联合改良剂对桉树吸收重金属的作用——以矿区土壤中Cd、Zn和Cu为例

通过5种矿区土壤的盆栽试验,研究了联合改良剂对桉树部分生理指标、根中Cd、Zn和Cu的含量、以及土壤中Cd、Zn和Cu的BCR提取形态的影响,探讨了其对矿区土壤还林的作用.结果表明,与对照相比,施用改良剂后桉树的生物量和叶绿素含量的增幅分别为-7.6%~158.8%和-0.7%~23.1%,丙二醛含量的降幅为2.6%~37.9%,其中部分处理的生物量和丙二醛含量的变化达到显著水平（P<0.05）;土壤中有效态Cd、Zn和Cu的含量分别下降12.5%~63.8%、1.6%~54.7%和16.2%~57.6%,桉树根中Cd、Zn和Cu的含量分别下降3.1%~56.6%、-1.5%~21.3%和9.3%~50.1%.土壤对桉树根中Cd、Zn和Cu的含量有显著影响（P<0.05）,改良剂的配比或施用量无显著影响（P>0.05）,但在5种矿区土壤中G3降低桉树根中Cu含量的效果优于G1和G2;在重金属含量最高的2种土壤中,G1降低桉树根中Cd和Zn含量的效果优于G2和G3.研究表明施用联合改良剂能降低桉树对重金属的吸收,有利于矿区土壤的还林.     

Fractionation of Cu, Pb and Zn in certified reference soils SRM 2710 and SRM 2711 using the optimized BCR sequential extraction procedure

Sequential extraction of metals from solid media is a common analytical tool used in environmental and exploration geochemistry. A number of procedures exist, but without harmonization and standardization, meaningful comparisons are tenuous without baseline data. A newly developed, standardized sequential extraction procedure (optimized BCR) was applied to two contaminated certified reference soils from Montana, US (SRM 2710 and SRM 2711) for Cu, Pb and Zn. Four operationally defined fractions were isolated, acid extractable, reducible, oxidizable, and residual (by aqua regia). Fraction-specific concentrations, percentages and recoveries for Cu, Pb and Zn were used to explore differences between the optimized BCR procedure and three other sequential extraction schemes with published data for SRM 2710 and 2711 (i.e. Tessier scheme, Geological Survey of Canada scheme and the original BCR scheme). Results indicate significant differences between the four schemes, even for schemes that are closely associated (i.e. the original and optimized BCR schemes). Order-of-magnitude fraction-specific concentration differences were observed, especially for Pb in the reducible fraction. Differences between schemes are worrisome because trends varied between metals, between fractions and between reference soils. These data reinforce the need for increased adoption of standardized sequential extraction procedures and further examination of different solid media.     

Methods for project-based mechanisms (JI/CDM)—relevance of IPCC inventory guidelines

A baseline for a project consists of estimates of annual emissions of greenhouse gases (GHG) for a given time period without implementing the project. A general three-step process for determining the baseline is suggested. The emission reduction of the project is given by the difference between the baseline and the monitored annual emissions. A preferred method, direct measurement of the emission reduction, is possible for some types of projects. Methods for estimating the annual baseline emissions are not necessary for the latter category, and a definition of this project category is suggested. IPCC Guidelines for National GHG Inventories categorise the emission sources so that only direct emissions from consumption of fuel and feedstock are calculated. There are thus no emission factors for indirect emissions (e.g. electricity consumption or km transported) or emission factors that depend on technology only, independent of consumption of fuel and feedstock. Technology-dependent emission factors may thus need to be developed for estimating indirect emissions and multi-project baselines. Consistency should be sought with the IPCC Guidelines when estimating annual baseline emissions and in monitoring project emissions to ensure comparability with the National Inventories.     

电子商务安全的探讨

介绍电子商务的发展规模以及可能会遇到的安全问题,分析电子商务安全的基本技术加密算法。根据对称加密算法和非对称加密算法的安全特点进行组合,从而提出电子商务交易的一般安全控制结构图,针对各个环节的优缺点,提出有效解决安全问题的方案,同时重点突出了各种相关新技术的特点;电子商务交易的发展,互联网的普及,网络上交易及其信息的安全性已经对人们的经济活动及日常生活产生了重要的影响,为此,提出的电子商务安全方案最大限度地降低了人们的风险;进一步探讨和展望电子商务的前景:随着电子商务的发展,电子交易的手段也更加多样化,安全问题也会变得重要和突出;同时,电子商务又是一个复杂的系统工程,它的安全还要依赖许多社会问题的解决。     

Tropical deforestation in a future international climate policy regime—lessons from the Brazilian Amazon

The possibility of adopting national targets for carbon dioxide (CO₂) emissions from tropical deforestation in a future international climate treaty has received increasing attention recently. This attention has been prompted by proposals to this end and more intensified talks on possible commitments for developing countries beyond the United Nations Framework Convention on Climate Change Kyoto Protocol. We analyze four main scientific and political challenges associated with national targets for emissions from tropical deforestation: (1) reducing the uncertainties in emission inventories, (2) preserving the environmental integrity of the treaty, (3) promoting political acceptance and participation in the regime, and (4) providing economic incentives for reduced deforestation. We draw the following conclusions. (1) Although there are large uncertainties in carbon flux from deforestation, these are in the same range as for other emissions included in the current Kyoto protocol (i.e., non-CO₂ GHGs), and they can be reduced. However, for forest degradation processes the uncertainties are larger. A large challenge lies in building competence and institutions for monitoring the full spectrum of land use changes in developing countries. (2 and 3) Setting targets for deforestation is difficult, and uncertainties in future emissions imply a risk of creating ‘tropical hot air’. However, there are proposals that may sufficiently deal with this, and these proposals may also have the advantage of making the targets more attractive, politically speaking. Moreover, we conclude that while a full carbon accounting system will likely be politically unacceptable for tropical countries, the current carbon accounting system should be broadened to include forest degradation in order to safeguard environmental integrity. (4) Doubts can be cast over the possible effect a climate regime alone will have on deforestation rates, though little thorough analysis of this issue has been made.

Antimony smelting process generating solid wastes and dust：Characterization and leaching behaviors

A large amount of solid waste has been produced by the antimony smelting process in the＂World Capital of Antimony＂, Xikuangshan area in China. This study comprehensively investigated the physical and chemical characteristics of the various solid wastes, as well as the leaching behavior of the solid wastes, which included water-quenched slag,arsenic-alkali residue, desulfurized slag and blast furnace dust. These four types of waste were enriched in a variety of heavy metals and metalloids and more specifically with As and Sb levels up to 8.6 × 104 and 3.16 × 105mg/kg, respectively, in arsenic-alkali residue. For desulfurized slag and water-quenched slag, the leaching concentration of Sb significantly exceeded the acceptable limits during the leaching tests using the toxicity characteristic leaching procedure and the synthetic precipitation leaching procedure. In addition, As leaching in arsenic-alkali residue was extraordinarily hazardous, being three orders of magnitude higher than the regulatory level of As. According to the results of the extraction tests, all the tested wastes were classified as hazardous waste.     

分布式防火墙系统

针对分布式防火墙系统体系结构,从新的网络应用环境出发,指出了传统边界防火墙的缺点;然后提出了分布式防火墙的基本原理,并给出了分布式防火墙的产品,重点分析了分布式防火墙产品中的主机防火墙原理;最后还介绍分布式防火墙对各种问题的解决方案及混合型防火墙的应用实例.     

Choosing policy instruments for controlling ozone depleting substances in a developing context: the case of Chile

Chile ratified the Montreal Protocol in 1990 which sets out an agenda for the reduction and then elimination of ozone depleting substances (ODS); however, by 1998 the country had not yet defined a strategy to encourage greater compliance, so that in the same year the National Environmental Commission decided to examine the policy options available. This paper examines the process followed to develop this strategy. As a first step it was necessary to look at how far the implicit policy of "business as usual" could be stretched without jeopardizing Chile's compliance obligations. A second step included quantifying compliance costs and their impact on different policy instruments and so policy choice. Finally, the attitudes of decision-makers or participants were identified, by interviews with officials of the different public agents involved, in order to weigh their views about policy. A strategy was proposed, based on this information, which the Chilean regulator has used, although not in its entirety. The methodology developed could well be useful for developing-country Protocol signatories building their own appropriate compliance strategy.     

Concentration and chemical speciation for the determination of Cu,Zn, Ni,Pb and Cd from refuse dump soils using the optimized BCR sequential extraction procedure

The optimized BCR sequential extraction procedure (proposed by the Standards, Measurements and Testing Programme (SM&T) of the European Union) was applied to seven topsoil samples from refuse dump sites for the determination of Cu, Zn, Ni, Pb and Cd. The metals were partitioned into four operationally defined chemical fractions: acid extractable, reducible, oxidizable and residual, and analysed using flame atomic absorption spectrophotometry, FAAS. The results were compared with total metal concentrations obtained using HNO₃, HClO₄ and HF digestion procedures. Results for total metal analysis ranged from - 15.55 to 43.45 for Cu, 37.15 to 222.35 for Zn, 5.15 to 12.10 for Ni, 10.30 to 93.05 for Pb and 0.35 to 3.75 for Cd in μgg⁻¹ dry weight. The results of the partitioning study showed that zinc prevailed in the more soluble fractions and was distributed between the acid-extractable (32.4%) and the reducible (40.3%) fractions, whereas Pb was distributed mainly in the reducible fraction. Copper and nickel were predominantly associated with the reducible and residual fractions - 53.4, 33.3 and 51.1, 24.1% respectively. The ranking of the four fractions for the partitioning of cadmium was: reducible > residual > oxidizable > acid extractable. The percentage recovery for all metals when comparing total metal concentration with the fractional sum of the optimized BCR procedure, were of the order: Zn(93%) > Pb(83%) > Cu(78) > Cd > (68%) > Ni(63%).     

Extraction of labile metals from solid media by dilute hydrochloric acid

Extraction of labile metals from solid media is environmentally more meaningful than a total digestion. A variety of reagents have been introduced in the literature, but dilute HCl has received the greatest attention. We compare metal concentrations liberated by a dilute HCl leach with the sum of the 3-step optimized (standardized) BCR sequential extraction procedure. This is the first study to compare these procedures over a range of grain sizes. Road-deposited sediments from 10 sites in Honolulu were fractionated into six grain size classes. Aliquots of individual fractions were digested with dilute HCl, the 3-step BCR procedure (‘labile’), and a 4-acid (total) procedure. Results indicated that the weighted labile concentrations of Al, Cu, Fe, Mn, Ni, Pb and Zn were statistically greater than those from the dilute HCl leach. However, regression analysis indicated strong statistically significant relationships between the two partial extraction procedures for all metals. On a whole-sample basis, the toxicity classifications for anthropogenic-enhanced metals (Cu, Pb and Zn) were similar between extractions. Taken together, results suggest that the application of dilute HCl to solid media provides a rapid, cost-effective, and environmentally meaningful approach for contaminant monitoring.