The rates of organic matter destruction in the central part of the Arctic Basin

The intensity of the processes of organic matter (OM) destruction in the deep-water part of the Arctic Basin is considered in terms of the activities of hydrolytic enzymes (alkaline phosphatase and proteases) and of redox enzymes of the electron transport system (ETS). High concentrations of mineral phosphorus are shown to cause low phosphatase activity (0.000–0.005 μM P/l h). The average time of the phosphate recycling amounted to about 240 h. The ranges of the total and specific activity of protease are 0.000–0.192 mg of azocasein/(l h) and 0.00–3.57 mg of azocasein/h mg of protein, respectively. It is found that the microplankton production of exo- and endopeptidase in the Arctic Basin is controlled by the concentration of nitrates in the water. The values of the total and the specific activities of the ETS enzymes vary within 0.27–8.96 μl O₂/(l h) and 8.4–583 μl O₂/mg of protein h, respectively. It is shown that the maximum values of the total activities of the hydrolytic and redox enzymes are characteristic for the photic layer. The vertical fluxes of organic carbon from the photic layer, being calculated by the activity of the ETS enzymes, amounted to 220–600 g of C_org/year m². The presence of ice intensifies the redox processes by factors of 2–15.     

Elemental and biochemical composition of organic matter in the waters of the Russian sector of the Arctic Basin under the present conditions

The considered area of the Russian sector of the Arctic Basin was characterized in August–September of 2008 by the wide horizontal and vertical variability of the concentrations of dissolved and particulate organic matter (OM), as well as of its elemental and biochemical composition. The concentration ranges amounted to 51.6–434 and 2.2–18.6 μM, respectively, for the dissolved and particulate C_org; up to 1.9–30.2 μM for N_org; and up to 0.08–1.53 μM for P_org. The maximum values were characteristic for the Russian Arctic shelf. The analysis of the authors’ and published data showed that a pronounced accumulation of OM, mainly in the dissolved form, took place in the Arctic Basin within the past 12 years. The concentrations of dissolved OM were higher in the western sector of the Russian Arctic than those in the eastern sector. The main biochemical components in all the waters constituting the Arctic Ocean are carbohydrates and lipids for dissolved OM and proteins and carbohydrates for particulate matter.     

Radiocarbon chronology of Holocene glacial and climatic events in southeastern Altai (Central Asia)

The geomorphological studies and radiocarbon dating of moraine complexes and the tree line within the North Chuya Ridge, along with active slope processes, soil formation, and peat formation in southeastern Gorny Altai, constrain the age of the main glacial and climatic events in this area at 7 ka to the first half of the 19th century. It is for the first time in the history of Altai studies that 57 absolute dates were obtained for glaciation in a vast but climatically and neotectonically homogeneous area. The new data refute the conventional idea that the Holocene glaciation in this mountain land comprised eight stages of the gradual retreat of the Late Würm (Sartan) glaciation. Also, they evidence that glaciation in the upper parts of the troughs retreated almost completely no later than 7 ka and valley glaciers in southeastern Altai were activated many times in the second half of the Holocene. Data are given on the morphology and age of three moraine generations reflected in the topography. A combination of temperature minima and humidity maxima led to a catastrophically rapid and the largest (up to 5–6 km) ice advance at the Akkem Stage (4.9–4.2 ka). In addition to the radiocarbon data, the time limits of the Historical stage (2.3–1.7 ka) were defined more precisely using dendrochronological and archaeological data from Scythian burials of Pazyryk culture in SE Altai. The moraines closest to the present-day glaciers formed at the Aktru Stage (late 13th–middle 19th century). During warm interglacials, the glaciers waned considerably or retreated completely and the zone of recent glaciation was reforested. As a result of progressive aridization in the Holocene, the glaciers in southeastern Altai waned at each successive stage, and their mass balance was not positive during the greatest temperature minimum of the last millennium (middle 19th century).     

Organic matter of the Kiziltashskie Limans

Data on biochemical ecosystem monitoring of Kiziltashskie Limans are given. The limans are the only natural water bodies in the Russian Black Sea where pascual breeding of very valuable commercial fish is implemented. The presented concentrations of dissolved and particulate organic matter are 2–5 times greater than the values typical of the coastal zone of the Black Sea (from 7.9 to 27.7 mg/L and from 0.3 to 1.5 mg/L, respectively). The main biochemical component of the dissolved organic matter is carbohydrates, and that of particulate matter is protein. The share of particulate organic matter in the Kiziltashskie Limans never exceeds 7%. The elemental (C, N, P) and biochemical composition of organic matter is studied (carbohydrates, proteins, lipids). The rates of enzymatic reactions vary from season to season. Thus, processes of hydrolytic splitting of phosphor-organic compounds during primary production are very intensive in the spring, while processes of organic matter oxidation, catalyzed by enzymes of electron-transport system, are intensive in the summer.     

Organic matter in present-day ecosystems of the Arctic Ocean

Doklady Earth Sciences -     

Strong Medieval Earthquake in the Northern Issyk-Kul Lake Region (Tien Shan): Results of Paleoseismological and Archeoseismological Studies

A number of archeological monuments in the northern Issyk-Kul Lake region (Tien Shan) in the basins of the Chet-Koysuu and Chon-Koysuu rivers are studied. All monuments have undergone significant seismogenic deformations and destructions. A cromlech (7th century BC to 8th centuries AD) was displaced along the sinistral strike-slip fault. A kurgan (7th–13th centuries AD) was deformed in a front of the reverse fault scarp. A fortress (14th–15th centuries AD) was submerged beneath the lake water during the catastrophic subsidence of the coastal zone. We identify a zone of the seismogenic rupture. It is located along the Kultor border fault, which separates the Issyk-Kul depression and its surrounding mountains (Kungey Ala-Too Range). During the earthquake, the seismogenic reverse fault scarp was formed. A total of 1.6 m was offset along the rupture, which corresponds to an earthquake with М _S ≥ 7 and seismic intensity of I ₀ ≥ IX. Judging by numerous radiocarbon datings of submerged wood, which was used in building the fortress (end of 14th to the beginning of 15th centuries AD), the earthquake occurred in the 16th century AD and could have caused the decline of the Mogul civilization in the northern Issyk-Kul Lake region.     

The First Data on Late Pleistocene Ostracods from the Kurai Depression (Gornyi Altai)

Doklady Earth Sciences - In the sections of Late Pleistocene deposits of the Kurai Depression of Gornyi Altai studied, an ostracod assemblage, including Leucocythere sp. 1, L. sp. 2, Leucocythere...     

Organic Matter and Its Transformation Rates in Spawning and Fattening Lakes in Kamchatka

The concentration of dissolved and particulate organic matter (OM) in Lakes Kuril'skoe and Azabach'e is shown to depend on the rate of its production by phytoplankton (and by macrophytes in Lake Azabach'e) and on the amount of allochthonous OM delivered by rivers. The rate of OM transformation in the production–destruction cycle and the regeneration of phosphates were evaluated based on the activities of redox enzymes of the electron-transport system and the hydrolytic enzymes of alkaline phosphatase and protease. The intense assimilation of allochthonous OM in lake ecosystems was found to take place due to active hydrolytic disintegration of the arriving OM.     

Spatiotemporal variability of the organic matter and the rates of its transformation in the Ob Inlet

The data on the qualitative and quantitative variability of the organic matter (OM) and its transformation rates in the waters of the Ob Inlet during different seasons are considered. The OM distribution was quite nonuniform over the entire Ob Inlet aquatic area: the concentrations of C_org varied from 2.8 to 14.1 mg/L and from 0.32 to 4.59 mg/L for the dissolved and particulate forms, respectively. The maximum concentrations of dissolved OM were registered in the main flow of the Ob River water supplied to the bay, whereas the minimum concentrations were characteristic for the near-bottom layers formed by the Kara Sea waters of high salinity in the northern part of the bay. Both in the summer and in the autumn, the fraction of particulate matter within the total OM reached its maximum values in the mixing zone of the Taz and Ob riverine waters, as well as in the mixing zone of the Ob River and Kara Sea waters. These boundary zones were characterized by the widest variability of the elemental (C: N: P) and biochemical (proteins and carbohydrates) composition of the OM, as well as of its transformation rates measured by the activities of the enzymes (alkaline phosphatase and the electron transport system).