Assessment of hormonal activity of UV filters in tadpoles of frog Xenopus laevis at environmental concentrations

Residues of UV filters used as ultraviolet absorbers in sunscreens, cosmetics and in light protection have been found in surface water and fish. Recently some of them were shown bearing estrogenic activity, however, very little is known about possible adverse effects to aquatic life. Here we investigate whether two UV filters, 4-methylbenzylidene camphor (4-MBC) and 3-benzylidene camphor (3-BC), interfere with the thyroid and sex hormone system during frog metamorphosis. Xenopus laevis tadpoles were exposed to 1, 5 and 50 μg/L of 4-MBC and 3-BC, respectively, for 35 days (NF stage 52–66). The rate of metamorphosis was not affected, and no obvious differences in body and tail length compared to controls were observed. Neither 4-MBC, nor 3-BC led to effects on the sex ratio or gross gonad morphology of X. laevis at stage 66. Our results indicate that these UV filters do not negatively affect the thyroid system and sex ratio of frogs at environmental concentrations.     

Variational data assimilation for deriving global climate analyses from GNSS radio occultation data

A comprehensive global navigation satellite system (GNSS) based radio occultation (RO) data set is available for meteorology and climate applications since the start of GNSS RO measurements aboard the CHAllenging Mini-satellite Payload (CHAMP) satellite in February 2001. Global coverage, all-weather capability, long-term stability and accuracy not only makes this innovative use of GNSS signals a valuable supplement to the data set assimilated into numerical weather prediction (NWP) systems but also an excellent candidate for global climate monitoring. We present a 3D variational data assimilation (3D-Var) scheme developed to derive consistent global analysis fields of temperature, specific humidity, and surface pressure from GNSS RO data. The system is based on the assimilation of RO data within 6 h time windows into European Centre for Medium-Range Weather Forecasts (ECMWF) short-term (24 h, 30 h) forecasts, to derive climatologic monthly mean fields. July 2003 was used as a test-bed for assessing the system’s performance. The results show good agreement with climatologies derived from RO data only and recent NWP impact studies. These findings are encouraging for future developments to apply the approach for longer term climatologic analyses, validation of other data sets, and atmospheric variability studies.     

基于频谱空间的高分辨率遥感图像城市道路绿地轮廓特征检测

通过高分辨率遥感图像频谱能量特征分析,提出了一种基于频谱空间的城市道路绿地轮廓特征检测方法.首先对遥感图像进行傅里叶变换,分析频谱能量分布曲线,确定道路绿地轮廓的方向和截止频率,设计Gabor滤波器提取绿地轮廓特征;然后利用低通滤波获取道路中心线,根据道路中心线的缓冲区对绿地轮廓进行定位,得到道路绿地轮廓特征.结果表明,基于图像频谱特征分析的方法,使滤波器参数的设计更加精确,可有效实现高分辨率遥感图像城市道路绿地轮廓特征提取.     

改进的 Clough-Penzien地震地面运动模型

简要介绍了Kanai-Tajimi模型、Clough-Penzien模型和改进的Kanai-Tajimi模型。基于Clough-Penzien和改进的Kanai-Tajimi模型，提出了改进的Clough-Penzien模型。利用拉普拉斯变换。导出了改进的Clough-Penzien模型。比较了Kanal-Tajimi模型、Clough-Penzien模型和改进的Kanai-Tajimi模型和改进的Clough-Penzien模型的统计特性。     

Phosphorus retention in constructed wetlands enhanced by zeolite- and clinopyroxene-dominated lava sand

Constructed wetlands (CWs) are engineered systems for treating wastewater by sequestering nutrients and contaminants. Our aim was to assess the main phosphorus (P) binding states in operating CWs to assess P saturation and indications on P recycling potential of filter materials, which might be necessary under future peak P scenarios. The investigated vertical flow CWs (operation time up to 16 years) are based on either fluviatile (Fluv) sand or zeolite- (Ze-LS) and clinopyroxene (Cl-LS)-dominated lava sand. Organic and inorganic P accumulated in all CWs independent of filter materials and showed a considerable increase with operation time. Concentrations of P decreased sharply with depth in the Fluv-CWs compared to only a slight decrease in the lava sand CWs, with P concentrations of deeper horizons approximating the relatively P enriched original lava sand substrates. Orthophosphate was the dominant pool in all CWs, while the sum of organic fractions ranged between 11% and 33%. Sequential extraction indicated that P was mainly associated with Fe and Al (hydr)oxides for Fluv-CWs and Ze-LS-CWs, while Ca and Mg bound mineral phosphates dominated in Cl-LS-CWs. Oxalate extractions pointed to a clear dominance of P fractions associated with poorly crystalline Fe- and Al-(oxy)hydroxides. Solution ³¹P NMR analyses revealed that inositol hexakisphosphates were a major pool of organic P in surface layers of CWs, which increased with operation time. With a maximum of 0.5% P content, filter sands do not appear to be a suitable fertilizer for direct application to agricultural fields. The dominance of inorganic, poorly crystalline P species point to potentially high desorption capacity which might be investigated further, to assess recycling potential of P or usage of filter materials as soil amendments with relatively high plant available P. The latter might become feasible and economically attractive under future P scarcity. Simultaneously, P saturation indexes (DPS) did not indicate an imminent P saturation of filters, since P accumulation was not restricted by binding to Al and Fe minerals.     

Enhancing the Sustainability of Household Fe0/Sand Filters by Using Bimetallics and MnO2

Filtration systems containing metallic iron as reactive medium (Fe⁰ beds) have been intensively used for water treatment during the last two decades. The sustainability of Fe⁰ beds is severely confined by two major factors: (i) reactivity loss as result of the formation of an oxide scale on Fe⁰ and (ii) permeability loss due to pore filling by generated iron corrosion products. Both factors are inherent to iron corrosion at pH > 4.5 and are common during the lifespan of a Fe⁰ bed. It is of great practical significance to improve the performance of Fe⁰ beds by properly addressing these key factors. Recent studies have shown that both reactivity loss and permeability loss could be addressed by mixing Fe⁰ and inert materials. For a non‐porous additive like quartz, the threshold value for the Fe⁰ volumetric proportion is 51%. Using the Fe⁰/quartz system as reference, this study theoretically discusses the possibility of (i) replacing Fe⁰ by bimetallic systems (e.g., Fe⁰/Cu⁰), or (ii) partially replacing quartz by a reactive metal oxide (MnO₂ or TiO₂) to improve the efficiency of Fe⁰ beds. Results confirmed the suitability of both tools for sustaining Fe⁰ bed performance. It is shown that using a Fe⁰:MnO₂ system with the volumetric proportion 51:49 will yield a filter with 40% residual porosity at Fe⁰ depletion (MnO₂ porosity 62%). This study improves Fe⁰ bed design and can be considered as a basis for further refinement and detailed research for efficient Fe⁰ filters.     

基于载波相位DGNSS/INS紧组合的平滑后处理算法

针对高精度的定位定姿需求,提出一种基于差分载波相位/惯导紧组合的平滑后处理算法。通过双卡尔曼滤波器实现模糊度的解算以及对导航状态误差和惯性器件误差的估计,利用RTS平滑对数据进行后处理。实测数据表明,该算法能得到较高的定位定姿和测速精度。     

活动态测量中滤材的选择及其应用

研究滤材对元素活动态测定结果及测定精密度的影响,综合考虑元素活动态测量结果的真实性以及土壤胶体的性质等因素,确定了2μm孔径的滤膜是用于活动态测量的较佳滤材,本研究对活动态测量方法的规范化、标准化具有重要意义。应用试验表明所选滤材适用于活动态测量。