Abstract: Dissolved organic carbon (DOC) is an active component in the peatland carbon cycle. While previous studies mostly focus on the northern peatlands, knowledge of the DOC dynamics in peatlands located at the subtropical monsoon region is quite limited. In this study, we investigated the DOC concentration and chemistry in the peat pore water extracted from 15 longterm monitoring sites in the Dajiuhu peatland, a typical subtropical peatland in central China, using ultravioletvisible spectrum (UV-Vis) and PARAFAC modeling of excitation emission matrix (EEM). EEM data are fitted into three humiclike components. The UVvisible and fluorometric indices reveal that the peat pore water samples have relatively small apparent molecular size and high aromaticity. The vertical patterns further indicate that DOC in deeper layers has a relatively important contribution from microbederived fresh organic matter that is less humified. These results highlight that microbederived or microbeprocessed organic matter is an important component of peat pore water in subtropical peatlands, and vertical transport or selective preservation of DOC is an important factor affecting the carbon dynamics in this subtropical subalpine peatland.

Key words: dissolved organic carbon, peat pore water, EEMPARAFAC, vertical profile, Dajiuhu Peatland