单一震源地震发生的等效物理模型

建立了模拟单一潜在震源区地震孕育和发生的等效物理模型，给出了通过调整各次地震之间断层位移速率来拟合已有地震序列的方法。通过考虑模型参数的不确定性，提出了在未来一定年限内潜在震源区发生震级在不同震级段的概率预报方法。通过两种等效物理模型的对比，本文认为就工程地震危险性评定而言，可用简单的滑块－弹簧模型代替滑块－弹粘塑性模型     

碳酸钙和海泡石组配对水稻中Pb和Cd迁移转运的影响

为研究组配改良剂LS(碳酸钙+海泡石)对农田土壤重金属Pb和Cd的固化效果以及水稻各部位吸收累积Pb和Cd的影响,在湘南2个矿区(矿区A和矿区B)附近污染稻田中施用了不同添加量的LS (0、2、4和8 g/kg),并进行了水稻种植的田间实验。结果表明,(1)施用2~8 g/kg的LS能使矿区A和矿区B土壤pH值分别增加1.11~1.95和1.61~2.31个单位,能使矿区A和矿区B土壤中Pb和Cd的TCLP提取态含量分别降低18.6%~62.7%、15.7%~37.1%和38.6%~66.7%、0~76.6%。(2)LS能不同程度地降低水稻各部位重金属含量。矿区A糙米中Pb和Cd含量降低9.4%~35.6%、56.1%~66.8%;矿区B糙米中Pb含量降低14.4%~36.6%,而Cd含量变化不明显。(3)LS对水稻中Pb和Cd在各部位之间的转运系数均有不同程度的影响,其中Pb和Cd从茎叶到谷壳的转运系数最大,说明水稻茎叶对重金属的转运能力最强。(4)LS添加量为8 g/kg时,Pb和Cd从谷壳到糙米的转运系数最小,且糙米中Pb和Cd含量最低。     

Microbial reduction of uranium (VI) by Bacillus sp. dwc-2: A macroscopic and spectroscopic study

The microbial reduction of U(VI) by Bacillus sp. dwc-2, isolated from soil in Southwest China, was explored using transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and X-ray absorption near edge spectroscopy (XANES). Our studies indicated that approximately 16.0% of U(VI) at an initial concentration of 100 mg/L uranium nitrate could be reduced by Bacillus sp. dwc-2 at pH 8.2 under anaerobic conditions at room temperature. Additionally, natural organic matter (NOM) played an important role in enhancing the bioreduction of U(VI) by Bacillus sp. dwc-2. XPS results demonstrated that the uranium presented mixed valence states (U(VI) and U(IV)) after bioreduction, which was subsequently confirmed by XANES. Furthermore, the TEM and high resolution transmission electron microscopy (HRTEM) analysis suggested that the reduced uranium was bioaccumulated mainly within the cell and as a crystalline structure on the cell wall. These observations implied that the reduction of uranium may have a significant effect on its fate in the soil environment in which these bacterial strains occur.     

CALPUFF模型在大气环境容量测算中的应用研究

本研究利用CALPUFF空气质量扩散模式模拟了凉山州2007年气象场和s02浓度场,通过现状监测结果与模拟结果的比较评述了模型的适用性;并根据西昌市现状污染源和虚拟污染源情况,通过CALPUFF模拟建立大气污染物传递矩阵,结合线性优化模型测算了西昌市大气环境容量。     

Technology of comprehensive disposal and utilization of municipal solid waste (MSW)

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Effects of Acid Rain on Competitive Releases of Cd, Cu, and Zn from Two Natural Soils and Two Contaminated Soils in Hunan, China

Leaching experiments of rebuilt soil columns with two simulated acid rain solutions (pH 4.6–3.8) were conducted for two natural soils and two artificial contaminated soils from Hunan, south-central China, to study effects of acid rain on competitive releases of soil Cd, Cu, and Zn. Distilled water was used in comparison. The results showed that the total releases were Zn>Cu>Cd for the natural soils and Cd>Zn≫Cu for the contaminated soils, which reflected sensitivity of these metals to acid rain. Leached with different acid rain, about 26–76% of external Cd and 11–68% external Zn were released, but more than 99% of external Cu was adsorbed by the soils, and therefore Cu had a different sorption and desorption pattern from Cd and Zn. Metal releases were obviously correlated with releases of TOC in the leachates, which could be described as an exponential equation. Compared with the natural soils, acid rain not only led to changes in total metal contents, but also in metal fraction distributions in the contaminated soils. More acidified soils had a lower sorption capacity to metals, mostly related to soil properties such as pH, organic matter, soil particles, adsorbed SO₄ ²⁻, exchangeable Al³⁺ and H⁺, and contents of Fe₂O₃ and Al₂O₃.     

蜡状芽孢杆菌WXZ-8的异养硝化/好氧反硝化性能研究

通过聚合酶链式反应(PCR)扩增、16S rDNA测序并结合同源性分析,鉴别出菌株WXZ-8为蜡状芽孢杆菌(Bacillus ce-reus).对菌株WXZ-8进行异养硝化/好氧反硝化性能测定,并通过正交实验进行培养条件的优选,选取的因素为COD/N、温度、转速和pH.结果表明,对菌株WXZ-8影响最大的因素是转速,其次为COD/N;在最优条件(即温度=30℃、COD/N=25、pH=9.0、转速=180 r/min)下,菌株WXZ-8的氨氮去除率最高达到96.06%.在最优条件下,提高初始氨氮质量浓度为211.52、429.16、897.29mg/L时.菌株WXZ-8在前48 h的氨氮去除速度均达到最大,分别为119.04、94.76,142.21 mg/(L·d),其氨氮去除率最高分别为94.41%、73.43%、51.08%.菌株WXZ-8具有良好的异养硝化/好氧反硝化性能.     

The research of market structures for remanufactured products

The rapid development of technology has made it easier to distribute products directly, and many enterprises excel at executing a multi-channel strategy to distribute products. The introduction of direct channel adds a new competition dimension to the enterprises. This paper considers three market channel structures: R-Channel, D-Channel and H-Channel. In R-Channel, both new products and remanufactured products are sold through a retailer. In D-Channel, new products are sold through retailers and remanufactured products are sold directly to consumers. In H-Channel, new products are sold through retailers, while remanufactured products through dual channel. Using the game theory, we obtain and analyse the equilibrium prices, market demands and the profits gain under these three settings. At the same time, the influence of consumers’ willingness to pay on the environment performance is researched. Our results show that the manufacturer prefers H-Channel. By introducing the direct channel the manufacturer is always economically better off, but it is not for the retailer. The numerical simulation also confirms the theoretical analysis and shows that H-Channel has advantages of economic benefit and environmental performance. It is feasible for practical application.     

土壤调理剂对土壤-水稻系统Cd、Zn迁移累积的影响及健康风险评价

选取湖南省长沙市北山镇某中重度Cd污染稻田,研究了土壤调理剂(石灰石+偏高岭土+钙镁磷肥)对稻田土壤重金属Cd、Zn的钝化效果,以及对水稻各部位累积Cd和Zn的影响,并进行了Cd的健康风险评价.结果表明,使用土壤调理剂提高了稻田土壤p H值.Cd的CaCl_2提取态含量降低了0.9%~24.1%,Zn的CaCl_2提取态含量降低了22.5%~69.6%.土壤调理剂显著降低了水稻糙米中Cd与Zn的含量,与对照相比分别降低了10.8%~47.3%、10.3%~17.5%;土壤调理剂对水稻糙米Cd的吸收和累积的影响要远大于Zn,水稻糙米中的Cd/Zn比随着土壤调理剂施用量的增加而显著降低.研究区大米重金属Cd目标危害系数THQ值大于1,说明当地人群通过食用大米途径摄入重金属Cd存在健康风险.土壤调理剂有效地抑制了水稻植株对土壤中Cd的吸收,并降低了Cd/Zn比,使糙米中的Cd含量显著降低,从而降低了当地人群通过食用大米途径摄入重金属Cd的健康风险.     

外源Cl-添加对不同母质土壤溶液Cd2+浓度的影响

土壤镉(Cd)的环境行为与其在土壤溶液中的存在形态以及陪伴离子有关,然而外源Cl~-与土壤溶液中Cd~(2+)的关系以及不同母质土壤对Cd~(2+)的环境行为的影响并没有明确的结论.选取2种水稻土(第四纪红色黏土母质发育的红黄泥、紫色砂页岩母质发育的紫泥田)为研究对象,添加离子态外源Cd~(2+)(0、1、2.5、5 mg·kg~(-1)),平衡老化后添加外源Cl~-(0、0.6、1.2 mg·kg~(-1)),在保持水分恒定的情况下进行模拟培养试验,研究外源Cl~-添加对土壤溶液Cd~(2+)浓度的影响.结果表明,随着外源Cd~(2+)的增加,土壤溶液Cd~(2+)的浓度提高,红黄泥土壤溶液Cd~(2+)的浓度显著高于紫泥田;添加Cl~-会使土壤溶液中Cd~(2+)浓度升高,且Cd~(2+)浓度与外源Cl~-呈显著正相关,红黄泥和紫泥田土壤溶液中Cd~(2+)的平均浓度比不添加Cl~-时Cd~(2+)的平均浓度分别增加了12.74%、51.49%;土壤对Cd~(2+)的吸附关系符合Freundlich等温吸附方程,紫泥田对Cd~(2+)的吸附量显著高于红黄泥,添加Cl~-对红黄泥Cd~(2+)的吸附影响很小,而对紫泥田的影响显著.Cl~-存在下,红黄泥和紫泥田的解吸率分别为12.50%～19.25%、14.76%～24.99%,外源Cl~-添加对Cd~(2+)解吸影响小.综合分析认为,Cl~-对不同土壤Cd~(2+)的吸附解吸行为影响有较大的差异.