РЕНТГЕНОФЛУОРЕСЦЕНТНОЕ ОПРЕДЕЛЕНИЕ БРОМА В ДОННЫХ ОТЛОЖЕНИЯХ ОЗЕР ДЛЯ ПАЛЕОКЛИМАТИЧЕСКИХ ИССЛЕДОВАНИЙ

One of the signals of changing paleoclimate is the concentration of bromine which is increased in the warm periods and correlated with the content of organic matter in sediments. A conventional wavelength dispersive X-ray fluorescence analysis (WDXRF) and total reflection X-ray fluorescence analysis (TXRF) have been applied to study the bromine distributions in the sediments ofLakeBaikal andLakeKhara-Nur. In order to carry out WDXRF, the samples weighing about 200-300 mg with diameter of10 mm were pressed as tablets on the boric acid base; the bromine concentrations were calculated by the internal standard method with correction using fundamental parameters. For TXRF measurements the powdered sample weighing 20 mg was suspended in the surface-active solution of Triton X-100 and Ge solution was added for the internal standardization. The detection limits of bromine were 1 mg/kg and 0.4 mg/kg for WDXRF and TXRF respectively. It was shown that the results of the bromine determination obtained with different XRF techniques were comparable to each other and can be used for palaeoclimatic reconstruction. One of the main advantages of the offered WDXRF and TXRF techniques is the lack of necessity for the standard reference materials of sediments with certified content of bromine.Keywords: X-ray fluorescence analysis, XRF, TXRF, SRXRF, sediments, bromine, paleoclimate(Russian) DOI: http://dx.doi.org/10.15826/analitika.2015.19.4.008G.V. Pashkova1*, E.V. Ivanov2,T.S. Aisueva2, А.А. Shchetnikov1, Yu.N. Markova2, A.L. Finkelshtein2 1Institute of the Earth’s Crust, Siberian Branch of Russian Academy of Sciences, Irkutsk,  Russian Federation2Vinogradov Institute of Geochemistry, Siberian Branch of Russian Academy of Sciences, Irkutsk, Russian FederationОценена возможность использования традиционного рентгенофлуоресцентного метода анализа (РФА) с волновой дисперсией (РФА ВД) и РФА с полным внешним отражением (РФА ПВО) для изучения распределения брома по глубине керна на примере донных отложений о. Байкал и о. Хара-Нур. Для проведения РФА ВД излучатели массой 200-300 мг и диаметром10 мм прессовали в виде таблеток на подложке из борной кислоты; содержания брома рассчитывали способом внутреннего стандарта с коррекцией с использованием фундаментальных параметров. Для РФА ПВО из измельченной пробы массой 20 мг готовили суспензию на основе поверхностно-активного вещества Triton X-100, в которую добавляли внутренний стандарт – раствор Ge. Пределы обнаружения брома равны 1 мг/кг и 0.4 мг/кг для РФА ВД и РФА ПВО соответственно. Показано, что результаты определения брома, полученные с помощью разных вариантов РФА, сопоставимы между собой и могут быть использованы при палеоклиматических реконструкциях. Одним из основных преимуществ предлагаемых методик РФА ВД и РФА ПВО является отсутствие необходимости наличия стандартных образцов донных отложений с аттестованным содержанием брома.Ключевые слова: рентгенофлуоресцентный анализ, РФА, РФА ПВО, РФА СИ, донные отложения, бром, палеоклимат.DOI: http://dx.doi.org/10.15826/analitika.2015.19.4.00

X-ray fluorescence determination of bromine in lake sediments for paleoclimatic studies

Оценена возможность использования традиционного рентгенофлуоресцентного метода анализа (РФА) с волновой дисперсией (РФА ВД) и РФА с полным внешним отражением (РФА ПВО) для изучения распределения брома по глубине керна на примере донных отложений о. Байкал и о. Хара-Нур. Для проведения РФА ВД излучатели массой 200-300 мг и диаметром 10 мм прессовали в виде таблеток на подложке из борной кислоты; содержания брома рассчитывали способом внутреннего стандарта с коррекцией с использованием фундаментальных параметров. Для РФА ПВО из измельченной пробы массой 20 мг готовили суспензию на основе поверхностно-активного вещества Triton X-100, в которую добавляли внутренний стандарт - раствор Ge. Пределы обнаружения брома равны 1 мг/кг и 0.4 мг/кг для РФА ВД и РФА ПВО соответственно. Показано, что результаты определения брома, полученные с помощью разных вариантов РФА, сопоставимы между собой и могут быть использованы при палеоклиматических реконструкциях. Одним из основных преимуществ предлагаемых методик РФА ВД и РФА ПВО является отсутствие необходимости наличия стандартных образцов донных отложений с аттестованным содержанием брома.One of the signals of changing paleoclimate is the concentration of bromine which is increased in the warm periods and correlated with the content of organic matter in sediments. A conventional wavelength dispersive X-ray fluorescence analysis (WDXRF) and total reflection X-ray fluorescence analysis (TXRF) have been applied to study the bromine distributions in the sediments of Lake Baikal and Lake Khara-Nur. In order to carry out WDXRF, the samples weighing about 200-300 mg with diameter of 10 mm were pressed as tablets on the boric acid base; the bromine concentrations were calculated by the internal standard method with correction using fundamental parameters. For TXRF measurements the powdered sample weighing 20 mg was suspended in the surface-active solution of Triton X-100 and Ge solution was added for the internal standardization. The detection limits of bromine were 1 mg/kg and 0.4 mg/kg for WDXRF and TXRF respectively. It was shown that the results of the bromine determination obtained with different XRF techniques were comparable to each other and can be used for palaeoclimatic reconstruction. One of the main advantages of the offered WDXRF and TXRF techniques is the lack of necessity for the standard reference materials of sediments with certified content of bromine

The human environment of the Xiongnu Ivolga Fortress (West Trans-Baikal area, Russia): Initial data

© 2019 Elsevier Ltd and INQUA This article deals with the initial data coming from the Ivolga Fortress archaeological site located in the Trans-Baikal area. Multidisciplinary investigations were performed, including palynological and archaeozoological studies. Palynological data reflects the palaeovegetation of the region and shows the abundance of forested landscapes in the past. The fauna was made of molluscs (7 taxa), fishes (14 taxa), amphibians (3 taxa), reptiles (1 taxon), and wild mammals (18 taxa). The species composition and environmental data show the mosaic character of landscapes surrounding the ancient settlement: taiga and forest, steppe and forest-steppe biotopes, as well as meadows in the Selenga valley with the prevalence of open steppe spaces. In the era of the Xiongnu Empire 209 BC – 48 AD (Kradin, 2001) the climate was less arid than it is now

Upper Paleolithic site Tuyana – a multi-proxy record of sedimentation and environmental history during the Late Pleistocene and Holocene in the Tunka rift valley, Baikal region

© 2019 Elsevier Ltd and INQUA The complex study of the 3.5-m thick section of the multi-genetic sediments of the Late Paleolithic Tuyana site (Tunka rift valley, Baikal region) resulted in a first detailed record of the change in environment and climate of the ancient humans’ habitation in the Tunka rift valley in Late Pleistocene and Holocene in the interval of >36 ka cal BP until Late Holocene. Sedimentation processes in the section are characterized by multiple remobilizations. Redeposition traces are most strongly expressed in МIS 3 sediments. Apparently, an intensive transient removal of slope sediments took place here at МIS 2. The common tendency of the natural environment and habitation conditions of the ancient humans in the Tunka valley show domination of the open and relatively dry tundra-steppe with areas of forests vegetation in the end of MIS 3, mostly dry steppes with limited forest-tundra and tundra associations in MIS 2 with the spread of boreal taiga in Holocene. Tunka rift valley around 50 ka cal BP had already been settled by humans and was visited by them during the periods of relatively favorable climatic conditions: during the MIS 3 optimums and in Middle Holocene. The Tuyana Paleolithic complexes have extensive analogies with the Aurignacian industries of Eurasia. The closest similarities could be drawn with the complexes of Kulbulakien culture in Middle Asia and Kazakhstan. The Tuyana site is currently the most eastern occurrence of the Aurignacian culture in Eurasia

Upper Paleolithic site Tuyana – a multi-proxy record of sedimentation and environmental history during the Late Pleistocene and Holocene in the Tunka rift valley, Baikal region

© 2019 Elsevier Ltd and INQUA The complex study of the 3.5-m thick section of the multi-genetic sediments of the Late Paleolithic Tuyana site (Tunka rift valley, Baikal region) resulted in a first detailed record of the change in environment and climate of the ancient humans’ habitation in the Tunka rift valley in Late Pleistocene and Holocene in the interval of >36 ka cal BP until Late Holocene. Sedimentation processes in the section are characterized by multiple remobilizations. Redeposition traces are most strongly expressed in МIS 3 sediments. Apparently, an intensive transient removal of slope sediments took place here at МIS 2. The common tendency of the natural environment and habitation conditions of the ancient humans in the Tunka valley show domination of the open and relatively dry tundra-steppe with areas of forests vegetation in the end of MIS 3, mostly dry steppes with limited forest-tundra and tundra associations in MIS 2 with the spread of boreal taiga in Holocene. Tunka rift valley around 50 ka cal BP had already been settled by humans and was visited by them during the periods of relatively favorable climatic conditions: during the MIS 3 optimums and in Middle Holocene. The Tuyana Paleolithic complexes have extensive analogies with the Aurignacian industries of Eurasia. The closest similarities could be drawn with the complexes of Kulbulakien culture in Middle Asia and Kazakhstan. The Tuyana site is currently the most eastern occurrence of the Aurignacian culture in Eurasia

The human environment of the Xiongnu Ivolga Fortress (West Trans-Baikal area, Russia): Initial data

© 2019 Elsevier Ltd and INQUA This article deals with the initial data coming from the Ivolga Fortress archaeological site located in the Trans-Baikal area. Multidisciplinary investigations were performed, including palynological and archaeozoological studies. Palynological data reflects the palaeovegetation of the region and shows the abundance of forested landscapes in the past. The fauna was made of molluscs (7 taxa), fishes (14 taxa), amphibians (3 taxa), reptiles (1 taxon), and wild mammals (18 taxa). The species composition and environmental data show the mosaic character of landscapes surrounding the ancient settlement: taiga and forest, steppe and forest-steppe biotopes, as well as meadows in the Selenga valley with the prevalence of open steppe spaces. In the era of the Xiongnu Empire 209 BC – 48 AD (Kradin, 2001) the climate was less arid than it is now