Study area: Urumqi Glacier No.1 Catchment in central Asia. Study focus: Chemical weathering at the basin scale is important process for understanding the feedback mechanism of the carbon cycle and climate change. This study mainly used the actual sampling data in 2013, 2014, and 2016, and the first collection from the literature in same catchment to analyze the seasonal and interannual characteristics of meltwater runoff, as well as cation denudation rate (CDR). New hydrological insights for the study region: The dominant ions of meltwater runoff are Ca2 +, HCO3- , and SO42-, which are mainly derived from calcite dissolution, feldspar weathering and sulfide oxidation. Meltwater runoff at Urumqi Glacier No.1 has higher concentrations of Ca2+ and lower concentrations of HCO3- than that from glaciers in Asia. Compared to 2006 and 2007, cation concentrations increased in 2013 and 2014, while SO42- concentration decreased. The daily ion concentration has seasonality and exhibits a negative relationship with discharge. Daily CDR is positively related to discharge and temperature. Annual CDR values range from 12.34 to 19.04 t/ km2/yr in 2013, 2014, and 2016, which are 1-1.7 times higher than those in 2006 and 2007 and higher than some glaciers in Asia. These results indicate that chemical weathering rate in the Urumqi Glacier No.1 catchment has increased with climate warming, and it is stronger than that of some glaciers in the Tibetan Plateau and surroundings.

Study area: Urumqi Glacier No.1 Catchment in central Asia. Study focus: Chemical weathering at the basin scale is important process for understanding the feedback mechanism of the carbon cycle and climate change. This study mainly used the actual sampling data in 2013, 2014, and 2016, and the first collection from the literature in same catchment to analyze the seasonal and interannual characteristics of meltwater runoff, as well as cation denudation rate (CDR). New hydrological insights for the study region: The dominant ions of meltwater runoff are Ca2 +, HCO3- , and SO42-, which are mainly derived from calcite dissolution, feldspar weathering and sulfide oxidation. Meltwater runoff at Urumqi Glacier No.1 has higher concentrations of Ca2+ and lower concentrations of HCO3- than that from glaciers in Asia. Compared to 2006 and 2007, cation concentrations increased in 2013 and 2014, while SO42- concentration decreased. The daily ion concentration has seasonality and exhibits a negative relationship with discharge. Daily CDR is positively related to discharge and temperature. Annual CDR values range from 12.34 to 19.04 t/ km2/yr in 2013, 2014, and 2016, which are 1-1.7 times higher than those in 2006 and 2007 and higher than some glaciers in Asia. These results indicate that chemical weathering rate in the Urumqi Glacier No.1 catchment has increased with climate warming, and it is stronger than that of some glaciers in the Tibetan Plateau and surroundings.

This study reviews the available and published knowledge of the interactions between permafrost and groundwater. In its content, the paper focuses mainly on groundwater recharge and discharge in the Arctic and the Qinghai-Tibet Plateau. The study revealed that the geochemical composition of groundwater is site-specific and varies significantly within the depth of the aquifers reflecting the water-rock interactions and related geological history. All reviewed studies clearly indicated that the permafrost thaw causes an increase in groundwater discharge on land. Furthermore, progressing climate warming is likely to accelerate permafrost degradation and thus enhance hydrological connectivity due to increased subpermafrost groundwater flow through talik channels and higher suprapermafrost groundwater flow. In the case of submarine groundwater discharge (SGD), permafrost thaw can either reinforce or reduce SGD, depending on how much pressure changes affecting the aquifers will be caused by the loss of permafrost. Finally, this comprehensive assessment allowed also for identifying the lack of long-term and interdisciplinary in situ measurements that could be used in sophisticated computational simulations characterizing the current status and predicting groundwater flow and permafrost dynamics in the future warmer climate.

A total of 256 water samples were collected from the river, precipitation, and permafrost active layer in a typical small alpine catchment during the ablation periods in 2020 and 2021. The results indicated that every water body was alkaline, and the TDS and EC concentrations were in the following order: precipitation Ca2+ & AP; Mg2+ and Na+ + K+ > Mg2+ > Ca2+, respectively; the anion concentration showed the order of SO42 � > Cl- > NO3 . The results revealed that permafrost and river water had similar geochemical compositions. Similar & delta;2H and & delta;18O values were also observed between river and permafrost water. Additionally, the water chemistry of rivers and permafrost revealed that the chemical weathering of carbonate and silicate rocks is an important source of riverine solutes; however, silicate weathering played a more crucial role. Both hydrochemistry and stable isotopes collectively indicated that there was a close hydraulic connectivity between the water content in river and permafrost active layer in the small alpine catchment. Based on the end-member mixing analysis model, the water in permafrost active layer and precipitation accounted for 62% and 38% of the runoff, respectively, indicating that it was dominated by permafrost during the ablation period. The warming and hu-midification of climate tend to facilitate permafrost degradation. Thus, studying the transformation of different water bodies in alpine regions is imperative to provide water resource security and sustainable development in alpine regions.

The permafrost headwater catchments in the Tibetan Plateau (TP) have experienced extensive permafrost degradation, which may cause major changes in riverine solutes. However, surface water hydrochemistry and its influencing factors in such catchments are poorly understood. Hydrochemistry data for different surface waters were obtained for the Yakou catchment in the Northeastern TP. The results indicate that the ionic and organic concentrations of frozen soil seeps (FSS) were higher on the north-facing slope compared to the south-facing slope, and that FSS may be involved in streamflow generation processes and in determining the spatial pattern of riverine solutes. The north-facing slope of the catchment has a thin active layer and wet moisture conditions compared to the south-facing slope; hence supra-permafrost water, with high ionic concentrations, can drain to the ground surface as FSS in the riparian zone and then recharge the surface ponding water and the main stream water. The high ionic concentrations of the supra-permafrost water and FSS can be attributed to intense rock weathering and evaporative effect, together with the high mobility of elements and the transport of organic matter. The tributaries, with low ionic concentrations, comprise a mixture of infiltrating precipitation and diluted supra-permafrost water. Carbonate weathering is the dominant weathering type within the catchment, but the weathering of evaporite and silicate is more important on the north-facing and south-facing slopes, respectively, and chemical weathering on the north-facing slope may be enhanced by strong physical erosion during repeated freeze-thaw cycles due to the wet conditions. The results indicate that the surface water hydrochemistry is heterogeneous on the different hillslope units, and that a thicker active layer under climate change may lead to a shift of hydrological and hydrochemical pathways, and thus a decrease in water and solute flux from the hillslopes, with underlying permafrost, to the river channel.

Arctic river basins are amongst the most vulnerable to climate change. However, there is currently limited knowledge of the hydrological processes that govern flow dynamics in Arctic river basins. We address this research gap using natural hydrochemical and isotopic tracers to identify water sources that contributed to runoff in river basins spanning a gradient of glacierization (0-61%) in Svalbard during summer 2010 and 2011. Spatially distinct hydrological processes operating over diurnal, weekly and seasonal timescales were characterized by river hydrochemistry and isotopic composition. Two conceptual water sources (meltwater' and groundwater') were identified and used as a basis for end-member mixing analyses to assess seasonal and year-to-year variability in water source dynamics. In glacier-fed rivers, meltwater dominated flows at all sites (typically >80%) with the highest contributions observed at the beginning of each study period in early July when snow cover was most extensive. Rivers in non-glacierized basins were sourced initially from snowmelt but became increasingly dependent on groundwater inputs (up to 100% of total flow volume) by late summer. These hydrological changes were attributed to the depletion of snowpacks and enhanced soil water storage capacity as the active layer expanded throughout each melt season. These findings provide insight into the processes that underpin water source dynamics in Arctic river systems and potential future changes in Arctic hydrology that might be expected under a changing climate. Copyright (c) 2013 John Wiley & Sons, Ltd.