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71.
异丙甲草胺与锌共存对斜生栅藻毒性手性差异影响 总被引:2,自引:2,他引:0
为评价重金属与手性农药共存的生物选择性毒性,采用毒性试验标准方法研究了Rac-、S-异丙甲草胺单独及与锌共存对斜生栅藻的手性毒性差异.结果表明,Zn2+存在条件下Rac-、S-异丙甲草胺对斜生栅藻的生长趋势影响与除草剂单独作用时的趋势基本相同,Zn2+的存在降低了高浓度除草剂对斜生栅藻的生长抑制作用,处理初期(24 h)0.30 mg·L-1Rac-和S-异丙甲草胺单独对斜生栅藻生长的抑制率分别为49.61%和59.73%,与Zn2+联合作用其抑制率分别为38.41%和42.52%.Zn2+的存在增加了Rac-和S-异丙甲草胺对斜生栅藻的立体选择性毒性差异,使S-异丙甲草胺急性毒性增大的程度大于Rac-异丙甲草胺毒性的增加;与Zn2+的联合毒性作用类型表现为除草剂在低浓度下为部分相加作用,高浓度下为拮抗作用;除草剂单独及与Zn2+联合作用处理96 h后的斜生栅藻叶绿素含量变化与其生长趋势基本一致. 相似文献
72.
落叶燃烧排放的颗粒物及有机碳、元素碳的研究 总被引:2,自引:0,他引:2
为研究落叶燃烧排放的颗粒物(PM)及有机碳(OC)、元素碳(EC),采用明燃和闷燃两种形式对10种乔木的落叶进行燃烧实验,采集了排放的烟尘,并用元素碳/有机碳分析仪测定样品的OC和EC含量.结果表明,落叶在明燃状态下PM、OC、EC的排放因子范围分别为7.9~31.9、0.9~9.7、3.6~13.9 g·kg-1,平均值分别为19.7、5.2、6.8 g·kg-1.闷燃状态下PM、OC、EC的排放因子范围分别为61.3~128.9、31.7~60.4、1.9~6.0 g·kg-1,平均值分别为91.0、43.0、4.0 g·kg-1.明燃和闷燃的OC/EC变化范围分别为0.21~1.82和8.16~16.84.明燃状态下OC/PM、EC/PM的范围分别为0.11~0.41和0.18~0.56.闷燃状态下OC/PM、EC/PM的范围分别为0.43~0.53和0.03~0.06.OC和PM的排放因子在两种燃烧状态下均呈现显著的相关性.在不同的燃烧状态下,各组分之间的排放因子具有较大的差异,OC的排放因子在闷燃状态下高于明燃状态,而EC的排放因子则相反.不同燃烧状态下PM、OC、EC的排放因子及它们之间的比值分析,对建立森林生物质燃烧源排放清单以及来源解析具有重要意义. 相似文献
73.
Elwyn S. Krous Joseph P. Wagner Harold L. Parkinson Milton S. Sachs 《Journal of the American Water Resources Association》1971,7(4):810-822
ABSTRACT .A case study was performed to evaluate potential applications of desalted saline water for agriculture using 2 distillation type processes and 2 membrane type processes. The investigation determined the costs and benefits associated with desalting saline water at concentrations of 1,500, 900, 400, 200, and 50 ppm. Benefits from desalting are generated by shifts to more profitable crops, reduced costs for drainage, and reduction in fertilizer and labor requirements with better quality water. Costs are based on the project features such as desalting plants, raw water diversion facilities, storage reservoirs, conveyance and distribution systems, brine disposal, blending facilities, and gypsum addition systems. Hydrologic studies determined the crop irrigation requirements, water demand schedules, desalted water storage requirements, brine disposal requirements, and size of facilities required. Reconnaissance design layouts were made for producing desalted water using a combination of 14 schemes. The study also included a review of irrigation practices. The benefit-cost ratios range from 0.4 to 1.0 for 1,500 ppm irrigation water to 0.8 to 1.0 for 50 and 200 ppm water. Investment costs per acre are high, ranging from $12,900 to $20,900. Irrigation benefits are based on the increase in production from a desert condition with no water supply to the irrigation conditions studied. 相似文献
74.
Donald Bruce 《Journal of Agricultural and Environmental Ethics》2002,15(1):7-16
Three interpretations of theprecautionary principle are identified, namely``soft,' ``hard,' and outright rejection. The ECCommunication of February 2000 is largely aresponse to the latter, to provide alegitimation in trade-related WTO disputes.This context leads to an over stress onscientific closure. This is critiqued asidealistic in respect of resolving long termuncertainties inherent in the GM food issue.While offering some useful guidelines in riskmanagement, the EC report seriously fails totake into account the ethical and societaldimension of risk. These are crucial both indetermining when precautionary principle isinvoked and the action to be taken. The EC viewleans too much to a scientific rationalist riskperspective. However, the ``Green'interpretation of the precautionary principleas a reversal of the burden of proof is alsocriticized as inconsistent both with the natureof technology and with the nature of reality asseen in a Christian perspective. Biblicalinsights on risk reveal a balance ofintervention and conservation in a world whererisk is inherent. The notion of risk as asocial contract reveals that ethical andsocietal issues have a crucial role to play inapplying the precautionary principle. 相似文献
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The word “electrocoagulation” (EC) will be sometimes used with “electroflotation” (EF) and can be considered as the electrocoagulation/flotation (ECF) process. Through the process of electrolysis, coagulating agents such as metal hydroxides are produced. When aluminium electrodes are used, the aluminium dissolves at the anode and hydrogen gas is released at the cathode. The coagulating agent combines with the pollutants to form large size flocs. As the bubbles rise to the top of the tank they adhere to particles suspended in the water and float them to the surface. In fact, a conceptual framework of the overall ECF process is linked to coagulant generation, pollutant aggregation, and pollutant removal by flotation and settling when it has been applied efficiently to various water and wastewater treatment processes. This review paper considers a significant number of common applications of EC and ECF processes which have been published in journal and conference papers. 相似文献
78.
Krein A Audinot JN Migeon HN Hoffmann L 《Environmental science and pollution research international》2007,14(1):3-4
Background, Aim and Scope
Current scientific studies and evaluations clearly show that an increase of urban dust loads, alone or combined with other
pollutants und certain meteorological conditions lead to different significant health effects. Premature death, increased
hospital admissions and increased respiratory symptoms and diseases as well as decreased lung function can be observed in
combination with high pollutant levels. Sensitive groups like elderly people or children and persons with cardiopulmonary
diseases such as asthma are more strongly affected. Because of the direct contact between fine particles and lung tissue more
information concerning the surface structure (mapping of toxic elements) is required.
Materials and Methods:
The NanoSims50 ion microprobe images the element composition at the surface of sub-micrometer air dust particles and documents
hot spots of toxic elements as a possible threat for human health.
Results:
The atmospheric fine dust consists of a complex mixture of organic and inorganic compounds. Heavy metals are fixed on airborn
particles in the form of hot spots in a nanometer scale. From a sanitary point of view, the hot spots consisting of toxic
elements are particularly relevant as they react directly with the lung tissues.
Discussion:
To what extent particles can penetrate the various areas of the lungs and be deposited there depends on the one hand on their
physical characteristics and on the other on breathing patterns and the anatomy of the lung, which is subject to change as
the result of growth, ageing or illness. Once inhaled, some particles can reach the pulmonary alveoli and thus directly expose
the lung tissues to toxic elements.
Conclusions:
Especially the mapping of toxic arsenic or heavy metals like copper on the dust particles shows local hot spots of pollution
in the dimension of only 50 nanometers.
Recommendations and Perspectives:
Imaging of elements in atmospheric particles with NanoSIMS will help to identify the material sources. 相似文献
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