Пути дальнего переноса пыли на ледники Кавказа и химический состав снега на Западном плато Эльбруса

We present and discuss the chronology of dust deposition events documented by the shallow firn and ice cores extracted on the Western Plateau, Mt. Elbrus (5150 m a.s.l.) in 2009, 2012 and 2013. Snow and ice samples were analysed for major ions and minor element concentrations including heavy metals. Dust layers are formed on the surface of the glaciers as a result of atmospheric transport of mineral dust and aerosol particles to the Caucasus region. Satellite imagery (SEVIRI), trajectory models, and meteorological data were used for accurate dating of each the dust layers revealed in the ice cores. Then we tried to determine origins of the dust clouds and to investigate their transport pathways with high resolution (50–100 km). It was found that the desert dust is deposited on Caucasus glaciers 3–7 times in a year and it comes mainly from deserts of the Middle East and more rarely from the Northern Sahara desert. For the first time average annual dust flux (264 µg/cm2 per a year) and average mass concentration (1.7 mg/kg) over the period 2007–2013 were calculated for this region. The deposition of dust resulted in elevated concentrations consists of mostly ions, especially Ca2+, Mg2+, K+, and sulphates. Dust originated from various sources in the Middle East, including Mesopotamia, or similar dust clouds passing over the Middle East are characterised by high concentrations of nitrates and ammonia that may be related to atmospheric transport of ammonium from agricultural lands that may explain high concentrations of ammonium in the dust originating from this region. Mean values of crustal enrichment factors (EF) for the measured minor elements including heavy metals were calculated. We believe that high content of Cu, Zn and Cd can be a result of possible contribution from anthropogenic sources. Studies of the Caucasus ice cores may allow obtaining new independent data on the atmosphere circulation and high-altitude environment of this region.Исследованы образцы из снежных шурфов и керна из неглубоких скважин, пробуренных на Западном плато Эльбруса на высоте 5100 м в 2009, 2012 и 2013 гг. Образцы снега и льда проанализированы на содержание основных соединений и микроэлементов, включая тяжёлые металлы. В результате переноса минеральных частиц на ледники Кавказа в снежно-фирновой толще формируются отчётливо различимые горизонты загрязнения. Анализ космических снимков SEVIRI, полей оптической толщины атмосферы, траекторий движения воздушных масс и метеорологических данных позволил определить первичные источники минеральных частиц для переноса пыли с высокой точностью (50–100 км). Cоставлена хронология событий переноса пыли. Установлено, что такие явления происходят на Кавказе 3–7 раз в год. Пыль принесена на ледники Эльбруса с Ближнего Востока и из Северной Африки. Выполнено первое для Кавказа прямое определение количества твёрдого вещества, выпадающего из атмосферы на поверхность на больших высотах – 264 мкг/см2 в год. Химический анализ образцов снега из горизонтов загрязнения, образовавшихся в 2009 г., показал высокое содержание нитратов, аммония и сульфатов, что связано с поступлением пыли из сельскохозяйственных районов в Месопотамии. Обнаружено повышенное содержание Cu, Zn и Cd по сравнению с естественным фоном, что может указывать на повышенный региональный фон этих элементов в Северной Африке и на Ближнем Востоке, а также на вероятный вклад антропогенных аэрозолей.

Holocene history of the Ullukam Glacier

Using instrumental archives, aerial photographs, satellite images, old maps, descriptions of early explorers and old photographs we identified and mapped nine front positions of the Ullukam Glacier (SW slope of Elbrus) for the period from the end of XIX to the early XXI centuries. In 1884–2009 glacier retreated by 775 m. It advanced from 1971 to 1987 (36 m). The glacier fluctuations in the previous period were reconstructed using geomorphologic data, lichenometry, modern and buried soil description and radiorarbon analyses. We identified three Little Ice Age moraines of almost equal magnitude when the Ullukam Glacier was 889 m longer than in 2009. Two later advances occurred in the first third to middle of XIX century and in 1870s The recent fluctuations of the Ullukam Glacier closely correspond to the retreat two other glaciers in Elbus area. The location of the buried soil in the valley of Ullukam glacier brings evidence that the glacier have not advanced lower than 2813 m a.s.l. at least during the last four thousand years

Ways of far-distance dust transport onto Caucasian glaciers and chemical composition of snow on the Western plateau of Elbrus

We present and discuss the chronology of dust deposition events documented by the shallow firn and ice cores extracted on the Western Plateau, Mt. Elbrus (5150 m a.s.l.) in 2009, 2012 and 2013. Snow and ice samples were analysed for major ions and minor element concentrations including heavy metals. Dust layers are formed on the surface of the glaciers as a result of atmospheric transport of mineral dust and aerosol particles to the Caucasus region. Satellite imagery (SEVIRI), trajectory models, and meteorological data were used for accurate dating of each the dust layers revealed in the ice cores. Then we tried to determine origins of the dust clouds and to investigate their transport pathways with high resolution (50–100 km). It was found that the desert dust is deposited on Caucasus glaciers 3–7 times in a year and it comes mainly from deserts of the Middle East and more rarely from the Northern Sahara desert. For the first time average annual dust flux (264 µg/cm2 per a year) and average mass concentration (1.7 mg/kg) over the period 2007–2013 were calculated for this region. The deposition of dust resulted in elevated concentrations consists of mostly ions, especially Ca2+, Mg2+, K+, and sulphates. Dust originated from various sources in the Middle East, including Mesopotamia, or similar dust clouds passing over the Middle East are characterised by high concentrations of nitrates and ammonia that may be related to atmospheric transport of ammonium from agricultural lands that may explain high concentrations of ammonium in the dust originating from this region. Mean values of crustal enrichment factors (EF) for the measured minor elements including heavy metals were calculated. We believe that high content of Cu, Zn and Cd can be a result of possible contribution from anthropogenic sources. Studies of the Caucasus ice cores may allow obtaining new independent data on the atmosphere circulation and high-altitude environment of this region

К голоценовой истории ледника Уллукам

Using instrumental archives, aerial photographs, satellite images, old maps, descriptions of early explorers and old photographs we identified and mapped nine front positions of the Ullukam Glacier (SW slope of Elbrus) for the period from the end of XIX to the early XXI centuries. In 1884–2009 glacier retreated by 775 m. It advanced from 1971 to 1987 (36 m). The glacier fluctuations in the previous period were reconstructed using geomorphologic data, lichenometry, modern and buried soil description and radiorarbon analyses. We identified three Little Ice Age moraines of almost equal magnitude when the Ullukam Glacier was 889 m longer than in 2009. Two later advances occurred in the first third to middle of XIX century and in 1870s The recent fluctuations of the Ullukam Glacier closely correspond to the retreat two other glaciers in Elbus area. The location of the buried soil in the valley of Ullukam glacier brings evidence that the glacier have not advanced lower than 2813 m a.s.l. at least during the last four thousand years.Представлена реконструкция колебаний ледника Уллукам во второй половине голоцена. На основе сравнения аэрофото- и космических снимков, старых фотографий и карт реконструировано девять положений языка ледника за последние 125 лет. С 1884 по 2009 г. ледник сократился в горизонтальной проекции на 775 м, а высота его фронта повысилась на 190 м. На основе датирования лихенометрическим методом установлено, что две молодые морены возникли в первой трети – середине XIX в. и в 1870-х годах. На расстоянии 1,5 км от современного конца ледника найдена погребённая почва, возраст которой, согласно радиоуглеродному датированию, составляет 3580±80 л.н. Ненарушенность почвенного профиля показывает, что ледник не спускался до высоты 2813 м, по крайней мере, в последние четыре тысячелетия, а возможно и с начала голоцена