Lee Y B, Bigham J M, Dick W A, Jones F S, Ramsier C
School of Environment and Natural Resources, The Ohio State Univ., 2021 Coffey Rd., Columbus, OH 43210, USA.
J Environ Qual. 2007 Jan 9;36(1):298-304. doi: 10.2134/jeq2006.0050. Print 2007 Jan-Feb.
Calcium sulfite hemihydrate (CaSO(3).0.5H2O), a common byproduct of coal-fired utilities, is fairly insoluble and can decompose to release toxic SO2 under highly acidic soil conditions; however, it can also oxidize to form gypsum. The objective of this study was to examine the effects of application rate and soil pH on the oxidation of calcium sulfite under laboratory conditions. Oxidation rates measured by release of SO4-S to solution decreased with increasing application rate. Leachate SO4-S from soils amended with 1.0 to 3.0 g kg-1 CaSO3 increased over a 21 to 28 d period before reaching a plateau. At 4 g kg-1, maximum SO4-S release was delayed until Week 7. Oxidation and release of SO4-S from soil amended with 3.0 g kg-1 calcium sulfite increased markedly with decreasing soil pH. After only 3 d incubation, the concentrations of SO4-S in aqueous leachates were 77, 122, 170, 220, and 229 mg L-1 for initial soil pH values of 7.8, 6.5, 5.5, 5.1, and 4.0, respectively. At an initial soil pH value of 4.0, oxidation/dissolution did not increase much after 3 d. At higher pH values, oxidation was maximized after 21 d. These results suggest that autumn surface applications of calcium sulfite in no-till systems should permit ample time for oxidation/dissolution reactions to occur without introducing biocidal effects related to oxygen scavenging. Soil and annual crops can thus benefit from additions of soluble Ca and SO4 if calcium sulfite is applied in advance of spring planting.
半水亚硫酸钙（CaSO₃·0.5H₂O）是燃煤电厂常见的副产品，其溶解性较差，在强酸性土壤条件下会分解并释放出有毒的二氧化硫；然而，它也会氧化形成石膏。本研究的目的是在实验室条件下研究施用量和土壤pH值对亚硫酸钙氧化的影响。通过向溶液中释放硫酸根硫（SO₄-S）来测量的氧化速率随着施用量的增加而降低。用1.0至3.0 g kg⁻¹ CaSO₃改良的土壤渗滤液中的SO₄-S在21至28天内增加，之后达到平稳状态。在4 g kg⁻¹时，最大SO₄-S释放延迟到第7周。用3.0 g kg⁻¹亚硫酸钙改良的土壤中，SO₄-S的氧化和释放随着土壤pH值的降低而显著增加。仅培养3天后，初始土壤pH值为7.8、6.5、5.5、5.1和4.0时，水浸出液中SO₄-S的浓度分别为77 mg L⁻¹、122 mg L⁻¹、170 mg L⁻¹、220 mg L⁻¹和229 mg L⁻¹。在初始土壤pH值为4.0时，3天后氧化/溶解增加不多。在较高的pH值下，21天后氧化达到最大值。这些结果表明，在免耕系统中秋季在地表施用亚硫酸钙应留出足够的时间让氧化/溶解反应发生，而不会引入与氧气清除相关的杀菌作用。因此，如果在春季种植前施用亚硫酸钙，土壤和一年生作物可以从添加的可溶性钙和硫酸根中受益。
