Pigmenting agents in Martian soils: inferences from spectral, Mossbauer, and magnetic properties of nanophase and other iron oxides in Hawaiian palagonitic soil PN-9

We have examined a Hawaiian palagonitic tephra sample (PN-9) that has spectroscopic similarities to Martian bright regions using a number of analytical techniques, including Mossbauer and reflectance spectroscopy, X-ray diffraction, instrumental neutron activation analysis, electron probe microanalysis, transmission electron microscopy, and dithionite-citrate-bicarbonate extraction. Chemically, PN-9 has a Hawaiitic composition with alkali (and presumably silica) loss resulting from leaching by meteoric water during palagonitization; no Ce anomaly is present in the REE pattern. Mineralogically, our results show that nanophase ferric oxide (np-Ox) particles (either nanophase hematite (np-Hm) or a mixture of ferrihydrite and np-Hm) are responsible for the distinctive ferric doublet and visible-wavelength ferric absorption edge observed in Mossbauer and reflectivity spectra, respectively, for this and other spectrally similar palagonitic samples. The np-Ox particles appear to be imbedded in a hydrated aluminosilicate matrix material; no evidence was found for phyllosilicates. Other iron-bearing phases observed are titanomagnetite, which accounts for the magnetic nature of the sample; olivine; pyroxene; and glass. By analogy, np-Ox is likely the primary pigmenting agent of the bright soils and dust of Mars.     

Mantle redox evolution and the oxidation state of the Archean atmosphere

Current models predict that the early atmosphere consisted mostly of CO2, N2, and H2O, along with traces of H2 and CO. Such models are based on the assumption that the redox state of the upper mantle has not changed, so that volcanic gas composition has remained approximately constant with time. We argue here that this assumption is probably incorrect: the upper mantle was originally more reduced than today, although not as reduced as the metal arrest level, and has become progressively more oxidized as a consequence of the release of reduced volcanic gases and the subduction of hydrated, oxidized seafloor. Data on the redox state of sulfide and chromite inclusions in diamonds imply that the process of mantle oxidation was slow, so that reduced conditions could have prevailed for as much as half of the earth's history. To be sure, other oxybarometers of ancient rocks give different results, so the question of when the mantle redox state has changed remains unresolved. Mantle redox evolution is intimately linked to the oxidation state of the primitive atmosphere: A reduced Archean atmosphere would have had a high hydrogen escape rate and should correspond to a changing mantle redox state; an oxidized Archean atmosphere should be associated with a constant mantle redox state. The converses of these statements are also true. Finally, our theory of mantle redox evolution may explain why the Archean atmosphere remained oxygen-deficient until approximately 2.0 billion years ago (Ga) despite a probable early origin for photosynthesis.     

Regional estimation of total recharge to ground water in Nebraska

Naturally occurring long-term mean annual recharge to ground water in Nebraska was estimated by a novel water-balance approach. This approach uses geographic information systems (GIS) layers of land cover, elevation of land and ground water surfaces, base recharge, and the recharge potential in combination with monthly climatic data. Long-term mean recharge > 140 mm per year was estimated in eastern Nebraska, having the highest annual precipitation rates within the state, along the Elkhorn, Platte, Missouri, and Big Nemaha River valleys where ground water is very close to the surface. Similarly high recharge values were obtained for the Sand Hills sections of the North and Middle Loup, as well as Cedar River and Beaver Creek valleys due to high infiltration rates of the sandy soil in the area. The westernmost and southwesternmost parts of the state were estimated to typically receive < 30 mm of recharge a year.     

Application of a novel phytotoxicity assay for the detection of herbicides in Hervey Bay and the Great Sandy Straits

A novel phytotoxicity assay was incorporated into an environmental assessment of Hervey Bay and the Great Sandy Straits, to investigate the role of run-off associated herbicides in the deteriorated health of intertidal seagrass meadows. Dose response curves of common herbicides were performed and their toxicity equivalents elucidated to assist in analysis. The results of the assay were reproducible and corresponded strongly with results of chemical analyses. The incorporation of the assay into the assessment of surface waters added an important aspect to the study by allowing investigation of the toxicity of cumulative herbicide concentrations and yielding biologically relevant data. The highest herbicide concentration detected during the study was equivalent to 0.23 microg l(-1) diuron; a concentration known to inhibit photosynthetic efficiency of the assay biomaterial by approximately 3%.     

法国业务预报系统EMERAUDE和PERIDOT中表层预报变量的初始化

一、前 言 过去,大多把注意力都集中于大气预报变量的资料同化问题上,虽然,在这一方面仍有大量需要改进的问题。但是,人们越来越广泛地认识到地表面预报变量(表面温度,土壤水分含量和雪的厚度)在预报模式的建立和预报产品的解释中都起着重要作用。然而,对这些变量如何初始化的问题比较缺乏兴趣,这是令人非常吃惊的。对于这一情况有许多解释:期待改进仍然是相当有限的;通常用于全球范围的这些量没有直接的测量;模式对控制地表面变量演变的物理过程采用非常简化的参数等等。 不过,当我们设计新的预报系统“EMERAUDE”和“PERIDOT”的时候,我们决定采用新的、可靠的和简单的方法,但不是处理这一问题的一般的方法,下面将用一些结果来描述这一方法。     

Biochemical and histological responses in mussel (Mytilus edulis) exposed to North Sea oil and to a mixture of North Sea oil and alkylphenols

Several environmental chemicals are suspected to be responsible for adverse health effects on the reproductive system in various organisms. During this work, environmentally relevant concentrations of North Sea oil were used alone or in combination with alkylphenols and additional PAH to study the effect on vitellogenin-like protein expression and gonadal development in mussels. North Sea oil (0.5 ppm) induced the expression of phospho-proteins in both sexes indicating that some compounds are oestrogen-mimics. This induction was not seen in samples dosed with the mixture but signs of toxic effects were observed in the gonads. Indeed, numerous degenerating ovarian follicles in females and foci, similar to vertebrate melanomacrophage centres, were observed in testes.     

2008年3月4日台湾东北部两次TAIGER爆破记录的地面旋转和平移运动

2008年3月4日在台湾东北部的N3爆破点实施了两次爆破。第一次3000kg炸药的爆破编号为N3P,第二次750kg炸药的爆破编号为N3。为了记录这两次爆破,我们使用了8个三轴旋转传感器、13个三轴加速度计以及12个装有全球定位系统接收器的6通道24位数据记录仪在爆破前后几小时进行连续观测。这些仪器安装在距离爆破点250m(1个台)、500m(11个台)、600m(1个台)的地方,其中距离爆破点500m的11个台站形成了台站间距约为5m的中心台阵。除一个旋转传感器外,都得到了量程内的记录。尽管N3P爆破使用的炸药是N3爆破的4倍,但是13个台站记录的N3P爆破的平移加速度和旋转速度的峰值却只有N3爆破的1.5倍。在台站间距大约5m的中心台阵的记录中,我们还发现平移加速度和旋转速度变化很大(百分之几十)。N3P和N3爆破的最大峰值旋转速度分别为2.74mrad/s和1.75mrad/s。本文的主要目的是报告台湾这两次爆破的旋转和平移运动记录,并在网上发布以开放访问。Langston等(2009)已经对本次试验的平移加速度数据进行了分析,我们计划未来发表一篇关于分析旋转速度数据的文章。     

RIPGIS-NET: a GIS tool for riparian groundwater evapotranspiration in MODFLOW

RIPGIS-NET, an Environmental System Research Institute (ESRI's) ArcGIS 9.2/9.3 custom application, was developed to derive parameters and visualize results of spatially explicit riparian groundwater evapotranspiration (ETg), evapotranspiration from saturated zone, in groundwater flow models for ecohydrology, riparian ecosystem management, and stream restoration. Specifically RIPGIS-NET works with riparian evapotranspiration (RIP-ET), a modeling package that works with the MODFLOW groundwater flow model. RIP-ET improves ETg simulations by using a set of eco-physiologically based ETg curves for plant functional subgroups (PFSGs), and separates ground evaporation and plant transpiration processes from the water table. The RIPGIS-NET program was developed in Visual Basic 2005, .NET framework 2.0, and runs in ArcMap 9.2 and 9.3 applications. RIPGIS-NET, a pre- and post-processor for RIP-ET, incorporates spatial variability of riparian vegetation and land surface elevation into ETg estimation in MODFLOW groundwater models. RIPGIS-NET derives RIP-ET input parameters including PFSG evapotranspiration curve parameters, fractional coverage areas of each PFSG in a MODFLOW cell, and average surface elevation per riparian vegetation polygon using a digital elevation model. RIPGIS-NET also provides visualization tools for modelers to create head maps, depth to water table (DTWT) maps, and plot DTWT for a PFSG in a polygon in the Geographic Information System based on MODFLOW simulation results.     

Long term monitoring of photosystem II herbicides--correlation with remotely sensed freshwater extent to monitor changes in the quality of water entering the Great Barrier Reef, Australia

Photosystem II (PSII) herbicides are used in large quantities on agricultural lands adjoining the Great Barrier Reef (GBR). Routine monitoring at 14 sites in inshore waters of the GBR using passive sampling techniques detected diuron (32-94% of sampling periods) at maximum concentrations of 1.7-430ng L(-1) in the relatively pristine Cape York Region to the Mackay Whitsunday Region, respectively. A PSII herbicide equivalent (PSII-HEq) index developed as an indicator for reporting was dominated by diuron (average contribution 89%) and typically increased during the wet season. The maximum PSII-HEq indicates the potential for photosynthetic inhibition of diatoms, seagrass and coral-symbionts. PSII herbicides were significantly positively correlated with remotely sensed coloured dissolved organic matter, a proxy for freshwater extent. Combining these methods provides for the first time the potential to cost-effectively monitor improvements in water quality entering the GBR with respect to exposure to PSII herbicides.