Target loads of atmospheric sulfur deposition for the protection and recovery of acid-sensitive streams in the Southern Blue Ridge Province

An important tool in the evaluation of acidification damage to aquatic and terrestrial ecosystems is the critical load (CL), which represents the steady-state level of acidic deposition below which ecological damage would not be expected to occur, according to current scientific understanding. A deposition load intended to be protective of a specified resource condition at a particular point in time is generally called a target load (TL). The CL or TL for protection of aquatic biota is generally based on maintaining surface water acid neutralizing capacity (ANC) at an acceptable level. This study included calibration and application of the watershed model MAGIC (Model of Acidification of Groundwater in Catchments) to estimate the target sulfur (S) deposition load for the protection of aquatic resources at several future points in time in 66 generally acid-sensitive watersheds in the southern Blue Ridge province of North Carolina and two adjoining states. Potential future change in nitrogen leaching is not considered. Estimated TLs for S deposition ranged from zero (ecological objective not attainable by the specified point in time) to values many times greater than current S deposition depending on the selected site, ANC endpoint, and evaluation year. For some sites, one or more of the selected target ANC critical levels (0, 20, 50, 100μeq/L) could not be achieved by the year 2100 even if S deposition was reduced to zero and maintained at that level throughout the simulation. Many of these highly sensitive streams were simulated by the model to have had preindustrial ANC below some of these target values. For other sites, the watershed soils contained sufficiently large buffering capacity that even very high sustained levels of atmospheric S deposition would not reduce stream ANC below common damage thresholds.     

新疆维吾尔自治区第一次全国污染源普查工作的若干经验

新疆维吾尔自治区污染源普查工作于2007年10月启动，历经一年多的艰辛努力，现已圆满完成普查清查、培训、入户调查报表填报、数据录入、质量审核、质量抽查、数据汇总上报、档案建立、集中式预验收等工作，取得了阶段性的成果。总结和探索新疆污染源普查工作经验，旨在为今后的环保专项调查、污染源普查工作提供有益、可借鉴的宝贵经验。     

阳极位置对新型ABR-BEF系统处理性能及微生物群落的影响

研究了阳极所处位置对新型厌氧折流板-生物电Fenton（ABR-BEF）系统处理中药废水效能与产电能力的影响,并对各格室污泥的疏松胞外聚合物（LB-EPS）及紧密胞外聚合物（TB-EPS）组分情况进行了分析,继而通过高通量测序技术对系统中微生物群落演替进行了探讨.结果表明,当将阳极电极位置由系统的第4格室调整到第3、第2格室后,由于阳极与阴极距离的增大,COD平均去除率由原来的90%分别下降到70%和65%;输出电压由149.8mV降至95.3mV、50.0mV左右,同时最大功率密度由76.78mW/m³减少到55.57mW/m³和52.87mW/m³;但阴极室对邻苯二酚的降解率仍保持在95%左右.改变阳极位置后LB-EPS、TB-EPS中蛋白质含量均下降,TB-EPS尤为明显;而对于多糖而言,阳极在第3号格室时,各组分多糖含量最高.阳极位置由第4格室改为第2格室后,第1到第4格室甲烷丝状菌属（Methanothrix）所占比例分别增大到71.09%、72.47%、58.03%和76.79%;在总细菌纲水平上产电菌所属的d变形菌纲（Deltaproteobacteria）在第1到第4格室中分别减少了2.54%、6.06%、4.40%和4.87%,阳极与阴极距离的增大使得产电菌数量减少,这成为该系统产电能力下降的重要原因.     

Risk-based Decision Process for Arsenic in Soils: Implications of Conservative Protocols

Making defensible risk-based decisions is a complex process that incorporates risk assessment into a risk management framework. Many site investigations require additional study, negotiations and/or actions for arsenic detected in soil samples, in many cases where no process related sources are identified and no other chemicals of concern are identified. Regulatory agencies develop guidance to standardize approaches to risk-based site investigations that focus on achieving "safe" concentrations. For arsenic, the action level is frequently in the "gray region", a U.S. Environmental Protection Agency (USEPA) term associated with a region of high uncertainty for risk management decisions in the "decision performance curve" associated with the data quality objective (DQO) process. Recognizing the conservative nature of the risk-based screening value for arsenic, approaches to enforce this level (or proof of comparability to natural background) may have numerous consequences including ineffective use of resources, stigmas on properties or actions at industrial or hazardous sites that are inconsistent with their regional setting. Florida has developed regulations and guidance on investigation of brownfield sites and has supported a study by the University of Florida (UF) to evaluate natural background concentrations in Florida soils. This paper discusses the sources of uncertainty near the soil cleanup target levels (SCTLs) in the Florida decision-making framework.     

考虑空间效应的出租车超速行为道路因素分析

为充分利用道路特征干预出租车超速行为,搜集成都市区内出租车全球定位系统(GPS)轨迹数据,识别其超速行为,并采集道路特征数据,以各道路的出租车超速频数及平均超速严重度为超速特征,应用全局莫兰指数和4类空间回归模型,分别确定超速特征及道路因素的空间自相关性和显著影响出租车超速特征的道路因素。研究结果表明:出租车超速行为和道路特征均存在明显的空间自相关性;空间自相关模型(SAC)对超速频数的拟合效果最好,空间杜宾模型(SDM)对平均超速严重度的拟合效果最佳;路段的相接道路数、出入口数及车道数明显增加超速频数;道路长度和车道数显著增大平均超速严重度;施工区和单行道均与超速特征无关。     

基于布朗运动的自由飞行下碰撞风险研究

自由飞行是解决空域拥挤的有效方式,为保证飞行安全,对自由飞行下的碰撞风险进行研究。首先,假设自由飞行下飞机的定位误差服从正态分布,在平面直角坐标系内,建立2架飞机水平投影面和垂直投影面的随机运动学模型;其次,当2架飞机在2个投影面上的相对运动距离同时小于最小安全间隔时认为碰撞发生,据此建立飞行碰撞风险模型,并利用欧拉(Euler)方法求解;最后,通过Matlab对一算例进行计算,得出碰撞风险概率。将计算结果与实际安全目标等级对比,验证该模型的合理性。     

基于UWB定位的变电站作业安全监控技术研究

UWB定位技术具备较高的定位精度,在未来电力安全生产中将得到广泛应用。简 要描述了UWB定位的原理,对比了各类无线定位技术,分析了变电站作业安全监控中的 定位精度需求,确定了UWB定位技术在变电站应用的可行性;在此基础上,以某个500kV 变电站为例,建立了基于UWB定位的变电站作业监控测试环境,并对变电站典型作业场 景进行了测试,根据测试数据,分析了在变电站环境影响UWB定位精度的主要原因;最 后总结了在变电站作业安全监控场景应用UWB定位技术需要解决的关键问题。     

塔里木河下游输水河道二侧地下水埋深动态变化

根据2000-2003年的实地监测资料,分析了塔里木河下游生态输水过程中河道二侧地下水埋深的动态变化及其对沿岸植被的影响,提出了进一步提高塔里木河下游生态输水效益和加强区域生态环境保护工作的对策建议。     

Target and nontarget discrimination of herbicides applied to vegetation in a power-line corridor

We tested two cutting regimens (cut/spray and cut/delay spray) and four radiarc-applied herbicides (Garlon + Tordon, Accord, Accord + Escort, and Krenite) in an Ohio power-line corridor to determine which management combination best eliminated target species (i.e., trees) and preserved nontarget species (i.e., low shrubs, vines, perennial herbs, and grasses). When spraying was delayed after cutting, the herbicide with the least impact on nontarget species (Krenite) also was least efficient at killing target trees. Spraying soon after cutting improved tree-killing efficiency of several herbicides, but it also increased the negative impact on nontarget species. The herbicide with the most consistent tree-killing ability (Accord + Escort) had the most impact on nontarget species. Because none of the herbicide/cutting treatments performed ideally, resource managers must decide the acceptable impact on nontarget species when considering herbicide use. Future success of herbicides as part of an integrated succession management approach requires more selective application methods and formulations so that target effects can be maximized and nontarget effects can be minimized.     

Factors influencing mercury accumulation in three species of forage fish from Caddo Lake, Texas, USA

Most studies that have examined mercury (Hg) contamination of fish have focused on game species feeding near the top of the food web, while studies that examine forage fish that feed near the base of the food web are rare. We conducted a survey of Hg contamination in three species of forage fish, brook silverside (Labidesthes sicculus), threadfin shad (Dorosoma petenense) and gizzard shad (Dorosoma cepedianum), from Caddo Lake, Texas, USA and found species-specific differences in Hg concentrations. We examined total length, age, trophic position (determined using δ15N), and growth rate of forage fish as factors that could have influenced within-and between-species differences in Hg concentration. Total length and age were the best predictors of within-species differences in Hg concentration. Between-species differences in Hg concentrations were most strongly influenced by trophic position.