太湖水动力扰动对有机物释放影响的试验

Effect of the hydrodynamic disturbance on the organic matter release in Lake Taihu via the experimental test

为了解浅水湖泊在不同水动力扰动下水体营养盐及有机物释放量的变化,在实验室进行了连续长时间的不同风浪条件下水土界面扰动试验,以确定不同风速引起的沉积物再悬浮对水体有机物的影响。结果表明,扰动促进了沉积物中颗粒态有机质(POM)的再悬浮,但随扰动强度加大,颗粒物中有机质的比例反而降低,而溶解态营养盐及有机质并未受到明显影响。利用三维荧光光谱(EEMS)并结合平行因子分析法(PARAFAC)解析有机物(DOM)的荧光特征,共识别出2类5个荧光组分,分别为类蛋白荧光组分C1(280 nm,322 nm)、C3(235 nm,353 nm)、C5(270 nm,<300 nm)和类腐殖质荧光组分C2(275 nm,383 nm)、C4(260 nm/335 nm,443 nm)。在试验过程中类蛋白组分所占比重接近80%,表现出明显的内源释放特征。同时,a355在对照组和试验组也无显著差异。研究表明,不同水动力扰动促进颗粒态有机物再悬浮,但对溶解态有机质的浓度和组分变化影响并不显著。此次室内模拟试验是水体有机物对水动力扰动响应的初步研究,原位观测需考虑更多影响因子。

The present paper is aimed to identify and examine the releasing change of the nutrients and organic matters in the shallow-water lakes under different hydrodynamic disturbances,with the purpose to deepen our understanding of the effects of the resuspension of the sedimentary deposits likely to be caused by the different wind velocities on the organic substances in the lake body. We have also conducted continuous and long-lasting experiments of the soil-water mixture interface disturbance under thedifferent wind and wave conditions（ e. g. the breeze,moderate wind and/or strong wind） in the Lab. The results of our experiment and testing have shown that the perturbation promotes resuspension of the particulate organic matters（ POM） in the sediments. But the ratio of the organic matters in the particles have been found in decrease with the increase of the disturbing strength,though no obvious effects can be found on the dissolved nutrient and organic contents. Further analysis has been done with the fluorescent features of the dissolved organic matters in the water by using the EEMS and PARAFAC,which let us find 2 categories and 5 types of fluorescent components,that is,C1,C3 and C5 of the category of protein-like fluorescent components at280 nm,322 nm and 235 nm,353 nm and 270 nm, 300 nm,respectively,and C2,C4,belonging to that of the humic-like fluorescent components at 275 nm,383 nm and 260 nm/335 nm,443 nm,respectively. And,in contrast,the protein-like component in the result of the experiment has been found equal to80%,implying clearly the endogenous release features. However,no significant difference of a355 has been noticed between the control group and the experimental group,which could be used to characterize the concentration of a chromophoric dissolved organic matters. Thus,it can be concluded that the different hydrodynamic disturbances are in a position to promote the resuspension of the particulate organic matters（ POM） in the sediments,whereas the concentration and the alteration of the components of the dissolved organic matters fail to. The indoor or laboratory simulated experiments can also be used to do the preliminary tests of the response of water organic matters to the hydrodynamic disturbance,in which it is necessary to take in account lots of factors involved in the given status in-situ observations.