Department of Renewable Resources, University of Alberta, Edmonton, Alberta, Canada T6G 2E3.
Chemosphere. 2011 Jul;84(4):457-63. doi: 10.1016/j.chemosphere.2011.03.034. Epub 2011 Apr 13.
The risk of soil acidification is high in the Athabasca oil sands region (AOSR) in Alberta, Canada, due to elevated SO(2) emission and the resultant acid deposition to sensitive, coarse-textured soils. Understanding the sulfate adsorption characteristics of soils sensitive to acidification will help establish critical loads of acid deposition in AOSR. Sulfate adsorption properties were evaluated and relationships between sulfate adsorption and soil properties were examined for soils in two contrasting watersheds (NE7 and SM8) in AOSR. The experimental data fitted well to both the Langmuir and the Freundlich models. The sulfate adsorption capacity was greater for soils in SM8 than in NE7 (p<0.01), even though it was relatively low in both watersheds as compared to other acid-sensitive soils in eastern North America. Based on the additional sulfate adsorbed when a soil was treated with 40mL of 200mg SO(4)(2-) L(-1) solution, the weakly developed Podzolic B horizon (Bfj)in NE7 could adsorb more sulfate than the Ae horizon while no difference was found among other horizons. In SM8, the Bfj and illuviated B (Bt) horizons had greater ability to adsorb sulfate than the other horizons, likely caused by the presence of muscovite in the Bfj and Bt horizons. The additional sulfate adsorbed accounted for about 80% of the total sulfate adsorption capacity and was correlated with pH(NaF) (soil pH extracted with 1 MNaF) and ΔpH(NaF)(the difference between pH(NaF) and pH measured with deionized water), with the following relationships: sulfate adsorption (mg SO(4)(2-) kg(-1))=exp(2.03 pH(NaF) - 18.0)+50.2 (R(2)=0.63, p<0.001) and sulfate adsorption (mg SO(4)(2-) kg(-1))=exp(1.83 ΔpH(NaF) - 6.57) + 48.9 (R(2)=0.70, p<0.001). The ΔpH(NaF) was likely a better indicator of the soil's sulfate adsorption capacity than pH(NaF) as the former excludes the effect of soil acidity. Our study indicates that the soil's capacity to adsorb sulfate should be considered in determining the critical load for acid deposition in AOSR in Alberta.
在加拿大阿尔伯塔省的阿萨巴斯卡油砂地区（AOSR），由于 SO(2)排放增加以及由此导致的酸沉降对敏感的粗质地土壤的影响，土壤酸化的风险很高。了解对酸化敏感的土壤中硫酸盐的吸附特性将有助于确定 AOSR 中酸沉降的临界负荷。对 AOSR 中两个具有代表性流域（NE7 和 SM8）的土壤进行了硫酸盐吸附特性评估，并研究了硫酸盐吸附与土壤性质之间的关系。实验数据与 Langmuir 和 Freundlich 模型拟合良好。尽管与北美东部其他敏感土壤相比，这两个流域的硫酸盐吸附能力相对较低，但 SM8 土壤的硫酸盐吸附能力大于 NE7 土壤（p<0.01）。基于用 40mL 200mg SO(4)(2-) L(-1)溶液处理土壤时额外吸附的硫酸盐，NE7 中的弱发育的灰化土 B 层（Bfj）比 Ae 层吸附更多的硫酸盐，而其他层之间没有差异。在 SM8 中，Bfj 和淋溶 B（Bt）层比其他层具有更大的硫酸盐吸附能力，这可能是由于 Bfj 和 Bt 层中存在白云母。额外吸附的硫酸盐约占总硫酸盐吸附能力的 80%，与 pH(NaF)（用 1 MNaF 提取的土壤 pH）和 ΔpH(NaF)（用去离子水测量的 pH(NaF)与 pH 之间的差异）相关，具有以下关系：硫酸盐吸附（mg SO(4)(2-) kg(-1))=exp(2.03 pH(NaF) - 18.0)+50.2（R(2)=0.63，p<0.001）和硫酸盐吸附（mg SO(4)(2-) kg(-1))=exp(1.83 ΔpH(NaF) - 6.57) + 48.9（R(2)=0.70，p<0.001）。与 pH(NaF)相比，ΔpH(NaF)可能是土壤硫酸盐吸附能力的更好指标，因为前者排除了土壤酸度的影响。我们的研究表明，在确定阿尔伯塔省 AOSR 中酸沉降的临界负荷时，应考虑土壤吸附硫酸盐的能力。
