A Comparison of DEM‐Based Indexes for Targeting the Placement of Vegetative Buffers in Agricultural Watersheds

Targeted placement of vegetative buffers may increase their effectiveness for improving water quality in agricultural watersheds. The use of digital elevation models (DEMs) enables precise mapping of runoff pathways for identifying where greater runoff loads can be intercepted and treated with buffers. Five different DEM‐based targeting indexes were compared and contrasted for the degree to which they identify similar locations in watersheds: Flow Accumulation [S.K. Jenson and J.O. Domingue (1988). Photogrammetric Engineering and Remote Sensing 54:1593], Wetness Index [I.D. Moore, R.B. Grayson, and A.R. Ladson (1991). Hydrological Processes 5:3], Topographic Index [M.T. Walter, T.S. Steenhuis, V.K. Mehta, D. Thongs, M. Zion, and E. Schneiderman (2002). Hydrological Processes 16:2041], and the Water Inflow and Sediment Retention Indexes [M.G. Dosskey, Z. Qiu, M.J. Helmers, and D.E. Eisenhauer (2011b). Journal of Soil and Water Conservation 66:362]. The indexes were applied in two different watersheds, one in New Jersey and one in Missouri. Results showed that they all tend to target similar locations in both watersheds which traces to the importance of larger contributing area to the rankings by each index. Disagreement among indexes traces to other variables which enable more accurate targeting under particular hydrologic circumstances. Effective use of these indexes poses special challenges, including selecting an index that better describes the hydrologic circumstances in a watershed and is simple enough to use, ensuring the accuracy of the DEM, and determining a maximum index value for the appropriateness of vegetative buffers. When properly applied, each index can provide a standardized basis and effective spatial resolution for targeting buffer placement in watersheds.     

基于Arcgis Server与ASP.Net Ajax的北京市应急避难场所信息管理平台设计与实现

北京作为＂国家首都、世界城市、文化名城和宜居城市＂,近两年加快了应急避难场所建设的步伐。针对北京市应急避难场所管理过程中存在的问题,在详细介绍ArcGIS Server的体系结构和内部运行机制的基础上,结合北京市应急避难场所的实际情况,开发了基于ASP.Net Ajax和Arcgis Server北京市应急避难场所信息管理平台。系统采用了Oracle数据库存储空间和业务数据,通过ArcSDE实现Arcgis Server和Oracle数据库的连接,实现了属性数据和空间数据的一体化存储。不仅有利于提供及时、直观、形象的应急避难场所属性信息和空间信息,同时在事故发生后抢险救灾、伤员疏散以及最大限度的减少事故损失方面起到了关键作用。     

Water quality changes of a closed underground coal mine in Korea

The objective of this study was to assess the changes in mine water quality as an underground mine flooded from July 2005 to October 2008. The effect of air injection with a blower into the water was used to evaluate the potential to convert ferrous to ferric iron and to provide in situ treatment and precipitation. Mine flooding averaged 31 cm/day with a linear shape until November 2007, when it flattened out due to outflow. During flooding, mine water pH remained around 6, but Eh shifted from 200 to −150 mV. After the mine water level stabilized, contents of elements such as Fe and SO₄ tended to decrease as time passed. Air was injected by diffusers (150 L/min/each) at three different depths of 2, 3, and 5 m below the water level in the shaft. Dissolved oxygen eventually increased to 4 or 5 mg/L depending on the depth of the diffusers. Aeration caused conversion of ferrous iron to ferric iron and about 30 mg/l of iron was removed from the mine water. Therefore, air injection shows potential as a semi-active treatment or part of conventional treatment to precipitate iron in the mine pool.     

果园地面覆盖管理的生态经济效益分析

分析了果园地面覆盖管理的生态和经济效益，并对果园地面管理方式在果树产量、质量、营养、病虫害和土壤有机质、肥力、水分、侵蚀以及生态环境上的影响进行了赋分综合评价。评价的有利效应顺序是：有机物覆盖〉间作〉生草带状覆盖〉生草覆盖〉除草剂除草〉翻耕。据此，针对我国生态环境、人口、经济状况，提出了在山区的经济林果园内应推广应用秸杆地面覆盖技术，对于减少水土流失，提高果树产量具有显著的生态和经济效益。     

Monitoring of reduced sulfur compounds in the atmosphere of Gosan, Jeju Island during the Spring of 2001

The atmospheric concentrations of dimethylsulfide (DMS) and carbon disulfide (CS2) were measured concurrently with relevant environmental parameters at Gosan, Jeju Island, Korea during 5-26 April 2001. The mean concentrations for these two compounds were 18.7+/-17.9 and 6.4+/-9.9 pptv, respectively. Results of our analysis indicated that relative temporal variations between DMS and CS2 can be best described by dividing the whole data set into three different periods which reflect the variable transport patterns of air masses into the study area. (Periods I, II, and III denote: 5-10, 10-18, and 19-26 April.) The environmental conditions during those three periods varied greatly. The effects of continental and/or oceanic processes were evident for certain periods, yielding diverse relationships between DMS and CS2 in both absolute and relative terms. Most observed variations were best explained in terms of an interplay between source/sink processes and air mass transport patterns. The sea-to-air flux of DMS, when estimated using our measurement data during this study period, was approximately 4 micromole m(-2)d(-1).     

Transport characteristics of gas phase ozone in unsaturated porous media for in-situ chemical oxidation

Encapsulation technology is being investigated as a method for controlling pH in situ at contaminated groundwater sites where pH may limit remediation of organic contaminants. This study examined the effectiveness of using KH2PO4 buffer encapsulated in a pH-sensitive coating to neutralize pH in laboratory sand columns (1.5-1) under a simulated groundwater flow rate and characterized the pattern of capsule release in the flow-through system. Denitrification was used in the columns to increase the pH of the pore water. Each of three columns was equipped with three miniature mesh wells to allow contact of the buffer with column pore water, but capsules (15 g) were inserted into only one column (amended). The two other columns served as amendment (no buffer) and abiotic (no denitrification) controls. Oxidation-reduction potential, dissolved organic and inorganic carbon, NH4+, NO3- +NO2-, PO(4)3-, and pH were measured in the influent, two side ports, and effluent of the columns over time. Near complete conversion of 80 mg N/1 of nitrate and 152 mg/l of ethanol per day resulted in a mean pH increase from 6.2 to 8.2 in the amendment control column. The amended column maintained the target pH of 7.0 +/- 0.2 for 4 weeks until the capsules began to be depleted, after which time the pH slowly started to increase. The capsules exhibited pulses of buffer release, and were effectively dissolved after 7.5 weeks of operation. Base-neutralizing capacity contributed by the encapsulated buffer over the entire study period, calculated as cation equivalents, was 120 mM compared to 8 mM without buffer. This study demonstrates the potential for this technology to mediate pH changes and provides the framework for future studies in the laboratory and in the field, in which pH is controlled in order to enhance organic contaminant remediation by pH-sensitive systems.     

Enhanced chemical oxidation of aromatic hydrocarbons in soil systems

Fenton's destruction of benzene, toluene, ethylbenzene, and xylene (BTEX) was investigated in soil slurry batch reactors. The purpose of the investigation was to quantify the enhancement of oxidation rates and efficiency by varying process conditions such as iron catalyst (Fe(II) or Fe(III); 2, 5, and 10mM), hydrogen peroxide (H2O2; 30, 150, 300 mM), and metal chelating agents (l-ascorbic acid, gallic acid, or N-(2-hydroxyethyl)iminodiacetic acid). Rapid contaminant mass destruction (97% after 3h) occurred in the presence of 300 mM H2O2 and 10 mM Fe(III). An enhanced removal rate (>90% removal after 15 min and 95% removal after 3h) was also observed by combining Fe(III), N-(2-hydroxyethyl)iminodiacetic acid and 300 mM H2O2. The observed BTEX mass removal rate constants (3.6-7.8 x 10(-4)s(-1)) were compared to the estimated rate constants (4.1-10.1 x 10(-3)s(-1)). The influence of non-specific oxidants loss (by reaction with iron hydroxides and soil organic matter) was also explored.     

Atmospheric concentrations of PM2.5 trace elements in the Seoul urban area of South Korea

Fine particles (PM2.5) were collected during all four seasons, from April 2001 to February 2002, in Seoul, South Korea, using an annular denuder system. Elemental compositions of ambient PM2.5 were analyzed using the proton-induced X-ray emission method. The greatest contributors (> or = 2%) to the PM2.5 mass were sulfur (S), silicon (Si), chlorine (Cl), aluminum (Al), and iron (Fe) in the spring; S in the summer; and S and Cl in the fall. S, Cl, and Si were the major elements in the winter. S was the most abundant species among the elements, ranging from 5.3 to 7.9%, followed by Si and Cl. From analysis of variance, PM2.5 mass, Al, Si, potassium, calcium, and Fe showed significant seasonal differences during the four seasons (p < 0.001). Enrichment factor (EF) analysis was carried out to identify the sources affecting the aerosol in the Seoul area. On the basis of the mean EF values, elemental S, copper, zinc, and lead may be emitted from anthropogenic sources (EF > 50). Elemental Al, Si, titanium, and Fe may be emitted from crustal sources (EF < 3). Additionally, a correlation analysis was carried out for source identification. The results of the correlation analysis were confirmed by the results of the EF analysis.     

水环境中苯丙胺类物质的快速前处理方法

在国内外研究的基础上,应用固相萃取技术,建立并优化了适用于野外条件的3种常见精神活性物质（甲基苯丙胺、苯丙胺和麻黄碱）的快速前处理方法.比较了污水快速前处理条件（样品pH值和上样流速）对目标物回收率的影响.结果表明,在本文测试条件下,理想的快速前处理参数为使用Oasis HLB柱,在碱性条件、流速为20mL/min的情况下加载样品.与传统方法相比,快速前处理方法所得的目标物浓度稍有降低,但仍很好地反映了生活污水中的目标物浓度水平和变化特征.北京、广东两地的野外验证结果显示,该方法对南北两地生活污水和地表水样品的处理效果都比较稳定.