Degradation of nitrogen-heterocyclic compounds by anodic oxidation and electro-Fenton methods.

This study describes the degradation of nitrogen-heterocyclic compounds (NHCs) by anodic oxidation and electro-Fenton. Using indole as a model nitrogen-heterocyclic compound, the removal of indole reached 68% and 97% by anodic oxidation and electro-Fenton, respectively, while the decay of TOC was 15% and 38% correspondingly. By the analysis of ultraviolet-visible spectra and liquid chromatography/mass spectrum, the degradation mechanism of indole by electro-Fenton was proposed as hydroxyl oxidation and anodic oxidation. The degradation of other NHCs including quinoline, isoquinoline and pyridine by anodic oxidation and electro-Fenton revealed the same sequence: quinoline approximately equal isoquinoline > indole > pyridine. A significant correlation between ln k (natural logarithm of rate constants) and E(LUMO) (the energy of the lowest unoccupied molecular orbit) was obtained by quantitative structure-activity relationship analysis. Degradation of coking plant wastewater showed the removal of COD and TOC were 42% and 22% respectively after 180 min treatment by electro-Fenton.     

Response of peroxidase and catalase to acid rain stress during seed germination of rice, wheat, and rape

Seed germination of plants with various acid-resistance display different responses to acid rain. To understand the reason why such differences occur, the effects of simulated acid rain (pH 2.5–5.0) on the activities of peroxidase (POD) and catalase (CAT) during seed germination of rice (O. sativa), wheat (T. aestivum), and rape (B. chinensis var. oleifera) were investigated. Results indicated that the maximum change in activities of CAT and POD by acid rain treatment with different acidity and time in relation to the referent treatment without acid rain, was in the order: rice (28.8%, 31.7%) < wheat (34.7%, 48.3%) < rape (79.3%, 50.0%). The pH level for which the treatment with acid rain did not cause significant difference (p < 0.05) was in the order: rice (3.5).wheat (4.0).rape (5.0). Moreover, the change in activity of POD was higher than that of CAT, which showed that POD was more sensitive to acid rain stress than CAT. The difference in the ability of POD and CAT in removing free radicals was one reason why the germination indexes of these three species behaved differently. __________ Translated from Environmental Science, 2005, 26(6): 123–125 [译自: 环境科学]     

配水管网中卤乙酸的研究

液氯消毒导致给水输配管网中产生消毒副产物对人体健康造成危害的问题引起了人们越来越多的关注。在对北方某城市配水管网水质大量调查的基础上,分析了卤乙酸与温度、余氯、氨氮、UV254等主要水质指标在配水管网中的变化规律。     

Using exploratory regression to identify optimal driving factors for cellular automaton modeling of land use change

Defining transition rules is an important issue in cellular automaton (CA)-based land use modeling because these models incorporate highly correlated driving factors. Multicollinearity among correlated driving factors may produce negative effects that must be eliminated from the modeling. Using exploratory regression under pre-defined criteria, we identified all possible combinations of factors from the candidate factors affecting land use change. Three combinations that incorporate five driving factors meeting pre-defined criteria were assessed. With the selected combinations of factors, three logistic regression-based CA models were built to simulate dynamic land use change in Shanghai, China, from 2000 to 2015. For comparative purposes, a CA model with all candidate factors was also applied to simulate the land use change. Simulations using three CA models with multicollinearity eliminated performed better (with accuracy improvements about 3.6%) than the model incorporating all candidate factors. Our results showed that not all candidate factors are necessary for accurate CA modeling and the simulations were not sensitive to changes in statistically non-significant driving factors. We conclude that exploratory regression is an effective method to search for the optimal combinations of driving factors, leading to better land use change models that are devoid of multicollinearity. We suggest identification of dominant factors and elimination of multicollinearity before building land change models, making it possible to simulate more realistic outcomes.     

Levels and body distribution of polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecanes (HBCDs) in freshwater fishes from the Yangtze River, China

Polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecanes (HBCDs) were determined in muscle, liver and eggs of freshwater fishes from the lower reach of the Yangtze River, China. The present study is the first to report HBCD concentrations in the environment of China. The concentrations of PBDEs and HBCDs in muscle of freshwater fishes from the Yangtze River ranged from 18 to 1100ng/g and 12 to 330ng/g lipid weight (wt.), respectively. When compared with other regions of the world, the contamination of PBDEs in biota could be regarded as moderate, whereas contamination of HBCDs in biota was relatively high. The PBDE congener profiles in fishes of the present study were markedly different from those observed in freshwater and marine fishes from other regions of the world. In the present study, BDE-15, BDE-28 and BDE-47 were the predominant congeners in the fishes. This particular congener profile in fishes from the Yangtze River revealed that a specific commercial PBDE formulation (probably made in China) might have been used in the Yangtze River Delta region.     

The response of mulberry trees after seedling hardening to summer drought in the hydro-fluctuation belt of Three Gorges Reservoir Areas

Interest has developed in the potential of mulberry (Morus alba), a woody perennial, for revegetating the hydro-fluctuation belt of the Three Gorges Reservoir due to its resistance to water-logging stress. To be useful, the trees must also be able to withstand dry conditions in summer when temperatures can be very high and droughts become severe quickly. Here, we report a study in which mulberry seedlings were grown in a greenhouse under a variety of simulated soil water conditions reflecting potential summer scenarios in the hydro-fluctuation belt of the Three Gorges Reservoir Area. We compared the responses of two pretreatment groups of mulberry seedlings to different levels of drought stress. The pretreatment groups differed with respect to drought hardening: the daily-managed (DM) group had relative soil moisture held constant in the range 70–80 %, while the drought-hardened (DH) group had relative soil moisture held constant at 40–50 %. Following the month-long pretreatment of seedlings, the two groups of young trees (DM and DH) were then respectively subjected to three levels of drought stress for a month: normal watering, moderate drought stress, and severe drought stress. A series of measurements comparing the physiological status of the plants in the two groups were then made, and the following results were obtained: (1) As drought stress increased, the heights, base diameters, root surface areas, photosynthetic rates (Pn), stomatal conductances (Gs), and transpiration rates (Tr) of the mulberry trees in both groups (DM and DH) decreased significantly, while the specific root area and abscisic acid (ABA) contents had increasing trends. Root activity and instantaneous water use efficiency of mulberry trees in both groups (DM and DH) were all raised under drought stress conditions than under normal watering, but the root/shoot ratio and leaf water potential were lowered. (2) At the same level of soil water content, the heights, base diameters, root/shoot ratios, root surface areas, specific root areas, photosynthetic rates (Pn), stomatal conductances (Gs), and transpiration rates (Tr) of the young mulberry trees in the DH were all significantly higher than those of the control group (DM). Leaf water potential, instantaneous water use efficiency, and abscisic acid content of DH were all significantly lower than DM. Under different degrees of drought stress, the growth of mulberry trees will be inhibited, but the trees can respond to the stress by increasing the root absorptive area and enhancing capacity for water retention. Mulberry trees demonstrate strong resistance to drought stress, and furthermore drought resistance can be improved by drought hardening during the seedling stage.     

长江水系河流与水库中鲤鱼的元素含量特征

针对长江三峡水库蓄水后引起水库汞活化效应对生态与环境的影响问题，系统地分析了长江水系水库与河流鲤鱼肌肉的Ａｓ，Ｃｄ，Ｃｕ，Ｆｅ，Ｈｇ，Ｍｎ，Ｐｂ，Ｓｅ，Ｎａ，Ｍｇ等元素含量的分布特征。并以丹江口水库－汉江，陈村水库－青戈江为例，用多元分析证明水库与河流的鲤肌肉中Ａｓ，Ｓｅ，Ｈｇ，Ｃｄ等元素含量存在显著差异，同时指出水库汞活化效应引起的鱼体汞含量增加是该元素的一种生物地球化学现象，并利用同一水系水库     

滤毒罐失效指示器的研究概况

失效指示器可以用来确定滤毒罐的使用寿命,有利于滤毒罐在化学战环境中的安全有效使用.本文系统地综述了失效指示器技术领域的研究概况,并指出了其发展趋势和应用前景.     

陕北能源开发区城镇生态环境建设战略

根据国内外城市发展趋势和我国城镇生态建设的基本要求，对陕北原源开发区城镇生态环境建设提出了战略性看法和建议。     

石油化工企业无组织排放气体污染物的探讨

介绍了石油炼制、石油化工企业有机液体储罐、有机液体装卸车、废水收集输送系统、废水处理系统、采样系统及装置泵阀等气体污染物无组织排放的过程和排放浓度的测定结果,为石油化工企业无组织排放气体污染物的治理提供基础数据。