Carbon and carbonate analyses of DSDP Leg 27 samples@en

Leg 27 sediments were analyzed for total carbon and acid-insoluble (organic) carbon using a LECO acid-base Analyzer. The 3-cc sediment samples were first dried at 105°-110°C and then ground to a homogeneous powder. The ground sediment was redried and two samples, a 0.1-g and a 0.5-g sample, were then weighed into LECO clay crucibles. The 0.5-g sample was acidified with diluted hydrochloric acid and washed with distilled water. The sample was then dried and analyzed for acid-insoluble carbon, listed in the table as \"organic\" carbon. The 0.1-g sample was analyzed for total carbon without further treatment. If the result showed less than 10% CaCO3, an additional 0.5-g sample was analyzed for greater accuracy. The calcium carbon percentages were calculated as follows: (% total C-% organic C) * 8.33 = % CaCO3. Although other carbonates may be present, all acid-soluble carbon was calculated as calcium carbonate. All results are given in weight percent.

本研究采用LECO酸碱分析仪对第27航次沉积物的总碳与酸不溶（有机）碳开展分析。具体实验流程如下：首先将3 cm³的沉积物样品置于105℃~110℃下烘干，随后研磨为均匀粉末。研磨后的沉积物经再次烘干后，称取0.1 g与0.5 g两份样品，分别放入LECO黏土坩埚中。对0.5 g样品使用稀盐酸进行酸化处理，再以蒸馏水冲洗，经再次烘干后测定其酸不溶碳含量，该结果在表格中以“有机碳”列示。0.1 g样品无需额外处理，直接测定总碳含量。若测定结果显示碳酸钙（CaCO₃）含量低于10%，则额外称取一份0.5 g样品进行分析以提升检测精度。碳酸钙质量百分比的计算公式为：(总碳百分比 - 有机碳百分比) × 8.33 = 碳酸钙百分比。尽管样品中可能存在其他碳酸盐，但所有酸溶碳均按碳酸钙进行折算。所有结果均以质量百分比形式给出。