鼎湖山季风常绿阔叶林某些沉积元素转移过程中的浓度分析

Analysis on the concentration of some sediment elements in their transport process through monsoon evergreen broad-leaved forest ecosystem in Dinghushan, Guangdong Province, China

对鼎湖山大气降水、季风常绿阔叶林林冠穿透水、土壤水 ( 30 cm和 80 cm深 )以及溪水中某些沉积元素进行了系统连续的观测研究 ,从沉积元素的转移过程阐明了鼎湖山自然保护区和季风常绿阔叶林所承受的环境压力 ,通过分析沉积元素在这些水文学过程中的浓度变化和相互联系 ,试图揭示该生态系统相应功能过程变化的规律。得到如下结果 :( 1 )大气降水中的 Pb含量远远高于穿透水、土壤水 ( 30 cm和 80 cm深 )以及溪水中的含量 ,随着水分由输入向输出流动 ,Pb的浓度逐渐降低 ;( 2 )在大气降水、林冠穿透水、土壤水 ( 30 cm和 80 cm深 )以及溪水中 ,Al离子的浓度逐步增加 ;( 3)除 Pb外 ,所有其他元素 ( Al、Mn、Sr、Mg、Na、K和 Ca)在土壤溶液中的浓度都高于 5个水文过程的平均值 ;( 4 ) Mn、K、Ca的输入和输出的浓度都不高 ;( 5 ) Na和 Mg在土壤水和溪水中的浓度超过 5个水文过程的平均值。这表明 :( 1 )鼎湖山的大气具有高浓度的 Pb含量 ,而且 Pb在季风常绿阔叶林系统中处于一个持续的积累过程 ;( 2 )酸性降水不仅活化了土壤中的 Al元素 ,对各个水文学过程中的离子浓度也有增大的作用 ;( 3) Na和 Mg在当前的大气环境下有可能加速地从季风常绿阔叶林生态系统中淋洗出来。总之 ,由于酸雨和大气污染的影响 。

The study was on this academic viewpoint that the hydrological chemistry of sediment elements in ecosystem provides some important information that is useful to diagnosticate the function of ecosystem and to evaluate the impact of outer environment on ecosystem. The experiment was carried out in monsoon evergreen broadleaved forest ecosystem, Dinghushan Biosphere Reserve, Guangdong Province, China, in which much measurement data were available. Water samples from 5 hydrological processes, ie, rainfall, throughfall, soil water of 30cm and 80cm in depth and stream flow were monthly gathered using ordinary ways during February 2001～August 2001. The sediment elements Al、Mn、Sr and Pb were analyzed by ICP (ps-1000AT, USA). Ca and Mg were measured by Atomic Absorption Spectrometer. K and Na were determined using Flame Atomic Absorption Spectrometer. By the researches on transfer of sediment elements through the 5 hydrological processes, the environmental impacts on Dinghushan Biosphere Reserve and the monsoon evergreen broad-leaved forest ecosystem were tested in the paper. From the information provided with the changes and interactions of sediment element concentrations, the paper found some important changes of the relevant functional process of monsoon evergreen broad-leaved forest ecosystem under the environment of high acid deposition. It was turned out that: (1) The concentration of Pb in rainfall was much higher than that in throughfall, soil water of 30cm and 80cm in depth and stream water, and with the flow of water from input to output, the concentration of Pb was decreasing; (2) The concentration of Al increased gradually according to the sequence of rainfall, throughfall, soil water of 30cm and 80cm in depth and stream water; (3) Except Pb, the concentrations of all other elements (ie, Al, Mn, Sr, Mg, Na, K and Ca) in soil water and stream water were higher than the average concentrations in the 5 hydrological processes; (4) The input and output of the concentrations of Mn, K and Ca were not high. All of the results indicated that: (1) The concentration of Pb in atmosphere of Dinghushan area was high and Pb in monsoon evergreen broad-leaved forest ecosystem was continually in accumulation processes; (2) Acid precipitation activated Al in the soil and increased the concentrations of sediment elements during the hydrological process; (3) Na and Mg were probably accelerated to be leached from the ecosystem due to the acid deposition. In a word, that the concentrations of sediment element in the transfer processes of monsoon evergreen broadleaved forest ecosystem in Dinghushan Biosphere Reserve were in a chaos state because of acid precipitation and air pollution, which would probably affect the stability of the ecosystem.