Corrected index properties for ODP Leg 127 and 128 sites

During Legs 127 and 128, we found a systematic error in the index property measurements, in that the wet bulk density, grain density, and porosity did not satisfy well-established interrelationships. We have found that an almost constant difference exists between the weight of water lost during drying and the volume of water lost. This discrepancy is independent of volume or water content of the sample. The water losses should be equal because the density of water is close to 1.0 g/cm**3. The pycnometer wet volume measurement has been identified as the source of the systematic error. The wet volume on average is 0.2 cm**3 too low. For the rare cases when the water content is negligible, there is no offset. The source of the wet volume error results from the partial vapor pressure of water in the pycnometer cell. Newly corrected tables of index properties measured during Legs 127 and 128 are included. The corrected index properties are internally consistent. The data are in better agreement with theoretical models that relate the index properties to other physical properties, such as thermal conductivity and acoustic velocity. In future, a standard volume sampler should be used, or the wet volume should be calculated from the dry volume and the water loss by weight.在第127和128航次期间，我们在指标物性测量工作中发现了一处系统误差：湿体积密度、颗粒密度与孔隙率未满足公认的内在关联关系。我们观测到，干燥过程中流失的水的质量与体积之间几乎存在恒定差值。该偏差与样品体积或含水量均无关。由于水的密度接近1.0 g/cm³，理论上二者的流失量应当相等。经确认，比重瓶湿体积测量环节是此次系统误差的来源，湿体积平均偏低0.2 cm³。仅在含水量可忽略不计的极少数场景下，不存在该偏差。该湿体积误差的根源在于比重瓶腔体内水的分蒸气压。本次数据集纳入了第127和128航次所测得指标物性的修正数据表，修正后的指标物性数据具备内部自洽性，且与将指标物性与导热系数、声速等其他物理性质关联的理论模型契合度更高。未来应采用标准体积采样器，或通过干体积与重量法测得的失水率计算湿体积。