Anion exchange between ubiquitous low‐molecular‐weight organic acids (LMWOA), such as oxalate, and surface‐retained inorganic anions, such as F⁻, SO₄²⁻ and OH⁻, can play a critical role in Al bioavailability and transport in acidic alpine tundra soil. A series of batch equilibration and composite soil column leaching studies were conducted to examine anion exchange reactions between F⁻, oxalate and OH⁻, and the impact of increased soil solution F⁻ concentration on Al transport. The addition of either F⁻ or oxalate to soil suspensions resulted in significantly higher solution pH, suggesting F⁻ and oxalate exchange with surface –OH groups. Distinct stages of OH⁻ release were observed for all soil horizons leached with 1.32 × 10⁻³ mol l⁻¹ F⁻, with OH⁻ release decreasing in the order O/A1 ~ A2> > Bw. A similar OH⁻ release pattern was observed in the O/A1 horizon for the 7.81 × 10⁻⁴ mol l⁻¹ oxalate treatment, suggesting that both F⁻ and oxalate may be competing for common exchange sites in the O/A1 horizon. Fluoride displacement by oxalate, in batch equilibration experiments, was observed for both the 2.84 × 10⁻⁴ mol l⁻¹ and 7.81 × 10⁻⁴ mol l⁻¹ oxalate treatment. Individual soil horizons leached with 7.81 × 10⁻⁴ mol l⁻¹ oxalate exhibited increased F⁻ leaching in the order O/A1 > A2 ~ Bw, with pulsed F⁻ movement being observed in the O/A1 horizon. Soil columns eluted with 1.32 × 10⁻³ mol l⁻¹ F⁻ exhibited increased Al solubilization and transport, with Al leaching increasing in the order Bw > A2 > O/A1. Sequential leaching of soil columns in the order D. I. H₂O → 1.32 × 10⁻³ mol l⁻¹ F⁻ → D.I. H₂O → 7.81 × 10⁻⁴ mol l⁻¹ oxalate indicated that previously adsorbed F⁻ was displaced by oxalate. Displacement of F⁻ by oxalate increased in the order O/A1 > A2 > Bw. Hydroxyl displacement by both F⁻ and oxalate may be an important source of acid neutralization in a soil wetting front, affecting Al speciation and transport.

中文翻译：

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高寒苔原土壤中的草酸盐-氟离子交换：对铝迁移的影响

普遍存在的低分子量有机酸（LMWOA），如草酸盐，和表面保留无机阴离子，如F之间的阴离子交换^-，SO ₄ ^2-和OH ^- ，可以以Al的生物利用度和运输中发挥关键作用酸性高山苔原土壤。一组间歇平衡和复合土柱浸出研究都是以检查F的阴离子交换反应^- ，草酸盐和OH ^- ，和增加了土壤溶液F的影响^-浓度对Al运输。或者F的加成^-或草酸盐土壤混悬液导致显著较高溶液的pH值，这表明˚F ^-与草酸与表面-OH基团交换。OH的不同的阶段^-中观察到用1.32×10浸出的所有土层释放^-3摩尔升^-1 ˚F ^- ，用OH ^-释放在阶为O递减/ A1〜A2>>了Bw。类似的OH ^-于O中观察到的释放模式/ A1地平线为7.81×10 ^-4摩尔升^-1草酸盐处理，这表明两个F ^-和草酸可以在O / A1地平线公共交换位点竞争。在批次平衡实验中，对于2.84×10 ^-4 mol l ^-1和7.81×10都观察到草酸盐对氟的置换。^-4 mol l ^-1的草酸酯处理。个别土层浸提7.81×10 ^-4摩尔升^-1草酸盐显示出增加的˚F ^-在顺序浸出O / A1> A2〜了Bw，与脉冲˚F ^-在O / A1地平线观察到运动。土柱洗脱1.32×10 ^-3摩尔升^-1 ˚F ^-显示出增加的铝的溶解和运输，用Al浸出的顺序带宽> A2> O / A1增加。按DI H ₂ O→1.32×10 ^-3 mol l ^-1 F ⁻  →DI H ₂ O→7.81×10 ^-4的顺序对土壤柱进行顺序淋洗摩尔升^-1草酸盐表明先前吸附˚F ^-通过草酸盐移位。的F位移^-通过草酸的顺序O / A1> A2>了Bw增加。由两个F羟基位移^-和草酸可以是酸中和在土壤湿润前的一个重要来源，影响的Al形态和运输。