基于^(18)O稳定同位素的银川平原北部4种灌木夏初水分来源的研究

Study on the Water Sources of 4 Bushes Based on the ^(18)O Stable Isotope Grew in Yinchuan Plain Northern Area in the Beginning of Summer

在宁夏西大滩,通过测定不同种类及不同年龄盐生灌木木质部水分及不同潜在水源稳定氧同位素组成(δ18O),应用同位素线性混合模型估算了不同灌木对不同水源的利用率。结果表明:不同深度土壤水δ18O值存在较大差异,并呈现规律性变化,140 cm以上δ18O值波动较大,说明该土壤剖面土壤水δ18O受蒸发与井水灌溉的双重影响;140 cm以下δ18O值连续下降,说明该土壤剖面土壤水δ18O主要受井水影响。20年生多枝柽柳平均利用19.9%的地下水,3年生四翅滨藜平均利用15.5%的地下水,3年生枸杞平均利用15.1%的地下水,3年生多枝柽柳平均利用13.3%的地下水。20年生多枝柽柳对表层土壤水的依赖最低(5%),3年生多枝柽柳对表层土壤水的依赖最高(38.9%)。

In northern area of Yinchuan Plain, the stable 1So isotope compositions （8180） of different potential water sources and xy- lem water of saltbush of different ages and kinds were determined to calculate the utilization rate of different water sources for the dif- ferent bushes using isotope linear mixing model. The result showed that： Soil water 8180 in different depth differed and displayed reg- ularity. Dramatic fluctuation in terms of 8180 value was observed in the soil profile above 140 cm,which could be explained by the double effects of evaporation and well-irrigation. Soil water 8~So value decreased continuously along the soil profile below 140 cm, in- dicating the sole effect of well water on soil water 8TM O was important. 20-year-old Tamarix ramosissima Lbd. tapped 19. 9% of groundwater,while 3-year-old Atriplex canescens （Pursh） Nutt. , 3-year-old Lycium Barbarum L. and 3-year-old Tamarix ramosis- sima Lbd. tapped 15. 5%, 15. 1% and 13.3% of groundwater, respectively. The 20-year-old Tamarix ramosissima Lbd. showed the lowest dependence on shallow soil water（5% ） and on which three-year-old Tamarix ramosissima Lbd. exhibited the highest depend- ence （38.9%）.