Atmospheric Sulfur Deposition, Neutralization, and Ion Leaching in Two Deciduous Forest Ecosystems
Atmospheric Sulfur Deposition, Neutralization, and Ion Leaching in Two Deciduous Forest Ecosystems
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DOI：
10.2134/jeq1983.00472425001200020023x
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发表时间：
1983
影响因子：
2.4
通讯作者：
D. Richter;Dale W. Johnson;D. Todd
中科院分区：
文献类型：
--
作者：
D. Richter;Dale W. Johnson;D. Todd
在1981水年，散装降水主要是稀H/sub 2/SO/sub 4/的解决方案，和SO/sub 4//sup 2 -/是穿透雨和土壤淋溶物中的主导阴离子在田纳西州东部的落叶林。SO/sub 4//sup 2 -/的生态系统输入（包括森林冠层的干沉积）可能比基于开阔地区大气沉积采样的输入估计值高出40%。体积加权平均年总降水pH值为4.3，穿透雨4.8，从O2，A1和B21土壤层的渗滤液约6.0。在这两个地点，降水中的强酸在雨水渗入矿物质土壤之前基本上被中和。在酸性降水中与H/sup +/（H2+）交换的盐基阳离子几乎全部由森林冠层和枯落物层提供，而不是直接来自可交换矿物土壤库。来自B12层位的HCO/sub 3//sup -/碱度的年通量表明，来自H/sub 2/CO/sub 3/的部分电离的天然H/sup +/输入与1981年大量降水中的H/sup +/输入具有相似的量级。然而，即使在这些低阳离子交换能力的贫瘠土壤中，交换性盐基也比全年大量降水中的H/sup +/输入多两个数量级以上，并且代表了与H/sup +/酸雨交换的冠层和凋落物层中盐基阳离子的大量储备。此外，输入的H/sup +/酸沉淀等于约0.4%的生物循环，并立即在这些生态系统中可用的碱阳离子。虽然数量不多，但矿物风化和深根会随着时间的推移为生物循环提供大量的额外阳离子。«少
In the 1981 water year, bulk precipitation was primarily a solution of dilute H/sub 2/SO/sub 4/, and SO/sub 4//sup 2 -/ was the dominant anion in throughfall and soil leachates in two eastern Tennessee deciduous forests. Ecosystem inputs of SO/sub 4//sup 2 -/, which included dry deposition of forest canopies, may have been up to 40% greater than input estimates based on atmospheric deposition sampling in open areas. Volume-weighted mean annual pH of bulk precipitation was 4.3; of throughfall 4.8; and of leachates from O2, A1, and B21 soil horizons about 6.0. At both sites, strong acids in precipitation were largely neutralized prior to rainwater's infiltration into mineral soil. Base cations that exchanged with H/sup +/ (hydrogen ions) in acid precipitation were almost entirely supplied by forest canopies and litter layers, and did not come directly from exchangeable mineral soil pools. Annual fluxes of HCO/sub 3//sup -/ alkalinity from B12 horizons, indicated that the natural H/sup +/ input from the partial ionization of H/sub 2/CO/sub 3/ was of similar magnitude to H/sup +/ input in bulk precipitation in 1981. However, even in these infertile soils with low cation exchange capacities, exchangeable bases were more than two orders of magnitude greatermore » than annual H/sup +/ input in bulk precipitation, and represented a substantial reserve for base cations in canopies and litter layers that exchanged with H/sup +/ acid rain. Furthermore, inputs of H/sup +/ from acid precipitation were equal to about 0.4% of the base cations that are biologically cycling and immediately available in these ecosystems. Although poorly quantified, mineral weathering and deep rooting will supply, over time, substantial amounts of additional base cations for biologic cycling.« less