Modeling the atmospheric transport and deposition of polychlorinated dibenzo-p-dioxins and dibenzofurans in North America

The atmospheric fate of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) was simulated for the year 2000 in North America using a SMOKE/CMAQ-based chemical transport model that was modified for this purpose. The 1999 USEPA emission inventories of PCDD/Fs and criteria pollutants were used. The 1995 Canadian emission inventory of criteria pollutants and the 1995 Canadian area source emissions for PCDD/Fs were used with the 2000 Canadian point source emissions. Modifications to CMAQ involved coupling it with dual organic matter (OM) absorption and black carbon (BC) adsorption models to calculate PCDD/F gas–particle partitioning. The model satisfactorily reproduced the particle bound fractions at all rural sites for which there were measured data and across the whole domain, the modeled vs. measured differences in particle bound fractions were less than 20% for nearly all congeners. The model predicted ambient air PCDD/F concentrations were also consistent with measurements. Simulated deposition fluxes were within 58% of direct measurements. PCDD/F atmospheric depositions to each of the Great Lakes were estimated for the year 2000. The results indicate that approximately 76% of the total deposition of PCDD/Fs to the Great Lakes (in W-TEQ, or toxic equivalent units as defined by the World Health Organization) is attributed to PCDD/Fs absorbed into OM in aerosol. For all of the lakes, more than 92% of all deposition is particle phase wet deposition and only 5–8% is particle phase dry deposition. Wet deposition from the gas phase is negligible. Of the 17 toxic PCDD/F congeners, the Cl_4–5DD/F compounds contribute approximately 70% to the total atmospheric deposition to the Great Lakes. The seasonal changes in the PCDD/F deposition flux track variations in ambient temperature.     

Atmospheric mercury emission from artisanal mercury mining in Guizhou Province,Southwestern China

Mercury (Hg) mining is an important anthropogenic source of atmospheric Hg emissions. The Guizhou Province in Southwestern China is a region with extensive artisanal mercury mining (AMM), but little Hg emission data from this area is available. Using a mass balance method, we estimated emission factors from artisanal mercury mining in Wuchuan mercury mining area (WMMA) and Gouxi area (GX). Average emission factors were 18.2% in WMMA (ranging from 6.9% to 32.1%) and 9.8% in GX (ranging from 6.6% to 14.5%), respectively, which were 2.2–36.4 times higher than the literature values used to estimate Hg emission from Hg mining. Furthermore, the average Hg emission factor of AMM in WMMA was much higher than that in GX, indicating that double condensation processes practiced in GX resulted in higher recoveries and lower emission factors compared to single condensation process applied in WMMA. Atmospheric Hg emission was estimated to be 3.7–9.6 metric tons in 2004 for WMMA and 1.3–2.7 metric tons in 2006 for GX, indicating artisanal Hg mining was an important atmospheric Hg emission source in the study area.     

Aquatic organotin pollution in Taiwan

The current status of aquatic organotin pollution in Taiwan is reviewed. In freshwater sediments and biota, especially in rice-field related habitats, phenyltins (PTs) were dominant among the organotin pollutants, whereas butyltins (BTs) were usually predominant in marine environments. Among the marine habitats, contamination levels were found to be in the descending order of harbour and estuary>fish cultural site>coastal>offshore>coral reefs. Imposex snails were observed in all the sampling years (1990-2003). Meanwhile, organotin concentrations were greater in winter than those in summer, whereas proportions of PTs were much higher in summer than in winter. Due to the lack of continuous monitoring data, the effectiveness of the ban on TPT usage in agriculture in 1999 and the prohibition of TBT use on small boats in 2003 is still not known.     

基于无线传感器网络的市政下水道可燃气体监测系统设计及应用

为防止下水道可燃气体积聚引发爆炸事故,利用无线传感器网络技术设计了市政下水道可燃气体监测系统.实测结果表明:气体传感器监测数据相对误差在2.0%以内,无线数据收发设备的年发送成功率达到98.0%,满足工程运用需求,系统具有较高的可靠性和稳定性.结合无线网络覆盖范围广、实时在线的特点,该系统实现了对不同区域下水道内可燃气体浓度的远程监测,为下水道的安全预警提供了有效依据.     

抗静电织物的研究及其发展应用

本文介绍了抗静电织物的分类和发展状况,对抗静电机理进行剖析。阐述了织物抗静电性能的测试方法,继而对其在生活中的应用进行探讨,最后对其发展的前景进行展望。     

污染区大气中多氯联苯的表征与分布研究初探

通过采集并分析污染区大气及大气颗粒物中PCBs的含量,揭示了污染区空气中PCBs的残留量,讨论了各样品中PCBs的组成及分布,气相样品中可检出的PCBs总浓度在19 1-641ng·m-3,颗粒物中可检出的PCBs同类物总浓度为0.191-0.373μg·g -1. 并对气相与颗粒物PCBs浓度的关系进行了初步探讨.对同类物分布的研究表明,无论气态还是大气颗粒物中低氯代的PCBs同类物都是其主要成份.     

Aging and improving reproductive success in horses: declining residual reproductive value or just older and wiser?

In many mammalian species, female success in raising offspring improves as they age. The residual reproductive value hypothesis predicts that each individual offspring will be more valuable to the mother as she ages because there is less conflict between the current and potential future offspring. Therefore, as mothers age, their investment into individual offspring should increase. Empirical evidence for an influence of declining residual reproductive value on maternal investment is unconvincing. Older mothers may not invest more, but may be more successful due to greater experience, allowing them to target their investment more appropriately (targeted reproductive effort hypothesis). Most studies do not preclude either hypothesis. Mare age significantly influenced maternal investment in feral horses living on the North Island of New Zealand. Older mares, that were more successful at raising foals, were more protective for the first 20 days of life, but less diligent thereafter. Total maternal input by older mothers did not seem to be any greater, but was better targeted at the most critical period for foal survival and a similar pattern was observed in mares that had lost a foal in the previous year. In addition, older mothers were more likely to foal in consecutive years, supporting the hypothesis that they are investing less than younger mares in individual offspring. Therefore, older mothers seem to become more successful by targeting their investment better due to experience, not by investing more in their offspring. Received: 22 September 1999 / Received in revised form: 30 October 1999 / Accepted: 6 November 1999     

Spatio-temporal variations in water quality of Nullah Aik-tributary of the river Chenab, Pakistan

This study reports the spatio-temporal changes in water quality of Nullah Aik, tributary of the Chenab River, Pakistan. Stream water samples were collected at seven sampling sites on seasonal basis from September 2004 to April 2006 and were analyzed for 24 water quality parameters. Most significant parameters which contributed in spatio-temporal variations were assessed by statistical techniques such as Hierarchical Agglomerative Cluster Analysis (HACA), Factor Analysis/Principal Components Analysis (FA/PCA), and Discriminant Function Analysis (DFA). HACA identified three different classes of sites: Relatively Unimpaired, Impaired and Less Impaired Regions on the basis of similarity among different physicochemical characteristics and pollutant level between the sampling sites. DFA produced the best results for identification of main variables for temporal and spatial analysis and separated eight parameters (DO, hardness, sulphides, K, Fe, Pb, Cr and Zn) that accounted 89.7% of total variations of spatial analysis. Temporal analysis using DFA separated six parameters (E.C., TDS, salinity, hardness, chlorides and Pb) that showed more than 84.6% of total temporal variation. FA/PCA identified six significant factors (sources) which were responsible for major variations in water quality dataset of Nullah Aik. The results signify that parameters identified by statistical analyses were responsible for water quality change and suggest the possibility of industrial, municipal and agricultural runoff, parent rock material contamination. The results suggest dire need for proper management measures to restore the water quality of this tributary for a healthy and promising aquatic ecosystem and also highlights its importance for objective ecological policy and decision making process.     

应用斑马鱼和凡纳对虾诊断污染场地污水的生物毒性

应用斑马鱼(Brachydanio rerio)和凡纳对虾(Penaeus vannamei)对某废弃有机污染场地中有毒有机废弃物堆积产生的污水(1号塘污水)和场地及周边地表径流积水(2号塘污水)的生物毒性进行了试验.结果表明,1号塘污水对斑马鱼和凡纳对虾96 hLC50分别为46.2%和59.6%, 2号塘污水的毒性试验中两种试验生物的死亡率皆为0.化学检测表明,1号塘污水中的主要污染物为苯酚类和酞酸脂类物质,而2号塘污水中均未检出有机污染物.化学检测结果与毒性试验结果具有较好的相关性.