Abstract Shifts in seasonal aluminum (Al) activity and speciation in poorly buffered alpine tundra soil, attributable to atmospheric deposition of reactive nitrogen, can result in increased Al bioavailability, adversely impacting high-altitude plant and microbial communities. To evaluate seasonal changes in Al soil solution chemistry, intact soil column leaching studies were conducted to determine pore water Al speciation and transport under saturated spring melt-off conditions and unsaturated late summer conditions. These results were compared with aqueous Al speciation in surface and groundwater seep samples collected during the June to August growing season. Analysis of soil column leachates, surface and groundwater seep samples, indicated that Al activity was controlled by the aluminum hydroxyl sulfate suite of minerals, jurbanite, basaluminite, and alunite. Soil pore water collected from saturated soil cores consisted primarily of aluminum fluoride (Al-F) complexes for pore volumes (PV) < 5.0, with aluminum hydroxyl (Al-OH) complexation increasing with continued elution. Leachates collected from unsaturated soil cores exhibited Al-F transport only within the soil wetting front, PV < 1.0, after which, Al-OH complexes were predominant. The presence of fluoride (F−) in the soil pore water in the reactive solution front resulted in notable shifts between Al controlling solid phases and aqueous speciation. Similar shifts in Al speciation and controlling Al solid phases were observed in surface and groundwater seep samples, with sampling date and elevation. Results suggest that Al speciation and transport within alpine tundra soil may be seasonally influenced by soil moisture content and F− release from soil solid phases within the O/A1 soil horizons.

中文翻译：

---

美国科罗拉多州落基山国家公园高山苔原土壤中的铝活性

摘要 由于活性氮的大气沉积，缓冲不良的高山苔原土壤中季节性铝 (Al) 活动和物种形成的变化可导致铝生物利用率增加，从而对高海拔植物和微生物群落产生不利影响。为了评估铝土壤溶液化学的季节性变化，进行了完整的土柱浸出研究，以确定饱和春季融化条件和非饱和夏末条件下孔隙水铝的形态和迁移。这些结果与 6 月至 8 月生长季节期间收集的地表和地下水渗漏样品中的含水铝形态进行了比较。对土柱渗滤液、地表和地下水渗漏样品的分析表明，铝的活性受矿物羟基硫酸铝组、黄铜矿、碱铝石和明矾石。从饱和土壤核心收集的土壤孔隙水主要由孔隙体积 (PV) < 5.0 的氟化铝 (Al-F) 复合物组成，羟基铝 (Al-OH) 复合物随着持续洗脱而增加。从非饱和土壤核心收集的渗滤液仅在土壤润湿前沿内表现出 Al-F 迁移，PV < 1.0，之后，Al-OH 复合物占主导地位。反应溶液前沿中土壤孔隙水中氟化物 (F-) 的存在导致 Al 控制固相和含水形态之间的显着转变。在地表和地下水渗漏样品中观察到类似的 Al 形态变化和控制 Al 固相，以及采样日期和海拔。