Onset voltages of atmospheric corona discharges on coniferous trees

In this article, the phenomenon of generation of corona discharges on the tops of trees and plants is described. In the first part of the text, the conditions for generation of this electric field which leads to formation of corona discharge and transfer of electric charge between atmosphere and Earth, are discussed. Experimental results of the onset voltage and its dependence on the discharge parameters are presented. The coincidence between released species from corona burning point and surrounding atmosphere is also discussed. Equation for the calculation of critical intensity of the electric field and onset voltage in dependence on radius of the tip are also discussed and compared with experimental data and equations for current–voltage characteristics are described. The attempt to explain differences between theory and measured data is proposed.     

山东兖州煤田16号煤层的成煤植物研究

采取多种手段相结合的研究方法,对山东兖州煤田16号煤层的成煤植物进行了详细的研究。研究了16号煤层中的煤核植物群,还通过孢粉分析及分散角质层的研究,对成煤植物群及其在垂向上的演化进行了细致的研究。结合煤岩光片中煤植体的研究,并对照煤系地层大化石所反映的成煤期前后的植物群面貌恢复了16号煤层的成煤植物群。分析并讨论了上述研究方法在反映成煤植物及其演化方面的作用,认为只有通过这种综合研究才可以较准确地反映成煤植物群面貌及其在成煤过程中的变化。     

Ab initio calculations of the Fe(II) and Fe(III) isotopic effects in citrates,nicotianamine, and phytosiderophore,and new Fe isotopic measurements in higher plants

Iron is one of the most abundant transition metal in higher plants and variations in its isotopic compositions can be used to trace its utilization. In order to better understand the effect of plant-induced isotopic fractionation on the global Fe cycling, we have estimated by quantum chemical calculations the magnitude of the isotopic fractionation between different Fe species relevant to the transport and storage of Fe in higher plants: Fe(II)-citrate, Fe(III)-citrate, Fe(II)-nicotianamine, and Fe(III)-phytosiderophore. The ab initio calculations show firstly, that Fe(II)-nicotianamine is ～3‰ (⁵⁶Fe/⁵⁴Fe) isotopically lighter than Fe(III)-phytosiderophore; secondly, even in the absence of redox changes of Fe, change in the speciation alone can create up to ～1.5‰ isotopic fractionation. For example, Fe(III)-phytosiderophore is up to 1.5‰ heavier than Fe(III)-citrate₂ and Fe(II)-nicotianamine is up to 1‰ heavier than Fe(II)-citrate. In addition, in order to better understand the Fe isotopic fractionation between different plant components, we have analyzed the iron isotopic composition of different organs (roots, seeds, germinated seeds, leaves and stems) from six species of higher plants: the dicot lentil (Lens culinaris), and the graminaceous monocots Virginia wild rye (Elymus virginicus), Johnsongrass (Sorghum halepense), Kentucky bluegrass (Poa pratensis), river oat (Uniola latifolia), and Indian goosegrass (Eleusine indica). The calculations may explain that the roots of strategy-II plants (Fe(III)-phytosiderophore) are isotopically heavier (by about 1‰ for the δ⁵⁶Fe) than the upper parts of the plants (Fe transported as Fe(III)-citrate in the xylem or Fe(II)-nicotianamine in the phloem). In addition, we suggest that the isotopic variations observed between younger and older leaves could be explained by mixing of Fe received from the xylem and the phloem.     

Organophosphates and Synthetic Musk Fragrances in Freshwater Streams in Hessen/Germany

Four small freshwater river systems in Hessen, Germany, have been investigated with respect to seasonal and spatial concentration variations and transported load of the organophosphates tri‐n‐butyl phosphate (TBP), tris(2‐butoxyethyl)phosphate (TBEP), tris(2‐chloroethyl)phosphate (TCEP), tris(1‐chloro‐2‐propyl)phosphate (TCPP), and tris(1,3‐dichloro‐2‐propyl)phosphate (TDCPP) and the synthetic musk fragrances 1,3,4,6,7,8‐hexahydro‐4,6,6,7,8,8‐hexa‐methylcyclopenta‐[γ]‐2‐benzopyran (HHCB) and 7‐acetyl‐1,1,3,4,4,6‐hexamethyl‐1,2,3,4‐tetrahydronaphthalene (AHTN). Data originate from water samples collected in the time span from September 2003 to April 2005 at 25 sampling locations. The detection frequency for all compounds was about 90%. Mean concentration levels of organophosphates were 502 ng/L (TCPP), 276 ng/L (TBP), 183 ng/L (TBEP), 118 ng/L (TCEP), and 117 ng/L (TDCPP). The synthetic musk fragrances HHCB and ATHN were detected with mean concentrations of 141 and 46 ng/L, respectively. The variability of the concentration of all compounds was high with respect to space and time. The highest concentrations were observed in the Schwarzbach system characterized by the highest proportion of wastewater compared to the other river systems. Concentration levels of synthetic musk fragrances were significantly lower in summer times compared to winter times.     

Wheat as food, wheat as industrial substance; comparative geographies of transformation and mobility

Wheat is the world’s second largest crop, supplies 19% of human calories, and is the largest volume crop traded internationally. Its uniquely malleable physical properties make it a valued industrial substance, albeit often an invisible one, as well as a food. This combination of transformation, invisibility and mobility demands new ways of thinking about wheat geographies. In this paper we document and analyse several ‘moments’ in the life of Australian wheat; at the supermarket, in the lives of coeliac sufferers, in laboratories, industrial factories and on the farm. We illustrate diverse patterns of interaction with wheat. The major plane of differentiation is between wheat as food and wheat as industrial substance. The explicit connection of food to the human body tends to fix the identity of wheat, whether as healthy staple of the nation, or harmful poison to coeliacs who must negotiate its presence using the regulatory regime of food labelling. This is no small task given the ubiquity of wheat; our survey of 10,235 supermarket items found it in 29.5% of labelled food items. In contrast, when wheat is physically and chemically disassembled to become an industrial substance, its presence and identity become mutable, hidden and often invisible.     

Plant species as indicators of geochemical anomalies: Experiences onIlex aquifolium (holly)

The distribution of Zn, Cd, Pb, and Cu, in plants growing in mineralized and sterile areas of Tuscany has been studied to verify if and to what extent metalaccumulating species represent evidence of geochemical anomalies in soils. Samples of leaves and twigs from trees were collected, and analyzed by means of differential pulse anodic stripping voltammetry (DPASV). Hollies, brambles, and Holm oaks in particular were considered in the mineralized area of Bottino, and the special aptitude of hollies in concentrating Cd with respect to the other metals has been verified. Cadmium has been previously recognized as a pathfinder for zinc ore bodies; the results of this investigation appear to point out the relevance of holly as a bioindicator of geochemical zinc anomalies. Lower metal concentration characterizes the same species from other mineralized and sterile zones, with the exception of the urbanized area of Florence, where relatively higher Zn concentrations in hollies appear to be due to atmospheric pollution.     

A survey of the non-marine Cretaceous in China

A review of the stratigraphy of the continental Cretaceous sequences is given. Conchastracans, ostracods and charophytes have proved useful in biostratigraphy, with additional aid from pelecypods, gastropods, larger plant fossil and, locally, dinosaur remains.The continental Lower Cretaceous deposits are considered to fall into three domains: the Circum-Pacific, the Tethyan and the NW Chinese. The continental Upper Cretaceous sediments occur mainly in the three domains: NW Chinese, SE Chinese and NE Chinese.     

Environmental assessment of the arsenic-rich,Rodalquilar gold–(copper–lead–zinc) mining district,SE Spain: data from soils and vegetation

The Rodalquilar mineral deposits (SE Spain) were formed in Miocene time in relation to caldera volcanic episodes and dome emplacement phenomena. Two types of ore deposits are recognized: (1) the El Cinto epithermal, Au–As high sulphidation vein and breccia type; and (2) peripheral low sulphidation epithermal Pb–Zn–Cu–(Au) veins. The first metallurgical plants for gold extraction were set up in the 1920s and used amalgamation. Cyanide leaching began in the 1930s and the operations lasted until the mid 1960s. The latter left a huge pile of ~900,000–1,250,000 m³ of abandoned As-rich tailings adjacent to the town of Rodalquilar. A frustrated initiative to reactivate the El Cinto mines took place in the late 1980s and left a heap leaching pile of ~120,000 m³. Adverse mineralogical and structural conditions favoured metal and metalloid dispersion from the ore bodies into soils and sediments, whereas mining and metallurgical operations considerably aggravated contamination. We present geochemical data for soils, tailings and wild plant species. Compared to world and local baselines, both the tailings and soils of Rodalquilar are highly enriched in As (mean concentrations of 950 and 180 μg g⁻¹, respectively). Regarding plants, only the concentrations of As, Bi and Sb in Asparagus horridus, Launaea arborescens, Salsola genistoides, and Stipa tenacissima are above the local baselines. Bioaccumulation factors in these species are generally lower in the tailings, which may be related to an exclusion strategy for metal tolerance. The statistical analysis of geochemical data from soils and plants allows recognition of two well-differentiated clusters of elements (As–Bi–Sb–Se–Sn–Te and Cd–Cu–Hg–Pb–Zn), which ultimately reflect the strong chemical influence of both El Cinto and peripheral deposits mineral assemblages.     

Behavior of Steroid Hormones and Conjugates During Wastewater Treatment – A Comparison of Three Sewage Treatment Plants

The fate of the steroid hormones 17 β‐estradiol, estrone, estriol, 16 α‐hydroxyestrone, and β‐estradiol 17‐acetate, the hormone‐conjugates β‐estradiol 3‐sulfate and estrone 3‐sulfate, and the oral contraceptives 17 α‐ethinylestradiol and mestranol were studied during wastewater treatment as wastewater treatment plants are the major source contamination of urban surface waters with steroid hormones. The elimination efficiencies of three different concepts of WWTPs, i. e., activated sludge versus trickling filter, were compared over four weeks at different weather conditions. While larger WWTPs operating on activated sludge eliminated hormones more constantly than smaller WWTPs, heavy rainfall events led to a collapse of the elimination efficiency. By using trickling filter techniques for the treatment of wastewater an elimination of the steroid hormones could not be observed. Additionally, mass flows on a per person basis are compared. In the three experiments, which ran continuously for four weeks each, it turned out that the concentrations of ethinylestradiol and mestranol were below 6 ng/L in all samples. The inflow concentrations were 70 to 82 ng/L (estrone), 17 to 44 ng/L (estradiol), 61 to 130 ng/L (hydroxyestrone), 189 to 255 ng/L (estriol), 10 to 17 ng/L (estrone‐3‐sulfate) and about 28 ng/L (estradiol‐3‐ sulfate). While in the activated sludge treatment plants the elimination of estrone was 90 and 50%, respectively, estrone was formed from precursors in the trickling filter plant. A similar situation occurred for 17β‐estradiol, estrone 3‐sulfate, and estradiol 3‐sulfate. Hydroxyestrone was eliminated with similar efficiencies in all wastewater treatment plants (64 to 82%), as well as estriol (34 to 69%). Accordingly, the emissions of the wastewater treatment plants differed largely and were not attributed to the size of the respective plant, only.