首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 78 毫秒
1.
正多年以来,全球化工巨头杜邦公司深知合成化学品全氟辛酸铵(Perfluorooctanoic Acid,缩写PFOA,是特氟龙的一种关键原料,特氟龙曾经广泛地用于家用不黏锅的涂层)对人体健康可能造成的潜在危害,但是为了巨大的商业利益一直对此秘而不宣,甚至把含有全氟辛酸铵的废弃物未经严格处理就堆在垃圾掩埋场里,造成全氟辛酸铵进入了数万居民的饮用水系统里,扩散到了全美各地。是美国一个普通的环境律师,经过不屈不挠的  相似文献   

2.
SPE-HPLC/MS联用法测定地表水中的PFOA及PFOS含量   总被引:29,自引:0,他引:29  
张倩  张超杰  周琪  陈玲 《四川环境》2006,25(4):10-12,28
本文建立了固相萃取与高效液相色谱/质谱(HPLC/MS)联用的方法来测定地表水中全氟辛酸(PFOA)及全氟辛烷基磺酸(PFOS)的含量。此方法中PFOA在水样中的线性范围为40ng/L到500ng/L,线性相关系数0.9986,PFOS在水样中的线性范围为5n异/L到500ng/L,线性相关系数0.9905。此方法中全氟辛酸及全氟辛烷基磺酸的平均回收率分另13为83.91%和86.63%。水样中全氟辛酸和全氟辛炕基磺酸的检出限均为0.5ng/L。方法准确、可靠,分析结果令人满意。采用此方法测定了上海部分地区地表水中全氟辛酸及全氟辛烷基磺酸的含量。实验结果表明,上海地区长江入海口处徐六泾段全氟辛酸的平均浓度是46.88ng/L,全氟辛烷基磺酸未检出;黄浦江段全氟辛酸及全氟辛烷基磺酸的平均浓度分别是1594.83ng/L(前处理后需稀释10倍以确保在方法线性范围内)和20.46ng/L。可见长江及黄浦江流域的全氟辛酸及全氟辛烷基磺酸的控制与治理亟待提上议程。  相似文献   

3.
全氟辛酸作为一类持久有毒化学污染物引起了人们的高度关注。本文总结了含全氟辛酸样品的前处理方法和检测方法。主要介绍了HPLC和GC等方法,并对今后的研究方向进行了展望。  相似文献   

4.
全氟类化合物已经生产并且应用超过50年。其中,全氟辛烷磺酸(PFOS)和全氟辛酸(PFOA)是最典型的两种化合物。它具有极好的理化性质,被大量的应用于生产生活当中。由于其具有生殖毒性、诱变毒性、发育毒性等,近几年来,相关研究人员及学者开始关注全氟化合物对环境、生物、人体等的影响。现有的去除典型全氟化合物的技术有光化学降解、吸附去除技术、电化学氧化法等。在对全氟类化合物的特性以及现状进行分析后,综述了近几年来国内研究学者对典型全氟化合物去除技术研究的进展,并对全氟化合物的未来研究方向与趋势进行了展望。  相似文献   

5.
通过对我国二氧化硫污染现状及控制要求的分析,提出了氨/硫铵法作为一种资源回收型脱硫方法,具有反应速度快、工艺流程简单、吸收剂利用率高、适用范围广及可实现资源回收利用的特点;以工程案例的形式分析了氨/硫铵法的技术经济指标,并对氨/硫铵法的应用前景和市场需求进行了预测。  相似文献   

6.
分析了全氟辛烷磺酰基化合物(PFOS)危害农业安全的几种途径,并对其危害机理进行了讨论,提出了降低PFOS危害农业安全的几点建议,并总结了PFOS作为新型POPs对于农业安全危害的特点。  相似文献   

7.
一、绪言对于感度极高的以环境大气浓度为对象的硫化氢分析方法,要保持捕集液内所捕集到的硫化氢离子并使其稳定是非常重要的。关于这一点,先是用镉盐方法而得到初步改进,然后由于用了锌铵溶液而得到很大改进。然而锌铵溶液在使用中也还会产生沉淀等  相似文献   

8.
工业生产与使用所造成的全球性全氟和多氟化合物(PFASs)环境污染问题已引起了广泛关注。本文综述了我国不同区域土壤、大气和水环境中PFASs的污染特征,同时对PFASs在不同环境介质中的迁移途径及其影响因素进行了阐述。最后基于控制废水中PFASs的环境排放量,探讨了废水中PFASs去除技术的主要研究内容和优缺点。  相似文献   

9.
以正丙醇、氯气和硫脲合成了2-氨基-5-甲基噻唑,将上述产物作为碱组分,与苯甲醛和苯乙酮反应得到曼尼希碱,最后采用溴代十二烷作为季铵化试剂,制得目标产物溴代2-氨基(1,4-二苯基-3-氧代丁基)-5-甲基噻唑铵(QADT)。静态失重法表明,QADT缓蚀效果显著。当温度为50℃,QADT的用量在200 mg/L时,缓蚀率达到95%以上。  相似文献   

10.
铵与碱性酚和次氯酸钠反应生成靛蓝化合物,其色度与铵的浓度成正比,亚硝基氰化物使蓝色增强,在660nm处测量吸光度值;采用Flow Solution-IV^+(FS-IV^+)流动注射仪测定地表水中氨氮,检测范围0~10.00mg/L,检出限0.008mg/L,分析速率51个样S/h;对方法精密度、准确度、加标回收进行了实验,结果令人满意。该方法具有自动进样、分析速率快、试剂耗量低等优点,可应用于大批量常规地表水分析。  相似文献   

11.
Fire and logging in nutrient-poor temperate forests with certain ericaceous understory plants may convert the forests into heaths. The process of disturbance-induced heath formation is documented by using examples ofCalluna in western Europe,Kalmia in Newfoundland, andGaultheria (salal) in coastal British Columbia. In a cool, temperate climate, rapid vegetative growth ofCalluna, Kalmia, and salal following disturbance results in increasing organic accumulation (paludification), nutrient sequestration, soil acidification, and allelochemicals. These are thought to be the main reasons to conifer regeneration failure in disturbed habitats. If continuation in forest is a land-use objective, then temperate forests with an ericaceous understory should not be logged unless effective silvicultural methods are devised to control the ericaceous plants and restore forest regeneration. Preharvest vegetation control may be considered as an option. Failure to control the understory plants may lead to a long-term vegetation shift, from forest to heathland, particularly in nutrient-poor sites. Successful methods of controllingKalmia andGaultheria, however, have yet to be developed. While theKalmia- andGaultheria- dominated heathlands are undesirable in Canada and the Pacific Northwest, a wide range ofCalluna heathlands of western Europe are being conserved as natural and seminatural vegetation.  相似文献   

12.
ABSTRACT: Mathematical models for predicting watershed surface flow responses are available, most of which are elaborate nonlinear numerical surface and channel flow models linked with infiltration models. Such models may be used to make predictions for ungaged areas, assuming an acceptable fitting of the model to the topography and roughness of the real system. For some application purposes, these models are impractical because of their complexity and expensive computer solutions. A procedure is developed that uses a complex model of an ungaged area to derive a simpler parametric nonlinear system model for repetitious simulation with input sequences. The predicted flow outputs are obtained with the simpler model at significant savings of money and time. The procedures for constructing a complex kinematic model of a 40 acre (161,880 m2) reference watershed and deriving the simpler system model are outlined. The results of predictions from both models are compared with a selected set of measured events, all having essentially the same initial conditions. Peak discharges ranged from 3 to 118 ft3/sec (0.085 to 3.34 m3/sec), which includes the largest event of record. The inherent limitations of lumped systems models are demonstrated, including the bias caused by their inability to model infiltration losses after rainfall ceases. Computer costs and times for the models were compared. The derived simple model has a cost advantage when repeated use of a model is required. Such an applications hydrologic model has an engineering tradeoff of reduced accuracy, and lumping bias, but is more economical for certain design purposes.  相似文献   

13.
Urban ecological systems: scientific foundations and a decade of progress   总被引:9,自引:0,他引:9  
Urban ecological studies, including focus on cities, suburbs, and exurbs, while having deep roots in the early to mid 20th century, have burgeoned in the last several decades. We use the state factor approach to highlight the role of important aspects of climate, substrate, organisms, relief, and time in differentiating urban from non-urban areas, and for determining heterogeneity within spatially extensive metropolitan areas. In addition to reviewing key findings relevant to each state factor, we note the emergence of tentative "urban syndromes" concerning soils, streams, wildlife and plants, and homogenization of certain ecosystem functions, such as soil organic carbon dynamics. We note the utility of the ecosystem approach, the human ecosystem framework, and watersheds as integrative tools to tie information about multiple state factors together. The organismal component of urban complexes includes the social organization of the human population, and we review key modes by which human populations within urban areas are differentiated, and how such differentiation affects environmentally relevant actions. Emerging syntheses in land change science and ecological urban design are also summarized. The multifaceted frameworks and the growing urban knowledge base do however identify some pressing research needs.  相似文献   

14.
Urban gardens are important sources of sustenance for communities with limited access to food. Hence, this study focuses on food production in gardens in the Toledo metropolitan area in Northwest Ohio. We administered surveys to 150 garden managers from November 2014 to February 2015 in our attempt to better understand how neighbourhood racial composition and poverty levels are related to staffing and voluntarism, food production and distribution, the development of infrastructure, and the adoption of sustainability practices in urban gardens. The results from 30 gardens are presented in this paper. We used Geographic Information Systems to map the gardens and overlay the map with 2010 census data so that we could conduct demographic analyses of the neighbourhoods in which the gardens were located. Though the gardens were small – two acres or less – up to 46 varieties of food were grown in a single garden. Gardens also operated on small budgets. Food from the gardens was gifted or shared with friends, family, and neighbourhood residents. Gardens in predominantly minority neighbourhoods tended to have fewer institutional partners, less garden infrastructure, and had adopted fewer sustainable practices than gardens in predominantly White neighbourhoods. Nonetheless, residents of predominantly minority and high-poverty neighbourhoods participated in garden activities and influenced garden operations. Volunteering and staffing were racialised and gendered.  相似文献   

15.
In water stressed regions, water managers are exploring new horizons that would help in long‐range streamflow forecasts. Oceanic‐atmospheric oscillations have been shown to influence streamflow variability. In this study, long‐lead time streamflow forecasts are made using a multiclass kernel‐based data‐driven support vector machine (SVM) model. The extended streamflow records based on tree ring reconstructions were used to provide a longer time series data. Reconstructed data were used from 1658 to 1952 and the instrumental record was used from 1953 to 2007. Reconstructions for oceanic‐atmospheric oscillations included the El Niño‐Southern Oscillation, Pacific Decadal Oscillation, Atlantic Multidecadal Oscillation, and North Atlantic Oscillation. Streamflow forecasts using all four oscillations were made with one‐year to five‐year lead times for 21 gages in the western United States. This is the first study that uses both instrumental and reconstructed data of oscillations in SVM model to improve streamflow forecast lead time. SVM model was able to provide “satisfactory” to “very good” forecasts with one‐ to five‐year lead time for the selected gages. The use of all the oscillation indices helped in achieving better predictability compared to using individual oscillations. The SVM modeling results are better when compared with multiple linear regression model forecasts. The findings are statistical in nature and are expected to be useful for long‐term water resources planning and management.  相似文献   

16.
Collisions with deer and other large animals are increasing, and the resulting economic costs and risks to public safety have made mitigation measures a priority for both city and wildlife managers. We created landscape models to describe and predict deer-vehicle collision (DVCs) within the City of Edmonton, Alberta. Models based on roadside characteristics revealed that DVCs occurred frequently where roadside vegetation was both denser and more diverse, and that DVCs were more likely to occur when the groomed width of roadside right-of-ways was smaller. No DVCs occurred where the width of the vegetation-free or manicured roadside buffer was greater than 40 m. Landscape-based models showed that DVCs were more likely in more heterogeneous landscapes where road densities were lower and speed limits were higher, and where non-forested vegetation such as farmland was in closer proximity to larger tracts of forest. These models can help wildlife and transportation managers to identify locations of high collision frequency for mitigation. Modifying certain landscape and roadside habitats can be an effective way to reduce deer-vehicle collisions.  相似文献   

17.
Manganese entering impounded water will undergo a cyclic transformation. Oxidation precipitates manganese from top waters. At the bottom of the lake, biological activity will render manganese soluble by both intracellular as well as extracellular activity. The study was made to demonstrate that biological reduction and transformation, organometallic complexation, together with the presence of carbon dioxide and the lowering of pH all have some effect on the solubility of manganese. Dissolved manganese may be brought back to top waters during the lake overturn and therefore deteriorates the water quality.  相似文献   

18.
The maintenance of biodiversity is urged from many quarters and on grounds ranging from aesthetic considerations to its usefulness, particularly for biotechnology. But regardless of the grounds for preserving biodiversity, writers are generally in agreement that it should be preserved. But, in examining the various references biodiversity, such as species diversity, genetic diversity, and habitat diversity, it is apparent that we cannot aim to preserve biodiversityas such, since there are a number of conflicts in any such undertaking. In preserving one aspect of biodiversity, we damage another aspect. Five arguments which attempt to ground our moral concern for biodiversity are reviewed and critiqued, not only for their consistency but also for their power to move us to action. The final section of the paper shows how conflicts in the values of personal and environmental health can impair ethical action and especially policy formation.An earlier version of this paper was read at the conference on Agriculture, Food, and Human Values: Tradition and Change, Orlando, Florida, October 7–9, 1987.  相似文献   

19.
Water treatment residuals (WTR) can reduce runoff P loss and surface co-application of P-sources and WTR is a practical way of land applying the residuals. In a rainfall simulation study, we evaluated the effects of surface co-applied P-sources and an Al-WTR on runoff and leacheate bioavailable P (BAP) losses from a Florida sand. Four P-sources, namely poultry manure, Boca Raton biosolids (high water-soluble P), Pompano biosolids (moderate water-soluble P), and triple super phosphate (TSP) were surface applied at 56 and 224kgPha(-1) (by weight) to represent low and high soil P loads typical of P- and N-based amendments rates. The treatments further received surface applied WTR at 0 or 10gWTRkg(-1) soil. BAP loss masses were greater in leachate (16.4-536mg) than in runoff (0.91-46mg), but were reduced in runoff and leachate by surface applied WTR. Masses of total BAP lost in the presence of surface applied WTR were less than approximately 75% of BAP losses in the absence of WTR. Total BAP losses from each of the organic sources applied at N-based rates were not greater than P loss from TSP applied at a P-based rate. The BAP loss at the N-based rate of moderate water-soluble P-source (Pompano biosolids) was not greater than BAP losses at the P-based rates of other organic sources tested. The hazards of excess P from applying organic P-sources at N-based rates are not greater than observed at P-based rates of mineral fertilizer. Results suggest that management of the environmental P hazards associated with N-based rates of organic materials in Florida sands is possible by either applying P-sources with WTR or using a moderate water-soluble P-source.  相似文献   

20.
The SPARROW (SPAtially Referenced Regression on Watershed attributes) model was used to simulate annual phosphorus loads and concentrations in unmonitored stream reaches in California, U.S., and portions of Nevada and Oregon. The model was calibrated using de‐trended streamflow and phosphorus concentration data at 80 locations. The model explained 91% of the variability in loads and 51% of the variability in yields for a base year of 2002. Point sources, geological background, and cultivated land were significant sources. Variables used to explain delivery of phosphorus from land to water were precipitation and soil clay content. Aquatic loss of phosphorus was significant in streams of all sizes, with the greatest decay predicted in small‐ and intermediate‐sized streams. Geological sources, including volcanic rocks and shales, were the principal control on concentrations and loads in many regions. Some localized formations such as the Monterey shale of southern California are important sources of phosphorus and may contribute to elevated stream concentrations. Many of the larger point source facilities were located in downstream areas, near the ocean, and do not affect inland streams except for a few locations. Large areas of cultivated land result in phosphorus load increases, but do not necessarily increase the loads above those of geological background in some cases because of local hydrology, which limits the potential of phosphorus transport from land to streams.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号