我国城市生活垃圾回收利用率测算及其统计数据收集对策

我国将生活垃圾分类收集定位为重要民生工程和生态文明建设的工作内容,并对实施生活垃圾强制分类的示范城市明确提出了"生活垃圾回收利用率"的绩效考核目标。由于城市生活垃圾处理和再生资源回收利用由不同职能部门负责管理,不同来源的生活垃圾回收利用统计数据未有效整合,目前还缺乏我国城市生活垃圾回收利用率指标测算的相关研究。本文界定了"生活垃圾回收利用率"的科学内涵,并以城市建设、再生资源利用等统计资料和物质流分析文献为基础,初步测算了全国尺度的城市生活垃圾回收利用率。研究表明,我国2006—2015年的城市生活垃圾回收利用率从12.1%上升至17.0%,然后又缓慢下降至15.6%,由于数据缺乏,该数值可能在-28%~+32%波动。生活垃圾中回收利用量较大的可再生资源分别为废纸、废塑料、废钢铁、废玻璃等。本文还分析了目前测算生活垃圾回收利用率的数据不确定性和局限性,提出了面向生活垃圾分类管理实际评价的统计数据收集对策。     

Long-term adequacy of metal resources

Although the earth's crust contains vast quantities of metals, extraction technologies and associated costs are inextricably bound to three fundamental geological factors — the amount of metal available in the earth's crust in each range of grades, the mineralogical form and chemical state of the metal, and the spatial distribution of the metal. The energy required to recover a given amount of metal increases substantially as grade declines. Most metal is produced from sulphide or oxide minerals, whereas most metal in the crust may be locked in the structures of the more refractory silicates. Recovery from silicate minerals could require orders of magnitude more energy than that used at present as also could exploitation of small, widely scattered or thin, deeply buried deposits. Although specific information on the fundamental factors is not available, each factor must in turn tend to further restrict exploitation. Independence of average grade and tonnage for many deposit types further reduces the availability of rock as a source of metal. In the long term, effects of these factors will be large increases in price for many metals.     

Metal pollution in sediments of Jamaica Bay,New York,USA—An urban estuary

Calculations of the annual input of heavy metals to Jamaica Bay, New York, USA, reveal that sewage effluent carries the largest quantities of Ni, Zn, Cu, and Cd to the bay. Storm sewers and atmospheric fallout are the main sources of Pb. Atmospheric fallout of Zn, Cu, and Cd, although smaller than the combined input from sewers, contributes a significant fraction of these metals. The metal input from landfill leachate is far smaller than that from other sources. Analysis of available data shows that metal concentrations in the sediment of the bay correlate with each other and with percent total organic carbon (%TOC). This is consistent with the observation that the input of metals is predominantly associated with sewage. It is demonstrated that metal-TOC ratios, rather than metal concentrations, must be used in efforts to detect local intensive sources of metals in solution; metal-TOC ratios in intertidal sediment adjacent to these landfills are elevated by the adsorption of leachate metals, while metal concentrations are not. Subtidal sediment within a few hundred meters from two landfills shows no evidence of the addition of metals from that source, which is consistent with the small input of metals estimated for these landfills. The evidence cited in this study sharply contradicts the implication made in a widely publicized report issued by an environmental advocacy group that a significant link exists between metals found in subtidal sediment of Jamaica Bay and landfill leachate.     

生活垃圾焚烧中重金属行为的研究进展

垃圾中的金属以氧化物、氮化物、碳化物及其它形态转移到焚烧产物如烟气、飞灰和底灰中，需严格控制焚烧过程中重金属的排放，故清楚了解金属在焚烧中的行为是很必要的。经研究发现，飞灰中重金属含量远远大于底灰中的含量，因此以垃圾焚烧飞灰中重金属的稳定化处理为目标，分析了目前国内外处理垃圾焚烧飞灰的方法和重金属在各种影响因素下的行为，并进行了比较，为飞灰的无害化和资源化处理提供参考。     

重金属废物稳定化处理技术现状及发展

本文在综述重金属废物的处理技术现状的基础上 ,重点论述了重金属危险废物的药剂稳定化机理和方法 ,提出重金属螯合剂在重金属污染治理中将发挥重要作用。     

Manganese nodules— an example of a Lasky distribution?

Readily accessible analytical data from 530 stations from which manganese nodules have been collected are used to investigate what relationship, if any, there is between grade (expressed as the combined copper and nickel content) and the number of samples. It is concluded that not only average grade but also cut-off grade have the relationships with cumulative quantities suggested by Lasky, subject to the exclusion of certain, apparently anomalous, data. These relationships can be used to derive information on the distribution of the quantity of contained metal at different average and cut-off grades, which may have applications to other mineral deposits.     

PARAMETRIC ESTIMATION OF COVARIANCES OF REGIONALIZED VARIABLES1

ABSTRACT: The usefulness of stochastic models in describing the spatial variability of hydrogeologic quantities, such as permeability, storativity, piezometric head, seepage velocity, and solute concentrations is now widely recognized. In practice, these quantities are represented as the sum of a well-structured component, or drift, and a more erratic fluctuation component which is described statistically through its covariance function. This paper reviews some of the most recent and most promising methods for the estimation of parameters of these covariances from existing data. They are maximum likelihood, restricted maximum likelihood, minimum-variance unbiased quadratic estimation, and minimum-norm (weighted least squares) estimation. The applicability of such methods to conditional and unconditional probability problems is discussed.     

AN APPLICATION OF OPERATIONS RESEARCH METHODS TO BEACH RENOURISHMENT PROJECTS1

ABSTRACT: Mathematical models have been widely used in business to minimize cost and maximize profit. In this paper such models are used to help determine the optimum strategy for a beach renourishment project including the initial and subsequent fill quantities and the length of a complete renourishment cycle. The importance of considering economic factors is emphasized, and the sensitivity of the optimal values to changes in the basic parameters of the models are discussed. The possible extensions and limitations of the models are considered.     

Impact of mercury on the activity pattern of a marker enzyme in a freshwater bivalve

Sessile benthic organisms are universally accepted as bio-indicators of environmental pollution and lysosomal membrane is often the target of injury by xenobiotics resulting in destabilization. Effect of mercury on the activity pattern of the marker enzyme, Acid Phosphatase in the gill and hepatopancreas of the freshwater mussel, Lamellidens corrianus (Lea) at 24, 72, and 168 h, post-exposure discussed. ACP activity was determined as given in Sigma Technical Bulletin (No. 104) and μmol of p-nitrophenol liberated/mg protein/h calculated. The work aimed to study the duration of exposure and concentration of the metal influence, the direction of the response of the enzyme in the two tissues studied and results show that the concentration of the metal as well as the period of exposure do influence the enzyme activity and may have predictive value as a biomarker of impending population changes. Higher concentration of the metal is assumed to have induced stress proteins like metallothioneins.     

Monitoring of Seasonal Variation in the Water Quality of Ubu River in Ekwusigo and Nnewi Local Government Areas of Anambra State,Nigeria

Investigation of the water quality of the Ubu river has been carried out. The upstream course of the river is slightly acidic (pH 5.45 ± 0.23), and the acidity decreases along the lower courses of the river. Turbidity, surfactant, and iron content parameters of the river increased during the wet season, and these changes have been attributed to inputs from flood, leachates of soil erosion, and storm water runoff discharged into the river in increased quantities during the season. Concentrations of some metals were found to increase during the dry season because of absence of dilution of the river by storm water runoff. Most water quality parameters are within World Health Organization acceptable limits set for potable water, and they include most of the cationic and anionic constituents. Although there is no hydrocarbon or metal ion pollution, potability is reduced along the mid to downstream courses of the river by unacceptable levels of turbidity, surfactant concentration, and iron content, particularly during the wet season.     

STRATEGIES FOR SEPARATING METALS FROM ACID MINE WATERS1

ABSTRACT: Strategies for the precipitation and separation of the primary metal ions, Fe(II), Cu(II), Zn(II), Mn(II), and Cd(II) in acid waste waters such as those in tributaries of the upper Sacramento River in northern California, are discussed. The strategies exploit the: (1) differential oxygen and hydrogen peroxide oxidation and precipitation properties of the metal ions as a function of pH, (2) the addition of ions, such as Mg^{2 +} and Cl^-, to reduce unfavorable coprecipitation, and (3) the facilitation of oxidation-reduction reactions between metal ions and the stabilization of particular oxidation states. This may be accomplished with specific complexing agents such as thiocyanate, SCN^-, and thiourea (TU), S = C(NH₂)₂ in order to separate copper at low pH as Cu(I) using Fe(II) as a reducing agent.     

Data search and environmental hazard assessment for post-seveso chemicals

After the serious accident with a chemical industrial plant at Seveso (Italy) in 1976, the Commission of the European Communities has made a directive on major accidents, usually called the Post-Seveso Guideline. In its annex III, a list of 178 substances is given for which potentially dangerous volumes in case of an accident are defined on the basis of human health criteria. For the implementation of environmental criteria, information on toxicity to aquatic organisms, dilution, and physical behavior in water is needed. A literature search for relevant data on these 178 substances revealed aquatic toxicity data for 116 substances, but only for 87 substances sufficient data were available to make a hazard assessment. As an example, the River Rhine was used to calculate the critical quantities that, after a sudden discharge in the Swiss part, could cause damage at the Dutch part some 800 km downstream. In the absence of a common opinion on the criteria for being a major accident and a serious environmental hazard, the impact of different criteria quantities is discussed. If, for example, in the whole River Rhine a mortality of 5% of the aquatic species is chosen as the criterion for damage to the ecosystem, the critical quantities as mentioned in the EEC directive have to be lowered drastically for the majority of the substances. For 18 substances it could be shown that release of the mentioned quantities would be catastrophic for aquatic life in the whole river.     

A COLORIMETRIC METHOD FOR THE DETERMINATION OF TRACE COPPER CONCENTRATIONS IN WATER1

Trace quantities of copper (II) ion can be found in natural water as waste products from industrial, mining, and agricultural operations. Because low concentrations of copper can be toxic to plant life, many workers have devised methods of analysis for this metal in water. These methods require expensive equipment and skilled technicians. The described study illustrates a simple method in which copper (II) ion is concentrated by a batch ion exchange technique and estimated colorimetrically after formation of the blue triethylenetetramine complex. Using the visible absorption peak of the complex at 600 nm it was possible to obtain accurate estimations of original copper concentrations in the range 0.5-3 ppm. Using the complex absorption peak at 260 nm in the ultra-violet region of the spectrum increased the sensitivity by a factor of twenty. Because of the dependence of the complex formation reaction on solution acidity it is possible to optimize conditions for the detection of copper (II) in the presence of other metal ions. This type of method, which could be extended to the analysis of other metal ions, could be performed by a relatively unskilled technician under field conditions.     

Bioremediation of Acidic and Metalliferous Drainage (AMD) through organic carbon amendment by municipal sewage and green waste

Pit lakes (abandoned flooded mine pits) represent a potentially valuable water resource in hot arid regions. However, pit lake water is often characterised by low pH with high dissolved metal concentrations resulting from Acidic and Metalliferous Drainage (AMD). Addition of organic matter to pit lakes to enhance microbial sulphate reduction is a potential cost effective remediation strategy. However, cost and availability of suitable organic substrates are often limiting. Nevertheless, large quantities of sewage and green waste (organic garden waste) are often available at mine sites from nearby service towns. We treated AMD pit lake water (pH 2.4) from tropical, North Queensland, Australia, with primary-treated sewage sludge, green waste, and a mixture of sewage and green waste (1:1) in a controlled microcosm experiment (4.5 L). Treatments were assessed at two different rates of organic loading of 16:1 and 32:1 pit water:organic matter by mass. Combined green waste and sewage treatment was the optimal treatment with water pH increased to 5.5 in only 145 days with decreases of dissolved metal concentrations. Results indicated that green waste was a key component in the pH increase and concomitant heavy metal removal. Water quality remediation was primarily due to microbially-mediated sulphate reduction. The net result of this process was removal of sulphate and metal solutes to sediment mainly as monosulfides. During the treatment process NH(3) and H(2)S gases were produced, albeit at below concentrations of concern. Total coliforms were abundant in all green waste-treatments, however, faecal coliforms were absent from all treatments. This study demonstrates addition of low-grade organic materials has promise for bioremediation of acidic waters and warrants further experimental investigation into feasibility at higher scales of application such as pit lakes.     

Passive treatment of acid mine drainage in bioreactors using sulfate-reducing bacteria: critical review and research needs

Acid mine drainage (AMD), characterized by low pH and high concentrations of sulfate and heavy metals, is an important and widespread environmental problem related to the mining industry. Sulfate-reducing passive bioreactors have received much attention lately as promising biotechnologies for AMD treatment. They offer advantages such as high metal removal at low pH, stable sludge, very low operation costs, and minimal energy consumption. Sulfide precipitation is the desired mechanism of contaminant removal; however, many mechanisms including adsorption and precipitation of metal carbonates and hydroxides occur in passive bioreactors. The efficiency of sulfate-reducing passive bioreactors is sometimes limited because they rely on the activity of an anaerobic microflora [including sulfate-reducing bacteria (SRB)] which is controlled primarily by the reactive mixture composition. The most important mixture component is the organic carbon source. The performance of field bioreactors can also be limited by AMD load and metal toxicity. Several studies conducted to find the best mixture of natural organic substrates for SRB are reviewed. Moreover, critical parameters for design and long-term operation are discussed. Additional work needs to be done to properly assess the long-term efficiency of reactive mixtures and the metal removal mechanisms. Furthermore, metal speciation and ecotoxicological assessment of treated effluent from on-site passive bioreactors have yet to be performed.     

Green accounting and sustainability of the Peruvian metal mining sector

This paper estimates the true economic income of Peru’s metal mining sector for the period 1992–2006, using a model of green economic income based on Hamilton (2000). The total depletion of natural capital caused by metal mining is calculated by estimating, on the one hand, the depreciation of mining resources (using the Hotelling rent approach) and, on the other, the environmental degradation provoked by metal mining activities. The results show that the total loss of natural capital represents between 31% and 51% of the metal mining GDP and between 2% and 4.9% of Peru’s GDP. On the other hand, correcting the usual GDP measure produced by the traditional National Account System (NAS) for the total loss of natural capital caused by mining activities shows that the GDP traditional measure overestimated by 51–64% the true economic income generated by Peruvian's metal mining sector during the period 1992–2006. The importance of the generation, taxation, and disposition of mining economic rents for Peru’s sustainable development in the future is also discussed.     

水体重金属污染的生态效应及生物监测

重金属污染是水体污染的一个重要方面,随着工业的发展和人口的不断增加,水体重金属污染已经成为全球的环境问题。本文主要介绍了水体重金属的污染现状以及对水生植物、水生动物和人体健康的危害,并探讨运用生物的敏感性来监测水体重金属污染的可行性,生物监测水体重金属污染有很好的发展前景。     

Survey of household waste composition and quantities in Abuja,Nigeria

Inadequate management of household solid waste is a serious problem in many developing cities. The study aimed to evaluate the quantities and composition of household solid waste generation in Abuja within different socioeconomic groups. The wastes from 74 households across different socioeconomic levels in Abuja were collected, weighted and classified on a daily basis for seven days in February 2012. The result showed that the average daily per capita household waste generation is 0.634 kg/capita/day. The characteristic of solid waste in Abuja are typical for the developing cities and dominated by organic waste. Households waste consisted of 63.6% organic waste, 9.7% paper, 8.7% plastics, 3.2% metal, 2.6% glass, 1.6% textile and 10.6% others (unclassified) and the bulk density was 240 kg/m³. The evaluation of relationship between income and daily per capita household waste generation showed a positive relationship. The study revealed a statistically significant difference between household size and daily per capita household waste generation in high-income group; a slight significant difference between household size and daily per capita household waste generation in medium income group and no statistically significant difference between household size and daily per capita household waste generation in low-income group.     

多相催化臭氧氧化技术机理研究进展

多相催化臭氧氧化技术能够有效去除水中的微量有机物。尽管有越来越多的研究致力于多相催化臭氧氧化技术领域,以及各种新的催化剂的引入,但对于多相催化臭氧氧化技术机理尚不清楚。因此,本文针对多相催化臭氧氧化技术中常用的负载型金属、负载型金属氧化物以及活性炭三类催化剂的反应机理进行了探讨。此外还对机理研究中存在的问题进行了探讨。     

煤矸石对环境的危害与开发利用研究

煤矸石是我国排放量最大的工业固体废弃物,它既压占土地又严重污染环境。概述了煤矸石的形成以及煤矸石大量堆放对环境所产生的危害和影响,并针对我国矿区实际,介绍了煤矸石污染的生态治理措施与开发利用途径。