饮马河流域典型湿地植物净化河流水环境效果研究

采取单种及混种方式,通过小型湿地模拟实验,研究松花江支流饮马河流域河流湿地中常见的芦苇、香蒲、槽秆荸荠、藨草、慈姑、花蔺、菱角、紫背浮萍和金鱼藻9种湿地植物及其组合对河流水体中化学需氧量(COD_(cr))、氮、磷等的净化效果。结果表明:所选湿地植物,在模拟环境条件下均能有效提升取自河流水体的水质;不同的湿地植物对污水中各污染物净化具有明显的差异,花蔺对总磷(TP)、COD_(cr)和氨氮(NH_3-N)净化效果最好,去除率依次为99.65%、68.22%和99.54%;香蒲、菱角、金鱼藻混合组对总氮(TN)的净化效果最好,去除率是66.19%;槽杆荸荠、芦苇和金鱼藻对亚硝酸盐氮(NO_2-N)的净化效果最好,去除率是83.64%。两种植物混种后对某一种污染物指标的处理效果弱于分别独种时的处理效果,但对多种污染物指标的综合处理效果一般要好于独种时的处理效果。     

Evaluation of landfill disposal boundary by means of electrical resistivity imaging

This paper deals with an employment of electrical resistivity imaging (ERI) for survey of leachate content on the waste disposal site in Northern Israel. The research consisted of conducting ten ERI lines and drilling investigation wells. Data simulation used a 2D EarthImager inversion program. Analysis of 2D ERI interpretation results shows that determination of the boundary between the landfill body bottom intensively saturated with leachates and underlying layers of highly water saturated fat nonconsolidated clays presents a challenge. However, statistical analysis of ERI data indicates that standard deviation and confidence interval of a set of resistivity data measured in the landfill body are significantly larger than those in underlying clays. Moreover, maximum changes of these parameters are found on the boundary between landfill body and underlying soil, thus reflecting natural differences in scattering of resistivity data measured in these two objects.     

Some Advantages of the Duckweed Test to Assess the Toxicity of Environmental Samples

In Germany, wastewater legislation requires all municipal and industrial leachate to be subjected to toxicity tests. However, no phytotoxicity tests using higher plants are currently included among the standard tests. Freshwater microalgae have been used in most phytotoxicity tests and have often been considered as surrogates for higher plants. However, microalgae often do not show the same sensitivity as higher plants and have major disadvantages for the testing of unmodified environmental samples. In the following study, we evaluated the suitability of the giant duckweed Spirodela polyrhiza for assessing the toxicity of a municipal landfill leachate and two leachates of copper mining residue. Duckweed static toxicity tests were performed, and frond number was the endpoint used to calculate EC₅₀ values. Symptoms of stress (chlorosis, necrosis, root destruction, and colony breakup) were also recorded. The landfill leachate was toxic with EC_50;96h values ranging from 1.3 to 2.7% leachate (v/v). Toxicity of the copper slag leachate was largely determined by the elution method used. Leachate obtained using conventional German leaching methods (S4-eluate) was not toxic to duckweed, whereas EC₅₀ values for the pH_stat4-eluate ranged from 3.2 to 4.2% leachate (v/v). The results demonstrate the suitability of S. polyrhiza for the testing of unmodified wastewater samples and provide further evidence for the addition of a duckweed toxicity test to the standard tests conducted in Germany.     

Risk minimization in water quality control problems of a river system

Methodologies are presented for minimization of risk in a river water quality management problem. A risk minimization model is developed to minimize the risk of low water quality along a river in the face of conflict among various stake holders. The model consists of three parts: a water quality simulation model, a risk evaluation model with uncertainty analysis and an optimization model. Sensitivity analysis, First Order Reliability Analysis (FORA) and Monte–Carlo simulations are performed to evaluate the fuzzy risk of low water quality. Fuzzy multiobjective programming is used to formulate the multiobjective model. Probabilistic Global Search Laussane (PGSL), a global search algorithm developed recently, is used for solving the resulting non-linear optimization problem. The algorithm is based on the assumption that better sets of points are more likely to be found in the neighborhood of good sets of points, therefore intensifying the search in the regions that contain good solutions. Another model is developed for risk minimization, which deals with only the moments of the generated probability density functions of the water quality indicators. Suitable skewness values of water quality indicators, which lead to low fuzzy risk are identified. Results of the models are compared with the results of a deterministic fuzzy waste load allocation model (FWLAM), when methodologies are applied to the case study of Tunga–Bhadra river system in southern India, with a steady state BOD–DO model. The fractional removal levels resulting from the risk minimization model are slightly higher, but result in a significant reduction in risk of low water quality.     

核废料处置库选址过程中自然灾害风险性评价

自然灾害是给人类及其设施带来严重灾难的危害。本文试图在了解灾害的危害性基础上，以火山作用为例，在核废料处置库选址中，通过圈定灾害高发区、确定风险评价参数、划出高风险区及风险等级三步骤，对灾害风险性进行评价。     

Shrinkage and desiccation cracking in bentonite–sand landfill liners

Data are reported on the shrinkage and desiccation cracking exhibited by bentonite-enhanced sand mixtures (BES) upon air-drying. Mixtures containing 10 and 20% bentonite by dry weight, compacted at moisture contents ranging from 8 to 32%, were investigated. Hydraulic conductivity data for BES specimens saturated and tested immediately after compaction, and for similar specimens that had no visible damage after air-drying, are also presented.

All the mixtures exhibited volumetric shrinkage upon air-drying with the amount of shrinkage increasing with increasing moisture content during compaction. At any initial moisture content mixtures containing 20% bentonite shrink more than those containing 10% bentonite, but the shrinkage is insensitive to the compactive effort. Compacted beds of BES containing 10 and 20% bentonite exhibit no visible desiccation cracking as the top surface is dried when compacted at 15 and 14% moisture content, respectively, and only minor cracking when compacted at initial moisture contents of 20 and 15%, respectively. For the range of mixtures tested, it appears that cracking only occurs when BES undergoes more than about 4% volumetric shrinkage when air-dried. The saturated hydraulic conductivity of intact BES specimens is unaffected by a drying episode prior to testing.     

金堆城钼矿固体废物对水环境的污染

本文通过对陕西华县金堆城钼矿区西川河流经废石堆的入口处和出口处采取的水样进行了常量组分、微量组分的测定,分析其污染特征,确定出金堆城钼矿废石堆对水环境的污染指标.     

Contaminant dispersion at the rehabilitated Mary Kathleen uranium mine, Australia

This study reports on the transfer of contaminants from waste rock dumps and mineralised ground into soils, sediments, waters and plants at the rehabilitated Mary Kathleen uranium mine in semi-arid northwest Queensland. Numerous waste rock dumps were partly covered with benign soil and the open pit mine was allowed to flood. The mineralised and waste calc-silicate rock in the open pit and dumps has major (>1 wt%) Ca, Fe and Mg, minor (>1,000 ppm) Ce, La, Mn, P and S, subminor (>100 ppm) Ba, Cu, Th and U, and trace (<100 ppm) As, Ni, Pb, Y and Zn values. Consequently, chemical and physical weathering processes have acted on waste rock and on rock faces within the open pit, mobilising many elements and leading to their dispersion into soils, stream sediments, pit water and several plant species. Chemical dispersion is initiated by sulfide mineral breakdown, generation of sulfuric acid and formation of several soluble, transient sulfate minerals as evaporative efflorescent precipitates. Radiation doses associated with the open pit average 5.65 mSv year⁻¹; waste dumps commonly have lower values, especially where soil-covered. Surface pit water is slightly acid, with high sulfate values accompanied by levels of U, Cu and Ni close to or above Australian water guideline values for livestock. Dispersion of U and related elements into soils and stream sediments occurs by physical (erosional) processes and from chemical precipitation. Plants growing in the mine void, on waste dumps and contaminated soil display evidence of biological uptake of U, LREE, Cu and Th and to a lesser degree of As, Ni, Pb, Y and Zn, with values being up to 1–2 orders of magnitude above background sites for the same species. Although rehabilitation procedures have been partly successful in reducing dispersion of U and related elements into the surrounding environment, it is apparent that 20 years after rehabilitation, there is significant physical and chemical mobility, including transfer into plants.     

Practical engineering approaches and infrastructure to address the problem of marine debris in Korea

As a solution to the problem of persistent solid marine debris, a nationwide project began in Korea in 1999 to develop and popularize fundamental changes to the infrastructure. The ten year project, called “A Practical Integrated System for Marine Debris,” consists of four linked types of technology: prevention, deep-water survey, removal and treatment (recycling). These reflect the characteristics of marine debris, which though widespread, vary by location and time of generation. Each technical component has each representative outcome that has been outreached the local governments and marine debris-related associations. The in situ infrastructures lead to enhance the retrieval of the marine debris and create direct and indirect benefits to industry. Both end-of-pipe technology improvement and the introduction of front-of-pipe technology should be considered as we strive to reduce the generation of marine debris in Korean coastal areas.     

Adsorption of Zinc using Tea Factory Waste: Kinetics,Equilibrium and Thermodynamics

In India, the annual production of tea is ca. 857,000 tonnes, which is 27.4% of the total world production. The amount of tea factory waste (TFW) produced per annum after processing is ca. 190,400 tonnes. TFW can be used as a low cost adsorbent for the removal of toxic metals from the aqueous phase. An investigation was carried out to study the feasibility of the use of TFW as an adsorbent for the removal of the heavy metal, zinc. Equilibrium, kinetic and thermodynamic studies were reported. The straight line plot of log (q_e–q) versus time t for the adsorption of zinc shows the validity of the Lagergren equation. The various steps involved in adsorbate transport from the solution to the surface of the adsorbent particles were dealt with by using a Weber‐Morris plot, q_e versus t^0.5 for the TFW. The rate controlling parameters, k_id,1 and k_id,2, were determined and it was found that the macro‐pore diffusion rate was much larger than micro‐pore diffusion rate. A batch sorption model, which assumes the pseudo‐second‐order mechanism, was used to predict the rate constant of sorption, the equilibrium sorption capacity and the initial sorption rate with the effect of initial zinc (II) ion concentration. Equilibrium data obtained from the experiments were analyzed with various isotherms, i. e., Freundlich, Langmuir, Redlich‐Peterson and Tempkin. The adsorption equilibrium was reached in 30 min and the adsorption data fitted well to all models. The maximum adsorption capacity of TFW for zinc (II) ions was determined to be 14.2 mg/g. The capacity of adsorption on Zn(II) increased with increasing temperatures and pH. The maximum uptake level of zinc was observed at pH of 4.2. The various thermodynamic parameters, i. e., ΔG°, ΔH° and ΔS°, were estimated. The thermodynamics of the zinc ion/TFW system indicated a spontaneous, endothermic and random nature of the process. The results showed that the TFW, which has low economical value, is a suitable adsorbent for the removal of zinc (II) ions from aqueous solutions.