南、北盘江流域枯水期水化学特征及离子来源分析

为进一步了解珠江上游南、北盘江流域水化学现状,对其枯水期36个河水样品进行水化学特征分析,结果表明:枯水期河水pH值在7.85~8.75之间,呈弱碱性,TDS均值为358 mg·L-1。河水中阴离子组成以HCO3-、SO42-为主,当量浓度占比均值达到65%与26%,阳离子中Ca2+和Mg2+是绝对的优势离子,当量浓度占比均值分别为65%和24%。与丰水期相关研究对比分析发现Ca2+、Mg2+、Na+、SO42-、HCO3-、Cl-的枯水期浓度普遍高于丰水期,K+、NO3-丰、枯水期浓度变化不大。Piper图、岩性端元分析以及离子浓度比值分析表明,研究区水化学主要受碳酸和硫酸共同参与下的碳酸盐岩风化控制。南、北盘江流域都受到农业施用的钾肥和氮肥的影响,此外,北盘江主要受到煤炭开采以及燃煤工业的影响,南盘江主要受到源头及上游河段化工企业废水和沿途市县的生活废水的影响。与前人数据对比发现,15年间人为活动对流域水化学的影响加剧。      

An alternative depth-integrated formulation for granular avalanches over temporally varying topography with small curvature

An alternative formulation is proposed for deriving depth-integrated equations for gravity-driven granular avalanches over a non-trivial topography with small curvature. The coordinate system of Bouchut and Westdickenberg (2004 Bouchut, F and Westdickenberg, M. 2004. Gravity driven shallow water models for arbitrary topography. Commun. Math. Sci., 2: 359–389. [Crossref] , [Google Scholar]) is combined with the unified coordinate (UC) method, so that it can evolve in accordance with the entrainment–deposition processes at the basal surface. The resultant mass and momentum equations are formulated as a conservation system of the Cartesian components of the conservative physical variables. The motion of the flows is driven by the basal topography-induced pressure, pressure gradient, and resisted by the basal friction. The best benefit of this formulation is that it greatly simplifies the computation of the varying coordinate orientations. The features and advantages of this formulation are illustrated by the sliding-mass examples where we simulate the motion of a finite mass of granular material sliding down an inclined chute, running through a transition zone, and being deposited onto a horizontal plane.     

Spatial interpolation using MLP–RBFN hybrid networks

It is easy for a multi-layered perception (MLP) to fit a stratified spatial interpolation pattern whose form is close to open surface; while it is easy for a radial basis function network (RBFN) to fit a pocket (radial) spatial interpolation pattern whose form is close to closed surface. However, in the real world, the spatial interpolation pattern may consist of stratified and pocket patterns. Neither MLP nor RBFN can fit the pattern easily. To combine their advantages to fit the complex hybrid spatial interpolation patterns, in this article we propose a novel neural network, MLP–RBFN hybrid network (MRHN), whose hidden layer contains sigmoid and Gaussian units at the same time. Although there are two kinds of processing units in MRHN, in this study we used the principle of minimizing the error sum of squares to derive the supervised learning rules for all the network parameters. This research took rainfall distribution in Taiwan as a case study. The results show that (1) the prediction error of the testing dataset outside the training dataset demonstrated that MRHN was the most accurate among the three networks, RBFN was the next best, and MLP was the worst; (2) the MLP model seriously underestimated the values of high observed rainfall; (3) over-learning may be a serious shortcoming of using RBFN in spatial interpolation applications; (4) MRHN may have better generalization learning capacity than RBFN in spatial interpolation applications.     

Locating, monitoring, and characterizing typhoon-linduced landslides with real-time seismic signals

Landslides induced by typhoon Morakot during its passage across Taiwan on 7–9 Aug 2009 claimed more than 700 lives and caused heavy economic loss. Unlike earthquake monitoring, precise locations of landslides could not be determined in near-real time because their seismic phases are difficult to identify. Here, we show that large, damaging landslide events are characterized seismically by a distinct waveform pattern of frequent intermixes of P and S waves over a time window of several tens of seconds. The predominant frequency band during these time windows ranges from 0.5 to 5?Hz. The high-frequency content is clearly deficient relative to that of local earthquakes by about one to two orders. We also demonstrate that large landslide events can be located and monitored with algorithms specifically designed for real-time seismic applications. This near-real-time monitoring capability would be particularly useful for emergency responders and government organizations to coordinate effective relief-and-rescue operations.     

Adjusting Chlorine Dosage and to Prevent Bio‐Growth and Minimize Trihalomethanes in Reverse Osmosis Filtrate in a Wastewater Reclamation Process

Feasibility of effluent reclamation for the Futian municipal WWTP in Taichung Taiwan was evaluated using an “SF‐UF‐RO” pilot plant. The optimal parameters of each unit were obtained during the pilot plant test. The pilot plant started the operation in late October 2008 and operated until January 2011. The reverse osmosis (RO) system produces 75 m³ water daily, and the produced water quality was comparable to the city water in Taichung. Chlorine dosed in the sand filtration (SF) inlet and ultrafiltration (UF) backwash had the most significant effect on the stability of system performance. When the chlorine was underdosed, biofilm clogged the bag filter (prefilter of UF) and led to the flow rate decay of the UF. The prefilter needed replacement every 1 or 2 weeks resulting in increased process cost. On the other hand, when the chlorine dosage was increased to mitigate the biofilm growth, the residual chlorine not only reacted with TOC and derived trihalomethanes (THMs) in the RO product water (more than 20 µg/L), but it also damaged the RO membrane. After trial and error, the chlorine concentration was optimized as 0.7 mg/L in SF inlet to prevent growth of biofilm as well as to control the residual chlorine in the RO inlet and THMs in the RO product water. It is suggested that cautiously adjusting chlorine dosage is essential for stably operating such a hybrid membrane system to reclaim the municipal wastewater.     

福建省平潭大风分析

平潭是福建省最大岛屿,处于东亚季风区,是东、西风带交替影响的过度区,其气候季节性特征明显。通过对平潭站1953年建站到2010年的气候资料进行统计分析,结果显示:平潭年大风日数递减趋势明显。通过平潭沿海自动站与本站气象资料对比分析发现,不论是偏北还是偏南风,沿海自动站的风速都大于本站观测值,说明平潭本站风力已经不能真实代表平潭沿海风力。经过仔细研究,进一步总结出平潭本站与沿海自动站风速的相关性,为沿海大风的预报提供科学参考。     

辽宁省柴河铅锌矿开采与重金属污染历史重建

通过对辽宁铁岭柴河铅锌矿及周边地区的土壤测量及柴河水库河漫滩沉积剖面的同位素测年研究,发现柴河铅锌矿开采导致的土壤重金属污染主要集中在柴河铅锌矿区周边3~5 km的范围内,土壤pH值表明土壤明显酸化。污染历史重建显示,1820年以来,随着沉积物中S含量的不断升高,其pH值累计下降2个单位;1900年以来河漫滩沉积物中的Cd、Pb、Zn累积明显;铅锌矿停止开采后,沉积剖面中Pb、Hg含量逐年降低;汇水域内的土壤酸化仍可导致土壤中累积的Cd和Zn对水库水体和库底沉积物造成二次污染,对水库鱼类的安全具有潜在风险。     

1959年来珠江三角洲地区的海平面变化与趋势

验潮站资料的低空间分辨率与卫星数据的短时序是区域海平面变化研究存在的关键难题。本文结合卫星高度计海平面高度距平资料及验潮站数据,基于EOF和最小二乘法重建过去53 年（1959-2011 年）珠江三角洲海平面变化时空序列,并利用主成分分析方法建立区域统一海平面变化时间序列。结果显示,基于EOF和最小二乘法的海平面高度场重建方法能很好地解决卫星高度计资料时间序列不长和验潮站分布稀缺时间不连续等问题,对于海平面变化研究,尤其是关于过去长期的变化过程及特征研究适用性良好。对统一海平面变化时间序列线性拟合显示,近53 年珠江三角洲区域海平面平均变化速率为4.08 mm/yr,且存在近期加速上升趋势。与单站研究相比,该方法较好地表达了区域海平面主要变化特征并剔除可能存在的噪音。径流及厄尔尼诺现象也对珠江三角洲海平面空间变化产生影响。