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We developed a tree ring-width chronology of Abies georgei at the timber line in the Big Snow Mountain Scenic Area in northwestern Yunnan, China. The climate-tree growth response analysis indicated that temperature was the predominant regulator of A. georgei growth in this region. An annual mean minimum temperature (AMMT) reconstruction spanning A.D. 1837–2016 was developed with a linear regression model (y = 1.0x − 6e − 5) that accounted for 50.7% of the actual temperature variance during the common period (1960–2016). Based on the reconstructed temperature series, the warmer periods were 1840–1845, 1855–1865, 1880–1895, 1945–1965, and from 1995 until the present day, and the cold periods were 1870–1880, 1900–1930, and 1966–1980. By comparing our results with other regional tree ring records from surrounding areas, a distinctive amount of common warm and cold periods were found, indicating the reliability of our temperature reconstruction and suggesting that the climate in the study area was part of a large-scale climate system.

Sources and implications of black carbon (BC) and mineral dust (MD) on two glaciers on the central Tibetan Plateau were estimated based on in situ measurements and modeling. The results indicated that BC and MD accounted for ~11 ± 1% and 4 ± 0% of the albedo reduction relative to clean snow, while the radiative forcing varied between 11 and 196 and 1–89 W m−2, respectively. Assessment of BC and MD contributions to the glacier melt can reach up 88 to 434 and 35 to 187 mm w.e., respectively, contributing ~9–23 and 4–10% of the total glacier melt. A footprint analysis indicated that BC and MD deposited on the glaciers originated mainly from the Middle East, Central Asia, North China and South Asia during the study period. Moreover, a potentially large fraction of BC may have originated from local and regional fossil fuel combustion. This study suggests that BC and MD will enhance glacier melt and provides a scientific basis for regional mitigation efforts., Journal of Glaciology, 66 (256), ISSN:0022-1430, ISSN:1727-5652

Air pollutants can be transported to the pristine regions such as the Tibetan Plateau, by monsoon and stratospheric intrusion. The Tibetan Plateau region has limited local anthropogenic emissions, while this region is influenced strongly by transport of heavy emissions mainly from South Asia. We conducted a comprehensive study on various air pollutants (PM2.5, total gaseous mercury, and surface ozone) at Nam Co Station in the inland Tibetan Plateau. Monthly mean PM2.5 concentration at Nam Co peaked in April before monsoon season, and decreased during the whole monsoon season (June–September). Monthly mean total gaseous mercury concentrations at Nam Co peaked in July and were in high levels during monsoon season. The Indian summer monsoon acted as a facilitator for transporting gaseous pollutants (total gaseous mercury) but a suppressor for particulate pollutants (PM2.5) during the monsoon season. Different from both PM2.5 and total gaseous mercury variabilities, surface ozone concentrations at Nam Co are primarily attributed to stratospheric intrusion of ozone and peaked in May. The effects of the Indian summer monsoon and stratospheric intrusion on air pollutants in the inland Tibetan Plateau are complex and require further studies.

This paper presents an assessment of the Soil and Water Assessment Tool (SWAT) on a glaciated (Qugaqie) and a non-glaciated (Niyaqu) subbasin of the Nam Co Lake. The Nam Co Lake is located in the southern Tibetan Plateau, two subbasins having catchment areas of 59 km2 and 388 km2, respectively. The scores of examined evaluation indices (i.e., R2, NSE, and PBIAS) established that the performance of the SWAT model was better on the monthly scale compared to the daily scale. The respective monthly values of R2, NSE, and PBIAS were 0.94, 0.97, and 0.50 for the calibration period while 0.92, 0.88, and −8.80 for the validation period. Glacier melt contribution in the study domain was simulated by using the SWAT model in conjunction with the Degree Day Melt (DDM) approach. The conjunction of DDM with the SWAT Model ensued improved results during both calibration (R2=0.96, NSE=0.95, and PBIAS=−13.49) and validation (R2=0.97, NSE=0.96, and PBIAS=−2.87) periods on the monthly time scale. Average contribution (in percentage) of water balance components to the total streamflow of Niyaqu and Qugaqie subbasins was evaluated. We found that the major portion (99.45%) of the streamflow in the Niyaqu subbasin was generated by snowmelt or rainfall surface runoff (SURF_Q), followed by groundwater (GW_Q, 0.47%), and lateral (LAT_Q, 0.06%) flows. Conversely, in the Qugaqie subbasin, major contributor to the streamflow (79.63%) was glacier melt (GLC_Q), followed by SURF_Q (20.14%), GW_Q (0.13%), and LAT_Q (0.089%). The contribution of GLC_Q was the highest (86.79%) in July and lowest (69.95%) in September. This study concludes that the performance of the SWAT model in glaciated catchment is weak without considering glacier component in modeling; however, it performs reasonably well in non-glaciated catchment. Furthermore, the temperature index approach with elevation bands is viable in those catchments where streamflows are driven by snowmelt. Therefore, it is recommended to use the SWAT Model in conjunction with DDM or energy base model to simulate the glacier melt contribution to the total streamflow. This study might be helpful in quantification and better management of water resources in data scarce glaciated regions.

The nitrogen emission from household food consumption (NEHFC) has played a vital role in sustainability development. Recent changes in household dietary have significantly accelerated reactive nitr...

We measured black carbon (BC) with a seven-wavelength aethalometer (AE-31) at the Nam Co Lake (NCL), the hinterland of the Tibetan Plateau (TP) from May 2015 to April 2016. The daily average concentration of BC was 145 &plusmn, 85 ng m&minus, 3, increasing by 50% since 2006. The seasonal variation of BC shows higher concentrations in spring and summer and lower concentrations in autumn and winter, dominated by the adjacent sources and meteorological conditions. The diurnal variation of BC showed that its concentrations peaked at 9:00&ndash, 16:00 (UTC + 8), significantly related to local human activities (e.g., animal-manure burning and nearby traffic due to the tourism industry). The concentration-weighted trajectory (CWT) analysis showed that the long-distance transport of BC from South Asia could also be a potential contributor to BC at the NCL, as well as the biomass burning by the surrounding residents. The analyses of the absorption coefficient and absorption &Aring, ngstr&ouml, m exponent show the consistency of sourcing the BC at the NCL. We suggest here that urgent measures should be taken to protect the atmospheric environment at the NCL, considering the fast-increasing concentrations of BC as an indicator of fuel combustion.

Glacierized mountain environments can preserve and release mercury (Hg) and play an important role in regional Hg biogeochemical cycling. However, the behavior of Hg in glacierized mountain environments and its environmental risks remain poorly constrained. In this research, glacier meltwater, runoff and wetland water were sampled in Zhadang-Qugaqie basin (ZQB), a typical glacierized mountain environment in the inland Tibetan Plateau, to investigate Hg distribution and its relevance to environmental risks. The total mercury (THg) concentrations ranged from 0.82 to 6.98ng·L-1, and non-parametric pairwise multiple comparisons of the THg concentrations among the three different water samples showed that the THg concentrations were comparable. The total methylmercury (TMeHg) concentrations ranged from 0.041 to 0.115ng·L-1, and non-parametric pairwise multiple comparisons of the TMeHg concentrations showed a significant difference. Both the THg and MeHg concentrations of water samples from the ZQB were comparable to those of other remote areas, indicating that Hg concentrations in the ZQB watershed are equivalent to the global background level. Particulate Hg was the predominant form of Hg in all runoff samples, and was significantly correlated with the total suspended particle (TSP) and not correlated with the dissolved organic carbon (DOC) concentration. The distribution of mercury in the wetland water differed from that of the other water samples. THg exhibited a significant correlation with DOC as well as TMeHg, whereas neither THg nor TMeHg was associated with TSP. Based on the above findings and the results from previous work, we propose a conceptual model illustrating the four Hg distribution zones in glacierized environments. We highlight that wetlands may enhance the potential hazards of Hg released from melting glaciers, making them a vital zone for investigating the environmental effects of Hg in glacierized environments and beyond.

Humic-like substances (HULIS) are major components of light-absorbing brown carbon that play an important role in Earth's radiative balance. However, their concentration, optical properties, and sources are least understood over Tibetan Plateau (TP). In this study, the analysis of total suspended particulate (TSP) samples from central of TP (i.e., Nam Co) reveal that atmospheric HULIS are more abundant in summer than that in winter without obvious diurnal variations. The light absorption ability of HULIS in winter is 2-3 times higher than that in summer. In winter, HULIS are mainly derived from biomass burning emissions in South Asia by long-range transport. In contrast, the oxidation of anthropogenic and biogenic precursors from northeast part of India and southeast of TP are major sources of HULIS in summer.

Light-absorbing impurities (LAIs), such as organic carbon (OC), black carbon (BC), and mineral dust (MD), deposited on the surface snow of glacier can reduce the surface albedo. As there exists insufficient knowledge to completely characterize LAIs variations and difference in LAIs distributions, it is essential to investigate the behaviors of LAIs and their influence on the glaciers across the Tibetan Plateau (TP). Therefore, surface snow and snowpit samples were collected during September 2014 to September 2015 from Zhadang (ZD) glacier in the southern TP to investigate the role of LAIs in the glacier. LAIs concentrations were observed to be higher in surface aged snow than in the fresh snow possibly due to post-depositional processes such as melting or sublimation. The LAIs concentrations showed a significant spatial distribution and marked negative relationship with elevation. Impurity concentrations varied significantly with depth in the vertical profile of the snowpit, with maximum LAIs concentrations frequently occurred in the distinct dust layers which were deposited in non-monsoon, and the bottom of snowpit due to the eluviation in monsoon. Major ions in snowpit and backward trajectory analysis indicated that regional activities and South Asian emissions were the major sources. According to the SNow ICe Aerosol Radiative (SNICAR) model, the average simulated albedo caused by MD and BC in aged snow collected on 31 May 2015 accounts for about 13% ± 3% and 46% ± 2% of the albedo reduction. Furthermore, we also found that instantaneous RF caused by MD and BC in aged snow collected on 31 May 2015 varied between 4–16 W m − 2 and 7–64 W m − 2 , respectively. The effect of BC exceeds that of MD on albedo reduction and instantaneous RF in the study area, indicating that BC played a major role on the surface of the ZD glacier.

The concentrations, depositions and optical properties of precipitation DOC at three remote stations (Nam Co, Lulang and Everest) were investigated in the Himalayas and Tibetan Plateau (HTP). The results showed that their volume-weighted mean DOC concentrations were 1.05±1.01mgCL-1, 0.83±0.85mgCL-1 and 0.86±0.91mgCL-1, respectively, close to those of other remote areas in the world and lower than those of typical polluted urban cities. Combined with precipitation amounts, the DOC depositions at these three stations were calculated to be 0.34±0.32gCm-2yr-1, 0.84±0.86gCm-2yr-1 and 0.16±0.17gCm-2yr-1, respectively. The annual DOC deposition in the HTP was approximately 0.94±0.87TgC, the highest and lowest values appeared in the southeastern and northwestern plateau, respectively. The sources of DOC in the precipitation at these three stations were remarkably different, indicating large spatial heterogeneity in the sources of precipitation DOC over the HTP. Nam Co presented combustion sources from South Asia and local residents, Lulang showed biomass combustion source from South Asia, and Everest was mainly influenced by local mineral dust. The values of the MACDOC at 365nm were 0.48±0.47m2g-1, 0.25±0.15m2g-1, and 0.64±0.49m2g-1, respectively, for the precipitation at the three stations. All of these values were significantly lower than those of corresponding near-surface aerosol samples because precipitation DOC contains more secondary organic aerosol with low light absorption abilities. Additionally, this phenomenon was also observed in seriously polluted urban areas, implying it is universal in the atmosphere. Because precipitation DOC contains information for both particle-bound and gaseous components from the near surface up to the altitude of clouds where precipitation occurs, the MACDOC of precipitation is more representative than that of near-surface aerosols for a given region.

Equivalent black carbon (eBC) mass concentrations were measured by an aethalometer (AE-31) in the Nam Co, central Tibet from 2010 to 2014. Different from previous filter-sampling studies (Ming et al., J Environ Sci 22(11):1748–1756, 2010; Zhao et al., Environ Sci Pollut Res 20:5827–5838, 2013), the first high-resolution online eBC measurement conducted in central Tibet is reported here, allowing to discuss the diurnal variations as well as seasonal variabilities of eBC. Average daily eBC concentration was 74 ± 50 ng/m3, reflecting a global background level. Meteorological conditions influenced eBC concentrations largely at seasonal scale, which are higher in February–May but lower in June–January. The highest eBC concentrations (greater than 210 ng/m3) were more associated with the W and WSW winds smaller than 6 m/s. The diurnal variations of eBC showed plateaus from 10:00 to 15:00 with seasonal variations, associated with local anthropogenic activities, such as indigenous Tibetan burning animal waste and tourism traffic. The PBLHs showed a co-variance with eBC concentrations, implicating close sources. The aerosol optical depths derived from the MODIS data over the Nam Co Observatory Station (NCOS)-included sub-area (30° N–40° N, 90° E–100° E) showed significant relationship with eBC concentrations. This suggests that nearby or short-distance sources other than long-distance transported pollutants could be important contributors to eBC concentrations at the NCOS, different from the conclusions suggested by previous studies.

Global warming greatly affects glacier retreat, which in turn influences local water resources and sea level altitudes. We used Landsat Operational Land Imager (OLI) images to extract glacier outlines in the western Nyainqentanglha Range, then used TerraSAR-X/TanDEM-X images and SRTM-C DEM to calculate changes in glacier elevation using a differential interferometric synthetic aperture radar (DInSAR) approach. The decreasing rate of glacier elevation in the western Nyainqentanglha Range was −0.30 ± 0.07 m per year (m yr−1) from 2000 to 2014. The annual thinning rate of the northern slope (−0.46 ± 0.07 m yr−1) was faster than that of the southern slope (−0.24 ± 0.07 m yr−1). We investigated two exemplary glacier sites in details: Zhadang glacier on the northern slope and Gurenhekou glacier on the southern slope. The annual elevation change of 39 points on Zhadang glacier calculated by the DInSAR and Real Time Kinematic Global Position System (RTK-GPS) seperately have a correlation coefficient of 0....

To investigate the atmospheric aerosols of the Himalayas and Tibetan Plateau (HTP), an observation network was established within the region's various ecosystems, including at the Ngari, Qomolangma (QOMS), Nam Co, and Southeastern Tibetan (SET) stations. In this paper we illustrate aerosol mass loadings by integrating in situ measurements with satellite and ground-based remote sensing datasets for the 2011–2013 period, on both local and large scales. Mass concentrations of these surface atmospheric aerosols were relatively low and varied with land cover, showing a general tendency of Ngari and QOMS (barren sites) > Nam Co (grassland site) > SET (forest site). Daily averages of online PM2.5 (particulates with aerodynamic diameters below 2.5 µm) at these sites were sequentially 18.2 ± 8.9, 14.5 ± 7.4, 11.9 ± 4.9 and 11.7 ± 4.7 µg m−3. Correspondingly, the ratios of PM2.5 to total suspended particles (TSP) were 27.4 ± 6.65, 22.3 ± 10.9, 37.3 ± 11.1 and 54.4 ± 6.72 %. Bimodal mass distributions of size-segregated particles were found at all sites, with a relatively small peak in accumulation mode and a more notable peak in coarse mode. Diurnal variations in fine-aerosol masses generally displayed a bi-peak pattern at the QOMS, Nam Co and SET stations and a single-peak pattern at the Ngari station, controlled by the effects of local geomorphology, mountain-valley breeze circulation and aerosol emissions. Dust aerosol content in PM2.1 samples gave fractions of 26 % at the Ngari station and 29 % at the QOMS station, or ∼ 2–3 times that of reported results at human-influenced sites. Furthermore, observed evidence confirmed the existence of the aerodynamic conditions necessary for the uplift of fine particles from a barren land surface. Combining surface aerosol data and atmospheric-column aerosol optical properties, the TSP mass and aerosol optical depth (AOD) of the Multi-angle Imaging Spectroradiometer (MISR) generally decreased as land cover changed from barren to forest, in inverse relation to the PM2.5 ratios. The seasonality of aerosol mass parameters was land-cover dependent. Over forest and grassland areas, TSP mass, PM2.5 mass, MISR-AOD and fine-mode AOD were higher in spring and summer, followed by relatively lower values in autumn and winter. At the barren site (the QOMS station), there were inconsistent seasonal patterns between surface TSP mass (PM2.5 mass) and atmospheric column AOD (fine-mode AOD). Our findings implicate that HTP aerosol masses (especially their regional characteristics and fine-particle emissions) need to be treated sensitively in relation to assessments of their climatic effect and potential role as cloud condensation nuclei and ice nuclei.

Little is currently known about the trophic transfer behavior of short-chain chlorinated paraffins (SCCPs) in terrestrial ecosystems. The trophodynamics of SCCPs were investigated in a typical terrestrial food chain (plant-plateau pika-eagle) from the interior of the Tibetan Plateau with an altitude of 4730 m. Pervasive contamination by SCCPs was found in the Tibetan Plateau samples, and the average concentrations of SCCPs in soil, plant, plateau pika, eagle, and gut content of eagle samples were 81.6 ± 31.1, 173 ± 70.3, 258 ± 126, 108 ± 59.6, and 268 ± 93.9 ng/g (average ± standard deviation, dry weight, dw), respectively. The trophic magnification factor (TMF) of SCCPs was 0.37, implying the trophic dilution of SCCPs in this terrestrial food chain. The TMF values of individual congener groups were positively correlated with the values of log

In recent years, with the development of social app, the Internet has created a different interactive mode from the previous daily life, which makes the development of society gradually presents the trend of “gamification”. “Social gamification” makes the life systematically integrated into the competition activities. Therefore, we propose a new idea for the realization of a sustainable society under the trend of “social gamification” by combining strategy game ecology mining for the first time. Specifically, we use big data mining to analyze the attributes of the smurf (subsidiary account), and then extract discriminative features and compute a score for each attribute using machine learning, which could accurately locate all the smurf in the game. By banning the smurf, the game ecology is optimized to improve the player’s game experience. Meanwhile, this paper proposes appropriate operation strategies for players at different stages based on multi-level clustering. In the real society, smurf represents the citizens who disturb social order, and different types of players represent the pyramid structure of social classes. The measures in the game provide references for the construction of a sustainable society.

In an effort to understand the biogeochemical cycling and seasonal characteristics of atmospheric Hg, a total of 80 daily sampled total suspended particulates were collected at Lhasa, the largest city of Tibet, from April 2013 to August 2014 for particulate-bound Hg (Hg P ) analysis. Daily concentrations of atmospheric Hg P ranged from 61.2 to 831 pg m −3 with an average of 224 pg m −3 , which were unexpectedly comparable to those measured in most of the Chinese metropolises. Both the daily/monthly average Hg P concentrations were slightly but not significantly higher during the non-monsoon season than during the monsoon season. Together with the fact that there was lack of significant relationship between Hg P concentration and most meteorological parameters, no significant and distinct pattern for the seasonal characteristics of atmospheric Hg P could be mainly attributed to the almost equal emission strength of two principal anthropogenic Hg sources (i.e., industrial emission sources during the non-monsoon season, and vehicular traffic and religious sources during the monsoon season). Moreover, the Hg P dry deposition rate was estimated to be 35.3 μg m −2 yr −1 by using a theoretical model, which was significantly higher than those Hg wet fluxes. The elevated deposition rate implied that dry deposition may play an important role in the biogeochemical Hg cycling over the Tibetan Plateau.

A mass and energy balance-based glacier melt module was coupled with the spatially distributed hydrological soil vegetation model and used to simulate the basin-scale water and energy balance in the Zhadang glacier basin. Observed hourly meteorological data from 2011 to 2014 were used as model forcing data. The basin-scale simulations were evaluated at both the point and areal scales using albedo, temperature, and height change on the glacier surface, as well as the mass balance and streamflow of the whole basin. The analysis showed that the model could effectively reproduce the key elements of the energy and mass balance of the Zhadang basin. The analysis demonstrates that radiation was the most important energy component accounting for 80% of total surface energy. On average, glacier runoff contributed to 64% of the total basin discharge during the study period. The overall streamflow was controlled by the glacier mass balance in 2012 and 2014, while temperature and precipitation affected hydrological processes the most during 2011 and 2013. Both high temperature and precipitation resulted in high total basin streamflow but via different mechanisms. High temperatures increase glacier mass loss and glacier melt runoff, whereas high precipitation decreases glacier melt runoff but produces high runoff in nonglacier areas. The early onset of the Indian monsoon with high snowfall reduces glacier surface melt but sustains basin discharge, positively affecting for water resources.

Hourly speciated measurements of atmospheric mercury made in a remote, high-altitude site in the Tibetan Plateau revealed the first field observations of the reduction of reactive mercury in the presence of sunlight in the atmosphere. Measurements were collected over four winter months on the shore of Nam Co Lake in the inland Tibetan Plateau. The data was analyzed to identify sources and atmospheric transformations of the speciated mercury compounds. The absence of local anthropogenic sources provided a unique opportunity to examine chemical transformations of mercury. An optimization algorithm was used to determine the parameters of a chemical box model that would match the measured reactive mercury concentrations. This required the presence of a photolytic reduction reaction previously observed in laboratory studies and in power plant plumes. In addition, the model estimated the role of vertical mixing in diluting reactive gaseous mercury during the day, and the role of bromine chemistry in oxidizing gaseous elemental mercury to produce reactive gaseous mercury. This work provides further evidence of the need to add the photolytic reduction reaction of oxidized mercury into atmospheric transport models in order to better simulate mercury deposition.

The Himalayas were recently identified as a global hot spot for deep stratosphere-to-troposphere transport (STT) in spring. Although the STT in this region may play a vital role in tropospheric chemistry, the hydrological cycle and aquatic ecosystems in Asia, there is no direct measurement of a chemical stratospheric tracer to verify and evaluate its possible impacts. Here we use cosmogenic S-35 as a tracer for air masses originating in the stratosphere and transported downward. We measure concentrations of S-35 in fresh surface snow and river runoff samples collected from Mount Everest in April 2013 to be more than 10 times higher than previously reported by any surface measurement, in support of the Himalayas as a gateway of springtime STT. In light of this result, measurements of (SO2)-S-35 and (SO42-)-S-35 at Nam Co in spring 2011 are reanalyzed to investigate the magnitudes of stratospheric air masses from the Himalayas to the tropospheric sulfur cycle and surface O-3 level over the Tibetan Plateau. A simple one-box model reveals that the oxidative lifetime of SO2 is reduced in aged STT plumes. Triple oxygen isotopic measurements of sulfate samples suggest that enhanced O-3 levels may shift the oxidation pathway of SO2 in the troposphere, which may be constrained by further intensive sampling and measurements. Comparison with surface O-3 measurements and traditional meteorological tracing methods shows that S-35 is a potentially unique and sensitive tracer to quantify the contribution of stratospheric air to surface O-3 levels in fresh or aged STT plumes.

We combined the mercury passive sampling method and plant biomonitoring together to understand the long-term changes of atmospheric mercury concentrations on the Tibetan Plateau. Through the analysis of leaves of Androsace tapete that represent growing periods spanning the past decade, we explored the historical records of atmospheric mercury from 2006 to 2015. Mercury concentration was stable in the leaves of Androsace tapete during the period between 2006 and 2009, while a significant decrease occurred after the year of 2010. The decreasing trend is consistent with the monitoring data of the ground-based stations in other regions globally. Despite the potential uncertainties using a passive sampling method and biomonitoring technique, we suggest that Androsace tapete is a potential biomarker that could provide reliable and effective historical records of atmospheric mercury concentrations and offer new perspectives in monitoring mercury and perhaps other atmospheric pollutants in regions where long-term active monitoring was missing.

Perfluoroalkyl acids (PFAAs) are ubiquitous in the environment. They are prone to accumulate in organisms and have raised public attention in recent decades. Feather samples have been successfully applied as nondestructive indicators for several contaminants. However, a sophisticated analytical method for determining PFAAs in feathers is still lacking. In the present study, a series of conditions, such as the use of the solid-phase extraction cartridge type and extraction/digestion methods, were optimized for the analysis of 13 PFAAs in feathers. According to the spiked recoveries, a weak-anion exchange cartridge was chosen and the methanol was selected as the extraction solvent. In the present study, an optimized pretreatment procedure combined with high-performance liquid chromatography–electrospray ionization–tandem mass spectrometric (HPLC–ESI–MS/MS) method was established for the determination of PFAAs in feathers. The recoveries and method detection limits of the PFAAs ranged from 71 to 120% and 0.16 to 0.54 ng/g, respectively. Finally, 13 PFAAs in four accipiter feather samples from Nam Co Basin, Tibetan Plateau, were analyzed, indicating that PFOS was the predominant PFAA in accipiter feathers, with an average of 4.67 ng/g, followed by the short-chain PFAAs, PFBS and PFBA, with averages of 1.91 and 1.39 ng/g, respectively. These results partly indicated the current situation of PFAA pollution in the Nam Co Basin, especially the existence of short-chain PFAAs in this region.

Rapid change of alpine lakes in the Tibetan Plateau (TP) is a clear manifestation of regional-scale climate variability that can be investigated by quantifying the regional hydrological cycle. The degree-day model (DDM) coupled with the Soil and Water Assessment Tool (SWAT) model were used to quantify the water budget of the Nam Co Lake over the period of 2007 to 2013. Driven by local observed meteorological data, the coupled model was successfully validated with the observed lake levels (with R2 = 0.65, NSE = 0.61, and PBIAS = &minus, 2.26). Analysis of the water balance revealed that rapid enlargement of the Nam Co Lake was primarily associated with precipitation increase while glacier melt played its role as the potential secondary driver in lake expansion. However, temporal analysis of lake expansion displayed that supremacy of precipitation and glacier melt interchanged between the years. It was found that average annual relative contributions of the precipitation, including direct precipitation on the lake, and glacier melt to the lake were 57% (or 667 mm), and 43% (or 502 mm), respectively. Besides, it was observed that annual values of actual evapotranspiration (ET) from the lake, glaciated, and non-glaciated subbasins were 615 mm, 280 mm, and 234 mm respectively. The average annual glacier mass balance (GMB) of the Nam Co basin was &minus, 150.9 millimeter water equivalent (mm w.e.). The relatively high amount of glacier melt was a consequence of the substantial increase in annual temperature in the lake basin. This work is of importance for understanding the rapid water cycle in the TP under global warming. Moreover, this work will also be helpful in monitoring and sustaining the local ecosystem and infrastructure, which is under risk due to rapid lake expansion as a result of climate change in the TP.

Climate variables that control the annual cycle of the surface energy and mass balance on Zhadang glacier in the central Tibetan Plateau were examined over a 2 year period using a physically based energy-balance model forced by routine meteorological data. The modelled results agree with measured values of albedo, incoming longwave radiation, surface temperature and surface level of the glacier. For the whole observation period, the radiation component dominated (82%) the total surface energy heat fluxes. This was followed by turbulent sensible (10%) and latent heat (6%) fluxes. Subsurface heat flux represented a very minor proportion (2%) of the total heat flux. The sensitivity of specific mass balance was examined by perturbations of temperature (±1 K), relative humidity (±20%) and precipitation (±20%). The results indicate that the specific mass balance is more sensitive to changes in precipitation than to other variables. The main seasonal variations in the energy balance were in the two radiation components (net shortwave radiation and net longwave radiation) and these controlled whether surface melting occurred. A dramatic difference in summer mass balance between 2010 and 2011 indicates that the glacier surface mass balance was closely related to precipitation seasonality and form (proportion of snowfall and rainfall).

In snow and ice, light-absorbing particles (LAPs), such as black carbon (BC) and dust, accelerate the melting of Third Pole glaciers (TPGs). In this study, we revaluated LAP concentrations in the snow pits of TPGs (SP-TPGs), measured LAP mass absorption cross-sections (MACs), and simulated their effects on glacier darkening and melting based on the Spectral Albedo Model for Dirty Snow and a surface energy and mass balance model. The results indicated that because of their short distances to emission sources, the average BC concentrations measured in snow pits in the periphery of Third Pole were much higher than those measured in the inland Tibetan Plateau, and the average dust concentrations generally decreased from north to south. The average MACs of BC in the SP-TPGs varied from 3.1 to 7.7 m2 g−1 at 550 nm, most of the average spectral values were comparable in the visible and near-infrared bands to those calculated by Mie theory, except those in Urumqi Glacier No. 1 (UR), Syek Zapadniy Glacier (SZ), and Laohugou Glacier No.12 (LH), while the average spectral MACs of dust in the SP-TPGs were considerably smaller in magnitude than most of the variations measured in other regions. Compared with the pure snow surfaces, BC and dust played comparable roles in reducing albedo in UR, SZ, LH, and Renlongba Glacier, whereas BC was the most prominent absorber in the other glaciers. The combined effect of BC and dust accelerated melting by 30.4–345.9 mm w.e. (19.7–45.3% of the total mass balance) through surface albedo darkening (0.06–0.17) and increased radiation absorption (25.8–65.7 W m−2) within one month of the ablation season. This study provides a new data set of LAP concentrations and MACs and helps to clarify the roles of these factors in the cryospheric environment of the Third Pole.