Tibetan Plateau Geladaindong black carbon ice core record(1843-1982):Recent increases due to higher emissions and lower snow accumulation

Black carbon(BC) deposited on snow and glacier surfaces can reduce albedo and lead to accelerated melt. An ice core recovered from Guoqu glacier on Mt. Geladaindong and analyzed using a Single Particle Soot Photometer(SP2) provides the ?rst long-term(1843-1982) record of BC from the central Tibetan Plateau. Post 1940 the record is characterized by an increased occurrence of years with above average BC, and the highest BC values of the record. The BC increase in recent decades is likely caused by a combination of increased emissions from regional BC sources, and a reduction in snow accumulation. Guoqu glacier has received no net ice accumulation since the 1980 s, and is a potential example of a glacier where an increase in the equilibrium line altitude is exposing buried high impurity layers. That BC concentrations in the uppermost layers of the Geladaindong ice core are not substantially higher relative to deeper in the ice core suggests that some of the BC that must have been deposited on Guoqu glacier via wet or dry deposition between 1983 and 2005 has been removed from the surface of the glacier, potentially via supraglacial or englacial meltwater.

Late Holocene glacier variations indicated by theδ18O of ice core enclosed gaseous oxygen in the central Tibetan Plateau

Theδ18O of ice core enclosed gaseous oxygen(δ18Obub)has been widely used for climate reconstruction in polar regions.Yet,less is known about its climatic implication in the mountainous glaciers as the lack of continuous record.Here,we present a long-term,continuousδ18Obub record from the Tanggula glacier in the central Tibetan Plateau(TP).Based on comparisons of its variation with regional climate and glacier changes,we found that there was a good correlation between the variation of theδ18Obub in this alpine ice core and the accumulation and melting of this glacier.The more developed the firn layer on glacier surface,the more positive theδ18Obub.Conversely,the more intense the glacier melting,the more negative theδ18Obub.Combined with the chronology of ice core enclosed gases,the glacier variations since the late Holocene in the central TP were reconstructed.The result showed that there were four accumulation and three deficit periods of glaciers in this region.The strongest glacier accumulation period was 1610-300 B.C.,which corresponds to the Neoglaciation.The most significant melting period was the last 100 years,which corresponds to the recent global warming.The Medieval Warm Period was relatively significant in the central TP.However,during the Little Ice Age,there was no significant glacier accumulation in the central TP,and even short deficit events occurred.Comparisons of the late Holocene glacier variation in the central TP with glacier and climate variations in the TP and the Northern Hemisphere showed that it was closely related to the North Atlantic Oscillation.

Sea Salt Sodium Record in a Shallow Ice Core from East Antarctica as a Potential Proxy of the Antarctic Sea Ice Extent in Southern Indian Ocean

Antarctic sea ice has experienced an increasing trend in recent decades,especially in the Ross Sea and Indian Ocean sectors.Sea ice variability affects greatly the maritime airmass transport from high latitude to Antarctic continent.Here we present a new ice core record of sea salt sodium(ssNa+)concentration at annual-resolution in the Princess Elizabeth Land spanning from 1990 to 2016,showing that this marker could be used as a potential proxy for reconstructing the sea ice extent(SIE)in the Southern Indian Ocean(SIO)given their significant correlation(R=-0.6,P<0.01)over the past 27 years.The correlation and composite analyses results show that the ssNa^+at the 202 km inland from Zhongshan Station and the SIE changes in SIO are closely related to the Indian Ocean Dipole(IOD)and Southern Annular Mode(SAM).The northward wind in central SIO occurs during positive IOD and the strengthened westerlies occurs during positive SAM,both of which favor increased sea ice in SIO and lead to the decreased ssNa^+concentration at the coastal site.

INTERACTION BETWEEN THE ENSO AND ASIAN MONSOON RECORDED IN DASUOPU ICE CORE FROM HIMALAYAS

Two of the most important climate interactions between the ocean and atmosphere are the Asian monsoon in the Indian Ocean and El Niň o\|Southern Oscillation (ENSO) in the Pacific Ocean. Previous analyses have variously concluded either that the Asian monsoon affects the ENSO or that the converse is true. But previous research about the relation between ENSO and Asian monsoon was focused on tropic or low\|latitude ocean. There was litter research on this relation in mid\|latitude continent.Dasuopu glacier is located in middle Himalayas (85 43°E, 28 23°N) at an altitude over 7000m . In 1996 and 1997, a collaboration between China and American scientists had a series of ice core drilling performed down to the bed of Dasuopu glacier. The core analysis now is still in progress. Here a record of oxygen isotopic composition and accumulation of the ice core provides a record of relation between ENSO phenomenon and the Asian monsoon.The growth rate of the core averages over 1m per year, which provides a high resolution to date layer. There is a strong seasonal cycle in δ 18 O, thus we used the seasonal δ 18 O cycle to count annual layers in the core. According to previous studying, we assigned the high δ 18 O extremes to winter. The complete δ 18 O time series indicates a increasing trend since 1980.The δ 18 O in the core correlate strongly with observed sea surface temperature (SST) over the last decade years. Thus, the δ 18 O in the ice core at the location of south Tibetan Plateau is a relatively simple proxy for SST, which is very different from that at the location of north Plateau where δ 18 O proxy for local temperature. Furthermore, the δ 18 O in the core is also corresponds with an index of monsoon strength, which demonstrates that the ice core successfully captures the large\|scale aspects of Asian monsoon behavior.Generally, negative δ 18 O anomalies in the core correspond with weak monsoons, warm SST and El Niň o, on the other hand, positive anomalies correlate with strong monsoons, cool SST and La Niň o. These imply interaction between the tropics and mid\|latitudes, channeled through the monsoon system.

Glaciochemical records from Naimona’Nyi ice core in the Himalayas

A 6-m ice core was recovered in 2004 from the Naimona＇Nyi Glacier, the middle Himalayas. Empirical orthogonal function （EOF） analysis on the major ion reveals that EOF1 represents the variations of majority of ions which may be originated from crustal aerosols. Comparing the calcium concentrations from the Naimona＇Nyi with these from Dasuopu, East Rongbuk and Guliya ice cores, it is observed that calcium, a good indicator of the input of crustal aerosol in snow, concentrates mostly in the Guliya ice core located on the northern Tibetan Plateau, and gradually decreases from west to east in the Himalayas.

A 290-a record of atmospheric circulation over the North Pacific from a Mt. Logan ice core, Yukon Territory

Calibrations between sodium （Na^＋） concentrations from a Mt. Logan ice core and sea level pressure （SLP） series show that Na^＋ concentrations are closely correlated with the autumn-time （September-October-November） Aleutian low （AleuLow）. A deepening of the AleuLow strengthens the transport of sea-salt aerosols from the North Pacific to the Mt. Logan region. The Mt. Logan Na^＋ record is used to develop a 292 a （1688-1979） reconstruction of the AleuLow revealing a dramatic intensification of atmospheric circulation over the North Pacific region since the 20th century. Mean SLP of the AleuLow was about 1 hPa lower during the 20th century than during prior periods. The strongest deepening of the AleuLow appeared in the 1950s. Significant correlations are also found between the Mt. Logan AleuLow proxy series and the Pacific decadal oscillation （PDO） and Pacific circulation （PC） index during the 20th century. Evolutionary spectral analysis of the proxy record shows significant periodicities from 15 to 30 a consistent with PDO fluctuations and the bidecadal oscillation of North Pacific atmosphere-ocean circulation. A period of 11 a in the AleuLow record may be associated with the Schwabe 11-a cycle of sunspot activity. Additional longer ice core records from this region will aid in the efforts to further understand the climatic change over the North Pacific region.

RECENT 200 YEARS CLIMATIC AND ENVIRONMENTAL RECORDS FROM THE FAR EAST RONGBUK ICE CORE, MT. QOMOLANGMA (EVEREST)

During the Sino\|American Expedition to Mt. Qomolangma in May 1997, a 41m ice core was recovered from an elevation of 6500m from the northern branch firn basin of the Far East Rongbuk Glacier in Mt. Everest. The ice core was dated down to 1814 by counting δ 18 O peaks and referring to the variations of β activity and major ion concentrations. The average annual accumulation is 224mm (ice equivalent). Five cold periods and five warm periods have been reconstructed from the ice core for the last 200 years and the general tendency of climatic change is warming, which is agree with the temperature change in the Northern Hemisphere. Also the climatic records in Far East Rongbuk ice core has good agreement with that in the Guliya ice core. This indicates that the climatic changes are consistent in the northwestern and southern Qinghai—Tibetan Plateau, and the ranges of climatic changes are larger in southern Plateau than that in northwestern Plateau. Though the δ 18 O variations has some negatively correlation with precipitation amount for short time scale, these do not effect δ 18 O changes reflecting temperature for long time scale.

A COMPARISON: PALAEOENVIRONMENTAL CHANGE RECORDS OF CHINESE LESS AND ANTARCTIC ICE CORES OVER LAST 150,000 YEARS

Studies on Chinese loess and a comparison with Antarctic ice cores provided a general pattern of global environmental change and the regional differentiation over last 150,000 years. Climatic change revealed by magnetic susceptibility of Linxia loess section in China was paralled with temperature variation revealed by δD of Vostok ice core over last 150,000 years, which indicates a pattern of climatic change tendencies on a long-scale (thousand years). However, the ranges of variation at the same phase, especially, during the last Inter-glacial age (80,000-140,000 a.B.P.) were more different between Chinese loess sections and Antarctic ice cores.

Variation of culturable bacteria along depth in the East Rongbuk ice core,Mt.Everest

Ice melt water from a 22.27 m ice core which was drilled from the East Rongbuk Glacier, Mt. Everest was incubation in two incubation ways： plate melt water directly and enrichment melt water prior plate, respectively. The abundance of cultivable bacteria ranged from 0-295 CFU mL-I to 0--1720 CFU mL-1 in two incubations with a total of 1385 isolates obtained. Comparing to direct cultivation, enrichment cultivation recovered more bacteria. Pigment-producing bacteria accounted for an average of 84.9% of total isolates. Such high percentage suggested that pigment production may be an adaptive physiological feature for the bacteria in ice core to cope with strong ultraviolet radiation on the glacier. The abundances of cultivable bacteria and pigment-producing isolates varied synchronously along depth： higher abundance in the middle and lower at the top and bottom. It indicated that the middle part of the ice core was hospitable for the microbial survival. Based on the physiological properties of the colonies, eighty-nine isolates were selected for phylogenetic analysis. Obtained 16S rRNA gene sequences fell into four groups： Firmicutes, Alpha-Proteobacteria, Gamma-Proteobacteria, and Actinobacteria, with the Firmicutes being dominant. Microbial compositions derived from direct and enrichment cultivations were not overlapped. We suggest that it is a better way to explorethe culturable microbial diversity in ice core by combining the approaches of both direct and enrichment cultivation.

An Unprecedented Record Low Antarctic Sea-ice Extent during Austral Summer 2022

Seasonal minimum Antarctic sea ice extent(SIE)in 2022 hit a new record low since recordkeeping began in 1978 of 1.9 million km^(2) on 25 February,0.17 million km^(2) lower than the previous record low set in 2017.Significant negative anomalies in the Bellingshausen/Amundsen Seas,the Weddell Sea,and the western Indian Ocean sector led to the new record minimum.The sea ice budget analysis presented here shows that thermodynamic processes dominate sea ice loss in summer through enhanced poleward heat transport and albedo-temperature feedback.In spring,both dynamic and thermodynamic processes contribute to negative sea ice anomalies.Specifically,dynamic ice loss dominates in the Amundsen Sea as evidenced by sea ice thickness(SIT)change,while positive surface heat fluxes contribute most to sea ice melt in the Weddell Sea.

250 years of accumulation, oxygen isotope and chemical records in a firn core from Princess Elizabeth Land, East Antarctica

A 51.85-m tim core collected from site DT001 （accumulation rate 127 kgm^-2a^-1, mean annual temperature -33.1 ℃） on Princess Elizabeth Land, East Antarctica, during the 1996-97 Chinese First Antarctic Inland Expedition has been analyzed for chemical composition and oxygen isotope ratio. A comparison between the seasonal variations of major ions was carried out in order to reduce the dating uncertainty, using the volcanic markers as time constrains. A deposition period of 251 years was determined. The calculated accumulation rates display an increasing trend before 1820, while after 1820, the trend of the accumulation is not obvious. Overall, temperature change in the region shows a slight increasing trend over the past 250 years. But, notably, a temperature decline of -2 ℃ is observed from 1860 to the present. This feature, at odds with the warming trend over the past century recorded in both hemispheres, likely reflects a regional characteristic related to the lack of a high latitude/low latitude link in the Southern Hemisphere circulation patterns. The results of the glaciochemical records of the firn core show that the mean concentrations of Cl^-, Na^＋ and Mg^2＋ are similar to those reported from other sites in East Antarctica. However, the mean concentration of Ca^2＋ is much higher than that reported from other regions, suggesting the influence of the strong local terrestrial sources in Princess Elizabeth Land. There is no evidence of a positive correlation between NO3^- concentrations and solar activity （11-year solar cycle and solar cycle length）, although solar proton events may account for some of the NO3^- peak values in the record.

A concise overview on historical black carbon in ice cores and remote lake sediments in the northern hemisphere

Black Carbon(BC),as a driver of environmental change,could significantly impact the snow by accelerating melting and decreasing albedo.Systematic documentation of BC studies is crucial for a better understanding of its spatial and temporal trends.This study reviewed the BC studies in the ice core and remote lake sediments and their sources in the northern hemisphere.The literature surveyed points to around 2.9 to 3.7 times increase of BC in the European Alps and up to a three-fold increase of BC in the Himalayan-Tibetan Plateau(HTP)after the onset of industrialization in Europe and Asia,respectively.BC concentration from Greenland ice core showed seven times increase with an interrupted trend after 1950's.South Asian emissions were dominant in the HTP along with a contribution from the Middle East,whereas Western European and local emissions were responsible for the change in BC concentration in the European Alps.In the Arctic,contributions from North America,Europe and Asia persisted.Similarly,a historical reconstruction of lake sediments records demonstrates the effects of emissions from long-range transport,sediment focusing,local anthropogenic activities,precipitation and total input of flux on the BC concentration.

Anthropogenic trace metals in an ice core at Vestfonna,Svalbard, Norway

A 211 m depth ice core observation was carried out at the top of the Vestfonna Ice Cap in Nordaustlandet, Svalbard, Norway in 1995. Chronology of the ice core was determined by tritium analysis and comparison to the volcanic eruption of Laki; the resulting accumulation rate is 0.34 0.35 m water eq.·yr -1 for the last 400 year. Concentrations of Al, V, Cr, Fe, Cu, Zn, As, Ag, Cd, Pb and U in an ice core have been determined by an inductively coupled plasma mass spectrometry (ICP MS) with a desolvated micro concentric nebulizer, which is a recent development and can achieve high sensitivity with low uptake rate of 60 mL/min. The concentrations of Pb, Cu, and Zn had increased from 1940s declined from 1970s to present. However, the profiles of Pb, Cu, and Zn were different and they seem to be influenced by the difference of sources. Since the ratios between Cu, Pb, and Zn in Svalbard is similar to that in French Alps, the source area of these elements is estimated to be Europe.

Source of major ions from an ice core of the No.12 Glacier in Laohugou Valley,Qilian Mountain

In June 2006,a 20.12 m shallow ice core was recovered from an elevation of 5,040 m in the northern branch firn basin of No.12 Glacier,Great Snow Mountain,in the western part of Qilian Mountain,China.Isotopes(δ 18 O),major soluble ions,and radionuclide(β-activity) measurements from the ice core revealed a 46-year record(1960-2006).In this paper,the method of sea-salt ion tracer,correlation analysis and trend analysis were used in this research to confirm the source of the chemical composition.The correlation analysis and HYSPLIT backward trajectory analysis suggests that atmospheric soluble dust species dominate the chemical signature.

Mineral and Sea-Salt Aerosol Fluxes over the Last 340 kyr Reconstructed from the Total Concentration of Al and Na in the Dome Fuji Ice Core

A quantitative analysis of the total concentrations of Al and Na in the Antarctic ice sheet during the past 340 kyr was performed by applying the acid digestion method to the Dome Fuji ice core. Atmospheric fluxes of mineral and sea-salt aerosol to Dome Fuji were calculated from the total concentration. The average fluxes of mineral aerosol to Dome Fuji in the periods of glacial maximum, 18.6 ± 10.1 mg·m–2·yr–1, were larger than the value in the interglacial periods, 3.77 ± 2.20 mg·m–2·yr–1. Conversely, the fluxes of sea-salt have no significant difference between the average value of glacial maximum, 130 ± 55 mg·m–2·yr–1, and that of interglacial, 111 ± 54 mg·m–2·yr–1. The results obtained in this study suggest that the variation of mineral aerosol flux in Dome Fuji, together with climate change, was much larger than that of sea-salt aerosol flux. This result may have occurred because the variety in the intensity of the source and transport during the glacial-interglacial cycle is more significant for mineral aerosol than that for sea-salt aerosol.

The pH value and electrical conductivity of atmospheric environment from ice cores in the Tianshan Mountains

Electrical Conductivity Measurement （ECM） from ice core is a representative index for atmospheric environmental change. The pH value and ECM from three shallow ice cores （each 3.85 m, 231 ice samples total） on Glacier No.1 at the headwater of Urumqi River, Glacier No.48 in Kuitun area, and Miaoergou Glacier in Hami area in the eastern Tianshan Mountains, western China, were measured and analyzed for atmospheric environment records research. Ice core record shows that the changing trend of pH and ECM in three sites in recent years is different： ECM in Kuitun increases with the ice depth change, but ECM in Hami and Urumqi Glacier No.1 ice cores show a decreasing trend. Average ECM value in Hami is much larger than other two sites, just as the dust concentration and ions concentration are also very high in this site. ECM records in all three sites are mainly affected by aerosol mineral dust of Central Asia, and correlative coefficients of ECM and mineral ions such as Ca^2＋, Mg^2＋, Na^2＋ are all significantly high. The pH value and ECM are also significantly high correlative coefficients in the eastern Tianshan Mountains. Comparison between the eastern Tianshan Mountains and other sites in western China, and Polar Regions, shows that the difference of ECM can very well reflect the spatial difference of worldwide atmospheric environment.

PROXY RECORD OF A FIRN-CORE FROM AN ALPINE GLACIER AND ITS IMPLICATION TO RECENT GLACIO-CLIMATIC VARIATIONS ON MT. YULONG, SOUTHEASTERN PART OF TIBETAN PLATEAU

Mt. Yulong, located in the eastern part of Tibetan Plateau, is the southmost present glaciation area both in China and Europe\|Asia continent,where distributes 19 typical sub\|tropics temperate glaciers. In the summer of 1999, a firn core, 10 10m long to the glacier ice, was successfully recovered in the accumulation area at the largest glacier (No.1 Baishui) on Mt. Yulong. Annual and seasonal variations of different climatic signals above the depth of 7 8m are apparent and five\|year snow accumulation can be clearly identified by the seasonal changes of isotopic and ionic composition, some higher values of electrical conductivity and pH values. These annual boundaries can be also verified by the positions of dirty refrozen ice layers at summer surface of each year. The mean annual net accumulation between the balance years of 94/95 and 97/98 are calculated to about 900mm water equivalent. The amplitude of isotopic changes becomes smaller with the increasing depth of the core and isotopic homogenization occurred below the depth of 7 8m. Concentrations of Ca 2+ and Mg 2+ are much higher than those of Na + and K +, reflecting that the air masses for precipitation came far from their marine sources and passed over a longer continental route. Cl - and Na + show well corresponding variation patterns in the firn profile,indicating their same genesis. Concentrations of SO 2- 4 and NO - 3 are low, reflecting very slight pollution caused by human activities in this area. According to the sum of net income recovered from the firn core and the estimated ablation amount, the average annual precipitation above the equilibrium line is estimated in the scope of 2250mm and 3200mm but it needed to be verified by long\|term observation of mass balance. As indicated by the trend of local climatic changes in last 50years, climatic signals in the firn core and recent observation at the terminal of glacier No.1 Baishui, the glaciers in Mt. Yulong start to advance in 1998 after continuous retreat from early 1980’s to late 1990’s.

Atmospheric Methane in Ice Cores

The reconstruction of air trapped in ice cores provides us the most direct information about atmospheric CH4 variations in the past history. Ice core records from the ＂Three Poles （Antarctica, Greenland and Tibetan Plateau）＂ reveal the detailed fluctuations of atmospheric CH4 concentration with time and are allowed to quantify the CH4 differences among latitudes. These data are indispensably in the farther study of the relationship between greenhouse gases and climatic change, and of the past changes in terrestrial CH4 emissions. Ice cores reconstruction indicates that atmospheric CH4 concentration has increased quickly since industrialization, and the present day＇s level of atmospheric CH4 （1800 ppby） is unprecedented during the past Glacial-Interglacial climate cycles.

Review of pre-processing technologies for ice cores

High-resolution ice core records covering long time spans enable reconstruction of the past climatic and environmental conditions allowing the investigation of the earth system's evolution. Preprocessing of ice cores has direct impacts on the data quality control for further analysis since the conventional ice core processing is time-consuming, produces qualitative data, leads to ice mass loss, and leads to risks of potential secondary pollution. However, over the past several decades, preprocessing of ice cores has received less attention than the improvement of ice drilling, the analytical methodology of various indices, and the researches on the climatic and environmental significance of ice core records. Therefore, this papers reviews the development of the processing for ice cores including framework, design as well as materials, analyzes the technical advantages and disadvantages of the different systems. In the past, continuous flowanalysis(CFA) has been successfully applied to process the polar ice cores. However, it is not suitable for ice cores outside polar region because of high level of particles, the memory effect between samples, and the filtration before injection. Ice core processing is a subtle and professional operation due to the fragility of the nonmetallic materials and the random distribution of particles and air bubbles in ice cores, which aggravates uncertainty in the measurements. The future developments of CFA are discussed in preprocessing, memory effect, challenge for brittle ice, coupling with real-time analysis and optimization of CFA in the field. Furthermore, non-polluting cutters with many different configurations could be designed to cut and scrape in multiple directions and to separate inner and outer portions of the core. This system also needs to be coupled with streamlined operation of packaging, coding, and stacking that can be implemented at high resolution and rate, avoiding manual intervention. At the same time, information of the longitudinal sections could be scanned andidentified, and then classified to obtain quantitative data. In addition, irregular ice volume and weight can also be obtained accurately. These improvements are recorded automatically via user-friendly interfaces. These innovations may be applied to other paleomedias with similar features and needs.

High-resolution mass spectrometric characterization of dissolved organic matter from warm and cold periods in the NEEM ice core

Dissolved organic matter(DOM) is an important component of ice cores but is currently poorly characterized. DOM from one Holocene sample(HS, aged at 1600–4500 B.P.) and one Last Glacial Maximum sample(LS, aged at 21000–25000 B.P.) from the North Greenland Eemian Ice Drilling(NEEM) ice core were analyzed by ultra-high resolution Fourier transform ion cyclotron resonance mass spectrometry(FT-ICR-MS). CHO compounds contributed 50% of the compounds identified in negative-ionization mode in these two samples, with significant contributions from organic N, S, and P compounds, likely suggesting that marine DOM was an important source in these samples. Overall, the chemical compositions are similar between these two samples, suggesting their consistent DOM sources. However, subtle differences in the DOM between these two samples are apparent and could indicate differences in source strength or chemistry occurring through both pre-and post-depositional processes. For example, higher relative amounts of condensed carbon compounds in the HS DOM(5%), compared to the LS DOM(2%), suggest potentially important contributions from terrestrial sources. Greater incorporation of P in the observed DOM in the LS DOM(22%), compared to the HS DOM(13%), indicate more active microbiological processes that likely contribute to phosphorus incorporation into the DOM pool. Although these two samples present only a preliminary analysis of DOM in glacial/interglacial periods, the data indicate a need to expand the analysis into a broader range of ice-core samples, geographical locations, and glacial/interglacial periods.