An eighteenth century tunnel as possible archive for palaeoclimate studies

The former Silva Lake (present “Pian del Lago”, Siena, Italy) developed during late Quaternary and formed as a poljie on the Triassic limestones. The depression, nowadays completely drained, is N-S oriented, 4.5 km wide and 12 km long. The lake never exceeded 6 m in depth, and it was mainly a grassy swamp during the dry season. The lake depression is filled with 20 to 30 m of a reddish siltyclayey succession. Starting from the Middle Age till late 18th century, the shallow waters of the lake and the humid area around acted as a swampy area infested by malaria. In 1766 a Sienese nobleman, Francesco Bindi Sergardi drained the lake excavating a drainage 2124m-long tunnel in Triassic limestones to connect the Silva Lake with the closeby Rigo Creek. However, quite often the tunnel was filled with debris and the lake swamped up again. In 1780 Pietro Leopoldo Grand Duke of Tuscany definitively reclaimed the Silva Lake and completed the construction of the drainage tunnel by paving and extending it for an additional 197 m. Since then, the tunnel is called the ”Canale del Gran Duca”. The entrance altitude of the canal is at 252 m a.s.l., and the exit is at 247 m a.s.l. The altitude difference is therefore of 5 m, and the canal floor has a slope of 0.2 %. The canal is for the most part paved but, in places, solid walls of Triassic limestone are still visible. Diffuse karst features are forming locally. Stalactites have lengths varying from 5 to 10 cm, and flowstones occur along the tunnel walls. The presence of these speleothems has allowed geochemical investigations to establish climatic variations of the last two centuries. The tunnel was probably cleaned and well maintained for sometime after its construction (1780), and it is likely that all the remaining speleothems have developed in the last two centuries with an estimated growth of a 0.5/6 mm per year. A petrographic investigation of a well laminated flowstone with a parasitic stalagmite has been undertaken to determine the growth mechanisms. Oxygen and carbon isotope data (δ18O and δ13C values) were used as indirect proxies for palaeoenvironmental reconstructions. Preliminary, data show significant variations along the axis of the flowstone possibly related to environmental and climatic variations within and above the “canale”

Radioactive elements in the environment

Indicated role of natural radioactive elements (U, Th) in geospherical layers and various environmental components is discussed. Induced radionuclide problems are examine

An eighteenth century tunnel as possibile archivi for paleoclimate studies

The former Silva Lake (present “Pian del Lago”, Siena, Italy) developed during late Quaternary and formed as a poljie on the Triassic limestones. The depression, nowadays completely drained, is N-S oriented, 4.5 km wide and 12 km long. The lake never exceeded 6 m in depth, and it was mainly a grassy swamp during the dry season. The lake depression is filled with 20 to 30 m of a reddish siltyclayey succession. Starting from the Middle Age till late 18th century, the shallow waters of the lake and the humid area around acted as a swampy area infested by malaria. In 1766 a Sienese nobleman, Francesco Bindi Sergardi drained the lake excavating a drainage 2124m-long tunnel in Triassic limestones to connect the Silva Lake with the closeby Rigo Creek. However, quite often the tunnel was filled with debris and the lake swamped up again. In 1780 Pietro Leopoldo Grand Duke of Tuscany definitively reclaimed the Silva Lake and completed the construction of the drainage tunnel by paving and extending it for an additional 197 m. Since then, the tunnel is called the ”Canale del Gran Duca”. The entrance altitude of the canal is at 252 m a.s.l., and the exit is at 247 m a.s.l. The altitude difference is therefore of 5 m, and the canal floor has a slope of 0.2 %. The canal is for the most part paved but, in places, solid walls of Triassic limestone are still visible. Diffuse karst features are forming locally. Stalactites have lengths varying from 5 to 10 cm, and flowstones occur along the tunnel walls. The presence of these speleothems has allowed geochemical investigations to establish climatic variations of the last two centuries. The tunnel was probably cleaned and well maintained for sometime after its construction (1780), and it is likely that all the remaining speleothems have developed in the last two centuries with an estimated growth of a 0.5/6 mm per year. A petrographic investigation of a well laminated flowstone with a parasitic stalagmite has been undertaken to determine the growth mechanisms. Oxygen and carbon isotope data (d18O and d13C values) were used as indirect proxies for palaeoenvironmental reconstructions. Preliminary, data show significant variations along the axis of the flowstone possibly related to environmental and climatic variations within and above the “canale”

Stratigraphic evidence for a “pluvial phase” between ca 8200–7100 ka from Renella cave (Central Italy)

A stratigraphic and chronological study of the upper level of Renella Cave (Apuan Alps, Central Italy) reveals that two episodes of flowstone accumulation bracket a thick clastic layer deposited between ca 8.2 and 7.1 ka. This layer, which represents a period of enhanced cave flooding, is substantially in phase with an interval of depleted oxygen isotope values previously recorded in a stalagmite from nearby Corchia Cave, interpreted to have resulted from an increase in local precipitation. These data confirm that during this period of time the region experienced relatively wetter conditions, including an increase in high-magnitude events capable of invading the higher passages of Renella Cave. The timing of the clastic phase occurred when the Eastern Mediterranean experienced deposition of sapropel layer S1, which is thought to reflect the stagnation of sea water produced largely by enhanced flood activity along the Nile in response to increased monsoon intensity in northern equatorial Africa. Recent estimates suggest that S1 may have lasted from ca 10.8 to ca 6.1 ka cal BP. Combined evidence from Renella and Corchia Cave indicates that the period corresponding to the wettest phase in the Apuan Alps was much shorter than this, and suggests that there is no straightforward connection between increased advection of water vapour from the Atlantic between 8.2 and 7.1 ka, as recorded in the Corchia and Renella records, and monsoon-driven enhancement of Nile discharge and S1 deposition in the eastern Mediterranean

Біомеханіка утворення панкреатичного секрету і тиску в ацинусі підшлункової залози

The article highlights the mechanism of the mathematical model of acinus, the components of the formation of pressure in its cavity and the formation of pancreatic juice. It has been established that the mechanism for creating pressure in the acinus cavity is similar to the intraductal one. In this case, the question remains open about the causes of such high pressure, which is measured in several hundred millimeters of a mercury column, especially since, as histologically established, the pancreas and its ducts do not have muscle structures, and those rudiments of myofibrils, which are noted in some places of the flow system, of course, cannot ensure the development of such pressure. The increase in pressure in the cavity of the acinus is associated with the phenomenon of osmosis in its cells. Since cell membranes have the property of conductivity, as a result of osmosis, water through the membrane first passes from the blood to the cell, then from the cell through the membrane into the acinus cavity. In addition to the mechanism of osmosis through the membrane, in the cells of the acinus epithelium, there is a filtering mechanism through the pores of the layer of connective tissue to the lymph channel. It has now been established that, together with simple osmosis, the phenomenon of electroosmosis takes place in secreting cells and organs of excretion, not only accelerates the transfer of substances, but also increases the pressure on the other side of the membrane against the gradient by almost several first-order units. Thus, the outflow of fluid from the acinus cavity proceeds continuously, but only with a change in the speed of movement, it is determined by the pressure drop in the acinus – tubule – excretory duct system, the opening of the Oddi sphincter and the pulse of the cardiovascular wave, which creates dynamic pressure in the capillary. This whole mechanism, as a result, leads to the filling of the cavity of the acinus and the creation of a certain pressure in it.В статье освещается механизм деятельности математической модели ацинуса, составляющих образования давления в его полости и образования панкреатического сока. Установлено, что механизм создания давления в полости ацинуса аналогичный внутрипротоковая. В этом случае открытым остается вопрос о причинах возникновения такого высокого давления, который измеряется в нескольких сотнях миллиметров ртутного столбца, тем более, что, как установлено гистологически, поджелудочная железа и ее протоки не имеют мышечных структур, а те зачатки миофибрилл, которые отмечаются в некоторых местах проточной системы, не могут, конечно, обеспечивать развитие такого давления. Повышение давления в полости ацинуса связано с явлением осмоса в его клетках. Так как клеточные мембраны имеют свойство проводимости, то в результате осмоса, вода через мембрану, сначала поступает из крови в клетку, затем из клетки через мембрану в полость ацинуса. Кроме механизма осмоса через мембрану, в клетках эпителия ацинуса действует механизм фильтрации через поры слоя соединительной ткани лимфоканалу. В настоящее время установлено, что вместе с простым осмосом в секретирующих клеток и органов выделения имеет место явление электроосмоса, не только ускоряет перенес веществ, но и повышает давление по другую сторону мембраны против градиента почти на несколько единиц первого порядка. Таким образом, отток жидкости из полости ацинуса идет непрерывно, но только с изменением скорости движения, определяется перепадом давлений в системе «ацинус-каналец-выводной проток», открытием сфинктера Одди и импульсом сердечно-сосудистой волны, создает динамическое давление в капилляре. Bесь этот механизм, в результате, приводит к наполнению полости aцинуса и создание определенного давления в нем.У статті висвітлюється механізм діяльності математичної моделі ацинуса, складових утворення тиску в його порожнині та утворення панкреатичного соку. Встановлено, що механізм створення тиску в порожнині ацинуса аналогічний внутрішньопротоковому. В цьому випадку відкритим залишається питання про причини виникнення такого високого тиску, який вимірюється в декількох сотнях міліметрів ртутного стовбчика, тим більше, що, як встановлено гістологічно, підшлункова залоза та її протоки не мають м’язових структур, а ті зачатки міофібрил, які відмічаються в деяких місцях протокової системи, не можуть, звісно, забезпечувати розвиток такого тиску. Підвищення тиску в порожнині ацинуса пов’язане з явищем осмосу в його клітинах. Так як клітинні мембрани мають властивість провідності, то в результаті осмосу, вода через мембрану, спершу поступає з крові в клітину, потім з клітини через мембрану в порожнину ацинуса. Крім механізму осмосу через мембрану, в клітинах епітелію ацинуса діє механізм фільтрації через пори шару сполучної тканини лімфоканалу. В даний час, встановлено, що разом з простим осмосом у секретуючих клітин та органів виділення мае місце явище електроосмосу, яке не тільки пришвидшує переніс речовин, але і підвищує тиск по іншу сторону мембрани проти градієнта майже на декілька одиниць першого порядку. Таким чином, відтік рідини з порожнини ацинуса йде безперервно, але тільки зі зміною швидкості руху, що визначається перепадом тисків у системі «ацинус-каналець-вивідна протока», відкриттям сфінктера Одді і імпульсом серцевосудинної хвилі, що створює динамічний тиск в капілярі. Bесь цей механізм, в результаті, призводить до наповнення порожнини aцинуса і створення певного тиску в ньому

A mid-Holocene stalagmite multiproxy record from southern Siberia (Krasnoyarsk, Russia) linked to the Siberian High patterns

A multiproxy record from a stalagmite collected from Torgashinskaya Cave (Southern Siberia, Russia) and growing between ca. 6 and 3.8 ka shows evidence for regional climatic changes occurring at ca. 5 ka. Inter- pretation of stable isotope ratios (δ18O and δ13C) and fluorescence data (intensity and wavelength of the emitted fluorescence) suggests that the interval between ca. 5 and 4.2 ka was generally warmer and drier than the in- terval between ca. 6 and 5 ka. The observed bipartitioning of the climate, attributable to the so-called ‘middle- late Holocene transition’, has a striking similarity to changes in K+ and Na+ concentration of Greenland ice cores (taken as indicators of the strength of the Siberian High and Icelandic Low, respectively), in the abundance of hematite-stained grains in subpolar North Atlantic sediments and, to lesser extent, in the summer Asian monsoon 18 18 intensity deduced by δ O from Chinese speleothems. In particular, the δ O record at Torgashinskaya Cave can be interpreted as mostly driven by temperature changes. Besides several episodes of drift towards higher tem- peratures, it also strongly suggests the presence of short cooling events centered at 4.1+0.08/-0.07, 4.85+0.05/-0.06, 5.1+0.09/-0.09, 5.3+0.08/-0.07 and 5.8+0.12/-0.13 ka. Notably, the last three such events are in very good corre- spondence with spikes in the K+ and Na+ concentration of Greenland ice cores. Instead, the cooling around 4.1 ka could be the local response to the 4.2 event, a cold/dry episode identified in several records in the Northern Hemisphere. This suggests that δ18O of speleothem calcite from this area could be a useful proxy for defining the evolution of the Siberian High and its effect on the wider regional climate

Stratigraphic evidence for a “pluvial phase” between ca 8200–7100 ka from Renella cave (Central Italy)

A stratigraphic and chronological study of the upper level of Renella Cave (Apuan Alps, Central Italy) reveals that two episodes of flowstone accumulation bracket a thick clastic layer deposited between ca 8.2 and 7.1 ka. This layer, which represents a period of enhanced cave flooding, is substantially in phase with an interval of depleted oxygen isotope values previously recorded in a stalagmite from nearby Corchia Cave, interpreted to have resulted from an increase in local precipitation. These data confirm that during this period of time the region experienced relatively wetter conditions, including an increase in high-magnitude events capable of invading the higher passages of Renella Cave. The timing of the clastic phase occurred when the Eastern Mediterranean experienced deposition of sapropel layer S1, which is thought to reflect the stagnation of sea water produced largely by enhanced flood activity along the Nile in response to increased monsoon intensity in northern equatorial Africa. Recent estimates suggest that S1 may have lasted from ca 10.8 to ca 6.1 ka cal BP. Combined evidence from Renella and Corchia Cave indicates that the period corresponding to the wettest phase in the Apuan Alps was much shorter than this, and suggests that there is no straightforward connection between increased advection of water vapour from the Atlantic between 8.2 and 7.1 ka, as recorded in the Corchia and Renella records, and monsoon-driven enhancement of Nile discharge and S1 deposition in the eastern Mediterranean