Age and growth rates of ferromanganese concretions from the gulf of Finland derived from 210Pb measurements

The formation of ferromanganese concretions on continental shelves is a widespread recent biogeochemical process, which is particularly intense in the Baltic Sea. The proposed new technique for dating ferromanganese concretions is based on the equilibrium ²¹⁰Pb, which is produced immediately within them due to the decay of ²²⁶Ra, which is intensely sorbed by concretions from the seawater. This method is principally different from the traditional dating of bottom sediments using nonequilibrium ²¹⁰Pb, which represents a decay product of atmospheric Ra. A mathematical tool for the calculation of the concretion ages is proposed. The latter is used for calculating the ages and growth rates of ferromanganese concretions belonging to two morphological varieties. The age and average growth rates of spheroidal concretions are estimated to be 670–850 years and 0.014 mm/year, respectively. The central part of a pancake-shaped concretion is dated back to 2500–3800 years, and its calculated respective horizontal and vertical growth rates are approximately 0.028 and 0.004 mm/year.     

Statistical study of the north–south asymmetry of the solar differential rotation based on various solar structures during 1966–1985

The time variation and latitude dependence of the solar rotation are found using observational data on Hα filaments and compact magnetic features with different polarities during solar activity cycles 20 and 21 (1966–1985). Statistical analysis of the observational data shows that there is a north–south asymmetry in the rotation, both for the Hα filaments and for compact magnetic features (structures) with negative and positive polarities. The N-S asymmetry in the differential rotation of the Hα filaments and the compact magnetic features with both polarities shows up quite distinctly in solar activity cycles 20 and 21, but the asymmetry for the compact magnetic features with positive polarity is comparatively lower in cycle 21. The confidence level is lower the compact magnetic features with positive polarity than for the compact magnetic features with negative polarity.     

Isotopes of sulfide and sulfate sulfur in nitrogen hot springs of the Bauntov group (Baikal Rift Zone)

Doklady Earth Sciences -     

Seeing and atmospheric extinction at Mt. Maidanak observatory from observations with the 1.5-m AZT-22 telescope

We have determined the realistic seeing of the 1.5-m AZT-22 telescope of the Mt. Maidanak Observatory (Astronomical Institute, Uzbek Academy of Sciences) using more than 20 000 CCD frames with stellar images in the UBV RI bands acquired in 1996–2005: ε = 1.065″ in the V band. The characteristic seeing reduced to unit air mass, ε _med ^V (M(z) = 1), is 0.945″. We derived color equations for the CCD detectors used with the telescope. Atmospheric-extinction coefficients in different photometric bands were also determined. The mean V -band atmospheric extinction is 0.20 ^m ± 0.04 ^m . The time needed for the conditions to settle, in the free atmosphere as well as inside the telescope dome, is 2–2.5 hours after the end of astronomical twilight. For nights with ε _med ^V > 0.9″, we find a persistent difference between the seeing found at this telescope and measured simultaneously with a differential image motion monitor, amounting to ∼0.1 ^m .     

山东九龙群炒米店组概念新议

山东地区寒武系-奥陶系界线以往是以三叶虫和角石生物带为依据来确定,由于在界线上下几十米难以获得这类可供鉴定的大化石,这一重要年代地层界线实际上就划在三山子组b段之底。在长清区崮山镇范庄剖面上该界线确定在炒米店组之顶界,因而山东炒米店组被定义为"上寒武统最上部的一个岩石地层单位"。近年来,在长清张夏—崮山地区、青州尧王山地区和莱芜黄羊山地区,根据牙形石"Cordylodus lindstromi"准确确定的寒武系-奥陶系界线均位于炒米店组内部,分别距炒米店组顶9.05m、58.10m和4.00m。根据上述成果和岩石地层单位命名原则,炒米店组应定义为跨寒武纪与奥陶纪的岩石地层单位。     

贵州省平坝区耕地土壤地球化学质量综合评价

利用COMSOL软件建立并验证了声屏障隔声降噪的仿真分析模型。以表面带有三角形扩散体的声屏障作为研究对象,分别研究了声屏障不同结构参数（声扩散体的宽度、间隔和角度）对于插入损失的影响。研究结果表明：对于带三角形凸起的声屏障而言,扩散体的角度对于插入损失的影响较大,宽度和间隔等参数影响不明显,为以后声屏障结构的设计研究提供了一定的参考意义。     

Icing of wires in mountain areas of Georgia

The peculiarities of wire icing in mountain areas of Georgia are investigated using the observational data of 14 meteorological stations of Georgia. Determined are the maximum frequency and the maximum mass of glaze-ice deposits, as well as the frequency of deposits of different mass and thickness. Considered are the effects of orography and meteorological conditions on the wire icing processes.     

Precipitation under Subtropical High Conditions: Evidence and Implications

The impact of the subtropical high （STH） on precipitation was investigated on a daily timescale using matched NCEP and the Global Precipitation Climatology Project （GPCP） datasets. Comparison of the conditional probability （intensity） of precipitation under STH conditions with that under non-STH conditions suggests that the presence of the STH conditions has a limited impact on local precipitation. In the West Pacific Subtropical High （WPSH） and the North Atlantic Subtropical High （NASH）, precipitation was only 30% lower under STH conditions than under non-STH conditions. The STH conditions had somewhat more impact on precipitation intensity, but it was still 50% less than the intensity under non-STH conditions （mean of roughly 5 mm d^-1）. Precipitation under STH conditions was found to be highly correlated with vertical motion. Active updrafts occurring even under STH conditions are essential for frequent occurrences and moderate intensities of precipitation.