Nonlinear and competitive sorption of apolar compounds in black carbon-free natural organic materials

Numerous studies have reported a spectrum of sorption phenomena in soils, sediments, and organic matter isolates of those materials that are inconsistent with a partition model proposed in the late 1970s and early 1980s, a model predicated on a hypothesis that sorption is linear and noncompetitive. To explain these nonideal phenomena, prior studies have proposed a hard-soft (glassy-rubbery) model for SOM (soil and sediment organic matter), while others have attributed them singularly to BC (black carbon: soot and charcoal) particles present in topsoils and sediments. In this study, we demonstrated nonideal sorption behavior (isotherm nonlinearity, competitive effects) for a group of apolar compounds in a large set of natural and model organic materials, including a commercial lignin and humic acids from different sources. Complete oxidation of samples by an acidic dichromate method was taken to signify the absence of BC. (However, polymethylene units are stable even if functionalized on both ends, making the technique unreliable for quantifying BC.) Other samples were inferred free of BC by their source and method of preparation. Characterization by thermalanalytical methods indicated the glassy character of the organic materials. The origin of the nonideal behaviors appears to be the glassy character of these materials. Sorption nonlinearity increased or decreased by changing temperature, cosolvent content, or degree of cross-linking by metal ions as predicted for organic solids in a glassy state. We conclude that macromolecular humic substances in the environment may exhibit nonideal sorption behavior in soils and sediments, quite apart from any such behaviors attributable to BC.     

饮用水砷污染治理研究进展

简述了饮用水中砷污染的来源和危害,砷在水环境的存在形态和毒性,分析了当前饮用水不同除砷方法的研究进展。     

最优环境工程方案遴选模型的建立与应用

根据层次分析法的原理,建立了遴选最优环境工程方案的层次结构模型。模型兼顾了效益与投资,不仅简化了专家或决策者的判断难度,而且判断结果直观,各方案的优劣对比清晰。给合某啤酒废水治理工程项目,介绍了层次分析模型应用于工程方案遴选中的计算过程。结果表明,应用此模型对环境工程方案进行优选比较科学、简便。     

Combined toxicity of three chlorophenols 2,4-dichlorophenol, 2,4,6-trichlorophenol and pentachlorophenol to Daphnia magna

The toxicity of single and combined mixtures of 2,4-dichlorophenol (2,4-DCP), 2,4,6-trichlorophenol (2,4,6-TCP), and pentachlorophenol (PCP) to Daphnia magna was studied. The toxicity ranking of these three single chlorophenols (CPs) to Daphnia magna was PCP > 2,4-DCP > 2,4,6-TCP. The toxic units (TU) approach was used to estimate the combined effects in experiments, the median effective concentration (EC(50)) values were 0.87-1.21 and 0.46-0.59 for binary and ternary mixtures, respectively. Response surface models of General Linear Models (R(2) > 0.90, residual deviation < 3.25) were established for all three binary mixtures. The toxicity for ternary mixtures based on the EC(50)-value and 10% effective concentration (EC(10))-value fixed mixture ratio presented a synergism. The risk based on the single CP's toxicity test may be underestimated. In addition, four approaches (concentration addition, toxicity equivalency factors, effect summation, and independent action) were used for the calculation of combined effects of the mixture. The experimental results showed that concentration addition and toxicity equivalency factor approaches were effective methods for calculation of additive effects of mixtures from binary systems of CPs; while independent action and effect summation (low simulated tail) predicted lower toxicity than experimental results. Limitations of the traditional focus on the effects of single agents were highlighted; hazard assessments ignoring the possibility of joint action of CPs will almost certainly lead to significant underestimations of risk.     

生物炭在土壤中的老化及其吸附重金属的研究进展

综述了生物炭在土壤中的老化机制及主要影响因素方面的研究进展,指出生物炭的理化性质和结构表征在土壤中发生变化是其老化机制,生物炭的特性、土壤特性和环境条件等因素共同影响着生物炭的老化。总结了老化生物炭在土壤中对重金属吸附的影响,生物炭在老化过程中理化性质和结构表征的变化影响了生物炭-土壤体系对重金属的吸附,并且吸附能力因老化方式和重金属不同而存在差异。提出了开展多种重金属共存条件下老化生物炭的吸附效果和机理研究、针对生物炭田间实际老化过程对土壤重金属的吸附行为开展季节性和多年长期观测研究,以及对生物炭修复的重金属污染土壤在生物炭老化过程中可能造成的环境和健康风险开展综合、长期的跟踪研究与评估等展望。     

沙尘暴的成因与防治措施初探

针对今春我国北方地工百北京连续７次的扬尘和沙尘暴龙击,分析其成因及危害,提出了防治沙尘暴的具体措施及建议,为沙尘暴的有效治理提供一定的科学依据和参考。     

室内空气污染调查

为了解室内空气污染状况,广州市环境监测中心站对刚装修不久的10套私人居室和5家单位办公室的室内空气进行了监测。结果表明,甲醛、苯、NH3、NOx浓度超标,最高超标倍数分别为：甲醛22.0倍,苯3.01倍,NH3 2.58倍,NOx0.30倍。指出,这些污染物主要来源于装修材料和建筑材料,会对人体健康造成危害。提出,为防止室内空气污染,应从源头抓起,装修时尽量选用低毒或无毒的材料,装修后的居室或办公室要保持通风,以降低室内污染物浓度,进驻前请有关权威部门进行监测评估。另外可在室内摆放绿色植物,以吸附一些有毒化合物。     

Occurrence and removal of endocrine-disrupting chemicals in wastewater treatment plants in the Three Gorges Reservoir area, Chongqing, China

Concentrations of six endocrine-disrupting compounds (EDCs), bisphenol A (BPA), estrone (E(1)), 17β-estradiol (E(2)), estriol (E(3)), 17α-ethynylestradiol (EE(2)) and diethylstilbestrol (DES), were assessed in influents, effluents and excess sludge in ten municipal wastewater treatment plants (WWTPs) in the Three Gorges Reservoir (TGR) area, Chongqing, China. Three types of activated sludge treatment processes, oxidation ditch (OD), reversed anaerobic-anoxic-oxic (rA(2)/O) technology and sequential batch reactor (SBR), were used in the surveyed WWTPs. These WWTPs were all combined landfill leachate-sewage treatment plants. All analytes were extracted by solid-phase extraction (SPE) in the dissolved phase and by accelerated solvent-based extraction (ASE) in sludge. Gas chromatography-mass spectrometry (GC-MS) was employed for the analysis of EDCs. Among these EDCs, BPA was the most frequently detected and abundant compound (100.0-10566.7 ng L(-1), 15.5-1210.7 ng L(-1) and 85.0-2470.4 ng g(-1) with respect to the influents, effluents and excess sludge samples). The greatest levels of steroidal estrogens in municipal influents were observed in E(3) which were all >100 ng L(-1), followed by E(1) (42.2-110.7 ng L(-1)) and E(2) (7.4-32.7 ng L(-1)), and in the effluents and sludge were E(1) > E(3) > E(2) which were all <31 ng L(-1) and 105 ng g(-1), respectively. Regarding synthetic estrogens, EE(2) was frequently detected in the influents, occurring below 50 ng L(-1), while DES was not detected at all. A high correlation coefficient was observed between the leachate-sludge ratio and concentrations of influent EDCs, and it was statistically significant (i.e., R > 0.65, P < 0.05), but removal efficiency of the EDCs did not show significant differences with OD, rA(2)/O and SBR processes. Furthermore, modification of treatment technology as well as operational parameters, such as hydraulic retention time (HRT), sludge retention time (SRT) and disinfection process (DP), were recommended to further eliminate the residual EDCs.     

倒置A2/O污水处理工艺的特点及应用实例

传统A2/O工艺在保证脱氮效果的同时除磷效果往往不佳.在充分分析传统A2/O工艺的基础上,提出了将缺氧池置于厌氧池前面,厌氧池后设置好氧池的分点进水倒置A2/O工艺.某污水厂的现场试验表明,在COD去除能力与常规A2/O工艺相当的情况下,倒置A2/O工艺的脱氮除磷功能明显优于常规A2/O工艺.