Simulation on forecast and control for groundwater contamination of hazardous waste landfill

The groundwater flow and solute transport models were established by Visual Modflow, which was used to forecast the transport process of Cr⁶⁺ in groundwater and simulate the effects of three control measures of contaminants transport after percolation solution leakage happened in the impermeable layer of the landfill. The results showed that the contamination plume of Cr⁶⁺ would reach the pool’s boundary in 10 years, and the distance of contamination transport was 1,450 m. However, the contamination plume will not be obviously expanded between 10 and 20 years. While the ground was covered by hardened concrete, the contamination plume would not reach the pool’s boundary in 20 years. When the leakage-proof barrier was set in the bottom of an unconfined aquifer, the concentration of Cr⁶⁺ was higher than that of the leakage-proof barrier unset, but the result was opposite when setting the leakage-proof barrier in the bottom of confined aquifer. The range of the contamination plume was effectively controlled by setting drainage ditches in which water discharge was 2,298.05 m³ d^?1, which produced monitoring wells which are not contaminated in 20 years. In sum, combining ground hardening with drainage ditches could produce the best effect in controlling contaminants diffusion, and meanwhile, the drainage ditches daily discharge was reduced to 1,710.19 m³ d^?1.     

A comparison of measured 137Cs and excess 210Pb levels in the cultivated brown and cinnamon soils of the Yimeng Mountain area

This contribution analyzes the similarities and differences between the measured activities of 137Cs and excess 210pb （210Pbex） in the cultivated brown and cinnamon soils of the Yimeng Mountain area, discusses the influ- ence of soil texture on the measurement of 210Pbex, and presents differences between the two types of soils. Fields A and B were selected to represent the fields that contain cultivated brown and cinnamon soils, respectively. From either study field, one site of sectioned core and six bulk cores were collected to measure 137Cs levels, 210Pbex levels, and the particle-size composition of soil samples. Three undisturbed soil samples were collected to measure capillary and aeration porosities. The 137Cs inventories for the two study fields are very similar. The 137Cs is a man-made ra- dionuclide, which means that its measured levels for soils are unaffected by soil texture. In contrast, levels of the naturally occurring 210Pbex of soils from Field A were lower than those of Field B by about 50%. In contrast to aquatic sediments, levels of 210Pbex in terrestrial surface soils are affected by the emanation of 222Rn from the soils. It can be assumed that the coarser the soils, the greater the emanation of 222Rn; in addition, the lower the measured 210pbex, the greater the underestimate of this value. The cultivated brown soils in Field A are coarser than the culti- vated cinnamon soils in Field B. As a result, 222Rn in Field A will diffuse more easily into the atmosphere than that in Field B. As a consequence, the measured 210pbex in soils from Field A is much lower than the actual value, whereas the value measured for Field B is much closer to the actual value.     

青藏高原东南缘晚新生代川滇地体旋扭构造体系地壳变形特征的古地磁学分析

通过对川滇地体、思茅地体白垩纪、古近纪地层古地磁数据以及新生代地壳构造特征的分析,结合青藏高原东南缘GPS监测研究结果,揭示了新生代时期青藏高原东南缘地壳块体的旋转变形特征.根据古地磁数据模拟计算得出～5Ma以来哀牢山-红河走滑断裂带(ARF)受川滇地体挤压而发生弯曲变形的南北向偏移速率至少为～13.05mm/a,奠边俯左旋走滑断裂带(DBPF)西侧思茅地体内部自～5Ma以来至少存在～2.08mm/a的东西向伸展分量,而DBPF 5Ma以来的南北向平均左旋走滑速度则至少为～1.66mm/a,与现今GPS监测结果基本一致.证明鲜水河-小江左旋走滑断裂带(XXF)的左旋走滑运动虽然没有切断ARF,但是川滇地体的南向顺时针旋转挤压作用导致了断裂带的南向弯曲变形,从而吸收了部分左旋走滑速率,造成左旋走滑运动在跨过ARF传递到DBPF后走滑速率发生了突变,由～10mm/a减小于2～3mm/a.缅泰地块和思茅地体在经历了渐新世-中新世时期以高黎贡山-实楷右旋走滑断裂带和ARF为边界的东南侧向顺时针旋转挤出运动之后,自5Ma开始,至少思茅地体与川滇地体一起,以XXF和DBPF为旋转边界发生了以东喜马拉雅构造节为近似中心的旋转挤出运动.     

Trace-element variations in an annually layered stalagmite as recorders of climatic changes and anthropogenic pollution in Central China

We analyzed variations in the Sr/Ca, Ba/Ca, REE/Ca (REE: rare earth element), Zn/Ca, and Pb/Ca ratios preserved in an annually layered stalagmite, XL21, from central China. The stalagmite record spans the 95 year period AD 1914–2008. The Sr/Ca and Ba/Ca ratios have a significant positive correlation with the stalagmite's growth rate, suggesting that they were primarily controlled by growth-rate variations. Variations in REE/Ca ratios are consistent with local temperature changes, suggesting temperature influenced REE concentrations in the stalagmite over decadal to annual timescales. Higher temperature in this humid area can increase vegetation cover, microbial activity, and organic decomposition in the soil, resulting in enhanced pCO₂, organic matter concentration and reduced pH, and consequently increased REE mobilization from the overlying soil layer and host rock. Higher temperatures may also increase the natural Zn mobilization from the overlying soil mediated by organic matter and consequently may have led to increased Zn retention in XL21. An increasing trend is seen in the Pb/Ca ratios from XL21 since 1985, which is consistent with increased lead production in this area, and indicates an increase in mine-derived lead pollution in the local environment over the past 30 years.     

顾及样本优化选择的多核支持向量机滑坡灾害易发性分析评价

滑坡灾害易发性分析评价对地质灾害的防治与管理具有重要意义。针对滑坡灾害样本选择策略,单核支持向量机多特征映射不合理的问题,本文提出顾及样本优化选择的多核支持向量机(multiple kernel support vector machine,MKSVM)滑坡灾害易发性分析评价方法。为了保证样本平衡性并提高负样本的合理性,采用相对频率比(relative frequency,RF)综合评价各状态对于滑坡灾害易发性影响的重要程度,实现各评价因子状态的合理划分;利用确定性系数法(certainty factor,CF)计算各评价因子各状态分级影响滑坡灾害的敏感性,并在此基础上进行加权求和得到各栅格单元的滑坡灾害易发性指数,在滑坡灾害易发性指数极低和低易发区内随机选择与滑坡灾害点数目一致的非滑坡灾害点作为负样本数据。利用MKSVM对各特征空间最优核函数进行线性组合,解决了单一核函数映射不合理的问题,提高了模型的分类准确率和预测精度。以湖南省湘西土家族苗族自治州为研究区,从滑坡灾害易发性分区图、分区统计及评价模型精度3个方面对CF样本策略的MKSVM模型、CF样本策略的单核SVM模型、随机样本策略的MKSVM模型、随机样本策略的单核SVM模型进行了对比分析。结果表明,4种模型的受试者工作特征曲线(receiver operating characteristic,ROC)下的面积(area under curve,AUC)分别为0.859、0.809、0.798、0.766,验证了CF样本策略的合理性、有效性及MKSVM模型的可靠性。     

A low order dynamical model for runoff predictability

Climate Dynamics - Recent work has identified potential multi-year predictability in soil moisture (Chikamoto et al. in Clim Dyn 45(7–8):2213–2235, 2015). Whether this long-term...     

雅鲁藏布江大拐弯地区河流形态特征及其意义

为探讨雅鲁藏布江大拐弯地区区域隆升的特点,通过DEM(数字高程模型)和遥感影像提取雅鲁藏布江干流和帕隆藏布江的形态特征,引入Hack剖面、SL参数和Amos河宽理论模型进行分析。雅鲁藏布江干流在大渡卡以下河段的Hack剖面表现为上凸形态,SL参数升高、河流宽度减小,在藏布巴东瀑布-雅鲁藏布江大拐弯顶端段,SL参数达到最大值,河流宽度达到最小值;大拐弯顶端以下河段,SL参数减小,河流渐宽。帕隆藏布江古乡以下河段SL参数梯级增高,河流宽度总体收窄,大拐弯顶端附近达到最大值。综合2条河流的地貌特征和区域地质与地理背景,认为雅鲁藏布江大拐弯地区的隆升具有不均一性,雅鲁藏布江在大渡卡附近开始进入快速隆升区段,隆升最强烈的区段位于藏布巴东瀑布-大拐弯顶端段,大拐弯顶端之后雅鲁藏布江逐渐远离隆升中心区。     

Mid-Holocene climate change in the eastern Xinjiang region indicated by the grain size and stable isotope record from Lake Barkol, northwest China

A sediment core from Lake Barkol located in the eastern Xinjiang autonomous region, northwest China, provided a high-resolution record of environmental change covering the last ~8.6 cal ka BP. Three major climate stages, 8.6–7.1, 7.1–2.0 and from 2.0 cal ka BP to the present, were divided by grain size and the authigenic carbonate stable isotope of the lake sediment. Climatic drought during the period 7.1–4.5 cal ka BP, deduced from Lake Barkol, prevailed in the mid-Holocene climate in northern Xinjiang and northwest Mongolia. In contrast, it was wet in central Xinjiang, northwest India and the Middle East during the same period. The climatic difference between northern and southern arid central Asia demonstrates the southward shifting of the Westerlies, which indicates the potential contribution of the Siberian high in the mid-Holocene.     

基于GIS 的城市内部人口空间结构研究 ——-以深圳市为例

社会科学开始借助于地理信息系统(GIS) 的空间统计分析方法, 来研究社会现象的空间 模式和非常态分布, 研究社会科学中的空间结构问题。人口是城市空间结构演变中最为活跃的因 素之一, 同时也较易获取、容易做到时空连续, 因此往往是衡量城市内部空间结构的重要指标之 一。借助于GIS 技术, 以20 世纪90 年代以来深圳市城市内部人口空间结构研究为例。研究结果 表明深圳市城市内部人口空间结构总体表现为集聚。具体来说: 1990 年和2000 年深圳市人口密 度均以特区内东门街道为最高, 特区外各街道人口密度增长较快; 1990~2000 年人口重心向西北 移动约4km; 1990 年人口密度函数和2000 年人口密度函数均以反函数模型拟合较好, 从市中心 随着距离增加, 人口密度递减; 空间相关性分析结果表明在市中心附近具有较大的向心效应, 带 来周边邻近区域人口的增长, 而在东部郊区人口分布相对稀疏, 出现部分离心效应。     

A Small Pore Observed with a 1.6 m Telescope

A small pore was observed with the New Solar Telescope of 1.6 m aperture at Big Bear Solar Observatory. At a wavelength of 705.68 nm, a diffraction limit of 0.09″ was reached and approximately 700 small structures were analyzed. The achieved high resolution has revealed details about the dynamics of small structures in and around the pore. The small structures either reside in the pore, enter the pore from the vicinity, or dip in and out of the pore. Their sizes are similar, ≈?0.2″, but their observed oscillations do not show power peaks at the same periods. Horizontal plasma flows were suppressed in the pore by 38 % for average velocities, and 65 % for maximum velocities, compared to the quiet Sun.