Distributions of 'bomb C-14', biogeochemistry and elemental concentration in Hani mire peat profiles, NE China: Implications of environmental change

摘要

Two 50 - cm long peat cores from the Hani mire on the western slope of the Changbai Mountains, northeastern China, were collected for investigating physical, biological and geochemical processes of the peatland in response to recent climate change. The C-14 dating using accelerator mass spectrometry (AMS) on the peat cores provides "a nuclear bomb carbon curve" which is used for peat chronological construction. The sedimentation rate (SR) of Core S1 from a Sphagnum magenllanicum hummock in the Hani mire was about 0.98 cm/y and deposited from 1957-2008 CE, whereas the SR of Core S2 from S. palustre hummock (1 km apart from S1) was 1.59 cm/y and accumulated during 1976-2008. The discrepancy of the SRs may mainly be attributed to the different inorganic material supplies from surface runoff which affected growth of Sphagnum spp. at different sites, with lower rate corresponding to higher inorganic contents (higher Ti, Ca and Mg contents thus lower values of loss on ignition, LOI%). On the other hand, the two cores had similar values and variation trends in the pH, C/N, N and P contents, and dry bulk density (DBD), implying that the organic source and decomposition were similar under the same climatic conditions. The variations of TOC%, C/N and Pb content in the peat cores matched well with the 5-y running average of local annual precipitation record, with higher TOC% and C/N but lower Pb content corresponding to higher rainfall; and vice versa. These properties in the meso-oligotrophic peat sequences can reflect climatic changes. The recent rates of carbon accumulation (RERCA) for S1 and S2 calculated from the TOC%, DBD and SR were averaged 121.6 +/- 24.3 and 175.5 +/- 35.1 g/m(2)/y, respectively. (C) 2017 Elsevier Ltd and INQUA. All rights reserved.