State Key Laboratory of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi, Xinjiang, China.
PLoS One. 2012;7(8):e44334. doi: 10.1371/journal.pone.0044334. Epub 2012 Aug 31.
With increasing interest in the carbon cycle on arid land, there is an urgent need to quantify both soil organic carbon (SOC) and inorganic carbon (SIC) thus to assess various methods. Here, we present a study employing three methods for determinations of SOC and SIC in the Yanqi Basin of northwest China. We use an elemental analyzer for both SOC and SIC, the Walkley-Black method for SOC, a modified pressure calcimeter method for SIC, and a simple loss-on-ignition (LOI) procedure for determinations of SOC and SIC. Our analyses show that all three approaches produce consistently low values for SOC (1-14 g kg(-1)) and high values for SIC (8-53 g kg(-1)). The Walkley-Black method provides an accurate estimate of SOC with 100% recovery for most soil samples. The pressure calcimeter method is as accurate as the elemental analysis for measuring SIC. In addition, SOC and SIC can be accurately estimated using a two-step LOI approach, i.e., (1) combustion at 375°C for 17 hours to estimate SOC, and (2) subsequent combustion at 800°C for 12 hours to estimate SIC. There are strong linear relationships for both SOC and SIC between the elemental analysis and LOI method, which demonstrates the capability of the two-step LOI technique for estimating SOC and SIC in this arid region.
随着人们对干旱地区碳循环的兴趣日益增加，迫切需要定量测定土壤有机碳 (SOC) 和无机碳 (SIC)，从而评估各种方法。在这里，我们采用三种方法研究了中国西北的焉耆盆地，以测定 SOC 和 SIC。我们使用元素分析仪同时测定 SOC 和 SIC，采用 Walkley-Black 法测定 SOC，改良压力测钙计法测定 SIC，简单灼烧损失法（LOI）同时测定 SOC 和 SIC。我们的分析表明，所有三种方法都产生 SOC 的低值（1-14gkg-1）和 SIC 的高值（8-53gkg-1）。对于大多数土壤样品，Walkley-Black 法提供了 SOC 的准确估计值，回收率为 100%。压力测钙计法与元素分析法在测量 SIC 方面同样准确。此外，通过两步 LOI 法（1）在 375°C 下燃烧 17 小时来估计 SOC，（2）随后在 800°C 下燃烧 12 小时来估计 SIC，SOC 和 SIC 可以被准确估计。SOC 和 SIC 与 LOI 方法之间存在很强的线性关系，这表明两步 LOI 技术在该干旱地区估计 SOC 和 SIC 的能力。
