共查询到20条相似文献，搜索用时 390 毫秒
1.
对草海不同区域沉积物上覆水及孔隙水、附近河流和雨水中砷的含量与分布特征进行了分析,并利用一维孔隙水扩散模型估算了砷在沉积物-水界面的扩散通量。结果表明:草海出口砷含量为1.59μg·L~(-1),明显高于流入草海的水体端元(平均值0.32μg·L~(-1))和雨水(0.37μg·L~(-1))中砷浓度;草海上覆水中砷的空间分布表现为挺水植物区(2.99~3.45μg·L~(-1))沉水植物区(1.79~2.34μg·L~(-1)),垂直分布上无明显变化,挺水植物区上覆水体中的砷以As(Ⅲ)(H_3AsO_3)形态存在,沉水植物区上覆水体中的砷以As(Ⅴ)(HAsO~(2-)_4)形态存在;而沉积物和孔隙水中总砷含量垂直方向上波动较大,规律与上覆水相似,均表现为挺水植物区沉水植物区,其中挺水植物区沉积物砷含量为19.86~36.45 mg·kg~(-1),平均值27.84 mg·kg~(-1),沉水植物区沉积物砷含量为13.05~32.32 mg·kg~(-1),平均值19.79 mg·kg~(-1);草海挺水植物区和沉水植物区三处取样点在沉积物-水界面的扩散通量分别为73.84μg·m~(-2)·d~(-1)和18.99、11.45μg·m~(-2)·d~(-1),均表现为沉积物孔隙水中的砷向上覆水释放,揭示沉积物可能是草海水体中砷重要的输入源。 相似文献
2.
3.
砷是环境中以低浓度广泛天然存在的一种非金属元素,与其它元素形成无机和有机的复合物。不同形式的砷通过化学的电子转移、甲基化和烷基化等复杂机制使不同形态的砷相互转化。砷转化机制的研究为砷污染的治理提供新的技术方法,但由于面临诸多的问题,目前还没有一种单一的修复技术被广泛地应用于砷污染环境的治理。本文就近年来有关环境中砷的来源和存在、生物转化和修复的机制进行综述,为砷污染的修复和环境治理提供科学指导。 相似文献
4.
5.
[目的]筛选到在自然条件下能有效去除水体中砷污染的微藻。[方法]以4种微型绿藻(小球藻Chlorella sp.(zfsaia)、Chlorellaminata、Chlorella vulgaris和羊角月牙藻Selenastrum capricormulum)为材料,选取6个不同浓度的As(III)(0.5、1.0、2.0、5.0、10.0、20.0mg/L)进行培养处理,以生物量、叶绿素a含量等生理指标研究这4种藻类对砷的耐受性及其吸附情况。[结果]小球藻Chlorella sp.(zf-saia)对砷的毒害有敏感性,当砷浓度超过10 mg/L时,其生长受到抑制,EC50值为17.32 mg/L;当砷浓度在0～20 mg/L范围内,羊角月牙藻Selenastrum capricormulum、小球藻Chlorella minata和Chlorella vulgaris生长不受影响,对砷具有较高的耐受性,24 h后,它们对砷的去除率分别达77.02%、72.18%和81.36%。[结论]该研究表明藻类在治理含砷废水和作为砷污染废水的指示性植物等方面具有良好的应用前景。 相似文献
6.
[目的]筛选到在自然条件下能有效去除水体中砷污染的微藻。[方法]以4种微型绿藻 (小球藻Chlorella sp.(zfsaia)、Chlorella minata、Chlorella vulgaris和羊角月牙藻Selenastrum capricormulum)为材料,选取6个不同浓度的As(III)(0.5、1.0、2.0、5.0、10.0、20.0 mg/L)进行培养处理,以生物量、叶绿素a含量等生理指标研究这4种藻类对砷的耐受性及其吸附情况。[结果]小球藻Chlorella sp. zfsaia对砷的毒害有敏感性,当砷浓度超过10mg/L时,其生长受到抑制,EC50值分别为17.32 mg/L;当砷浓度在0～20 mg/L范围内,羊角月牙藻Selenastrum capricormulum、小球藻Chlorella minata和Chlorella vulgaris生长不受影响,对砷具有较高的耐受性,24 h后,它们对砷的去除率分别达77.02%、72.18%和81.36%。[结论]该研究表明藻类在治理含砷废水和作为砷污染废水的指示性植物等方面具有良好的应用前景。 相似文献
7.
[目的]为砷的检测寻求一种快速、简便的新方法。[方法]研究在铜离子存在条件下,通过玻碳悬汞电极测定饮用水中砷含量,考查了电沉积电位、电沉积时间、平衡电位、平衡时间对测定结果的影响。[结果]铜离子浓度范围为42.8-57.145 ng/ml;随着电沉积电位、平衡电位的增大,底液空白和加标液的峰高及差比值先增大后减小;随着电沉积时间、平衡时间的增加,底液空白和加标液的峰高先增大后趋向平缓,而其差比值先增大后减小;当电沉积电位为-1.1 V、电沉积时间为100 s、平衡电位为-0.7 V、平衡时间为30 s时,测定结果最好。测定砷的线性范围为0-200 ng,回收率为93.2%-105.4%,相对标准偏差为2.35%。[结论]该法操作快速、简便,结果准确、可靠。 相似文献
8.
The ecology of arsenic 总被引：10，自引：0，他引：10
Arsenic is a metalloid whose name conjures up images of murder. Nonetheless, certain prokaryotes use arsenic oxyanions for energy generation, either by oxidizing arsenite or by respiring arsenate. These microbes are phylogenetically diverse and occur in a wide range of habitats. Arsenic cycling may take place in the absence of oxygen and can contribute to organic matter oxidation. In aquifers, these microbial reactions may mobilize arsenic from the solid to the aqueous phase, resulting in contaminated drinking water. Here we review what is known about arsenic-metabolizing bacteria and their potential impact on speciation and mobilization of arsenic in nature. 相似文献
9.
Malasarn D Saltikov CW Campbell KM Santini JM Hering JG Newman DK 《Science (New York, N.Y.)》2004,306(5695):455
Arsenate [As(V)]-respiring bacteria affect the speciation and mobilization of arsenic in the environment. This can lead to arsenic contamination of drinking water supplies and deleterious consequences for human health. Using molecular genetics, we show that the functional gene for As(V) respiration, arrA, is highly conserved; that it is required for As(V) reduction to arsenite when arsenic is sorbed onto iron minerals; and that it can be used to identify the presence and activity of As(V)-respiring bacteria in arsenic-contaminated iron-rich sediments. The expression of arrA thus can be used to monitor sites in which As(V)-respiring bacteria may be controlling arsenic geochemistry. 相似文献
10.
吉林地区香椿水培生产研究 总被引：1，自引：1，他引：0
［目的］为把高档蔬菜香椿引入吉林地区提供科学依据。［方法］以清水为对照,用3种传统培养液,即凡尔赛营养液、道格拉斯的孟加拉Ⅲ营养液、波司特营养液作为基本营养液,各自添加不同的微量生长激素对香椿进行水培试验。［结果］3种配方的水培营养液均适合对香椿进行水培,但其中以道格拉斯的孟加拉Ⅲ营养液添加IBA0.5mg/L为最好,在水培的各个生长阶段都表现优良,水培到25d平均高度和侧枝的长度最大,单株平均重268g。而采用凡尔赛基本营养液＋IAA0.5mg/L和波司特基本营养液＋NAA0.5mg/L作为水培营养液配方的单株平均重分别为248、250g。［结论］建议在生产香椿水培苗的过程中采用道格拉斯的孟加拉Ⅲ基本营养液＋IBA0.5mg/L作为水培营养液配方。 相似文献
11.
James L. Wescoat Jr. 《Agriculture and Human Values》1990,7(2):73-87
Water has a dual role in the Sundarbans area of southwestern Bangladesh. Hydrologic processes are vital to the ecological functioning and cultural identity of the mangrove ecosystem. But at the same time, large scale water development creates external forces that threaten the Sundarbans environment. Water is managed to a limited degree as a common property resource, both in the Sundarbans and in larger regions. It is also managed as private property, a public good, a state-controlled resource, an open access resource, and a natural hazard. And to a large degree, it is not managed at all. By focussing on water, we begin to understand the linkages between the Sundarbans area and larger regional contexts; and between common property resource systems and the broader array of institutional, political, and property relations. Section one of this paper provides an overview of the role of water in the Sundarbans, including modern human modifications of deltaic hydrology. Section two surveys water management issues and institutions at six geographical scales: the International Basin; 2) India and Bangladesh; 3) Greater Bengal; 4) Bangladesh; 5) southwestern Bangladesh; and 6) Khulna district. The conclusion stresses the role that the political geography of water will play both within and outside the Sundarbans ecosystem.James Wescoat is Assistant Professor of Geography at the University of Colorado—Boulder. His research deals with the historical geography of water development in South Asia and the United States. He is currently working on a three year study of the effects of global climate change in the Indus River basin with the Pakistan Water and Power Development Authority for the U.S. Environmental Protection Agency. 相似文献
12.
Several recently suggested Venus cloud condensates, including aluminum chloride and halides, oxides, and sulfides of arsenic and antimony, are assessed for their thermodynamic and geochemical plausibility. Aluminum chloride can confidently be ruled out, and condensation of arsenic sulfides on the surface will cause arsenic compounds to be too rare to produce the observed clouds. Antimony may be sufficiently volatile, but the expected molecular form is gaseous antimony sulfide, not the chloride. Arsenic and antimony compounds in the atmosphere will be regulated at very low levels by sulfide precipitation, irrespective of the planetary inventory of arsenic and antimony. Thus arguments for a volatile-deficient origin for Venus based on depletion of water and mercury (relative to the earth) cannot be tested by a search for atmospheric arsenic or antimony. 相似文献
13.
砷对烤烟叶片水分代谢的影响 总被引：1，自引：0，他引：1
为了探讨砷毒害与烤烟水分代谢的关系,采用盆栽试验研究了砷对烤烟叶片水分代谢的影响。结果表明,砷使烤烟叶片的水势、蒸腾速率、气孔导度、自由水含量和单叶水分利用效率降低,但使叶片含水量、束缚水含量、束缚水和自由水比值提高。土壤中砷含量越高,砷对烤烟叶片水分代谢的影响程度越大。砷对烤烟生育前期叶片水分代谢的影响大于中、后期。说明砷严重影响了烤烟的水分代谢,降低了水分在生理代谢方面的功能。 相似文献
14.
陕西白水县无公害苹果园环境质量评价 总被引：16，自引：0，他引：16
监测了陕西白水县无公害苹果生产示范区大气、土壤、灌溉水的质量,并对其进行了评价。监测结果表明,无公害苹果生产的4项大气质量指标、6项土壤质量指标和6项灌溉水质量指标均未超过国家《无公害食品苹果产地环境条件》限制,产地环境条件完全能够满足无公害苹果生产的要求。评价结果还表明,可悬浮颗粒物、As和Cd有可能成为无公害苹果生产示范区大气、土壤和灌溉水未来的主要污染物,并提出提倡果园种草,增加植被覆盖,降低大气可悬浮物,减少苹果果面污染,禁止果园使用福美砷等砷制剂,以避免土壤砷污染的增加等措施。 相似文献
15.
Stable isotope enrichment in paleowaters of the southeast atlantic coastal plain, United States 总被引：1，自引：0，他引：1
Plummer LN 《Science (New York, N.Y.)》1993,262(5142):2016-2020
Paleowaters from the Floridan aquifer system in the southeastern Atlantic coastal plain have higher D/H and (18)O/(16)O ratios than local Holocene ground water. Maximum delta(18)O enrichments in ground water having adjusted radiocarbon ages of 20,000 to 26,000 years are 0.7 to 2.3 per mil. The trend in isotopic enrichment in paleowaters is the reverse of that normally observed in continental glacial age ground water. Dissolved nitrogen and argon concentrations indicate, however, that the average recharge temperature was 5.3 degrees C cooler than that today. The data indicate cool conditions in the southeast Atlantic coastal plain during the last glacial maximum, with recharge limited primarily to late summer tropical cyclones and hurricanes. 相似文献
16.
不同砷形态在水产品中的毒理及转化研究进展 总被引：1，自引：0，他引：1
为了研究不同砷形态化合物在水产品体内的毒力大小、毒理效应和转化机制，本文综述了国内外近二十年几种常见砷化合物在水产品中蓄积规律的研究，发现在所有砷化合物中，无机砷的毒性往往大于有机砷，但也有研究发现三价态的有机砷MMA毒性比无机砷高数几倍；在对水产品体内不同砷化合物含量测定的研究中可以得出有机砷是主要的存在形式。但研究也还存在不足，对水产品的砷含量研究多集中于沿海地区的海产品类，今后还需要加大对淡水性水产品类砷含量以及蓄积规律的研究力度。本文主要阐述了砷的几种常见形态As3+、As5+、DMA、MMA、AsB、AsC、TMAO、TETRA(TMAs+)、砷糖和砷脂间的毒力大小比较及其毒性产生机理、环境中砷元素的来源和砷形态在水产品内的迁移、转化、代谢机理，旨在不同价态砷化合物在水产品中的研究提供参考价值。 相似文献
17.
Environmental impact of a geothermal power plant 总被引：1，自引：0，他引：1
Axtmann RC 《Science (New York, N.Y.)》1975,187(4179):795-803
The Wairakei plant discharges approximately 6.5 times as much heat, 5.5 times as much water vapor, and 0.5 times as much sulfur, per unit of power produced, as would a modern coal plant in New Zealand. It also contaminates the Waikato River with H(2)S, CO(2), arsenic, and mercury at concentrations that have adverse but not calamitous effects. Designed and built at a time when environmental sensibilities were less acute and geothermal technology was less developed, Wairakei produces an overall environmental impact that would be neither acceptable nor necessary in a new plant. Despite its imperfections, however, the Wairakei plant has been under development or in operation for more than 20 years without presenting any serious environmental problems for the local population. Reinjection of the hot waste water, an as yet unproven procedure for liquid-dominated fields, would reduce the plant's environmental impact sharply. Ground subsidence is not a severe problem at Wairakei but may prove to be one at the nearby Broadlands field. There are several environmental characteristics that are unique to geothermal power: (i) pollutant formation may be independent of the power productionc rate; (ii) effluent pathways may change abruptly; (iii) preoperational testing and wild bores contribute significantly to the overall impact; and (iv) waste water may be discharged at temperatures high enough so that utilization of the waste heat becomes both practical and imperative. 相似文献
18.
Md. Salim Azad Md. Tabiur Rahman Md. Abdul Matin 《Frontiers of Agriculture in China》2011,5(2):241-246
A new experiment on seed germination technique for Phoenix dactylifera, an exotic species was conducted in the nursery of Forestry and Wood Technology Discipline, Khulna University, Bangladesh.
The seeds imported from Saudi Arabia were collected from Nirala Central Mosque, Khulna, Bangladesh, in September 2008 and
treated with four presowing treatments (control, immersion in normal water at room temperature (20–22°C) for 12 h, immersion
in sun-heated water (25–35°C) for 12 h, and immersion in hot water (50°C) for 10 h) before seed germination with different
germination media (well dried loamy soil, coarse sand, mixture of coarse and fine sand at a ratio of 3:1, mixture of coarse
and fine sand at a ratio of 3:2, and mixture of coarse and fine sand at a ratio of 1:1). The experiment showed that presowing
treatments significantly increased the germination rates of seeds compared to those in control (68%) and hot water treatment
(69%). The highest germination success (84%) was found in the immersion in normal water and sunheated water for 12 h. Experiment
also showed that seed germination with course sand and mixture of coarse and fine sand with a ratio of 3:1 performed better
than the loamy soil. Germination started from 21 to 26 days and completed between 38–40 days of the germination period in
all treatments. ANOVA showed a significant difference among the treatments in seed germination, but there was no significant
difference among the media in seed germination. Normal water and sun-heated water for 12 h for pretreatment and coarse sand
or mixture of coarse and fine sand at a ratio of 3:1 may be recommended for seed germination of the species in rural Bangladesh. 相似文献
19.
Detection sensitivities of a few parts per billion for ten gaseous pollutants have been evaluated by measuring the strength of the absorption of infrared radiation from carbon monoxide and carbon dioxide lasers. Ethylene concentrations as small as 5 parts per billion have been detected in air. The measured absorption strengths indicate that in mixtures of pollutants, such as nitrogen dioxide and water vapor, the sensitivity is reduced by overlapping absorption bands. However, calculations indicate that it should be possible to detect nitrogen dioxide concentrations of 0.01 part per million in the presence of water vapor concentrations of 105 parts per million. 相似文献