This study investigated the effects a dilute solution of bleach (4% sodium hypochlorite), has on charcoal. We were particularly interested in considering if charcoal formed under different conditions of pyrolysis was differentially affected by this treatment, which is commonly used for the quantification of charcoal in sediments. We first produced a series of charcoal samples, under laboratory conditions (at temperatures between 250°C and 800°C and under oxygen limited conditions) and then measured total surface area of charcoal before and after treatment in a solution of 4% bleach. We found that charcoal formed ⩽400°C showed nearly complete bleaching after 24 h, while high temperature charcoal (>400°C) was much more resistant. These results indicate this treatment bleaches charcoal formed at lower temperatures: this means particles charred at low temperature may not be quantified in common optical counting or image analysis methods. This could have serious ramifications for sediment-based paleofire research as low intensity fire may be lost from a record, and the resulting fire history biased towards high intensity (high temperature) fires. Our findings suggest the need for a new, non-destructive method for extracting charcoal from sediment.

这项研究调查了漂白剂的稀释溶液（4% 次氯酸钠）对木炭的影响。我们特别感兴趣的是考虑在不同热解条件下形成的木炭是否受到这种处理的不同影响，这种处理通常用于沉积物中木炭的量化。我们首先在实验室条件下（温度在 250°C 到 800°C 和氧气限制条件下）生产了一系列木炭样品，然后测量了在 4% 漂白剂溶液中处理前后木炭的总表面积。我们发现，形成 ⩽400°C 的木炭在 24 小时后几乎完全漂白，而高温木炭 (>400°C) 的耐受性要强得多。这些结果表明这种处理可以漂白在较低温度下形成的木炭：这意味着在低温下烧焦的颗粒可能无法在常见的光学计数或图像分析方法中进行量化。这可能会对基于沉积物的古火研究产生严重影响，因为低强度火灾可能会从记录中消失，并且由此产生的火灾历史偏向于高强度（高温）火灾。我们的研究结果表明，需要一种新的、无损的方法来从沉积物中提取木炭。