Recent changes in Red Lake (Romania) sedimentation rate determined from depth profiles of Pb and Cs radioisotopes

This work presents a first estimation of the sedimentation rate for the Red Lake (Romania). The sediment accumulation rates were determined by two well-known methods for recent sediment dating: ²¹⁰Pb and ¹³⁷Cs methods. Both techniques implied used the gamma emission of the above-mentioned radionuclides. The ²¹⁰Pb and ¹³⁷Cs concentrations in the sediment were measured using a gamma spectrometer with a HpGe detector, Gamma-X type. Activities ranging from 41 ± 7 to 135 ± 34 Bq/kg were found for ²¹⁰Pb and from 3 ± 0.5 to 1054 ± 150 Bq/kg for ¹³⁷Cs. The sediment profile indicates acceleration in sedimentation rate in the last 18 years. Thus, the sedimentation process for the Red Lake can be divided in two periods, the last 18 years, and respectively, the period before that. Using the Constant Rate of ²¹⁰Pb Supply method values between 0.18 ± 0.04 and 1.85 ± 0.5 g/cm² year (0.32 ± 0.08 and 2.83 ± 0.7 cm/year) were obtained. Considering both periods, an average sedimentation rate of 0.87 ± 0.17 g/cm² year (1.17 cm/year) was calculated. Considering an average depth of 5.41 m for the lake and the sedimentation rate estimated for the last 18 years, it could be estimated that the lake will disappear in 195 years.     

Elasticity Ratio of Resource Consumption and the Resource Consumption

Today the resources are becoming scarcer, which should not be regarded as unexhausted any more. Correspondingly, the production would be constrained by the scarcity of resources clearly. Then the economic researchers would pay much more attention to reducing the consumption of natural resources in the future. Therefore this paper brings foreword the conception of elasticity ratio of resource consumption based on the concept of elasticity and analyzes the relationship between the parameters. For the certain relationships between the elasticity ratio of resource consumption and resource consumption, this paper will try to reveal, to keep economy growing while resource consumption reducing, what conditions should be met as to the relationships among resource productivity, its growth rate, energy saving efficiency, economic growth rate and elasticity ratio of resource consumption. This paper proves the relationship between the China＇s energy consumption and economy growth using statistic data from 1978 to 2003.     

低曝气下PAC强化SBR工艺同步脱氮除磷

采用序批式反应器(SBR)处理模拟生活污水,研究不同曝气量(30、24、18和12 L/h)下活性污泥同步脱氮除磷规律,并在最佳曝气量下,比较了粉末活性炭-序批式反应器(PAC-SBR)和SBR的脱氮除磷效率,分析了低曝气下PAC-SBR的运行特性和优越性。实验结果表明,当曝气量为24 L/h时,SBR内出水效果较好,其COD、TN和TP的平均去除率分别可以达到90.02%、81.13%和88.12%。在这个最佳曝气量下,PAC-SBR具有明显的优势,其COD、TN和TP的平均去除率均高于SBR,并且PAC-SBR具有较好的污泥沉降性能和较高的活性污泥浓度。在PAC-SBR中,活性污泥以PAC作为微生物载体强化了生物降解效果,并改善了低曝气下污泥絮体的结构,促使反应器内先后形成缺氧-厌氧-微氧/缺氧-缺氧的环境,利于同步硝化反硝化和反硝化聚磷,提高了PAC-SBR的同步脱氮除磷效率。     

对于土地使用权升值问题的探讨

基于经济和社会等方面的原因，土地所有权的价格一般会不断上涨，固定年期土地使用权价格也会随之上升。但受让土地使用权价格存在类似折旧的现象。投资人能否从地价普遍上涨中获得增值收益，取决于土地所有权增值比率、土地还原利率、剩余使用年期等多种因素。     

T型氧化沟提高脱氮效率的技术改造

采用延长边沟闷曝时间的方法对BOD降解模式T型氧化沟进行提高脱氮效率的改造。结果表明，边沟闷曝时间由0.5 h增至1 h，系统反硝化和硝化运行时间比t_DN/t_N由0.56调整至0.50时，提高了系统的NH₃-N的硝化效率，强化了脱氮能力。工艺改造后出水NH3-N浓度由改造前15.5 mg/L显著降低至10.4 mg/L，达到了广东省地方标准（DB 44/26-2001）第一时段的二级排放要求；系统脱氮效率由改造前52.1%显著提高到68.3％，有效地解决了污水厂出水NH₃-N浓度过高的问题；具有投资少、效果明显的特点，有一定的推广价值。     

改性粉煤灰去除硝基苯废水的研究

粉煤灰经过废硫酸改性处理后吸附能力大大提高,用改性粉煤灰对生化后的硝基苯废水进行了实验研究,实验考察了粉煤灰的投加量、pH值、吸附时间对硝基苯去除率的影响,并对机理进行了分析.粉煤灰改性后应用于硝基苯废水处理中达到以废治废,具有一定的经济意义.     

Effects of initial iron corrosion rate on long-term performance of iron permeable reactive barriers: Column experiments and numerical simulation

Column experiments and numerical simulation were conducted to test the hypothesis that iron material having a high corrosion rate is not beneficial for the long-term performance of iron permeable reactive barriers (PRBs) because of faster passivation of iron and greater porosity loss close to the influent face of the PRBs. Four iron materials (Connelly, Gotthart-Maier, Peerless, and ISPAT) were used for the column experiments, and the changes in reactivity toward cis-dichloroethene (cis-DCE) degradation in the presence of dissolved CaCO₃ were evaluated. The experimental results showed that the difference in distribution of the accumulated precipitates, resulting from differences in iron corrosion rate, caused a difference in the migration rate of the cis-DCE profiles and a significant difference in the pattern of passivation, indicating a faster passivation in the region close to the influent end for the material having a higher corrosion rate. For the numerical simulation, the accumulation of secondary minerals and reactivity loss of iron were coupled using an empirically-derived relationship that was incorporated into a multi-component reactive transport model. The simulation results provided a reasonable representation of the evolution of iron reactivity toward cis-DCE treatment and the changes in geochemical conditions for each material, consistent with the observed data. The simulations for long-term performance were also conducted to further test the hypothesis and predict the differences in performance over a period of 40 years under typical groundwater conditions. The predictions showed that the cases of higher iron corrosion rates had earlier cis-DCE breakthrough and more reduction in porosity starting from near the influent face, due to more accumulation of carbonate minerals in that region. Therefore, both the experimental and simulation results appear to support the hypothesis and suggest that reactivity changes of iron materials resulting from evolution of geochemical conditions should be considered in the design of iron PRBs.     

自然环境因素对铝合金大气腐蚀的影响性研究

目的 研究铝合金大气腐蚀受自然环境因素的影响性，探索环境因素对铝合金腐蚀的影响规律。方法 采用多层感知器神经网络分析环境因素对7种铝合金平均腐蚀速率的影响。结果 确定了影响铝合金腐蚀损伤的重要因素为SO2沉积率、Cl^–沉积率、NOx沉积率；辅要因素为年降雨量、年雾露时数、相对湿度、年日照时数、温度、铝合金成分；次要因素为年累积降水时数、雨水pH值。结论 基于多层感知器神经网络分析有效展现了环境因素对平均腐蚀速率的影响性。     

生石灰强化机械通风法修复三氯乙烯污染土壤

机械通风法是一种操作简单、效果好、成本低的土壤修复技术,特别适合大型挥发性有机化合物(VOC)污染场地的土壤修复,但在环境温度低、土壤含水率高、土壤黏性大等情况下,其修复效果和修复周期会受到极大影响,且土壤中高浓度的污染物残留将严重影响场地修复目标的实现。为了解决这一问题,采用了在土壤中添加一定量生石灰的强化措施。结果表明:(1)生石灰可以显著提高机械通风法修复三氯乙烯(TCE)污染土壤的效果,缩短修复周期,降低污染物在土壤中的残留浓度。(2)生石灰对TCE的强化作用与生石灰的添加量和土壤类型有关,粉质黏土的强化效果要好于粉土和细砂,生石灰添加量越多,强化效果越好;(3)生石灰强化处理TCE的主要机制是提高土壤温度、降低土壤含水率、增加土壤通透性,促进土壤中TCE的解吸和挥发。     

木屑黄原酸盐对双离子体系中铜镍的吸附

利用木屑制备木屑黄原酸盐吸附剂,对其进行FTIR、XRD和BET分析,并考察了对双离子体系中铜镍离子的吸附情况,重点研究了木屑黄原酸盐吸附量的预测和吸附初始速率的计算。结果表明,在铜镍双离子体系中,利用扩展的Langmuir模型能很好地预测木屑黄原酸盐对铜镍离子的吸附;吸附之初,吸附速率很快,并且随着干扰离子的浓度增大,所考察离子的初始速率逐渐减小。吸附情况说明,木屑黄原酸盐是一种具有良好吸附性能的吸附材料。