Genetic relation between Holocene transgression and chemical composition of the shallow groundwater in Hangzhou, China

The shallow groundwater in Hangzhou area has the characteristics of high mineralization, high salinity and high contents of iron and manganese. Statistical analyses and the experiments of simulation show that the Holocene transgressive strata has a crucial effect on the formation of chemical composition of the shallow groundwater in the plain area of Hanghzhou. The degree of transgression is in consonance with the variation tendency of the thickness of the transgressive strata. The chemical compositions of the subsurface water in the hilly area depend on the lithology of the aquifers.     

Measurement of free heavy metal ion concentrations in soils using Donnan membrane technique

In natural systems heavy metals are present in very low concentrations (less than micro-molar) , so precise measurement of the free metal ions is difficult. Recently, a new method has been developed called the Donnan membrane technique (DMT). Several heavy metals could be measured simultaneously using this method. Furthermore, all the metals did not interfere with each other, and the balance between the measured system and the surrounding condition could not be disturbed. Improvements were made according to the internal condition. The free heavy metal ion concentrations were measured in different systems using the improved method, and satisfied results have been obtained.     

雷暴中双极性窄脉冲事件的位置与辐射强度

双极性窄脉冲事件（NBE）是一类特殊的大气放电现象,能产生强甚低频/低频（VLF/LF）和甚高频（VHF）辐射。为了探索NBE发生的气象环境和放电特性,选出重庆双频段闪电定位网络在一次雷暴过程中观测到的608次正极性NBE（简称正NBE）和82次负极性NBE（简称负NBE）,对比发生位置和辐射强度。结果表明:正NBE主要分布于7~15 km高度处,归一化到距离辐射源100 km处的VLF/LF电场变化峰值的平均值为13.4 V·m-1,平均VHF辐射功率为73.5 kW。负NBE主要发生在两个高度范围,72例负NBE分布于16~20 km高度,它们倾向于发生在30~35 dBZ回波顶高大于18 km的对流云顶及附近,其平均归一化VLF/LF电场变化峰值为42.7 V·m-1,平均VHF辐射功率为76.9 kW。10例负NBE分布于4~8 km高度,全部发生于对流核内部。其平均归一化的VLF/LF电场变化峰值为2.7 V·m-1,平均VHF辐射功率为18.2 kW。从统计结果看,在VLF/LF频段,上部负NBE的辐射强度普遍强于正NBE和下部负NBE;在VHF频段,上部负NBE的辐射强度与正NBE基本相当,大于下部负NBE;下部负NBE在两个频段的辐射通常弱于正NBE。     

Coupled mobilization of dissolved organic matter and metals (Cu and Zn) in soil columns

Dissolved organic carbon (DOC) is a key component involved in metal displacement in soils. In this study, we investigated the concentration profiles of soil-borne DOC, Cu and Zn at various irrigation rates with synthetic rain water under quasi steady-state conditions, using repacked soil columns with a metal-polluted topsoil and two unpolluted subsoils. Soil solution was collected using suction cups installed at centimeter intervals over depth. In the topsoil the concentrations of DOC, dissolved metals (Zn and Cu), major cations (Ca²⁺ and Mg²⁺) and anions ( and ) increased with depth. In the subsoil, the Cu and Zn concentrations dropped to background levels within 2 cm. All compounds were much faster mobilized in the first 4 cm than in the rest of the topsoil. DOC and Cu concentrations were higher at higher flow rates for a given depth, whereas the concentrations of the other ions decreased with increasing flow rate. The decomposition of soil organic matter resulted in the formation of DOC, , and and was the main driver of the system. Regression analysis indicated that Cu mobilization was governed by DOC, whereas Zn mobilization was primarily determined by Ca and to a lesser extent by DOC. Labile Zn and Cu²⁺ concentrations were well predicted by the NICA-Donnan model. The results highlight the value of high-resolution in-situ measurements of DOC and metal mobilization in soil profiles.     

Uncertainty of AMSU-A derived temperature trends in relationship with clouds and precipitation over ocean

Microwave Sounding Unit (MSU) and Advanced Microwave Sounding Unit-A (AMSU-A) observations from a series of National Oceanic and Atmospheric Administration satellites have been extensively utilized for estimating the atmospheric temperature trend. For a given atmospheric temperature condition, the emission and scattering of clouds and precipitation modulate MSU and AMSU-A brightness temperatures. In this study, the effects of the radiation from clouds and precipitation on AMSU-A derived atmospheric temperature trend are assessed using the information from AMSU-A window channels. It is shown that the global mean temperature in the low and middle troposphere has a larger warming rate (about 20–30 % higher) when the cloud-affected radiances are removed from AMSU-A data. It is also shown that the inclusion of cloud-affected radiances in the trend analysis can significantly offset the stratospheric cooling represented by AMSU-A channel 9 over the middle and high latitudes of Northern Hemisphere.     

艺术介入乡村：两种乡村发展转型典型模式的多级效益比较分析

在明晰国内艺术介入乡村内涵与典型模式的基础上,以马斯洛需求层次理论建构并解析艺术介入乡村的效益层次体系,并选取广州市小洲村、凤和村为典型案例,通过田野调查等方法识别艺术家主导型与资本主导型两种艺术介入模式的效益特征与问题。结果表明：1）艺术介入乡村是在乡村振兴背景下,政府、资本、艺术家与文化团体等主体,通过艺术实践实现乡村景观重构、综合经济效益、社区营造治理、地方文化传承等多级效益的乡村振兴典型模式。依据不同的驱动主体,可将艺术介入乡村模式主要划分为艺术家主导型和资本主导型两种类型。2）艺术介入乡村具有物质、经济、社会、文化四级效益,呈现逐级递进的特征。3）艺术家主导型在实现高层级效益方面作用显著,低层级效益有所欠缺;资本主导型在实现低层级效益方面作用显著,高层级效益有所欠缺。4）构建资本与艺术家协同、政府支持、村民参与的多方合作模式,能够综合两种模式的效益优势,使艺术介入的乡村实践更具推广性。     

A Generalized Plasticity-Based Model for Sandstone Considering Time-Dependent Behavior and Wetting Deterioration

Based on the concept of generalized plasticity, this study proposes a constitutive model to describe the time-dependent behavior and wetting deterioration of sandstone. The proposed model (1) exhibits nonlinear elasticity under hydrostatic and shear loading, (2) follows the associated flow rule for viscoplastic deformation, (3) adopts a creep modulus that varies with the stress ratio, (4) considers the primary and secondary creep behaviors of rock, and (5) considers the effect of wetting deterioration. This model requires 13 material parameters, comprising 3 for elasticity, 7 for plasticity, and 3 for creep. All parameters can be determined easily by following the suggested procedures. The proposed model is first validated by comparison with triaxial tests of sandstone under different hydrostatic stress and cyclic loading conditions. In addition, the model is versatile in simulating time-dependent behavior through a series of multistage creep tests. Finally, to consider the effects of wetting deterioration, triaxial and creep tests under dry and water-saturated conditions are simulated. Comparison of the simulated and experimental data shows that the proposed model can predict the behavior of sandstone in dry and saturated conditions.     

Quantitative assessment of drought in a lacustrine wetland based on a water balance model

Upstream inflow decline and excessive water withdrawal are the major reasons for failure in maintaining ecological functions of wetlands and could lead to wetland drought and degradation. Quantitative evaluation of wetlands drought constitutes the basis for managing and scheduling water resources and guaranteeing biological safety. In the study, we proposed a Palmer wetland drought index (PWDI) based on the water balance model that describes wetland hydrological characteristics linked to its located basin to describe drought-reflected ecological characteristics in lacustrine Baiyangdian Wetland and compared it with Palmer drought severity index (PDSI). The results presented that PWDI is able to reflect the worst drought in history, and the drought is mainly affected by water stored in the wetland, but PDSI is inadequate for evaluating the wetland drought. The PWDI methodology provides a clear, objective approach for describing the intensity of drought and can be readily adapted to characterize drought on an operational basis.     

基于OMI的亚洲地区对流层NO2高分辨率反演产品POMINO v2.1及其与其他产品的定量对比

对流层二氧化氮(NO₂)是一种重要的痕量污染气体。现有基于OMI卫星探测器、覆盖亚洲地区的NO₂公开产品QA4ECV、OMNO2和POMINO受到广泛使用,然而对于这3个产品的差异的定量认识仍然不足。我们将前期开发的POMINO产品进行了改进和优化,更新至v2.1并将反演区域扩大至覆盖东亚、东南亚和南亚大部分地区,随后定量分析了QA4ECV、OMNO2 v4和POMINO v2.1对流层NO₂垂直柱浓度在2015年—2020年在不同采样条件下的异同。结果显示,POMINO版本的更新对自身NO₂柱浓度反演结果的整体影响较小(<10%)。当3个产品均基于POMINO v2.1进行一致采样时,产品之间在整个亚洲区域的平均差异约为10%,在京津冀等污染地区的差异最高可达40%。3个产品均显示,京津冀地区NO₂柱浓度在五年间下降了约30%,而长三角地区的变化趋势较小。当3个产品进行分别采样时,POMINO v2.1的有效数据量比其他两个产品增加了11%—44%,特别是更好地保留了重...     

青藏高原晴天太阳直接辐射的计算和分析

本文根据1979年5～8月青藏高原气象科学实验资料,研究了利用卡斯特洛夫公式计算青藏高原晴天太阳直接辐射的有关问题。首先从原始资料中挑选出晴天太阳直接辐射并计算其日平均辐照度,然后以此为标准,利用迭代法反求可能太阳直接辐射日平均辐照度理论公式中的系数C,建立该系数与平均水汽压的经验公式,再利用经验式反演晴天太阳直接辐射。本文还比较了由乌克兰英采夫法确定的可能太阳直接辐射与实际晴天太阳直接辐射的差异,证实前者要比后者偏大,其偏离程度随站点拔海高度增加而缩小。文中最后讨论了青藏高原晴天太阳直接辐射日平均辐照度的地理分布,并分析了其随拔海高度的变化。