流域水电开发环境影响后评价实践与思考

环境影响后评价必将是未来环境影响评价领导另一新的研究课题,而目前尚未出台相关规范导则。本文根据流域环境影响后评价的工作实践,明确提出开展流域梯级水电开发环境影响后评价的理论框架和评价思路,供国内重点流域梯级水电开发开展环境影响后评价提供经验和参考。     

Combined fluorescence and electrochemical investigation on the binding interaction between organic acid and human serum albumin

Human serum albumin (HSA) is a plasma protein responsible for the binding and transport of fatty acids and a variety of exogenous chemicals such as drugs and environmental pollutants. Such binding plays a crucial role in determining the ADME (absorption, distribution, metabolism, and excretion) and bioavailability of the pollutants. We report investigation on the binding interaction between HSA and acetic acid (C2), octanoic acid (C8) and dodecanoic acid (C12) by the combination of site-specific fluorescent probe, tryptophan intrinsic fluorescence and tyrosine electrochemistry. Two fluorescent probes, dansylamide and dansyl-L-proline, were employed in the displacement measurement to study fatty acid interaction with the two drug-binding sites on HSA. Intrinsic fluorescence of tryptophan in HSA was monitored upon addition of the fatty acids into HSA. Electrocatalyzed response of the tyrosine residues in HSA by a redox mediator was used to investigate the binding interaction. Qualitatively, observations made by the three approaches are very similar. HSA did not show any change in either fluorescence or electrochemistry after mixing with C2, suggesting there is no significant interaction with the short-chain fatty acid. For C8, the measured signal dropped in a single-exponential fashion, indicative of independent and non-cooperative binding. The calculated association constant and binding ratio is 3.1×106 L/mol and 1 with drug binding Site I, 1.1×107 L/mol and 1 with Site II, and 7.0×104 L/mol and 4 with the tryptophan site. The measurement with C12 displayed multiple phases of fluorescence change, suggesting cooperativity and allosteric effect of C12 binding. These results correlate well with those obtained by the established methods, and validate the new approach as a viable tool to study the interactions of environmental pollutants with biological molecules.     

Phragmites australis and Typha orientalis in removal of pollutant in Taihu Lake, China

Two plant populations of Phragmites australis and Typha orientalis grown in gravel and sediment substrate were studied to assess their capabilities for purifying polluted water in Taihu Lake, China. The substrate displayed most significant effects on the suspended matter (P < 0.01), with the reduction of 76%-87% and 52%-63% for P. australis, and 83%-86% and 45%-62% for T. orientalis in gravel substrate and sediment substrate, respectively. Both species and substrates significantly decreased the N and P conc...     

Microbiological parameters and maturity degree during composting of Posidonia oceanica residues mixed with vegetable wastes in semi-arid pedo-climatic condition

The aim of this study was to characterize the biological stability and maturity degree of compost during a controlled pile-composting trial of mixed vegetable residues (VR) collected from markets of Tunis City with residues of Posidonia oceanica (PoR), collected from Tunis beaches. The accumulation in beaches (as well as their removal) constitutes a serious environmental problem in all Mediterranean countries particularly in Tunisia. Aerobic-thermophilic composting is the most reasonable way to profit highly-valuable content of organic matter in these wastes for agricultural purposes. The physical, chemical, and biological parameters were monitored during composting over 150 d. The most appropriate parameters were selected to establish the maturity degree. The main result of this research was the deduction of the following maturity criterion: (a) C/N ratio < 15; (b) NH₄⁺-N < 400 mg/kg; (c) CO₂-C < 2000 mg CO₂-C/kg; (d) dehydrogenase activity < 1 mg TPF/g dry matter; (e) germination index (GI) > 80%. These five parameters, considered jointly are indicative of a high maturity degree and thus of a high-quality organic amendment which employed in a rational way, may improve soil fertility and soil quality. The mature compost was relatively rich in N (13.0 g/kg), P (4.74 g/kg) and MgO (15.80 g/kg). Thus composting definitively constitutes the most optimal option to exploit these wastes.     

Biodegradability of soil water soluble organic carbon extracted from seven di erent soils

Water soluble organic carbon (WSOC) is considered the most mobile and reactive soil carbon source and its characterization is an important issue for soil ecology study. A biodegradability test was set up to study WSOC extracted from 7 soils di erently managed. WSOC was extracted from soil with water (soil/water ratio of 1:2, W/V) for 30 min, and then tested for biodegradability by a liquid state respirometric test. Result obtained confirmed the finding that WSOC biodegradability depended on the both land use and management practice. These results suggested the biodegradability test as suitable method to characterize WSOC, and provided useful information to soil fertility.     

Characterization of organic matter in total suspended particles by thermodesorption and pyrolysis-gas chromatography-mass spectrometry

The organic matter in tropospheric aerosol plays an important role in atmospheric physical and chemical processes. The bulk of organic matter, representing a significant proportion of the total suspended particulate (TSP) mass, is bound to polymeric material whose structure and properties are largely unknown. Here we used thermodesorption gas chromatography/mass spectrometry (Td- GC/MS) to study organic compounds of low molecular mass and pyrolysis gas chromatography/mass spectrometry (Py-GC/MS) to characterize the chemical structure of macromolecules in TSP samples collected in di erent seasons from di erent sites in Guangzhou. n-Alkanes, fatty acids and nitriles were the predominant compounds in the thermodesorption products, whereas aromatics, fatty acids, nitriles and n-alkanes/alkenes were the major compounds in the pyrolysates. The results indicated that aromatics were main units in macromolecules. The fatty acids and nitriles formed from carboxylic ammonium salts were detected in both thermodesorption products and pyrolysates at a certain concentration, indicating the importance of these compounds in TSP formation. The TSP source mainly determined the occurrence of compounds in samples from urban, suburban and forest sites, whereas the TSP source and formation process maybe controlled the seasonal variation in compounds detected. High levels of nitriles in summer samples from suburban and forest sites coincide with the release of ammonium from the land and of fatty acids from vegetation at these sites.     

水解(酸化)工艺预处理难降解有机废水应用技术分析

本文对水解(酸化)工艺进行了原理分析,论述了该工艺的优缺点,以及对后续工艺的影响.分析论述了该工艺对几种典型的难降解有机废水的降解机理.认为水解(酸化)作为难降解有机废水的预处理工艺具有很高的推广应用价值.     

低分子量有机酸对岩源磷释放的实验研究

低分子量有机酸是微生物和植物根系分泌物中重要的组成部分.采用浸泡实验比较了4种常见低分子量有机酸(草酸、酒石酸、柠檬酸、苹果酸)对巢湖北岸东部富磷地层中岩源磷的释放量,并对浸提后的部分残渣进行磷的赋存形态分析.结果表明,当有机酸浓度小于5mmol·L-1时,柠檬酸的释磷量最大;大于5mmol·L-1时,草酸和酒石酸的释磷量最大,此时释磷量与有机酸的浓度具有一定的线性关系,其增加趋势远大于浓度小于5mmol·L-1时的增加趋势,而其中草酸和酒石酸又远大于柠檬酸和苹果酸.在有机酸溶液终止pH≥4时,有机酸溶液终止pH与释磷量有较好的线性关系.在50mmol·L-1相同浓度时,草酸对各赋存形态磷转化作用均最大,酒石酸次之.而4种酸对有机磷释放率最大,均高达97%以上,对闭蓄态磷的释放率最小.     

组合人工湿地对城镇污水处理厂尾水中有机物的去除特征研究

采用物理分级和三维荧光光谱法,研究了组合人工湿地对城镇污水处理厂尾水中不同形态有机物的去除特征.结果表明,组合人工湿地对污水处理厂尾水具有较好的深度处理效果,出水水质基本可以达到国家地表水环境质量标准(GB38382-2002)Ⅲ或Ⅳ类水标准.组合人工湿地处理系统对尾水中CODCr和BOD5总体去除率分别达到35.2%和44.3%,对尾水中总有机碳(TOC)、溶解性有机碳(DOC)、颗粒有机碳(POC)的平均去除率分别为46.9%、45.9%、48.3%.组合人工湿地系统不同单元对尾水中有机物的去除贡献率存在差异,其中,潜流湿地单元对尾水中CODCr和BOD5及其不同组分有机碳的去除效率较高.试验期间,由于藻类滋生,表流湿地单元出水中有机物含量波动较大,去除效果明显降低,藻类被打捞后,出水水质明显改善.三维荧光光谱分析结果显示,各个处理单元取样点的水样三维荧光光谱均出现4个明显的荧光峰.人工湿地各单元出水溶解性有机质(DOM)中,类蛋白和类腐殖酸物质含量较高,类富里酸物质含量较低.人工湿地对类蛋白和类腐殖酸物质有较强的去除作用.     

基于稳定同位素示踪的流域颗粒有机物质来源辨析

为有效控制流域水质污染,保证饮用水水源的水质安全,通过采集和测定流域内土壤、植物以及河流断面水体悬浮颗粒有机质(POM)在枯水期和丰水期的碳、氮稳定同位素值和C/N比值,对石头口门水库汇水流域水体POM的来源进行研究.结果表明,水体中POM主要来源于土壤有机质,其贡献为69.2%,藻类等大型水生生物和浮游植物的贡献分别为23.1%和7.7%.流域水体中POM的来源存在时空差异.丰水期,浮游植物和藻类等大型水生植物的贡献均为15.4%,而枯水期后者的贡献提高到了30.8%.水体POM主要来源于双阳河和饮马河下游的土壤有机质,说明该区域土壤侵蚀较重,易发生非点源污染;岔路河和饮马河上游支流小黄河,水体POM以浮游植物的贡献占主导,其贡献分别为86.3%和94.8%,这些区域侵蚀较弱,非点源污染发生的风险小;大中型水库区域的POM主要由藻类等大型水生植物贡献,表明悬浮颗粒物在进入水库后可能发生了明显沉积.