Water environment

About: Water environment is a research topic. Over the lifetime, 13384 publications have been published within this topic receiving 125138 citations.

Studies on Anhydrobiosis of Pratylenchus thornei.

Abstract: Large populations of Pratylenchus thornei, a winter pest of cereals, legumes, and potatoes in the northern Negev region of Israel, survive 7-8 months of summer drought and return to full activity at the beginning of the rainy season. To demonstrate that it survives the summer in an anhydrobiotic state, all developmental stages of P. thornei were exposed to gradually reduced relative humidity (RH) using glycerin water solutions. At 97.7% RH the nematodes were coiled and able to survive exposure to 0% RH. About 40% of artificially desiccated nematodes could be reactivated by gradually increasing the humidity to the final water environment. Desiccated nematodes could withstand temperatures up to 40 C. Reactivated individuals showed intestines apparently devoid of reserve materials. Only 3% survived three cycles of desiccation and reactivation. P. thornei reactivated after anhydrobiosis multiplied twice as much within Vicia sativa roots as did fresh nematodes.

Imaging the inside of a Continuous Nanoceramic Synthesizer under Supercritical Water Conditions Using High-Energy Synchrotron X-Radiation

Abstract: Continuous hydrothermal flow synthesis (CHFS) offers a controllable route to the production of nanocrystalline materials. We describe the application of tomographic X-ray methods to image, for the first time, crystallization at the interior of an in operando CHFS reactor. In the experiment, the steady-state formation of nanoparticulate CeO2 was followed: the synthesis proceeds by rapid hydrolysis of cerium ammonium nitrate and hydrothermal coprecipitation in a near/super-critical water environment (T = 340−450 °C, P = 24 MPa). The results identify the location of particle growth with accompanying indications of crystallite size, and also reveal the build-up of material on the reactor wall during long syntheses. The imaging represents a significant achievement in that information of this kind can be gleaned from such an inhospitable environment as that of a CHFS reactor. The novel combination of tomographic angle- and energy-dispersive diffraction employed was particularly appropriate for this in situ stud...

Devonian trilobites of the southern Cantabrian Mountains (northern Spain) with a systematic description of the Asteropyginae

Abstract: This paper shows the results of a research into the Devonian trilobites of the southern Cantabrian Mountains. The systematics of the most common group, the subfamily of the Asteropyginae, forms the major part of this work. More than 50 species, belonging to sixteen (sub)genera are distinguished; thirteen species are newly described and four species are redescribed. It turned out that many species recently described from Aragon, Asturias and the Armorican Massif also occur in the southern Cantabrian Mountains. The find of Metacanthina lavidensis n.sp. in the La Vid Fm. makes it probable that the genus Metacanthina descended from Pilletina in the Siegenian. The morphological features and age of Delocare? dalii n.sp. support the theory that Delocare descended from Paracryphaeus in the Siegenian. A first time a Neocalmonia species N. cantabrica n.sp.) has been found outside Afghanistan. Its morphological features and occurrence in the Huergas Fm. indicate it descended from the genus Bradocryphaeus in the lowermost Givetian. The genus Neocalmonia therefore originated in Europe. The find of G. (Greenops) ultimus n.sp. in the Portilla Fm. prolongs the known existence of the genus Greenops far into the Frasnian. Bradocryphaeus sexspiniferus n.sp. is the first species of Frasnian age with six pairs of lateral pygidial spines which has been found outside Afghanistan. Meraspides of Kayserops obsoletus are discussed. Apart from the Asteropyginae more than 60 other trilobite species are mentioned per stratigraphic level and for the greater part depicted. In the Devonian the trilobite faunas of the Asturo-Leonese and Palentian Basins show a gradually growing difference. In the Gedinnian and Siegenian the difference is not very marked. In the Emsian the Palentian Basin yields, beside common species with the Asturo-Leonese Basin, many elements which indicate a deeper water environment (Odontochile, Reedops, Cheirurus (Pilletopeltis), Xiphogonium and Astycoryphe). In the Middle and Upper Devonian the two basins do not have any species in common. In the Asturo-Leonese Basin Asteropyginae and some subspecies of the “North American” Phacops rana dominate; in the Palentian Basin a restricted fauna occurs which indicates a deeper water environment (with Eocryphops, Paraaulacopleura and Trimerocephalus). It has been attempted to correlate the deposits in both basins with other areas (a.o. Aragon and the Armorican Massif). Most striking are the correlations which have been made of the Requejada Member (Abadia Fm.; Palentian Basin) with the upper part of the Faou Fm. (Armorican Massif) and of the upper part of the limestone member of the La Vid Fm. (Asturo-Leonese Basin) with the lower part of the Mariposas Fm. (Aragon). As a result of correlations with Asteropyginae within the Ibero-Armorican region a provisional zonation has been designed. It turned out that the Asteropyginae, which originated in the Lower Gedinnian in Europe (or northern Africa) and extended in the Middle Devonian to the east and the west, were restricted to the tropical part of the southern hemisphere.