挪威云杉林枯枝落叶层元素浸提量的研究

A Study on the Element Extraction from OrganicMatter of Forest Floor of Norway Spruce

对取自德国Solling的挪威云杉林的不同枯枝落叶层样品进行了一系列浸提实验 ,结果表明 ,枯落物分解程度、水∶物的比值和浸提液pH值都是元素浸提的主要控制因素。多数阳离子的浸提受到H+交换机制的很大影响 ,较低的pH值会导致较高的浸提量 ;而较高的pH值和稀释作用导致的pH值升高会导致较低的浸提量。在水∶物的比值增加到某一数值之前 ,水∶物的比值增加会导致浸提液内元素浓度与枯落物元素含量的新平衡 ,并导致浸提量增大。另外一方面 ,水∶物的比值增加导致的pH值升高会成为新的限制因素 ,导致较低的浸提量 ,尤其对于 2、3价阳离子。这两种作用机制的复合效应使浸提量与水∶物的比值的关系曲线非常复杂。建立了森林枯枝落叶层元素含量 (T ,μmol(+ )·kg- 1)、浸提液pH值、水∶物的比值 (W ,kg·kg- 1)对元素浸提量 (Y ,μmol(+ )·kg- 1枯落物 )影响的数学模型。对Na+、K+,Ca2 +、Mg2 +、Mn2 +、Al3+和Fet,模型为Y =A + (T -A)·exp(-B·pH) / [1+C·exp(-W) ];对H+,模型为Y =a +bW c。对严重酸化的枯枝落叶层元素的浸提 ,不存在所期盼的最优水∶物的比值。水∶物的比值较低时 ,元素浓度比值变化较大 ;在水∶物的比值较高时 ,元素数量比值变化较大。但对严重酸化的枯枝落叶层元素进行浸提时 ,可把?

The samples of organic matter on forest floor of a Norway spruce stand in Solling, Germany, were extracted. It shows that the decomposition degree of forest floor materials, water: sample ratio, and the pH value in extracting solution are important factors controlling the element extraction. The extraction of most cations is strongly influenced by the H + exchange mechanism. Therefore lower pH value leads to more extraction; while higher pH value and its increase due to dilution leads to less extraction. Widening water: sample ratio until a certain value leads to a new balance of element concentration between solution and forest floor materials towards more extraction. In addition, the increase of pH value caused by further widening water: sample ration becomes a limiting factor and leads to less extraction, especially for the di and trivalent cations. Combination of these 2 influencing aspects makes the extraction curves versus water: sample ratio very complex. The influences of total element content ( T , μmol(+)·kg -1 forest floor materials), pH value in extracting solution and water: sample ratio ( W , kg·kg -1 )on element amount extracted( Y, μmol(+)·kg -1 forest floor materials) can be described in mathematical models. The model is Y=A+(T-A)· exp (-B·pH)/[1+C· exp (-W)] for Na + , K + ,Ca 2+ ,Mg 2+ ,Mn 2+ ,Al 3+ and Fe t; while Y=a+b W c for H +. For the water extraction of strongly acidified forest floor materials no expectant optimal water: sample ratio exists. With lower water:sample ratio the variance of element concentration ratios is greater; with higher water: sample ratio the variance of element amount ratios is greater. However, the water content of saturation can be used as a compromised water: sample ratio for the water extraction of strongly acidified sample of organic matter on forest floor. The water content of saturation is 3.4, 3.2, 2.0 kg·kg -1 for O L, O F and O H, respectively.