2-JC-90号。 |
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| THE CONCENTRATIONS OF DISSOLVED INORGANIC NITROGEN, PHOSPHORUS AND SILICON IN THE CHANGJIANG (YANGTZE) RIVER ESTUARY IN 2003 |
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GAO Xue-Lu1,2, SONG Jin-Ming1
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1.Key Laboratory of Marine Ecology & Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences,Qingdao,266071;2.Key Laboratory of Tropical Marine Environmental Dynamics, South China Sea Institute of Oceanology, Chinese Academy of Sciences,Guangzhou,510301
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| Abstract: |
| An observation was conducted in the Changjiang (Yangtze) River Estuary from May 19 to 26, 2003. In spatial and diurnal variations, dissolved inorganic nitrogen, phosphorus and silicon were examined. Data show that the trends of spatial distribution for these nutrients were clear. Generally, in downriver direction, the concentration of SiO3-Si decreased, while those of NO3-N, NO2-N, NH4-N and PO4-P increased first, reaching the maximum at 130.0, 3.14, 31.43 and 2.06 μmol/L respectively in the area where the freshwater and saline water met, and then decreased. Both NO3-N and SiO3-Si concentrations were above l00 μmol/L in freshwater sector and decreased quickly as salinity increased; the minimum, about 2 and 10 μmol/L respectively, were at the eastern part of the study area. In south-north direction, distribution of nutrient showed in overall the same trend that differences between the surface and bottom layers were more apparent in the northern part than in the southern part. The data obtained from anchor stations indicated that for NO3-N, NO2-N, PO4-P and SiO3-Si, concentration could vary greatly within 4 hours. In the mixed water sector, shallow depth made the water mixing easily; therefore, the mean nutrient concentrations of them showed no significant differences among the studied layers. In the seawater sector, the average concentration of NO3-N and NO2-N decreased downward, while it was opposite for PO4-P; the average concentrations between different layers were close for SiO3-Si. According to the National Standard No. GB3097-1997 issued by the Standardization Administration of China (SAC), the dissolved inorganic nitrogen concentrations qualified Chinese seawater Grade I in the seawater sector with few exceptions, while it exceeded the limit of Grade IV in the freshwater sector and the western part of the mixed water sector. In this paper, two different methods were used to analyze the trophic status; and both showed that in downriver direction, the status was gradually shifted from being eutrophic to oligotrophic. Because of the dynamic pattern in this estuary, spatial and diurnal variations in dissolved inorganic N, P and Si were very variable. Accurate estimate on their fluxes to the East China Sea demands more spatial and temporal investigation data, as well as those from hydrological, chemical and biological aspects. |
| Key words: Nutrients, Spatial distribution and diurnal variation, Trophic status, Changjiang (Yangtze) River Estuary |
