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951.
Núbia Maria Correia Caio Antônio Carbonari Edivaldo Domingues Velini 《Journal of environmental science and health. Part. B》2020,55(6):574-582
AbstractThe objective of this study was to identify and quantify herbicide residues in water samples of rain, cisterns, streams, ponds, springs, semi-artesian wells, dams and a river in the Rio Samambaia sub-basin in the Federal District and eastern Goiás. A total of 287 samples were collected from 20 farms in the sub-basin in the rainy (February, summer) and dry (August, winter) seasons in 2016. Aminomethylphosphonic acid (AMPA, a glyphosate metabolite), clethodim, chlorimuron-ethyl, diuron, fluazifop acid (a fluazifop-p-butyl metabolite and the active ingredient), haloxyfop acid (a haloxyfop-methyl metabolite and the active ingredient), imazamox, mesotrione, metsulfuron, nicosulfuron and pendimethalin were not identified in any water sample. In the rainy season, approximately 99% of the samples contained residues at least one of the evaluated herbicides; in the dry season (, 100% of the samples contained residues of at least one of the evaluated herbicides. When considering only detection frequency, metribuzin, atrazine, clomazone and haloxyfop-methyl were the main herbicides found in the water of the Samambaia River sub-basin. In turn, based on levels higher than the limit of quantification, the main compounds detected were atrazine, clomazone, haloxyfop-methyl and glyphosate. In both seasons, the highest relative concentrations of herbicides for the rainy and dry seasons were found in spring water, 25% and 56%, respectively, and dam water, 23% and 16%, respectively. 相似文献
952.
Yan R Liang DT Tay JH 《Environmental science and pollution research international》2003,10(6):399-407
GOAL, SCOPE AND BACKGROUND: Mercury (Hg) emission from combustion flue gas is a significant environmental concern due to its toxicity and high volatility. A number of the research efforts have been carried out in the past decade exploiting mercury emission, monitoring and control from combustion flue gases. Most recently, increasing activities are focused on evaluating the behavior of mercury in coal combustion systems and developing novel Hg control technologies. This is partly due to the new regulatory requirement on mercury emissions from coal-fired combustors to be enacted under the U.S. Title III of the 1990 Clean Air Act Amendments. The aim of this review work is to better understand the state-of-the-art technologies of flue gas mercury control and identify the gaps of knowledge hence areas for further opportunities in research and development. MAIN FEATURES: This paper examines mercury behaviors in combustion systems through a comprehensive review of the available literature. About 70 published papers and reports were cited and studied. RESULTS AND DISCUSSION: This paper summarizes the mechanisms of formation of mercury containing compounds during combustion, its speciation and reaction in flue gas, as well as subsequent mobilization in the environment. It also provides a review of the current techniques designed for real-time, continuous emission monitoring (CEM) for mercury. Most importantly, current flue gas mercury control technologies are reviewed while activated carbon adsorption, a technology that offers the greatest potential for the control of gas-phase mercury emissions, is highlighted. CONCLUSIONS AND RECOMMENDATIONS: Although much progress has been achieved in the last decade, techniques developed for the monitoring and control of mercury from combustion flue gases are not yet mature and gaps in knowledge exist for further advancement. More R&D efforts are required for the effective control of Hg emissions and the main focuses are identified. 相似文献
953.
河流水体中重金属形态模型研究 总被引:5,自引:0,他引:5
本文提出了一种重金属形态模型,用于模拟水体中的水溶态、颗粒态和底泥、悬浮物的活动态和非活动态。以乐安江水体中铜污染为背景,计算结果与现场调查分析的数据比较表明,两者基本吻台,说明模型基本上是合理的,概括了重金属污染的重要过程,参数的选择反映了河流的实际情况。 相似文献
954.
955.
Principal Biogeochemical Factors Affecting the Speciation And Transport of Mercury through the terrestrial environment 总被引:2,自引:0,他引:2
It is increasingly becoming known that mercury transport and speciation in the terrestrial environment play major roles in methyl-mercury bioaccumulation potential in surface water. This review discusses the principal biogeochemical reactions affecting the transport and speciation of mercury in the terrestrial watershed. The issues presented are mercury-ligand formation, mercury adsorption/desorption, and elemental mercury reduction and volatilization. In terrestrial environments, OH–, Cl– and S– ions have the largest influence on ligand formation. Under oxidized surface soil conditions Hg(OH)2, HgCl2, HgOH+, HgS, and Hg0 are the predominant inorganic mercury forms. In reduced environments, common mercury forms are HgSH+, HgOHSH, and HgClSH. Many of these mercury forms are further bound to organic and inorganic ligands. Mercury adsorption to mineral and organic surfaces is mainly dictated by two factors: pH and dissolved ions. An increase in Cl– concentration and a decrease in pH can, together or separately, decrease mercury adsorption. Clay and organic soils have the highest capability of adsorbing mercury. Important parameters that increase abiotic inorganic mercury reduction are availability of electron donors, low redox potential, and sunlight intensity. Primary factors that increase volatilization are soil permeability and temperature. A decrease in mercury adsorption and an increase in soil moisture will also increase volatilization. The effect of climate on biogeochemical reactions in the terrestrial watershed indicates mercury speciation and transport to receiving water will vary on a regional basis. 相似文献
956.
The potential accumulation of platinum group elements (PGE) in the environment from automobile catalysts is high in urban
areas, with the major sinks being roadside soils. Therefore, this investigation presented the detailed study on characterized
concentrations of Pt and Pd and their enrichment ratios in urban roadside soils in Xuzhou, China in March 2003. Data from
21 roadside topsoil samples analyzed by inductively coupled plasma-mass spectrometer (ICP-MS) illustrated that the medians
of concentrations of Pt and Pd were 2.9 and 2.8 ng/g, respectively. Hierarchical clustering analysis indicated that Pt and
Pd were mainly from traffic emissions. Compared to unpolluted soils, computation of Pt and Pd enrichment ratios suggested
that the Xuzhou roadside soils had average enrichment factors of 3.53 for Pt (in range of 1.22–5.73) and of 3.37 for Pd (in
range of 1.35–4.46). Lower Pt/Pd ratios (in range of 0.35–2.86) in relation to similar studies in other countries were observed,
which might be due to the different Pt/Pd ratios in Chinese automobile catalytic converters. Moreover, fine fraction (<250
μm) contained higher concentrations of Pt and Pd compared to the coarse fraction (250–500 μmm). 相似文献
957.
LIU Xiaojie CHENG Jinping Song Yuling HONDA Shun’ichi WANG Li LIU Zheng SAKAMOTO Mineshi LIU Yuanyuan 《环境科学学报(英文版)》2008,20(10):1258-1262
This investigation was made to estimate current normal concentrations of total mercury in the hair of Chinese coastal people. Hair samples were collected from 659 healthy inhabitants in the areas along the coast and the rivers (such as Shanghai, Ningbo, Dalian, Xiamen, and Zhoushan) of China from Feb. 2005 to June 2006. Total mercury concentrations in the samples were analyzed by the cold vapor atomic adsorption spectrometry method (CVAAS). The results showed the geometric mean concentration of total mercur... 相似文献
958.
959.
放射性污染植物修复中超富集植物的数值评价 总被引:4,自引:0,他引:4
目前超富集植物在放射性污染植物修复评价体系中还没有明确的核素富集量限定值,借鉴辐射环境评价方式,明确放射性污染低剂量概念,推算达干预水准时的植物富集系数,结合放射性废物管理规定,计算富集系数应达到的水平,提出了重要核素的超富集植物评价的新的量值概念;建立修复年限模式,讨论了一定生物量和生物富集系数对修复年限的影响。结果表明,根据上述因素导出的各重要核素的超富集植物最低富集系数略有不同,分别是Cs-137:0.70、Sr-90:0.86、Co-60:2.89、Pu-239:0.26、Am-241:0.21、Cm-244:0.12、U-235:0.18、U-238:0.052。良好的超富集植物,其富集系数应再提高一个数量级。 相似文献
960.
The development of two comprehensive modelling systems and a test application to estimate the mercury budget for the State of New York is discussed in the present study. The modelling tools developed are based on two well known meteorological modelling systems namely, RAMS and SKIRON/Eta. Both models have been modified and the developed modules describing the physico-chemical processes of mercury have been incorporated in each modelling system. Model calculations and measurements have been compared during the 14 to 26 August 1997 simulation period. Two different simulations were performed, scenario1 where all available sources of mercury were used and scenario2 where the New York State mercury sources were excluded. An attempt was made to identify and quantify critical gaps in the current understanding of regional scale transport deposition and fate of mercury in New York State, improving modelling capabilities and understanding of mercury as an air pollutant, and provide a tool for policy makers in mitigating the impacts of mercury pollution. 相似文献