Excellent dye degradation performance of FeSiBP amorphous alloys by Fenton-like process

Amorphous alloys are being newly applied in wastewater treatment because of their unique atomic packing structure. They possess excellent degradation efficiency, stability and reusability. In this work, Fe₈₀Si₁₀B₁₀ and Fe₈₃Si₅B₈P₄ amorphous ribbons exhibited advanced catalytic performance for the degradation of Methyl Blue (MB) and Rhodamine B (RhB) dyes, and the color removal reach nearly 100% within 11 min for both the dyes. Compared with the Fe₈₀Si₁₀B₁₀ amorphous ribbon, the Fe₈₃Si₅B₈P₄ ribbon showed higher degradation efficiency due to its lower reaction activation energy, higher electron transfer ability and higher Fe content, and the formation of the galvanic cell between the strong Fe–P bonds and the weak Fe–B bonds. It also exhibited high stability and reusability. The degradation efficiency was improved when the appropriate concentration of H₂O₂ is added. As regards the pH, high degradation efficiency was observed in acidic MB solution, but it decreased as the pH increased up to pH 7. The application of the electro–Fenton–like process is discussed, which can effectively improve the degradation performance in a nearly natural solution. This study presents a high efficiency low-cost catalyst for synthetic dye degradation and expands the functional applications of Fe-based amorphous alloys.     

Recent survey and effects of cooking processes on levels of PCDDs,PCDFs and Co-PCBs in leafy vegetables in Japan

We report here the latest levels of polychlorinated dibenzo-p-dioxins/polychlorinated dibenzofurans (PCDD/Fs) and coplanar polychlorinated biphenyls (Co-PCBs) in leafy vegetables in Japan as well as the effect of cooking processes on the reduction of these contaminants. Three kinds of leafy vegetables (“komatsuna”, lettuce and spinach) from seven districts in Japan in 1998 were analyzed for the 2,3,7,8-chlorine substituted PCDD/Fs and three non-ortho-PCBs (#77, 126 and 169). The mean total TEQ levels (using the WHO-TEFs) in the komatsuna, lettuce and spinach were 0.094, 0.025 and 0.196 pg/g fresh weight, respectively. The TEQ levels are dominated by 2,3,7,8-TCDD, 1,2,3,7,8-PeCDD, 2,3,4,7,8-PeCDF and 3,3^′,4,4^′,5-PeCB in many of the samples. For one of these isomers, the 2,3,4,7,8-PeCDF TEQ levels showed good correlation with the total TEQ levels in the samples (r=0.957). This suggests that 2,3,4,7,8-PeCDF may be an indicator for dioxin contamination in the analysis of the leafy vegetables. Also, the effects of two cooking processes (washing and washing followed by boiling) on the dioxin levels in two types of spinach samples were investigated. On average, in both samples, the total concentrations of the PCDDs, PCDFs and Co-PCB were reduced to about 38%, 73% and 88% of the initial concentrations by washing, and to 21%, 35% and 61% of the initial concentrations by washing followed by boiling. The total TEQ levels were reduced to about 30% of the initial TEQ levels by washing followed by boiling. Significant reductions in the TEQ levels were observed in the cooked samples. Thus, the cooking processes may reduce the risk of dioxin intake from the leafy vegetables.     

Rapid Geomorphic and Habitat Stream Assessment Techniques Inform Restoration Differently Based on Levels of Stream Disturbance

Visual‐based rapid assessment techniques provide an efficient method for characterizing the restoration potential of streams, with many focusing on channel stability and instream habitat features. Few studies, however, have compared these techniques to see if they result in differing restoration priorities. Three rapid assessment techniques were contrasted at three wild trout streams in western New York with different amounts of channel disturbance. Two methods focused only on geomorphic stability, whereas the third addressed physical habitat condition. Habitat assessment scores were not correlated with scores for either geomorphic assessment method and they varied more between channels with different degrees of disturbance. A model based on dynamic equilibrium concepts best explains the variation among the streams and techniques because it accounts for a stream's capacity to maintain ecological integrity despite some inherent instability. Geomorphic indices can serve as effective proxies for biological indices in highly disturbed systems. Yet, this may not be the case in less disturbed systems, where geomorphic indices cannot differentiate channel adjustments that impact biota from those that do not. Dynamically stable streams can include both stable and unstable reaches locally as characterized by geomorphic methods and translating these results into restoration priorities may not be appropriate if interpretations are limited to the reach scale.     

Creating and using objectives for ecological risk assessment and management

This paper provides guidance for ecological risk assessors and managers about how to structure objectives for these efforts. It first outlines why objectives are crucial for ecological risk assessment and management. Then, it draws on the writing within applied decision analysis to outline a process for structuring objectives for ecological risk-management efforts involving one or several decision-makers. The characteristics of a good set of objectives are outlined, and the various uses for a set of objectives within ecological risk-management efforts are summarized. The paper concludes with practical advice for managers and facilitators charged with developing objectives to guide these complex processes.     

DIE‐OFF OF PATHOGENIC E. COLI O157:H7 IN SEWAGE CONTAMINATED WATERS1

E. coli O157:H7 is a pathogen that can be present in sewage contaminated waters. This organism poses a health risk for humans who come in contact with these waters via drinking, swimming, or shellfish consumption. A risk assessment model is needed to evaluate or quantify this risk. One possibility is the use of a computer model to simulate the fate and transport of E. coli O157:H7 downstream from a discharge point [e.g., a separate sanitary sewer overflow (SSO)]. However, this computer model would require input data regarding characteristics of this organism, which have not been previously available. One necessary input parameter is the rate at which die off of this organism occurs in a stream or river environment. Several studies were conducted to evaluate the die‐off rate of E. coli O157:H7 in an SSO impacted stream. Indicator bacteria (total coliforms, E. coli, and enterococci) were evaluated simultaneously. The results suggest that E. coli O157:H7 is not persistent — decay rates are high relative to the indicator bacteria. However, the decay plots suggest a biphasic response: initial decay is rapid, followed by an attenuated, slower decay. Hence traditional simulation methods using a single, first‐order decay rate may be inaccurate.     

长江南通站含沙量及水化学变化与流域的风化过程

1960—2001年间长江河水含沙量递减趋势方程为：S=-4．7273a 582．94。近些年来泥沙含量递减趋势可能会对流域生态环境产生重要影响，应引起社会的关注。长江河水化学组分在1997-2001年的5年间受到季节和年际变化的影响较为有限。河水中HCO3^-与Ca^3 占主导地位，占总离子当量浓度的55％以上。主要受到碳酸盐类溶解的控制。硅酸盐类的风化过程较弱，可能主要是钙镁硅酸盐类的溶解，对流域离子的总体贡献不大。岩盐、石膏和芒硝的水解对河水中的Na^ 、SO4^2-和Cl^-的贡献最大。由此长江流域发生的主要风化过程有：白云石和方解石的溶解、钙镁长石的分解和岩盐、石膏、芒硝等的水解过程等，这与长江流域的岩石特征是基本一致的。粗略的估计．大气CO2对河流中HCO3^-的贡献量占河水中离子总当量浓度的20％左右，其余80％河水溶解质为风化岩石提供。     

The Need to Rationalize and Prioritize Threatening Processes Used to Determine Threat Status in the IUCN Red List

Abstract: Thorough evaluation has made the International Union for Conservation of Nature (IUCN) Red List the most widely used and accepted authority on the conservation status of biodiversity. Although the system used to determine risk of extinction is rigorously and objectively applied, the list of threatening processes affecting a species is far more subjectively determined and has not had adequate review. I reviewed the threats listed in the IUCN Red List for randomly selected groups within the three most threatened orders of mammals: Artiodactyla, Carnivora, and Primates. These groups are taxonomically related and often ecologically similar, so I expected they would suffer relatively similar threats. Hominoid primates and all other terrestrial fauna faced similar threats, except for bovine artiodactyls and large, predatory carnivores, which faced significantly different threats. Although the status of bovines and hominoids and the number of threats affecting them were correlated, this was not the case for large carnivores. Most notable, however, was the great variation in the threats affecting individual members of each group. For example, the endangered European bison (Bison bonasus) has no threatening processes listed for it, and the lion (Panthera leo) is the only large predator listed as threatened with extinction by civil war. Some threatening processes appear spurious for the conservation of the species, whereas other seemingly important factors are not recorded as threats. The subjective nature of listing threatening processes, via expert opinion, results in substantial biases that may be allayed by independent peer review, use of technical manuals, consensus among multiple assessors, incorporation of probability modeling via decision‐tree analysis, and adequate coordination among evaluators. The primary focus should be on species‐level threats rather than population‐level threats because the IUCN Red List is a global assessment and smaller‐scale threats are more appropriate for national status assessments. Until conservationists agree on the threats affecting species and their relative importance, conservation action and success will be hampered by scattering scarce resources too widely and often by implementing conflicting strategies.     

Critical Loads – Is There A Need For A New Concept?

The concept of critical loads has been an important andsuccessful tool for the development of control strategiesfor transboundary air pollution in Europe. The use of theconcept has led us to a situation where very few areas inEurope will have an exceedance of critical loads foracidification in 2010, indicating that the benefits offurther control acidifying substances will be lessuseful. The critical loads concept does not, however,take into account the large benefits of further controlin damaged systems but where critical loads are nolonger exceeded. In this paper we discuss the importanceof widening the critical loads concept to include thesebenefits and we propose an additional effect-relatedmeasure, Dynamic Impact Analysis, to be included infurther control strategies and assessments. With such aconcept the actual situation and its further developmentwill be included in assessments and control strategies.     

均相/异相催化剂光降解垃圾渗滤液效果的研究

垃圾渗滤液是一种复杂有毒的、生化降解性差的高浓度有机废水,高级氧化技术具有氧化能力强和无二次污染等特点,被认为是处理难降解有机污染物最有应用前景的方法.本研究在500 W汞灯、25℃、2.5 h反应条件下,对比了TiO_2、K2S2O_8、K2S2O_8/Fe2+、施氏矿物、施氏矿物/H2O_2、Fe2+/H2O_26种催化剂组合光化学处理垃圾渗滤液的效果.结果表明,施氏矿物/H2O_2和Fe2+/H2O_2光催化降解垃圾渗滤液中有机污染物的效果优于其它催化剂组合,渗滤液中CO_D去除率分别为41.6%和46.5%,TO_C去除率分别为76.0%和78.1%.然而,Fe2+/H2O_2组合在光催化处理垃圾渗滤液后会产生大量难以沉降的Fe(O_H)3絮状物,且渗滤液色度明显增加,由初始的40倍上升到175倍.而施氏矿物/H2O_2组合则避免了上述问题,色度去除率达100%,被认为是一种具有应用前景的光化学降解垃圾渗滤液的催化剂组合.