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Bacteriohopanepolyols (BHPs) are lipid constituents of diverse bacteria and have great potential as taxonomically and environmentally diagnostic biomarkers. In order to examine their environmental behavior and potential for tracing biogeochemical processes, we analyzed BHPs and geohopanoids (the diagenetic products of BHPs) in soils and surface sediments from the middle Yangtze River catchment to the East China Sea (ECS) shelf. These data are compared to an up-to-date survey of BHP distributions in soils, including regions collectively covering the Arctic, temperate, subtropics, and tropics. Regional climatic differences, particularly temperature, likely exert an important control on BHP distributions in soils. In the aquatic (river-estuaryshelf) setting, BHP concentrations and structural diversity are substantially lower than in soils, suggesting that in aquatic environments either bacterial biodiversity is lower or there is not the same requirement for hopanoid synthesis. However, different aquatic regimes vary substantially: high BHP diversity and enhanced BHP production occur in the biogeochemically dynamic Yangtze estuary, whereas BHP distribution is uniform with much less structural diversity in the oligotrophic ECS open shelf. The R soil index, based on the relative abundances of soil-marker BHPs against bacteriohopanetetrol, is suggested as a new approach to trace soil organic matter input into marine sediments. The R soil indices decrease from the river to the ECS, correlating strongly with branched and isoprenoid tetraether indices and moderately correlating with δ 13 C of organic carbon values and the concentrations of higher plant biomarkers, demonstrating their ability to trace soil organic matter inputs at least to the ECS.

During the last decade, the distribution of branched glycerol dialkyl glycerol tetraethers (brGDGTs) in lacustrine sediments has been widely used to reconstruct past variations in lake temperature. A prerequisite for the application of brGDGTs to lacustrine paleoclimate reconstructions is to understand the sources of brGDGTs in lake systems and the processes that influence their distribution. In this study, we investigated the distribution of brGDGTs in core-top sediments from 35 lakes across China, with a broad mean annual air temperature (MAAT) range but a constrained pH range, to explore the effect of temperature. The results reveal a contrasting response of MBT'5ME and MBT'6ME to temperature in lake environments compared to that in soils. The sedimentary distributions of 5-and 6-methyl brGDGTs exhibit different relationships with temperature, with most of the latter being correlated to MAAT while the former responding to temperature by only hexamethylated compounds. In both global and Chinese soils, most 6-methyl brGDGTs have no relationship with MAAT but the distribution of 5-methyl brGDGTs is correlated with MAAT. The different behaviors suggest that both 5-and 6methyl brGDGTs-producing communities might be different in lakes and soils. In addition, in lakes from cold regions (MAAT < 5 °C), the brGDGT distribution correlates only with warm season temperatures (April to October) but exhibits no correlation with cold seasons, suggesting a seasonal bias in brGDGT production in these lakes. This bias towards the warm season is not found in lakes from warmer regions (MAAT > 5 °C). Based on these results we propose new temperature calibrations for paleotemperature reconstructions in Chinese alkaline lakes.Highlights 5-and 6-methyl brGDGTs measured in 35 Chinese lakes Seasonal bias towards warm months in cold region lakes Different responses to temperature between lakes and soils Highlights (for review)

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