210Po and 210Pb variations in fish species from the Aegean Sea and the contribution of 210Po to the radiation dose

In recent years, there has been increasing interest in the significance of natural radionuclides, particularly (210)Po, in the marine environment. (210)Po, a naturally occurring alpha emitter, accumulates in marine organisms and reflects differences in their diets. In the literature, there is no data for (210)Po and (210)Pb activity concentrations for fish species on the Turkish coast of Aegean Sea. Therefore, in this study, multiple fish species were collected from six stations seasonally on the Turkish coast of Aegean Sea and were analyzed for their (210)Po and (210)Pb content. The (210)Po and (210)Pb concentrations in the fish samples were found to vary from undetectable levels to 499 ± 44 Bq kg(-1) dry weight (dw) and from 1.0 ± 0.3 Bq kg(-1) to 35 ± 4.0 Bq kg(-1) (dw), respectively. There were no significant differences in the activity concentrations of (210)Po and (210)Pb in fish samples between seasons (ANOVA, P>0.05). The highest dose contribution of (210)Po to humans was calculated to be 10,530 μSv year(-1).     

Biomarker responses in Atlantic cod (Gadus morhua) exposed to produced water from a North Sea oil field: laboratory and field assessments

Biological markers of produced water (PW) exposure were studied in Atlantic cod (Gadus morhua) in both laboratory and field experiments, using authentic PW from a North Sea oil field. In the laboratory study, the PW exposure yielded significantly elevated levels of metabolites of polycyclic aromatic hydrocarbons (PAHs) and alkylphenols (APs) in bile even at the lowest exposure dose (0.125% PW). Other biomarkers (hepatic CYP1A induction and DNA adduct formation) responded at 0.25% and 0.5% PW concentrations. In the field study, bile metabolite markers and hepatic CYP1A were clearly increased in fish caged close to the PW outfall. Induction of plasma vitellogenin was not found in laboratory or field exposures, suggesting that the levels of oestrogen agonists (such as APs) might not have been sufficient to elicit induction, under the present conditions. The applicability of the biomarkers for use in water column biomonitoring programs is discussed.     

Dredged marine sediments used as novel supply of filling materials for road construction

The dredged marine sediments are classified as waste and how to deal with such kind of abandoned materials is a great challenge. The main objective of this experimental work is to provide a novel way to reuse dredged sediment as filling materials in road section. The laboratory dewatering test is performed to model the in situ evaporation and dewatering process of untreated and treated sediment with chemical binder. The impact of binder amount and time is discussed on the change of water content influenced by evaporation. To valorize dredged sediments as roadbed materials, a hydraulic binder is incorporated to investigate its effect on the bearing capacity and strength performance. The suitability of stabilized sediment is assessed based on the obtained mechanical results followed by a detailed discussion on the in situ test roads.     

EXOTIME: searching for planets around pulsating subdwarf B stars

In 2007, a companion with planetary mass was found around the pulsating subdwarf B star V391 Pegasi with the timing method, indicating that a previously undiscovered population of substellar companions to apparently single subdwarf B stars might exist. Following this serendipitous discovery, the EXOTIME (http://www.na.astro.it/~silvotti/exotime/) monitoring program has been set up to follow the pulsations of a number of selected rapidly pulsating subdwarf B stars on time scales of several years with two immediate observational goals:

1. determine $\dot{P}$ of the pulsational periods P
2. search for signatures of substellar companions in O–C residuals due to periodic light travel time variations, which would be tracking the central star’s companion-induced wobble around the centre of mass

These sets of data should therefore, at the same time, on the one hand be useful to provide extra constraints for classical asteroseismological exercises from the $\dot{P}$ (comparison with “local” evolutionary models), and on the other hand allow one to investigate the preceding evolution of a target in terms of possible “binary” evolution by extending the otherwise unsuccessful search for companions to potentially very low masses. While timing pulsations may be an observationally expensive method to search for companions, it samples a different range of orbital parameters, inaccessible through orbital photometric effects or the radial velocity method: the latter favours massive close-in companions, whereas the timing method becomes increasingly more sensitive toward wider separations. In this paper we report on the status of the on-going observations and coherence analysis for two of the currently five targets, revealing very well-behaved pulsational characteristics in HS?0444+0458, while showing HS?0702+6043 to be more complex than previously thought.     

Determination of Soil Parameters via the Solution of Inverse Problems in Infiltration

In this paper, we propose an efficient method for the identification of soil parameters in unsaturated porous media, using measurements from infiltration experiments. The infiltration is governed by Richard's nonlinear equation expressed in terms of effective saturation. The soil retention and hydraulic permeability functions are expressed using the Van Genuchten-Mualem ansatz in terms of the soil parameters. The mathematical algorithm is based on a transformation of Richard's equation to a system of ordinary differential equations completed by the governing equation for the movement of the wetness front. This system can be efficiently solved by specialized packages for the solution of stiff systems of ODE. The unknown parameters are determined using the optimization approach of minimizing a cost functional for the discrepancy between the model output and the measurements. The gradient and Hessian of the solution with respect to soil parameter vector are determined using automatic differentiation. Several numerical experiments are included.     

Über die Auswahl der Sterne bei der Methode der Gleichen Höhen

В статье рассматривается вопрос наиболее целесообразного выбора звезд по методу равных высот. Были рассмотрены равномерные выборы звезд, симметричные вокруг двух взаимно пернендикулярных осей. Такие выборы не определяют с одинаковой точностью координаты ? и λ. Расположение обеих взаимно перпендикулярных осей относительно меридиана или первого вертикала может быть также произвольным, причем точность определения ? и л сохраняется неизменной. К таким выборам относятся секторные выборы, как напр. ранее применяемый выбор вокруг меридиана и ? вертикала [2] а также равномерное распределение по всему альмукантарату. В целях получения однородного материала в обеих координатах по методу равных высот, выбор звезд не должен быть равномерный. Для симметричного выбора звезд (имеющего то достоинство, что при нем погашается влияние возможных систематических изменений высоты в течение измерений на ? и λ и не предоставляющего преимущества звездам в некотором квадранте) и для наиболее равномерного распределения звезд по альмукантарату, при одновременном вынолнении условия равноточности получается выбор звезд таким образом, что их распределение в экваториальных областях имеет равномерный характер и что звезды с возрастанием широты неуклонно все более и более сгущаются вокруг ? вертикала, в то время как вокруг меридиана их число убывает. На более высоких широтах, превышающих 70°, метод равных высот, собственно говоря, превращается в метод Цингера, так как практически все звезды (конечного числаn одной серии наблюдений) расположены в секторах ±30° вокруг первого вертикала. Это значит, что на более высоких щиротах с помощью этого метода оказалось бы возможным определить обе координаты так, как бы измерялосьz отдельных пар или как бы все пары проходили на равной высоте. Однородный выбор (обозначим его через ?) одновременно обеспечивает определение каждой координаты с наибольщей точнбстью. А это по той причине, что никакой симметрический выбор не обеспечивает определение обеих координат с больщей точностью или одной из координат с одинаковой точностью, а другой с больщей точностью, чем однородный выбор ?. Если же в результате иного симметрического выбора точность определения одной из координат повысится, то точность определения другой по сравнению с ? всегда понижается. Отыскивался симметрический выбор (обозначим его через Ω), который обладал бы наибольщей общей точностью, что касается положепия определяемого места. Такой выбор существует. Аналогично тому, как это было следано у ?, определялось снова наиболее равномерное распределение выбора Ω. В основном, выбор Ω походит на ?, У Ω звезды с возрастанием щироты сгущаются вокруг ? вертикала несколько менее, чем у ?. В области 35° вокруг экватора оба выбора практически совпадают. В качестве пригодных выборов можно принять все выборы, расположенные между ? и Ω. Все эти выборы с наблюдательской точки зрения вытодны, так как распределение звезд находится в хорошем согласии с естественной частотой прохождений через альмукантарат. В качестве предела для метода точных симультанных определений (применясмого для определення положения точек Лапласа в астрономо-геодезической сети) была найдена щирота, соответствующая примерно полярным кругам. Для высокоточной работы этот предел будет несколько ниже и будет находиться примерно на 60°. Метод равных высот более выгоден для определения ?, чем для λ. После математической обработки было применено идеализированное распределение звезд, которое в программе наблюдений практически никогда не может быть вынолнено. Однако для теоретического анализа идеализирование пригодно и принимается в качестве масщтаба и примера для действительных случаев, более или менее приближающихся к идеальным случаям. При составлении программы наблюдений достаточно лищь учитывать общие принципы, касающиеся распределения звезд на определенной щироте и сохранять лищь число звезд, находящихся в теоретическом распределении между ? и Ω, в интервалах азимутов, проходящих по 20° или 30° и заполняющих весь альмукантарат.     

Cadmium (Cd) concentration in wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis>) grown in Cd-spiked soil varies with the doses and biochar feedstock

Biochar is considered a promising amendment for the reduction of metal concentration in plants; however, the effects of biochar in terms of dose and feedstock on metal uptake by plants remain widely unclear. In the current study, three individual biochars were prepared at 450 °C from different feedstocks (wheat straw, sukh chain (Pongamia pinnata), and cotton sticks). The main aim was to evaluate their ability to remediate cadmium (Cd)-spiked soil in terms of growth response and Cd uptake by wheat (Triticum aestivum) tissues. Biochars were separately applied at 0, 1, and 2% (w/w) in Cd-spiked soil and wheat was grown until maturity in pots and then morphological and physiological parameters and Cd concentrations in grains, roots, and shoots were determined. The post-harvest soil was analyzed for extractable Cd concentrations. Plants grown in Cd-spiked soil treated with biochars had higher seed germination, lengths of roots, shoots, and spikes, grains per spike and leaf relative water contents, chlorophyll contents, and dry weight of roots, shoots, and grains as compared to the untreated control. Biochar treatments significantly decreased the Cd concentrations in shoots, roots, and grains as well as total Cd uptake by grains. Soil extractable Cd concentrations were significantly decreased with biochar treatments. The application of 2.0% wheat straw biochar was the most efficient treatment in increasing grain yield and decreasing Cd in grains as well as soil extractable Cd than the other two biochars and doses applied.     

First identification and characterization of Borrobol‐type tephra in the Greenland ice cores: new deposits and improved age estimates

Contiguous sampling of ice spanning key intervals of the deglaciation from the Greenland ice cores of NGRIP, GRIP and NEEM has revealed three new silicic cryptotephra deposits that are geochemically similar to the well‐known Borrobol Tephra (BT). The BT is complex and confounded by the younger closely timed and compositionally similar Penifiler Tephra (PT). Two of the deposits found in the ice are in Greenland Interstadial 1e (GI‐1e) and an older deposit is found in Greenland Stadial 2.1 (GS‐2.1). Until now, the BT was confined to GI‐1‐equivalent lacustrine sequences in the British Isles, Sweden and Germany, and our discovery in Greenland ice extends its distribution and geochemical composition. However, the two cryptotephras that fall within GI‐1e ice cannot be separated on the basis of geochemistry and are dated to 14358 ± 177 a b2k and 14252 ± 173 a b2k, just 106 ± 3 years apart. The older deposit is consistent with BT age estimates derived from Scottish sites, while the younger deposit overlaps with both BT and PT age estimates. We suggest that either the BT in Northern European terrestrial sequences represents an amalgamation of tephra from both of the GI‐1e events identified in the ice‐cores or that it relates to just one of the ice‐core events. A firm correlation cannot be established at present due to their strong geochemical similarities. The older tephra horizon, found within all three ice‐cores and dated to 17326 ± 319 a b2k, can be correlated to a known layer within marine sediment cores from the North Iceland Shelf (ca. 17179‐16754 cal a BP). Despite showing similarities to the BT, this deposit can be distinguished on the basis of lower CaO and TiO₂ and is a valuable new tie‐point that could eventually be used in high‐resolution marine records to compare the climate signals from the ocean and atmosphere.     

An evaluation of structural analyses of discontinuities in carbonate rock

The main goal of the study was to compare two methods of structural analysis, based on different principles: an engineering method and the Eraso method. The first one was developed with the intention of studying geotechnical and hydraulic properties on freshly exposed rock surfaces, while the second one is based on microtectonic analysis and is mainly applied on surface outcrops. Structural analysis of discontinuities in fractured and karstified rock at one experimental field site in Slovenia was performed. Measurements were carried out on surface outcrops and in an underground artificial tunnel, twice in two different seasons (autumn 1999 and summer 1996), but by the same personnel. Both methods were found to be more or less repeatable and applicable both on the surface outcrops (weathered rock) and on freshly excavated rock surfaces (artificial tunnels and quarries), and on a macroscale. The results have shown that we can infer from the macroscale data set to the (regional) mega-scale. Copyright © 1998 John Wiley & Sons, Ltd.