The lightness of the paralic sediments collected from the top-54m of Borehole LZ908 taken from the southern coast of the Laizhou Bay was studied and several factors influencing the lightness of the sediments were discussed by comparing the lightness values obtained after different sample preparations.In addition,the feasibility for using the lightness as an environmental indicator of paralic sediments was also discussed.The measurements of lightness were performed twice,during which a Minolta CM-2002 spectrophotometer was used for measuring the original and fresh samples collected from the borehole and a Minolta CR400/410 system for air-dried and ground samples.The results indicate that the lightness values of the samples studied,especially those from the air-dried and grounded samples,show a prominent correlation to the calcium carbonate content and grain size which have been considered to be the proxies of palaoclimate,indicating that the lightness could be,as a proxy of calcium carbonate content,used for the study of the environment evolution of the paralic sediments.The inconsistency between the lightness values and the calcium carbonate contents may possibly be attributed to the properties and contents of non-carbonate components in the sediments.The correlation between lightness and grain size show that the higher the proportion of（31 μm in grain size,the bigger the lightness is,whereas the higher the proportion of（31 μm is,the smaller the lightness is.It can be seen from the twice measurements that dehydration,oxidation and grinding may possibly be the main reasons for the differences in the lightness varieties.
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