Loss on ignition as a method for estimating organic and carbonate content in sediments: reproducibility and comparability of results
Loss on ignition as a method for estimating organic and carbonate content in sediments: reproducibility and comparability of results
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DOI：
10.1023/a:1008119611481
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发表时间：
2001-01-01
影响因子：
2.1
通讯作者：
Lemcke, G
中科院分区：
文献类型：
--
作者：
Heiri, O;Lotter, AF;Lemcke, G
进行了五次试验，以评估烧失量（LOI）法估计湖泊沉积物的有机质和碳酸盐含量时可能存在的偏差。在950 ℃下燃烧纯CaCO 3 2 h后，实现了准确和稳定的重量损失，而在530 ℃下纯石墨的LOI与样品尺寸和暴露时间直接相关，暴露2 h后仅达到可能的重量损失的40-70%，并且较小的样品比较大的样品更快地失去重量。标准化湖泊沉积物的实验显示，在550 degreesC下，初始重量损失很大，但样品在暴露64 h后继续以缓慢的速度减轻重量，这可能是挥发性盐、粘土矿物或金属氧化物的结构水或有机物初始燃烧后无机碳损失的影响。进一步的测试表明，在550摄氏度时，炉中心的样品比边缘的样品失去了更多的重量。在950 ℃时，这种模式仍然很明显，但差异变得可以忽略不计。同样，LOI取决于样本量。包括十个不同实验室的分析LOI质量控制实验使用每个实验室自己的LOI程序以及标准化LOI程序进行，以分析三种不同的沉积物。当每个实验室使用自己的方法时，在550 ℃下测量的实验室之间的LOI值的范围通常大于使用标准方法时的范围。这与950 ℃相似，尽管数值范围趋于更小。对于一个给定的沉积物，实验室内的LOI测量范围一般很小。个体方法和标准化方法的结果比较表明，结果中存在实验室特定的模式，这可能是由于实验室设备和/或处理的差异，这些差异不能通过标准化LOI程序来消除。影响LOI结果的因素包括样品大小、暴露时间、样品在炉中的位置和实验室测量。550 ℃下的LOI比950 ℃下的LOI更易受这些因素的影响。因此，我们建议分析人员在所用LOI方法中保持与燃点温度、暴露时间和样本量相关的一致性，并在参考该方法时包括有关这三个参数的信息。
Five test runs were performed to assess possible bias when performing the loss on ignition (LOI) method to estimate organic matter and carbonate content of lake sediments. An accurate and stable weight loss was achieved after 2 h of burning pure CaCO3 at 950 degreesC, whereas LOI of pure graphite at 530 degreesC showed a direct relation to sample size and exposure time, with only 40-70% of the possible weight loss reached after 2 h of exposure and smaller samples losing weight faster than larger ones. Experiments with a standardised lake sediment revealed a strong initial weight loss at 550 degreesC, but samples continued to lose weight at a slow rate at exposure of up to 64 h, which was likely the effect of loss of volatile salts, structural water of clay minerals or metal oxides, or of inorganic carbon after the initial burning of organic matter. A further test-run revealed that at 550 degreesC samples in the centre of the furnace lost more weight than marginal samples. At 950 degreesC this pattern was still apparent but the differences became negligible. Again, LOI was dependent on sample size.An analytical LOI quality control experiment including ten different laboratories was carried out using each laboratory's own LOI procedure as well as a standardised LOI procedure to analyse three different sediments. The range of LOI values between laboratories measured at 550 degreesC was generally larger when each laboratory used its own method than when using the standard method. This was similar for 950 degreesC, although the range of values tended to be smaller. The within-laboratory range of LOI measurements for a given sediment was generally small. Comparisons of the results of the individual and the standardised method suggest that there is a laboratory-specific pattern in the results, probably due to differences in laboratory equipment and/or handling that could not be eliminated by standardising the LOI procedure.Factors such as sample size, exposure time, position of samples in the furnace and the laboratory measuring affected LOI result?;, with LOI at 550 degreesC being more susceptible to these factors than LOI at 950 OC. We, therefore, recommend analysts to be consistent in the LOI method used in relation to the ignition temperatures, exposure times, and the sample size and to include information on these three parameters when referring to the method.