重金属铅,镉,锌对小麦DNA构象的影响

采用紫外吸收谱法，研究了不同浓度铅，镉，锌对小麦ＤＮＡ构象的影响。结果显示重金属铅，镉，锌均可影响小麦ＤＮＡ构象，使其紫外吸收峰值发生变化。其中，铅离子对小麦ＤＮＡ构象影响最大，５０μｇ／ｍｌ＾ｐｂ＾２＋处理使小麦出现明显减色反应，１０００μｇ／ｍｌｐｂ＾２＋处理使其沉淀析出；镉离子对小麦ＤＮＡ构象影响不大，可使其产生轻微减色反应，低浓度锌离子使小麦ＤＮＡ发生增色反应，而高浓度使小麦ＤＮＡ发生减色     

等温气相色谱法测定土壤中甲基汞

样品采用碱消化，室温下在pH＝4．9时进行乙基化反应，氢气为载气，Carbotrap富集有机态汞，等温气相色谱（GC）分离，用冷原子萤光仪（CVAFS）测定。方法检出限20pg。线性范围100～600pg。回收率在95％～105％之间。     

中国高等环境教育体系现状分析

通过中国高等环境教育体系现状的系统分析，就面向２１世纪的中国高等环境教育的改革和发展提出了完善专业环境教育的层次结构，尽快建成合理完善的环境类学科专业体系及其相应的课程体系，大力发展成人高等环境教育，在非环境专业全面普及环境教育等建议．     

中压加氢裂化装置危险和可操作性研究

针对中压加氢裂化生产过程存在很大的火灾、爆炸、毒害等危险性的特点，以加氢裂化反应器出口至冷高压分离器进口之间管线为分析节点，对工艺参数流量可能发生的各种偏差进行了危险和可操作性研究，找出了偏差发生的原因及可能导致的后果，提出了相应的控制措施，对提高装置的安全可靠性，预防和减少事故发生具有重要作用。     

Comparison of biochar- and activated carbon-supported zerovalent iron for the removal of Se(IV) and Se(VI): influence of pH,ionic strength,and natural organic matter

Biochar (BC) and activated carbon (AC) were both produced from corn straw. Biochar-supported zerovalent iron (BC-ZVI) and activated carbon-supported zerovalent iron (AC-ZVI) were synthesized and applied for Se(IV)/Se(VI) removal. The sorption capacity of BC-ZVI for Se(IV) and Se(VI) was reported at 62.52 and 35.39 mg g^?1, higher than that of AC-ZVI (56.02 and 33.24 mg g^?1), respectively, due to its higher iron content and more positive charges. The spectroscopic analyses showed that Se(IV)/Se(VI) were reduced to Se(0)/Se(-II) of less toxicity and solubility. The effects of various factors such as pH, ionic strength, co-existing cations and anions, and natural organic matter (NOM) were also investigated. Ionic strength showed no significant effect on Se(IV)/Se(VI) removal, but pH was critical. The presence of NO₃^? and SO₄^2? did not cause obvious inhibition to the removal, while PO₄^3? inhibited the sorption capacity of BC-ZVI and AC-ZVI for Se(IV)/Se(VI) significantly. Common cations (K⁺, Ca²⁺, and Mg²⁺) were found to slightly enhance the removal, while NOM significantly decreased the sorption capacity of BC-ZVI and AC-ZVI for Se(IV)/Se(VI). Besides, NOM showed stronger inhibition effect on AC-ZVI than that on BC-ZVI. These results indicated that BC-ZVI, compared with AC-ZVI, could be a promising sorbent to remove Se(IV)/Se(VI) due to its low cost and high efficiency.

     

氧化剂对土壤中石油污染物去除率的影响

以FeSO_4-柠檬酸为催化剂,探讨了不同氧化剂的类型、浓度、与催化剂的比例等因素对土壤中石油污染物去除率的影响。实验结果表明:各氧化剂体系的石油去除率大小顺序为KMnO_4CaO_2≥H_2O_2K_2S_2O_8;随着反应时间的延长,各体系的石油去除率均呈现出先快速增涨、再缓慢增加后略有降低的趋势;在氧化剂浓度相同条件下,H_2O_2体系和Na_2S_2O_8体系的石油去除率分别比对照增加了145.5%~238.7%和112.6%~167.5%;在催化剂用量相同条件下,H_2O_2体系和Na_2S_2O_8体系达到最高石油去除率时的n(氧化剂)∶n(催化剂)分别为50∶1和100∶1;H_2O_2体系对残油族组分的去除率大小顺序为非烃芳烃饱和烃沥青质。     

Rural migrants’ participation in old-age insurance: a case study of the inter-provincial migrant workers from Sichuan,China

Old-age pension, a fundamental part of the Chinese social security system, is perceived by the Chinese government as the last support for rural-to-urban migrant workers upon retreating from the labor market. Using survey data collected by the authors, this paper examines a host of factors which influence migrant workers’ participation in the old-age scheme. The result shows that individual characteristics, employment status, attitudes toward old-age support and perception of the old-age pension system significantly differentiate two groups of migrant workers between those that have participated in and their counterparts who have not participated in the old-age pension schemes. Among a number of factors, age, educational attainment, holding labor contract, etc. are found to be significant factors influencing migrants’ behavior participating (or not participating) the available age-pension schemes. Policy implications for how to improve the rate of participation in existing old-age pension schemes among migrant workers are drawn from the findings.     

Bioavailability of polycyclic aromatic hydrocarbons (PAHs) to short-neck clam (<Emphasis Type="Italic">Paphia undulata</Emphasis>) from sediment matrices in mudflat ecosystem of the west coast of Peninsular Malaysia

The bioaccumulation and bioavailability of polycyclic aromatic hydrocarbons (PAHs) were characterized in sediment and Paphia undulata (short-neck clam) from six mudflat areas in the west coasts of Peninsular Malaysia. The concentrations of total PAHs varied from 357.1 to 6257.1 and 179.9 ± 7.6 to 1657.5 ± 53.9 ng g ^?1 dry weight in sediment and short-neck clam samples, respectively. PAHs can be classified as moderate to very high level of pollution in sediments and moderate to high level of pollution in short-neck clams. The diagnostic ratios of individual PAHs and principal component analysis indicate both petrogenic and pyrogenic sources with significant dominance of pyrogenic source. The first PAHs biota-sediment accumulation factors and relative biota-sediment accumulation factors data for short-neck clam were obtained in this study, indicating a preferential accumulation of lower molecular weight PAHs. Evaluation of PAH levels in sediments and short-neck clams indicates that short-neck clam could be introduced as a good biomonitor in mudflats. The results also demonstrated that under environmental conditions, the sedimentary load of hydrocarbons appears to be one of the factors controlling their bioavailability to biota.     

Leaching variations of heavy metals in chelator-assisted phytoextraction by Zea mays L. exposed to acid rainfall

Chelant-enhanced phytoextraction method has been put forward as an effective soil remediation method, whereas the heavy metal leaching could not be ignored. In this study, a cropping-leaching experiment, using soil columns, was applied to study the metal leaching variations during assisted phytoextraction of Cd- and Pb-polluted soils, using seedlings of Zea mays, applying three different chelators (EDTA, EDDS, and rhamnolipid), and artificial rainfall (acid rainfall or normal rainfall). It showed that artificial rainfall, especially artificial acid rain, after chelator application led to the increase of heavy metals in the leaching solution. EDTA increased both Cd and Pb concentrations in the leaching solution, obviously, whereas EDDS and rhamnolipid increased Cd concentration but not Pb. The amount of Cd and Pb decreased as the leaching solution increased, the patterns as well matched LRMs (linear regression models), with R-square (R ²) higher than 90 and 82% for Cd and Pb, respectively. The maximum cumulative Cd and Pb in the leaching solutions were 18.44 and 16.68%, respectively, which was amended by EDTA and acid rainwater (pH 4.5), and followed by EDDS (pH 4.5), EDDS (pH 6.5), rhamnolipid (0.5 g kg⁻¹ soil, pH 4.5), and rhamnolipid (pH 6.5).

     

岩爆倾向性的改进有限云评价模型与工程应用

为解决深部开采顶板岩爆评价问题,以挑水河磷矿为例,提出由3个岩爆倾向性评价指标e0/ec、e1/ec、ec/et组成的综合性评价指标体系,采用消除云雾化的综合权重法,建立顶板多指标岩爆倾向性的改进有限云评价模型;通过FLAC3D模拟计算采场的应力值,获得e0/ec、e1/ec、ec/et的参数值;开展挑水河磷矿顶板岩爆...