A two-agent dynamic model with an invasive weed diffusion externality: an application to Yellow Starthistle (Centaurea solstitialis L.) in New Mexico

This paper presents a bioeconomic model for two agents, a cattle rancher and a non-rancher, with interdependencies between their individual effort of invasive weed management and profitability. Dynamic simulations allow us to find numerically the optimal effort of weed control over a 5-year time horizon under a variety of beginning infestation levels. In a base-case scenario without governmental cost-share of control costs, we find that efforts to control the weed are not profitable. The base-case scenarios also indicate that grazing contributes to giving the invasive weed a competitive edge. A second series of simulations include incentive payments for weed control which are set at the minimum level required to have a net positive impact on the rancher's profitability. From these simulations, we find that the level of infestation impacts the size of the incentive necessary to get the agent to control the weeds and that the incentive payments impact the level of effort of the rancher. In addition, results reveal that the higher incentive payments for lower levels of weed infestations reduce the total cumulative incentive payments over time. Efficient policies directed towards management of invasive weeds may need to be adjusted for each individual case.     

甲醇等5种强极性有机物污染事故中的监测分析方法

建立了在突发性水污染事故中定量分析水样中甲醇、丙酮、乙腈、N,N-二甲基甲酰胺和N,N-二甲基乙酰胺等5种极性有机物的实验室和现场应急监测分析方法。采用顶空-车载气相色谱质谱法用于现场快速定性定量分析;顶空-气相色谱法用于实验室准确定量分析。通过优化顶空及气相参数,在最佳实验条件下测得顶空-气相色谱质谱法中甲醇、丙酮、乙腈、N,N-二甲基甲酰胺、N,N-二甲基乙酰胺等5种化合物的检出限分别为1.0、0.06、0.5、10.0、15.0 mg/L,平行测定7次结果的相对标准偏差分别为2.1%~3.8%,加标回收率为69.4%~104%;顶空-气相色谱法灵敏度高于气相色谱质谱法,检出限分别为0.08、0.01、0.03、1.7、1.7 mg/L,平行测定7次结果的相对标准偏差分别为2.5%~4.1%,加标回收率为78.1%~116%。     

基于电阻率法的垃圾渗滤液渗漏及迁移规律动态监测技术探讨

为探讨垃圾渗滤液侵入地下介质的动态变化过程,引入基于电阻率法原理的地球物理探测手段,开展室内和室外渗滤液污染扩散的动态监测试验。结果表明,渗滤液在土壤中的扩散过程会引起不同时期视电阻率低阻异常区的动态变化,且变化幅度和污染程度存在一定量化关系,基于此特征可确定渗漏点和渗滤液扩散区的污染范围、程度及趋势。     

动态顶空气相色谱法测定水中极性水溶性有机物

采用动态顶空气相色谱FID法测定水中乙醛、丙酮、甲醇、丙烯醛、丙烯腈、乙腈、吡啶等7种极性水溶性有机物,通过优化动态顶空条件,使该方法在0．157mg／L～7．92mg!L之间线性良好。方法检出限在0．008mg／L～0．048mg／L之间,空白水样的加标回收率为103％～111％,RSD为5．4％～8．7％。用该方法测定某制药企业排口污水和地表水,只有污水中甲醇、乙腈、吡啶有响应值。     

基于多星遥感影像的太湖北部湖湾春季沉水植被分布动态监测

利用多星遥感影像动态监测了2015年春季太湖北部湖湾沉水植被分布的变化过程,并对水生植被遥感监测中的几个关键问题展开了探讨。决策树方法获取的水生植被分布结果表明,2015年4月28日太湖北部湖湾发现明显沉水植被分布面积约11.2 km~2,与2014年同期相比,新出现的较大面积沉水植被分布区域主要集中在田鸡山西和锡东水厂附近。提出应及时清理打捞,避免水生植被死亡腐烂,威胁水质安全。     

动态顶空-气相色谱/离子阱质谱法测定土壤中苯系物

采用动态顶空进样,气相色谱/离子阱质谱法测定土壤中的苯系物。对样品的吹扫温度、吹扫时间和解析时间进行了优化,各组分的方法检出限：苯为0.43 μg/kg,甲苯为1.13 μg/kg,对、间二甲苯均为1.74 μg/kg,邻二甲苯为0.37 μg/kg;对5种苯系物的低、中质量浓度标液进行加标,回收率为82.0%～115%,重复测定7次的RSD为4.8%～15.1%。对某造纸厂周边土壤样品中苯系物进行测定,结果固废堆存处周边土壤中苯和甲苯检出。     

傅立叶变换红外多组分气体分析仪在水污染应急监测中的应用

为了更好地为水污染应急监测工作服务,利用顶空原理,采用傅立叶变换红外多组分气体分析仪,测定水样中的有机污染物,快速筛查定性水体中主要污染物,再选用标准方法准确定量污染物浓度。结果表明,该方法具有测定范围广、仪器携带方便、筛查定性快速的优点。     

静态顶空气相色谱法顶空装置的改进

水中三氯甲烷和四氯化碳的气相色谱分析,无论是检测自来水的标准方法还是环境监测统一方法,都规定为顶端空间气相色谱法.新近文献报道测定硝基苯类化合物也采用顶端空间法.在这些方法中都使用50ml比色管作为气液平衡瓶,比色管用医用反口橡皮塞封口,本改进设计了玻璃球封口比色管作为气液平衡瓶,利用乳胶管中玻璃球的滚动来达到密封针孔的目的,从而提高了分析方法的精密度和准确性.     

顶空-气相色谱-质谱法测定土壤中卤代烃

建立顶空-气相色谱-质谱法同时测定土壤中挥发性及半挥发性卤代烃的方法。实验优化顶空平衡温度、顶空平衡时间及盐度条件,并对优化后方法的线性、检出限、精密度及回收率进行分析。结果表明:29种目标化合物在线性范围内线性良好,相关系数均大于0.997,方法检出限为2.2~5.9μg/kg,样品不同浓度水平加标回收率范围为80.0%~120%,相对标准偏差小于20%。该方法适用于土壤样品中挥发及半挥发性卤代烃的测定。     

Quantitative risk assessment integrated with dynamic process simulation for reactor section in heavy oil desulfurization process

A new methodology for quantitative risk assessment (QRA) integrated with dynamic simulation and accident simulation is proposed. The objective of this study is to discover inherent risks that are undetectable by conventional risk analysis methods based on steady-state conditions. The target process is the reactor section in the heavy oil desulfurization (HOD) process, which is likely to pose vast potential risks due to the high operating conditions of pressure and temperature. First, a dynamic simulation of a shut-down procedure was performed to observe the behavior of process variables using Aspen HYSYS V10, which is a commercially available process software. Based on the results of the dynamic simulation, several blind spots indicating a higher operating pressure than that in the steady-state simulation were identified. To assess the risks of the detected blind spots, a QRA was performed using the commercial software of SAFETI V8.22, which performs risk calculation based on consequence and frequency data. As a result of applying the proposed method to the HOD process, the risk assessment outcome was identified as intolerably risky unlike that of steady-state conditions, thereby indicating that dynamic simulations can serve as a method to spot inherent risks that are undetectable in steady-state conditions. In addition, mitigation procedures that reduce the risk of the process to a tolerable level are performed, thereby enabling a safer and more reliable process.