Ice sheets and glaciers have been shown to deliver large amounts of labile dissolved organic carbon (DOC) to downstream aquatic ecosystems, but recent studies may underestimate the release of DOC from mountain glaciers. To date, continuous measurements of DOC from mountain glaciers throughout entire glacier melt season are very limited. Here we present high-density data on DOC from two Asian mountain glaciers over a full melt season in 2013 and compile a global data set of DOC from 42 mountain glaciers. Based on our study and previously published DOC data, we estimate the storage and release of DOC associated with Asian mountain glaciers to be 8.8 to 13.8 Tg C and 0.19 Tg C/a, respectively. Rough extrapolation of glacier runoff to a global scale suggests that DOC release from mountain glaciers is on the order of 0.8 Tg C/a, which is 1.4 times higher than the most current estimates. The current release of DOC from mountain glaciers is therefore far more significant than previously thought and should be considered in future evaluation of the global carbon cycle.

Climate change (CC) and land use/cover change (LUCC) are the main drivers of streamflow change. In this study, the effects of CC and LUCC on streamflow regime as well as their spatial variability were examined by using the Distributed Hydrology Soil Vegetation Model (DHSVM) for the Beichuan River Basin in the northeast Tibetan Plateau. The results showed that CC increased annual and maximum streamflow in the upstream but decreased them in the downstream. CC also enhanced minimum streamflow in the whole river basin and advanced the occurrence of daily minimum streamflow. Temperature change exerted greater influence on streamflow regime than wind speed change did in most situations, but the impact of wind speed on streamflow reflected the characteristics of accumulative effects, which may require more attention in future, especially in large river basins. As for LUCC, cropland expansion and reservoir operation were the primary reasons for streamflow reduction. Cropland expansion contributed more to annual mean streamflow change, whereas reservoir operation greatly altered monthly streamflow pattern and extreme streamflow. Reservoir regulation also postponed the timing of minimum streamflow and extended durations of average, high, and low streamflow. Spatially, CC and LUCC played predominant roles in the upstream and the downstream, respectively.Hydrological response to CC and LUCC at global or large basin scales help us to understand the general condition of the impacts [7-9]. However, significant spatiotemporal variations of CC and LUCC in different regions indicate that regional or local responses deviate from the general conditions. Further, understanding regional or local hydrological responses is especially relevant to everyday people's life, as the knowledge can be directly used in water resources management [10-16]. Regional or localized knowledge is especially important for the Tibetan Plateau, which hosts the numerous smalland meso-scale headwaters of large rivers in Asia, including the Yellow, the Yangtze, the Mekong, the Indus, the Salween, and the Tarim, [17][18][19][20].Quite a few studies on CC and LUCC impacts on hydrology have substantially sprung up in the last 50 years [7]. The earliest review articles examined the LUCC effects on the basis of paired catchment studies [21-23], but the approach was only suitable for small catchments (<10 km 2 ) that have uniform vegetation cover and the same climate, contributing little to water resource management, which usually covers varied land cover types and climate conditions [7]. Recent studies employed statistical methods [24][25][26] and hydrological models [10,17,20,27,28] to assess the impacts from both CC and LUCC. Statistical methods are simple and effective [29], but reveal few physical mechanisms. Moreover, this method is generally applied to describe interannual and interdecadal hydrological processes due to the foundation of equations based on annual or multi-year average [30]. Physically-based hydrological models, especially distributed hydrologi...

Ancient Chinese sauce glaze porcelain has recently received growing attention for the discovery of epsilon iron oxide (ε-Fe2O3) crystals in glaze. In this work, we first confirm the presence of ε-Fe2O3 microcrystals, in large quantiteis, in sauce glaze porcelain fired at the Qilizhen kiln in Jiangxi province during the Southern Song dynasty. We then employed focused ion beam scanning electron microscopy (FIB-SEM) to investigate the three-dimensional microstructure of ε-Fe2O3 microcrystals, which revealed three well-separated layers (labeled, respectively, as LY1, LY2, and LY3 from the glaze surface to inside) under the glaze surface. Specifically, LY1 consists of well-defined dendritic fractal structure with high ordered branches at micrometers scale, LY2 has spherical or irregular-shaped particles at nanometers scale, while LY3 consists of dendrites with four, six, or eight primary branches ranging from several nanometers to around 1 μm. Given these findings, we proposed a process for the possible growth of ε-Fe2O3 microcrystals in ancient Chinese sauce glaze.

Climate warming has caused rapid shrinkage of glaciers in the Tibetan Plateau (TP), but the impact of glacier retreat on the chemical denudation rate remains largely unknown at the temperate glacial basins. The chemical weathering processes were examined at a temperate glacial basin (HLG) in the southeastern TP based on comprehensive data from the supraglacial meltwater, proglacial river water, precipitation and groundwater over two glacier melt seasons in 2008 and 2013. The concentrations of major ions and suspended sediments in river water exhibit a pronounced seasonality and display a close relationship with river discharge, suggesting a strong hydrological control on the chemical and physical weathering processes. Runoff chemistry is dominated by carbonate weathering and sulfide oxidation. HCO3−, Ca2+, and/or SO42− are the dominant ions in meltwater, river water, precipitation and groundwater. For river water, HCO3− and Ca2+ primarily come from calcite weathering, and SO42− is mainly derived from pyrite oxidation. Both solute and sediment fluxes are positively related to river discharge (r = 0.69, p < 0.01 for sediments). The solute flux and yields are 18,095–19,435 t·year−1 and 225–241 t·km−2·year−1, and the sediment load and yields are 126,390 t·year−1 and 1570 t·km−2·year−1, respectively. The solute yields, cationic denudation rate (CDR; 2850–3108 Σ*meq+ m−2·year−1) and chemical weathering intensity (CWI; 616–711 Σ*meq+ m−3·year−1) at HLG are higher than those at most basins irrespective of the lithology, suggesting more intense weathering in the TP in comparison to other glacial basins worldwide.

Ice sheets have been shown to deliver large amounts of labile iron (Fe) to aquatic ecosystems; however, the role of glaciers distinct from ice sheets in supplying labile Fe to downstream ecosystems is less well understood despite their rapid volume loss globally. Direct and continuous measurements of Fe from glaciers throughout an entire melt season are very limited to date. Here we present extensive seasonal data on 0.45‐μm‐filtered Fe (dFe) from three glaciers in Asia. Concentrations of dFe are negatively correlated with glacier discharge, and dFe yields are closely related to specific discharge. Based on our study and previously published dFe data, we estimate the release of dFe from Asian glaciers to be 23.8±14.1 Gg/a. We further compile a global data set of dFe from more than 12 glaciers, which, when combined with data on glacier discharge, suggest that the release of dFe from glaciers globally is on the order of 185±172 Gg/a. This finding suggests that glaciers may provide a substantial, but largely unrecognized source of potentially labile Fe, and may become increasingly important for the Fe biogeochemical cycle in a warming climate.