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As an important source, sink and pool of carbon, lake sediment plays an important role in carbon cycle. Inorganic carbon (IC) in lake sediment is abundant, however the role of inorganic carbon in lake systems in terrestrial carbon cycling remains less clear. In this paper, the spatial variations, source and transformation of IC in sediments of Lake Hulun were investigated and compared with typical lakes of Inner Mongolia Plateau by analyzing the influencing factors. The results showed that contents of total IC in surface sediment in Lake Hulun ranged from 17.2 to 66.7 mg g–1 with a mean of 42.6 mg g–1, and the pattern of spatial distribution showed obviously decreasing trend from southwest to northeast lake districts. The order size of IC fractions in surface sediment was in a sequence of EX (extracted by NaCl) < SAL (extracted by NaOH) < WAL (extracted by NH3·H2O) ⪡ SAC (extracted by HCl) < WAC (extracted by HO-NH2·HCl), the WAC and SAC fractions were the major fractions, accounted for 80% of total IC. In vertical distribution, the WAC and SAC fractions presented obviously opposite spatial distribution, indicted that these fractions could transform into each other in sediments. The ratio of IAP/Ksp in lake water ranged from 8.87 to 108.5, suggested that this lake had what it took to form the authigenic carbonate precipitation. A differential analysis study indicated that the mechanisms what made the difference of IC content in four lakes were multiple, the chemical properties and temperature of lake water, the defusion or dissolve of CO2, biomass and sediment environment were the key factors that might affect the contents of inorganic carbon in the lake sediment. [ABSTRACT FROM AUTHOR]

The reliability of the ratio between Artemisia and Chenopodiaceae pollen percentage (i.e. A / C) in differentiating vegetation and reflecting moisture conditions in arid and semi-arid regions has been disputed and this hindered its potential application in palaeoclimate reconstructions. In this paper, we investigated the A / C ratios of lake-centre surface sediment from 45 lakes in the Inner Mongolia Plateau and the Qaidam Basin in arid and semi-arid China, and numerically studied the relationships of A / C ratios with vegetation and moisture. We found that the A / C ratio of lake-centre surface sediments can be used as an effective index to differentiate desert and steppe and also can be used as a valid indicator to infer mean annual precipitation (MAP) in the Inner Mongolia Plateau and the Qaidam Basin in arid and semi-arid China. Moreover, the A / C ratio from lake-centre surface sediments is more reliable and robust than that of soil-surface samples in differentiating vegetation and reflecting moisture conditions, and this might be attributed to its larger pollen source area and regional representation. In addition, the (A − C)/(A + C) index helps to overcome the inherent weakness of non-linearity of the A / C ratio and may be useful in paleo-vegetation reconstruction. These findings provide useful references for pollen-based vegetation and climate reconstructions of lake cores in arid and semi-arid China. [ABSTRACT FROM AUTHOR]

Grain size is commonly used as a proxy to reconstruct past lake hydrology; however, published research rarely links grain size with modern processes, and uncertainties exist for interpretation. In this paper, we decompose the grain size frequency distributions (GSFD) for 196 lake surface sediments from 61 lakes and 9 reservoirs across the Inner Mongolia Plateau and adjacent areas and divide them into five GSFD components. We statistically analyze the relationship between the GSFD components and influencing variables to determine the taphonomic dynamics and their environmental implications. Within individual lakes, we found that GSFD component 4 (74.00–209.30 μm) and GSFD component 5 (209.30–592.00 μm) dominate near the lake margin and reduce toward the lake center in proportions. By contrast, GSFD component 2 (2.75–15.56 μm) increases toward the lake center. Therefore, the proportions of GSFD component 2, 4, and 5 reflect the relative distance to the lakeshore and allow inferences about lake area changes. We apply this large modern dataset to a sediment core obtained from Lake Wulanhushao (WLHS) on the Inner Mongolia Plateau and link the lake surface sediment-based GSFD components to BEMMA end-members of grain size records to define their environmental implications over the last 18.59 cal. kyrs BP. We found that the Lake WLHS has responded to the orbital and suborbital climate changes since the last deglaciation. Specifically, maximum lake transgression prevailed during the early to middle Holocene (11.70–7.10 cal. kyr BP), medium lake transgression dominated during 17.05–15.80 cal. kyr BP, and weak transgression developed during 14.60–12.90 cal. kyr BP. Maximum lake regressions prevailed before 17.05 cal. kyr BP, during 15.80–14.60 cal. kyr BP and 12.90–11.70 cal. kyr BP. Our reconstructed early Holocene maximum lake area is consistent with regional abiotic proxy-based moisture records, but contrasts with the regional biotic proxy-based moisture records, which reconstruct increasing moisture conditions. Our new method to determine lake area changes will provide valuable data to understand the climate dynamics of northern China. • We numerically revealed the environmental implications of grain size components of lake surface sediment. • Linking lake surface sediment grain size component to core end members provide basis for interpretations. • Maximum lake transgression prevailed during the early Holocene in northern China. • Abiotic proxies-based early Holocene lake transgression is distinct with biotic proxies' reconstructions. [ABSTRACT FROM AUTHOR]

Understanding the evolution of the Holocene East Asian summer monsoon (EASM) and vegetation response regimes can help predict the climatic variability and vegetation change of future warming. Here, we reconstructed Holocene vegetation and climate change based on pollen, grain size and percent organic matter from a lake sediment profile in Huitengxile Plateau of central Inner Mongolia, northern China. We found that temperate deciduous forest steppe and temperate mixed forest steppe prevailed under maximum EASM during the middle Holocene (~8.3–5.9 cal. kyr BP), with more open vegetation and a weak EASM prior to and following this period. The vegetation succession is consistent with regional records, suggesting a regional vegetation pattern, i.e., oak forest replacing birch and elm forest during the middle Holocene and pine forest expanding at the expense of birch and oak forest since ~6.0 cal. kyr BP. A regional synthesis suggests the maximum EASM began at 8.3–7.8 cal. kyr BP in northern China, indicating a significant delay when compared with published records from southern China. The maximum EASM in northern China ended at 5.9–5.5 cal. kyr BP, being similar or slightly delayed from that in southern China. • Maximum middle Holocene (~8.3 – ~5.9 cal. kyr BP) East Asian summer monsoon (EASM) in northern China • Asynchronous start and synchronous end of maximum EASM in northern and southern China • Synchronous forest succession in mountain area of marginal monsoon area • Elm forest disappeared at ~7.9 cal. kyr BP and oak forest expanded during 7.6–5.3 cal. kyr BP. [ABSTRACT FROM AUTHOR]

Abstract: Background: Recent studies suggest that central obesity is an important predictor of cardiovascular disease (CVD) in addition to overall obesity. Both inflammation and endothelial dysfunction are associated with increased risk of CVD. We examined the association between body mass index (BMI) and waist circumference (WC) with plasma concentrations of biomarkers of inflammation and endothelial dysfunction. Methods: We conducted a cross-sectional study of 2589 lean, moderately active participants aged 20years and older in Inner Mongolia, China. Overnight fasting blood samples were obtained to measure the biomarkers including C-reactive protein (CRP), soluble inter-cellular adhesion molecule-1 (sICAM-1), soluble E-selectin (sE-selectin), and angiotensin II. Height, body weight, and WC were measured by trained staff and BMI was calculated (kg/m2). Results: In univariate analysis, CRP, sICAM-1, and sE-selectin were all significantly higher among individuals with a higher BMI and WC. In multivariate analysis, each standard deviation (SD) increase in WC (9.6cm) was associated with about 46% higher risk (odds ratio [OR] 1.46, 95% confidence interval [CI] 1.21–1.76) of elevated CRP but a 1 SD increase in BMI (3.5kg/m2) was not associated with the risk of elevated CRP (OR 0.96, 95% CI 0.80–1.16). However, each SD increase in BMI was associated with about 30% higher risk of having elevated E-selectin (OR 1.30, 95% CI 1.08–1.55). Conclusions: WC is a stronger predictor of inflammation while BMI is a stronger predictor for endothelial dysfunction. These results suggest measuring both BMI and WC will help to assess the risk of CVD in the Chinese population. [Copyright &y& Elsevier]