SBR系统中活性污泥内源呼吸速率的研究

在SBR污水处理系统中应用呼吸速率测定仪对活性污泥的呼吸速率进行测定,探讨了污泥浓度和温度对内源呼吸速率的影响.对大量的比内源呼吸速率数据进行处理后发现,在混合液温度基本不变的基础上,内源呼吸速率与污泥浓度变化趋势一致,即比内源呼吸速率与污泥浓度无关;而温度对比内源呼吸速率的影响十分显著.这些结论为呼吸速率成为SBR工艺的控制参数提供了基础.     

单因子超载的综合环境承载力计算方法研究

文章分析了当前普遍使用的矢量模法计算综合环境承载力的不足,建立了单因子超载的环境承载符号函数法模型,提出了以环境占用率为表征的环境承载占用率法;验证结果表明新模型和方法较矢量模法更为合理。     

东海春季赤潮前后沉积物-海水界面营养盐交换速率的研究

应用实验室培养法现场研究了3～5月东海硅藻赤潮发生前后10个站位的营养盐在沉积物-海水界面的交换,并应用连续函数拟合法计算了营养盐的界面交换速率.结果显示,NO^-₃-N在赤潮前向沉积物中汇聚［-1.33～－0.68 mmol/(m²·d)］,赤潮后却基本由沉积物向海水中释放［－0.69～0.82 mmol/(m²·d)］.NH⁺₄-N在赤潮前后大都从沉积物中释放［－0.65～1.46 mmol/(m²·d)］,赤潮后释放速率小于赤潮前.NO^-₂-N赤潮前后除Zc17站外都向沉积物中汇聚［－0.09～0.05 mmol/(m²·d)］,赤潮后汇聚速率稍高.SiO^2-₃-Si在所有站位都由沉积物向海水释放［0.85～9.23 mmol/(m²·d)］,其赤潮后速率高于赤潮前.PO^3-₄-P在赤潮前向沉积物中汇聚［－0.06～－0.01 mmol/(m²·d)］,在赤潮后却由沉积物向海水中释放［0～1.26 mmol/(m²·d)］.NO^-₃-N和PO^3-₄-P向东海近海沉积物的汇聚在春季不利于硅藻赤潮的暴发,但其在硅藻赤潮暴发后从沉积物的大量释放为后面紧接的大面积甲藻赤潮的暴发提供了重要的营养物质补充.     

Time discounting and the decision to protect areas that are near and threatened or remote and cheap to acquire

Should conservation organizations focus on protecting habitats that are at imminent risk of being converted but are expensive or more remote areas that are less immediately threatened but where a large amount of land can be set aside? Variants of this trade‐off commonly arise in spatial planning. I used models of land‐use change near a deforestation frontier to examine this trade‐off. The optimal choice of where to protect was determined by how decisions taken today accounted for ecological benefits and economic costs of conservation actions that would occur sometime in the future. I used an ecological and economic discount rate to weight these benefits and costs. A large economic discount rate favored protecting more remote areas, whereas a large, positive ecological discount rate favored protecting habitat near the current deforestation frontier. The decision over where to protect was also affected by the influence economic factors had on landowners' decisions, the rate of technological change, and ecological heterogeneity of the landscape. How benefits and costs through time are accounted for warrants careful consideration when specifying conservation objectives. It may provide a niche axis along which conservation organizations differentiate themselves when competing for donor funding or other support.     

On Characteristics of Production and Destruction Processes in Lowland and Mountain Tundras of the Extreme North

Parameters of the production and destruction processes in different types of tundras are compared. It is shown that there is a fairly high degree of correspondence between the structure of tundra communities and the ecotopes occupied by them. On the other hand, typologically similar lowland and mountain tundras markedly differ in the functional respect. The rate of decomposition processes is higher under environmental conditions of the mountain tundra belt.     

Study of high-frequency electromagnetic field effect on some somatic and neuro-behavioral characteristics in healthy and neurodefective mice

The effect of long-term exposure to high frequency electromagnetic field (HF EMF) on some somatic and neural characteristics was studied in neurodefective Lurcher mutant (+/Lc) and normal wild type mice (+/+). Both newborn and young adult (3 months) animals derived from two strains (C3H, B6CBA) were exposed to HF EMF (870 MHz) from 1st to 21st day or from 91st to 120th day respectively. In animals of both groups and controls we observed the development of body weight. Moreover, in the HF EMF exposed adult B6CBA animals we studied spatial learning ability, motor functions and the CNS excitability. To investigate specific energy absorption rate (SAR) in experimental animals we have done the basic 3D calculations of the electromagnetic energy distribution in the simplified model of the mouse. The HF EMF exposed animals exhibited mild differences of body weight between them and unexposed controls. The long-term exposure to HF EMF did not significantly influence the ability to learn in the Morris water maze. However, significant lower swimming speed was found in the irradiated +/Lc as well as lower motor activity of +/+ in the open field when compared to controls. No significant differences were found between HF EMF irradiated animals and controls in examination of the CNS excitability and motor functions.     

Modification of Evacuation Time Computational Model for Stadium Crowd Risk Analysis

The complexity of the evacuation process is associated with the flow of occupants through various egresses available inside the building. Several methods and algorithms are now available to analyse the problem related to evacuation. In the present paper an algorithm, evacuation discrete time model (EDTM) has been presented to analyse the building egress evacuation time problem with previous works. The algorithm is based on the crowd flow theory and uses discrete computational approach to identify various widths of egresses available for movement of the people, which is more accurate and practicable because the crowd flow rate is variable. The developed model has been compared with an existing model to show the capabilities of the developed algorithm. A case of stadium stand egress is chose for the validity of EDTM, and a comparison of EDTM, previous model and computer simulation indicates that both the EDTM and the simulation curves were found to give better predictions than the previous model. Based upon the comparison analysis with stranded crowd and evacuation crowd at a certain time, EDTM shows great value in explaining the cause of stampede-trampling and crushing incident of egress or narrow passage zone.     

Sedimentary Processes of the Qingdao Nearshore Traced Using a Multi-radionuclide Approach

Sediment cores were collected from two sites (A2 and ZQ) in the Qingdao sea area of the Yellow Sea. Radionuclides ⁴⁰K, ¹³⁷Cs, ²¹⁰Pb, ²²⁶Ra, ²²⁸Ra, ²²⁸Th, ²³⁴Th, and ²³⁸U in the cores were measured using HPGe γ spectrometry. The sedimentation rate of the A2 Core using ²¹⁰Pb_ex and ¹³⁷Cs was 0.665 cm yr⁻¹, therefore this 32 cm long core represents a 48 year timespan leading to the sampling date in 2001. The mixing layer was restricted to the upper 5 cm as determined from the profile of ²³⁴Th. The uniformity of the activity distributions of ⁴⁰K and ²³⁸U throughout the A2 Core and the activity distributions of ²²⁶Ra, ²²⁸Ra and ²²⁸Th below the mixing layer suggested that no significant oceanographic event or change in sediment material source had occurred during this timespan. The ²¹⁰ Pb was in excess relative to ²²⁶Ra, but ²²⁶Ra was deficient with respect to ²³⁸U in the entire A2 Core, while excess ²³⁴Th and ²²⁸Th were apparent only in the surface 5 cm. Total organic matter (TOM) in Core A2 decreases with depth. The second core, taken to a depth of 14 cm, was from Site ZQ, which is located near Zhanqiao, Qingdao. The variations of the nuclide activity ratios in this core were similar to those in the A2 Core, i.e., the excess ²¹⁰ Pb and ²²⁶Ra deficiency were consistent throughout the core but excess ²²⁸Th was only in the surface to a depth of 2 cm. The ⁴⁰K activity in the ZQ Core fluctuated and showed no real trend with depth. The activities of ¹³⁷Cs, ²¹⁰Pb, ²²⁶Ra and ²³⁸U in the entire length of Core ZQ, and ²²⁸Ra and ²²⁸Th from 2 cm to the bottom, were comparable within the uncertainty of measured activity.