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There are differences in the response of long-term mercury (Hg) deposition to climate change, so it is necessary to clarify the influencing factors of Hg deposition in different locations. The Dahu and Daping Swamps are located in the eastern and western parts of the Nanling Mountains in South China, respectively. They are asynchronous variations of Hg deposition reflected by the two swamps since the last deglaciation. Based on the comprehensive comparative analysis of physical, chemical, and biological proxies, it is indicated that Hg deposition changes in the Dahu and Daping mainly record the changes in Hg content in the catchment input from organic matter. The differences in organic matter sources, core surrounding environment, Hg sources and atmospheric sedimentation contribution are reasons associated with the catchment environment for the observed differences in swamp Hg deposition and the response to climate. In cold/dry periods, Hg adsorption by terrestrial organic matter in Dahu Swamp were more significant, while in warm/humid periods, Hg adsorption by endogenous organic matter in Daping Swamp and wet deposition of nearby Hg sources, were the main climate-related processes for their asynchronous response. In addition, Dahu and Daping Swamps show similarities and differences in their Hg deposition variations. In both swamps, multi-millennial (∼1000−2200yr) and multi-centennial cycles (∼300–500yr) were observed and may be related to the harmonic period of the Earth's precession cycle and the solar activity cycle. This study helps to understand the differences in response between sedimentary Hg and climate, and to understand the regional and global proxies used to record climate and environmental changes. • Hg deposition investigated in two swamps in the Nanling Mountains in South China. • Hg deposition in subtropical swamps responds to climate changes since the Last Deglaciation. • Changes in Hg deposition are asynchronous in the two swamps. • Low latitude climate processes affect EASM strength and Hg deposition in South China. • Millennial and centennial scale cycles in Hg deposition are also recorded. [ABSTRACT FROM AUTHOR]

An alpine wetland core was obtained to a depth of 4.0 m from the Fanjing Mountain in southwest China. Sections of the core were dated with 14C data obtained with high resolution mass spectrometry (AMS), and Holocene climate changes were inferred by categorizing predominant tree and fern vegetation identified from pollen and spore counts at various core depths. The temperature increased during 11.9–8.0 cal ka BP, and the warmest period was during 8.0–4.6 cal ka BP. Then, it gradually became cooler during the late Holocene. Our temperature estimates were in good agreement with the previous studies of the Holocene temperature in the Asian monsoon areas. There were two relatively wet periods of 10.7–8.0 cal ka BP and 4.6–2.6 cal ka BP. There was an asynchronous precipitation trend in the south, north and southwest China, which was probably due to the different monsoon impacts. In East Asian summer monsoon (EASM) area, the monsoon precipitation gradually transgressed northward during the early to middle Holocene and regressed southward during the late Holocene. Our results will be useful to improve the understanding of the coherent spatio-temporal patterns of climate evolution in EASM region in China. Image 1 [ABSTRACT FROM AUTHOR]

This study provides a 16.2-kyr record of mercury (Hg) deposition derived from a lacustrine sedimentary sequence in Dahu Swamp, eastern Nanling Mountains. Results indicate that changes in climatic conditions had a significant effect on Hg concentrations (Hg – C) and accumulation rates (Hg -AR). Multi-proxy records including dry density, grain size, geochemical elements, organic matter and pollen indicators were compared with Hg accumulation. The results revealed that the contributions of detrital input and atmospheric deposition were minor, and Hg accumulation in the sediments was closely related to changes in climatic conditions: relatively drier and colder climate would result in shrinkage of the lake water body thus favoring increased formation of organic-rich peat or gyttja and leading to enhanced absorption of Hg by organic matter and result in increases of Hg – C and Hg -AR in sediments, and vice versa. Our results indicate that variations of Hg accumulation in Dahu Swamp were greatly impacted by climate under the influences of solar insolation changes and shrinkage or expansion of ice sheets in high latitudes to the north. The results of this study provide an insight into the response of Hg accumulation to low latitude climate processes in the East Asian summer monsoon region. [ABSTRACT FROM AUTHOR]