LOESS SEDIMENTARY ORGANIC MATTER RECORDS FROM THE CENTRAL CHINESE LOESS PLATEAU AND THE IMPLICATION OF C/N

C/N ratio is extensively used to reflect the sources of the organic matter in the lake sediments. In some districts, such as frozen soil distriets, the tropical zone and Mediterranean area, it indicates the degree of soil organic matter (SOM) degradation. However, there are few discussions about the implica-tion of C/N ratio in Chinese loess sediments until now. Therefore, we chose two phreatic profiles in Xifeng and Luochuan from the central Chinese Loess Plateau in arid semiarid area, and obtained the temporal dis-tribution of soil organic carbon and total nitrogen content since the last interglacial. The result shows that, the downcore distributions of magnetic susceptibility, TOC and TN content, and C/N ratio exhibit the similar trends with higher value in paleosol and lower in loess. Besides that, TN content is in the low range of 0. 03~0. 05% in the whole sequence. So, we preliminarily suggest that C/N ratio mainly re-spond to the input amount of the organie matter from the above coverage. Accordingly, C/N ratio is more likely to indicate the relative production of the above eoverage in temperate arid-semiarid loess sediments.