摘要
本文通过对北京古北口蟠龙山段明长城城墙砖缝间粘合剂样品的碘-淀粉实验和淀粉粒分析,发现长城粘合剂样品中残留有植物淀粉粒,碘-淀粉实验显红棕色,表明淀粉以支链淀粉为主,具糯性;镜下检测到的淀粉粒具十字消光特征,粒径大于10μm,具有粟类淀粉粒的一些形态特征。进一步通过对现代小米的糊化过程实验和淀粉粒形态变化对比分析,表明长城粘合剂样品中观察到的淀粉粒与现代小米加热后糊化-半糊化的淀粉粒相似。本研究发现了长城粘合剂中粘性植物添加料的直接证据,与史料记载的一些古建筑所使用的"糯米灰浆"有相似之处,但添加植物显然不是糯米。本研究丰富了对古代粘性植物材料的认识,为了解我国明代长城的建筑工艺及文物保护提供了依据。
Mortar,with its sticky content as the additive,plays a major role in the durability of the Great Wall. Altnougn some previous studies suggested that ＂sticky rice＂ was possibly used in samples of ancient mortar,there is no direct evidence to conclude which specific species of plant was employed. My study used a mortar sample from the Ming Great Wall at Gubeikou, Beijing,and applied starch analysis to identify the microfossil evidence of Poaceous crops. The finding was corroborated with an iodine test and a contrast experiment of the response of modern millet starch grains to boiling.
Four recognizable starch grains were detected from the mortar sample. The morphological characteristics of these four starch grains were not compatible with those of sticky rice. The grain sizes were bigger than 10μm. Furthermore, the iodine test showed brown color, indicating amylopectin. This led to the conclusion that macroscopically glutinous starch is the dominating type of starch in the additive.
For comparison,modern millet samples were boiled around 70 degree Celsius and sampled at 5min,20min, 40rain and 60rain. Starch analysis of those samples demonstrated that boiling caused millet starch grains to swell, losing diagnostic features and extinction crosses. The observations coincided with morphological characteristics of starch grains in Great Wall mortar samples.
My study provided direct microfossil evidence for glutinous plant content as the additive. The finding will also be applicable to ancient building restoration and preservation.
出处
《第四纪研究》
CAS
CSCD
北大核心
2013年第3期575-581,共7页
Quaternary Sciences
