Spatial distributions of soil chemical conditions in a serpentinitic wetland and surrounding landscape
Spatial distributions of soil chemical conditions in a serpentinitic wetland and surrounding landscape
复制标题
蛇纹石湿地及周围景观土壤化学条件的空间分布
DOI：
10.2136/sssaj2001.6541183x
复制
发表时间：
2001
影响因子：
2.9
通讯作者：
R. M. Creasy
中科院分区：
文献类型：
--
作者：
Brad D. Lee;R. Graham;T. Laurent;C. Amrhein;R. M. Creasy
由蛇纹岩形成的土壤含有丰富的铁、锰、铬、镍和镁，而植物必需的营养物质钙和钾的浓度很低。由此产生的植被通常是旱生的，特征是发育迟缓。本研究的目的是(1)确定超镁铁质湿地及其周围滑坡地形中重金属和交换性阳离子(ME)的空间分布；(2)解释与环境条件和成壤作用有关的景观组成部位的分布。用克立格法和景观单元、特征景观位置、土壤和植被评价了表层土壤(0~15 cm)中二亚硫酸盐可提取金属(Md)和Me的分布。S的丰度大小顺序为：镁、钙、钾、锰、镍。Ca/Mg比值变化范围为0.13~3.77(平均0.43)，以非蛇纹石变质堆积物高于蛇纹岩残留物的景观单元最高。相对于周围地形，可交换阳离子集中在湿地内。二亚硫酸盐可提取的铁、锰和镍集中在湿地水文排泄点附近氧化、非氢化的较低地貌位置的土壤中。铬和铝主要集中在非氢化物的上部地貌部位。由于条件的减少，湿地相对于周围的非氢化地形而言，含有较低浓度的MD。水分等级间植被差异较大，同一水分等级内景观单元间植被差异适中，说明研究区内植被的发生主要受水文条件的控制，其次受要素条件的控制。
Soils formed from serpentinite contain an abundance of Fe, Mn, Cr, Ni, and Mg, and low concentrations of the plant-essential nutrients Ca and K. The resulting vegetation is commonly xeromorphic and characteristically stunted. This study was conducted to (i) determine the spatial distributions of heavy metals and exchangeable cations (M e ) in an ultramafic wetland and surrounding landslide terrain, and (ii) to interpret the distributions relative to environmental conditions and pedogenic processes on the component landscape positions. Distributions of dithionite-extractable metals (M d ) and M e in surface soils (0-15 cm depth) were assessed by kriging and by landscape units, characteristic landscape position, soils, and vegetation. Abundance of M e s ranked in the following order: Mg > Ca » K > Mn > Na > Ni. The Ca/Mg ratios range from 0.13 to 3.77 (mean 0.43), with the highest ratios in a landscape unit with nonserpentine metamorphic colluvium over serpentinitic residuum. Exchangeable cations are concentrated within the wetland relative to surrounding terrain. Dithionite-extractable Fe, Mn, and Ni are concentrated in soils on the oxidizing, nonhydric lower landscape positions, near the hydrologic discharge point of the wetland. Chromium and Al are concentrated in the nonhydric upper landscape positions. Due to reducing conditions, the wetland contains low concentrations of M d relative to the surrounding nonhydric terrain. Large vegetation differences between moisture class coupled with moderate vegetation differences between landscape units within the same moisture class, suggest that vegetation occurrence within the study area is controlled primarily by hydrology, and secondarily by elemental conditions.