淮河支流污染物综合降解系数动态测算

确定河流污染物综合降解系数动态变化规律对提高水环境容量测算精度和水环境管理具有重要意义。通过现场模拟法,采用一维稳态模型测算了淮河支流洪河五沟营-塔桥乡河段COD、氨氮和总磷在枯水期、平水期和丰水期的综合降解系数,COD、氨氮和总磷降解系数在各水期的关系为枯水期平水期丰水期,提出了建议值并利用实测浓度对计算结果进行了检验,结果表明,不同水期综合降解系数吻合情况较好。     

Ultrasonic preparation of nano-nickel/activated carbon composite using spent electroless nickel plating bath and application in degradation of 2,6-dichlorophenol

Ni was effectively recovered from spent electroless nickel （EN） plating baths by forming a nano-nickel coated activated carbon composite. With the aid of ultrasonication, melamine- formaldehyde-tetraoxalyl-ethylenediamine chelating resins were grafted on activated carbon （MFT/AG）. PdC12 sol was adsorbed on MFT/AC, which was then immersed in spent electroless nickel plating bath; then nano-nickel could be reduced by ascorbic acid to form a nano-nickel coating on the activated carbon composite （Ni/AC） in situ. The materials present were carefully examined by Fourier transform infrared spectroscopy, X-ray diffraction, field emission scanning electron microscopy, X-ray photoelectron spectroscopy and electro- chemistry techniques. The resins were well distributed on the inside and outside surfaces of activated carbon with a size of 120 ± 30 nm in MFT/AC, and a great deal of nano-nickel particles were evenly deposited with a size of 3.8 ± 1.1 nm in Ni/MFT. Moreover, Ni/AC was successfully used as a catalyst for ultrasonic degradation of 2.6-dichloronhenol.     

Phytoremediation of levonorgestrel in aquatic environment by hydrophytes

Adsorption and degradation of levonorgestrel （LNG） by two hydrophytes, Cyperus alternfolius （CA） and Eichhornia crassipes （EC）, were investigated under light-shielding conditions in the water column. Variations of LNG concentrations in water, plant root epidermis, root, stem and leaf of the plants were analyzed. The results indicated that the removal efficiency of LNG by hydrophytes over the period of 50 days was significantly greater than the blank control （p 〈 0.05）, with the removal rates of 79.80%± 3.10% and 78.86% ± 2.55% for CA and EC, respectively. Compared with bio-adsorption, bio-conversion of LNG was found to be the dominant elimination pathway, evidenced by relatively high conversion rates （77.31% ±2.68% for CA and 77.82% ± 2.95% for EC）, while the adsorption rates were lower （1.77% ± 0.90% for CA and 1.05% ± 0.40% for EC）. The bio-adsorption and conversion of LNG showed no significant differences between the two hydrophytes. Additionally, the mineralization on root epidermis played an important role in the reduction of LNG in water.     

The multiple communities of low-carbon transition: an assessment of communities involved in forest carbon measurement

In recent writing on sociotechnical transitions theory communities are mostly conceived of as being local and place-based (“grassroots”). In this paper the implications for sociotechnical transitions theory of having multiple communities operating at different geographical scales, and with different objectives, are examined through a case study of low-carbon innovation in forests. The focus of analysis is the communities promoting sociotechnical innovations in the measurement of forest carbon. Innovation is being driven by the international United Nations climate policy initiative “Reducing Emissions from Deforestation and forest Degradation” (REDD+). The rise of REDD+ policy has prompted a flurry of activity in related scientific research, especially in the field of remote sensing. But other types of community are also actively positioning themselves as experts in forest carbon measurement: there are multiple communities at work, each with varying claims to innovation and expertise, from local (place-based) forest communities to international communities of foresters and forest ecologists. Recognition of the multiple communities operating within sociotechnical systems usefully draws our attention to the politics of innovation.     

Enhanced triallyl isocyanurate (TAIC) degradation through application of an O3/UV process: Performance optimization and degradation pathways

• UV/O₃ process had higher TAIC mineralization rate than O₃ process. • Four possible degradation pathways were proposed during TAIC degradation. • pH impacted oxidation processes with pH of 9 achieving maximum efficiency. • CO₃^2– negatively impacted TAIC degradation while HCO₃^– not. • Cl^– can be radicals scavenger only at high concentration (over 500 mg/L Cl^–). Triallyl isocyanurate (TAIC, C₁₂H₁₅N₃O₃) has featured in wastewater treatment as a refractory organic compound due to the significant production capability and negative environmental impact. TAIC degradation was enhanced when an ozone(O₃)/ultraviolet(UV) process was applied compared with the application of an independent O₃ process. Although 99% of TAIC could be degraded in 5 min during both processes, the O₃/UV process had a 70%mineralization rate that was much higher than that of the independent O₃ process (9%) in 30 min. Four possible degradation pathways were proposed based on the organic compounds of intermediate products identified during TAIC degradation through the application of independent O₃ and O₃/UV processes. pH impacted both the direct and indirect oxidation processes. Acidic and alkaline conditions preferred direct and indirect reactions respectively, with a pH of 9 achieving maximum Total Organic Carbon (TOC) removal. Both CO₃^2– and HCO₃^– decreased TOC removal, however only CO₃^2– negatively impacted TAIC degradation. Effects of Cl^– as a radical scavenger became more marked only at high concentrations (over 500 mg/L Cl^–). Particulate and suspended matter could hinder the transmission of ultraviolet light and reduce the production of HO· accordingly.     

Photodegradation of quinestrol in waters and the transformation products by UV irradiation

Quinestrol is synthetic estrogen used in contraceptive and hormone replacement therapy and occasionally for treating breast cancer and prostate cancer. It can make its way into the environment through sewage discharge and waste disposal produced by human excretions. In this study, the photodegradation kinetics of quinestrol in various conditions was investigated by UV and solar irradiation. The affecting factors were studied including concentration of hydrogen peroxide, different water types, and the initial concentrations of quinestrol. Concurrently, the transformation products and presumed pathways of quinestrol in distilled water by UV irradiation were identified and proposed. The results showed that the degradation of quinestrol in both irradiation conditions followed the pseudo-first-order kinetics. More rapid degradation was observed by UV irradiation (k = 0.018 min⁻¹) than solar irradiation (k = 0.004 h⁻¹), and the photodegradation rate of quinestrol depended on the concentration of hydrogen peroxide, the initial concentration of quinestrol and water types. The transformation products of quinestrol in distilled water were identified by gas chromatography/mass spectrometry. When exposed to UV irradiation, quinestrol in aqueous solution was rapidly degraded, giving at least ten photodegradation products. The chemical structures of ten degradation products were identified on the basis of mass spectrum interpretation and literature data.     

Recent progress on application of UV excilamps for degradation of organic pollutants and microbial inactivation

Excilamps as modern mercury-free sources of narrow-band UV radiation represent an attractive alternative in environmental applications. This review focuses on recent studies on the water and surface decontamination with excilamps by means of direct photolysis and advanced oxidation processes. To date, direct photolysis and advanced oxidation processes (AOPs) such as UV/H₂O₂, UV/Fenton and UV/O₃ have been applied for degradation of organic compounds (mainly, phenols, dyes and herbicides) in model aqueous solutions. Special emphasis is placed on studies combining UV irradiation (as a pre-treatment or post-treatment step) with biological treatment. In this review, the efficiencies of direct UV, UV/H₂O₂ and UV/TiO₂ processes for inactivation of a variety of pathogenic microorganisms in water and on surfaces are discussed. The analysis of the literature shows that more works need to be done on scaling up the processes, degradation/mineralization of target pollutant(s) in real effluents and evaluation of energy requirements.     

Determination of specific gravity of municipal solid waste

This investigation was conducted to evaluate experimental determination of specific gravity (G_s) of municipal solid waste (MSW). Water pycnometry, typically used for testing soils was adapted for testing MSW using a large flask with 2000 mL capacity and specimens with 100–350 g masses. Tests were conducted on manufactured waste samples prepared using US waste constituent components; fresh wastes obtained prior and subsequent to compaction at an MSW landfill; and wastes obtained from various depths at the same landfill. Factors that influence specific gravity were investigated including waste particle size, compaction, and combined decomposition and stress history. The measured average specific gravities were 1.377 and 1.530 for as-prepared/uncompacted and compacted manufactured wastes, respectively; 1.072 and 1.258 for uncompacted and compacted fresh wastes, respectively; and 2.201 for old wastes. The average organic content and degree of decomposition were 77.2% and 0%, respectively for fresh wastes and 22.8% and 88.3%, respectively for old wastes. The G_s increased with decreasing particle size, compaction, and increasing waste age. For fresh wastes, reductions in particle size and compaction caused occluded intraparticle pores to be exposed and waste particles to be deformed resulting in increases in specific gravity. For old wastes, the high G_s resulted from loss of biodegradable components that have low G_s as well as potential access to previously occluded pores and deformation of particles due to both degradation processes and applied mechanical stresses. The G_s was correlated to the degree of decomposition with a linear relationship. Unlike soils, the G_s for MSW was not unique, but varied in a landfill environment due both to physical/mechanical processes and biochemical processes. Specific gravity testing is recommended to be conducted not only using representative waste composition, but also using representative compaction, stress, and degradation states.     

Age-dating Diesel Fuel Spills: Using the European Empirical Time-based Model in the U.S.A.

In 1993, a paper was published by Christensen and Larsen that offered a method for determining the age of diesel oil spills in soil (Christensen and Larsen, 1993 Ground Water Mount. R . Fall , 142-149). It presented an empirical time-based model of the degradation of diesel fuel in soils using chemical data gathered at petroleum release sites in Denmark and the Netherlands. Now, evaluation of the validity of the application of this work to subsurface petroleum releases in other countries remains. In the U.S.A., investigations assessing date(s) of release of diesel fuel in soils, e.g. age dating of subsurface petroleum contamination, have considerable interest. Litigation-driven scientific investigations with accompanying expert testimony in a court of law are underway. The number of instances where application of the Christensen and Larsen empirical time-based model to petroleum-contaminated properties is growing in the U.S.A. This paper presents two case studies which evaluate the applicability of the Christensen and Larsen empirical time-based model to petroleum-contaminated properties in general. It illustrates the approach using gas chromatographic data from two recently-completed projects evaluating the applicability of the Christensen and Larsen model to a No. 2 fuel oil/diesel fuel surface spill in the U.S.A. Results showed that the application of the model to petroleum-contaminated soils was scientifically valid, provided its applicability was evaluated using hypothesis testing for specific changes in the characteristics of the petroleum hydrocarbon distribution in a number of soil samples collected over time at one site. The paper offers observations on the application of the Christensen and Larsen model to petroleum found in the light non-aqueous phase liquid (LNAPL) phase and groundwater.     

Application of Forensic Techniques for Age Dating and Source Identification in Environmental Litigation

A multitude of forensic techniques are available for age dating and source identification, including corrosion models for underground storage tanks, the commercial availability of a compound, chemical associations with discrete types of manufacturing processes, chemical profiling, proprietary additives, stable isotope analysis, degradation models, biomarkers and contaminant transport models. The selection and use of these techniques in environmental litigation must be thoroughly understood and applied to be effective as forensic evidence. When introduced as scientific evidence, the governing assumptions and quality of the data are critically evaluated and frequently successfully challenged. The purpose of this paper is to present an overview of commonly used environmental forensic techniques and their possible applications so that a user can decide which technique or combination of methods is most appropriate for their case.