| 摘要: |
| 2005 年3—5 月, 选取位于长江口崇明东滩的3 个典型站点, 对沉积物间隙水中营养盐剖面进行了观测; 同时, 通过模拟现场环境培养的方法测定了营养盐在沉积物-上覆水界面的交换通量。结果表明, 间隙水中NH4+ 和SiO32? 浓度比PO43? 和NO2? + NO3? 一般要高2—3 个数量级。沉积物-水界面交换过程在春季表现为对NO3?和SiO32?的吸收, 吸收的量在很大程度上取决于上覆水中这两种营养盐的浓度; 由上覆水和表层间隙水浓度梯度所决定的分子扩散通量对实际交换通量的控制有限。对NO3? , 分子扩散通量占交换通量的比例不到21%; 对SiO32?, 前者和后者的方向相反; 对NH4+, 较大的浓度梯度支持显著的释放通量, 而在培养过程中并没有发现上覆水中NH4+浓度持续的增长。以上结果都说明其它因素, 如浮游植物吸收、颗粒物吸附以及底栖动物扰动在更大程度上决定着崇明东滩沉积物-水界面营养盐的交换过程。
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| 关键词: 营养盐, 沉积物-水界面, 间隙水, 生物扰动, 盐沼, 长江口 |
| DOI：10.11693/hyhz200902001001 |
| 分类号: |
| 基金项目:国家重点基础研究发展规划项目“中国典型河口-近海陆海相互作用及其环境效应”, 2002CB412405 号 |
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| SEDIMENT-WATER EXCHANGE OF NUTRIENTS IN DONGTAN SALT MARSH WITHIN THE CHANGJIANG (YANGTZE RIVER) ESTUARY IN SPRING |
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GAO Lei1,2, LI Dao-Ji2, YU Li-Hua2, KONG Ding-Jiang2, WANG Yan-Ming2
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1.State Key Laboratory of Marine Geology, Tongji University;2.State Key Laboratory of Estuarine and Coastal Research, East China Normal University
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| Abstract: |
| From March to May 2005, nutrient profiles in sediment pore waters were studied at the three representative stations in Dongtan salt marsh within the Changjiang (Yangtze River) estuary. Meanwhile, incubation experiments were conducted to measure the benthic nutrient fluxes. Concentrations of NH4+ and SiO32? in pore water were generally much higher than other nutrients by 2—3 orders of magnitude. During incubations, significant uptake fluxes of NO3? and SiO32? were commonly shown at the sediment-water interface, and largely controlled by their concentrations in the overlying water. The molecule diffusive fluxes, calculated from the concentration gradients between overlying water and surface pore water, seemed not so important in the exchange fluxes. For NO3?, the molecule diffusive fluxes were no more than 21% of the measured fluxes; and for SiO32?, the former was always provided with an opposite direction of the latter. With respect to NH4+, the concentration gradient at the interface was sharp, suggesting significant and consistent release fluxes out of sediments; however, that was not the case in practice. Therefore, factors such as phytoplankton assimilation, particulate adsorption and bioturbation might have a larger influence on benthic nutrient exchanges.
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| Key words: Nutrients, Sediment-water exchanges, Pore water, Bioturbation, Salt marshes, the Changjiang (Yangtze River) estuary |
