Graphene-supported nanoscale zero-valent iron：Removal of phosphorus from aqueous solution and mechanistic study

Excess phosphorus from non-point pollution sources is one of the key factors causing eutrophication in many lakes in China,so finding a cost-effective method to remove phosphorus from non-point pollution sources is very important for the health of the aqueous environment. Graphene was selected to support nanoscale zero-valent iron(nZVI)for phosphorus removal from synthetic rainwater runoff in this article. Compared with nZVI supported on other porous materials,graphene-supported nZVI(G-nZVI) could remove phosphorus more efficiently. The amount of nZVI in G-nZVI was an important factor in the removal of phosphorus by G-nZVI,and G-nZVI with 20 wt.% nZVI(20% G-nZVI)could remove phosphorus most efficiently. The nZVI was very stable and could disperse very well on graphene,as characterized by transmission electron microscopy(TEM) and scanning electron microscopy(SEM). X-ray photoelectron spectroscopy(XPS),Fourier Transform infrared spectroscopy(FT-IR) and Raman spectroscopy were used to elucidate the reaction process,and the results indicated that Fe-O-P was formed after phosphorus was adsorbed by G-nZVI. The results obtained from X-ray diffraction(XRD) indicated that the reaction product between nZVI supported on graphene and phosphorus was Fe3(PO4)2·8H2O(Vivianite). It was confirmed that the specific reaction mechanism for the removal of phosphorus with nZVI or G-nZVI was mainly due to chemical reaction between nZVI and phosphorus.     

Sorption, degradation and mobility of microcystins in Chinese agriculture soils: Risk assessment for groundwater protection

In the present paper, sorption, persistence, and leaching behavior of three microcystin variants in Chinese agriculture soils were examined. Based on this study, the values of capacity factor and slope for three MCs variants in three soils ranged from 0.69 to 6.00, and 1.01 to 1.54, respectively. The adsorption of MCs in the soils decreased in the following order: RR > Dha7 LR > LR. Furthermore, for each MC variant in the three soils, the adsorption rate in the soils decreased in the following order: soil A > soil C > soil B. The calculated half-time ranged between 7.9 and 17.8 days for MC-RR, 6.0-17.1 days for MC-LR, and 7.1-10.2 days for MC-Dha7 LR. Results from leaching experiments demonstrated that recoveries of toxins in leachates ranged from 0-16.7% for RR, 73.2-88.9% for LR, and 8.9-73.1% for Dha7 LR. The GUS value ranged from 1.48 to 2.06 for RR, 1.82-2.88 for LR, and 1.76-2.09 for Dha7 LR. Results demonstrated the use of cyanobacterial collections as plant fertilizer is likely to be unsafe in soils.     

Future private car stock in China: current growth pattern and effects of car sales restriction

Mitigation and Adaptation Strategies for Global Change - Car stock projection is essential to evaluating the energy and environmental impacts of private cars in China. Since the private car...     

自适应滤波法在洪水预测中的应用

尝试用时间序列分析中的自适应滤波法对江河灾害性洪水进行预测，认为加权因子个数和自适应常数的确定是关键。以荆江沙市站１９５０～１９９５年的年最高水位资料为研究对象，借助计算机编程与计算，确定了最优加权因子个数和自适应常数，建立了适合于该站未来年最高水位的预测模型。预测结果与误差分析表明，自适应滤波法用于江河洪水预测是可行的。     

中国重大自然灾害监测与评估信息系统的建设与应用

中国在１９９１～１９９５年期间，应用遥感（ＲＳ）和地理信息系统（ＧＩＳ）技术建立了重大自然灾害监测与评估信息系统，它包括洪水、林火、干旱、雪灾、地震、沙漠化和松毛虫灾害等七种自然灾害。整个研究和应用工作主要包括下述几部分：·建立灾害历史数据库和灾害背景数据库；·研究重大自然灾害的区划和危害程度分区；·建立单灾种的监测与评估系统（在微机或工作站系统上）；·对突然发生的自然灾害（如洪水、林火、地震等）建立应急反应系统；·应用这些技术和系统对１９９１年以来发生的洪水、干旱、林火等进行监测与评估，为主管部门防灾救灾提供辅助决策依据。本文是在集体研究成果的基础上加以概括，并提出一些个人的看法。     

Degradation of N-nitrosodimethylamine (NDMA) in landscape soils

N-nitrosodimethylamine (NDMA), a potential carcinogen, was commonly found in treated wastewater as a by-product of chlorination. As treated water is increasingly used for landscape irrigation, there is an imperative need to understand the leaching risk for NDMA in landscape soils. In this study, adsorption and incubation experiments were conducted using landscape soils planted with turfgrass, ground cover, and trees. Adsorption of NDMA was negligibly weak (K(d) < 1) in all soils, indicating that NDMA has a high potential for moving with percolating water in these soils. Degradation of NDMA occurred at different rates among these soils. At 21 degrees C, the half-life (t(1/2)) of NDMA was 4.1 d for the ground cover soil, 5.6 d for the turfgrass soil, and 22.5 d for the tree soil. The persistence was substantially prolonged after autoclaving or when incubated at 10 degrees C. The rate of degradation was not significantly affected by the initial NDMA concentration or addition of organic and inorganic nutrient sources. The relative persistence was inversely correlated with soil organic matter content, soil microbial biomass, and soil dehydrogenase activity, suggesting the importance of microorganisms in NDMA degradation in these soils. These results suggest that the behavior of NDMA depends closely on the vegetation cover in a landscape system, and prolonged persistence and increased leaching may be expected in soils with sparse vegetation due to low organic matter content and limited microbial activity.     

遥感与地理信息系统一体化技术在重大自然灾害监测与评估中的应用

本文结合国家“八五”科技攻关的实例，阐述了遥感和地理信息系统技术在重大突发性自然灾害监测与评估中的作用和良好效益，并提出今后着重的三个方面：建立国家自然灾害监测与评估中心；解决关键性的技术问题，牢固用户观点。     

氯氟烃替代物的开发研究进展

重点介绍了近年来国内外对氯氟烃替代物的研究开发动向，并简要地介绍了主要替代物的性能及应用情况。     

Influence of the residence time of street trees and their soils on trace element contamination in Paris (France)

Environmental Science and Pollution Research - With the actual increasing interest for urban soils, the evaluation of soil contamination by trace elements and the dynamics of this contamination...     

Preparation of Liquid Epoxidized Natural Rubber by Oxidative Degradations Using Periodic Acid,Potassium Permanganate and UV-Irradiation

Epoxidized natural rubber (ENR) needs to be degraded into shorter chain lengths, to form liquid epoxidized natural rubber (LENR), for applications such as coating and adhesives. Since ENR contains both C=C and epoxide groups as reactive sites for degradation reactions, thus, LENR could be prepared by different methods through cleavages of C=C or epoxide groups, or a combination of both sites. Different mechanisms would produce different terminals on the LENR. This paper reports the oxidative degradation by (a) periodic acid, (b) potassium permanganate and (c) ultra violet (UV) irradiation. The degraded rubbers were characterized by gel permeation chromatography (GPC), nuclear magnetic resonance (NMR) and Fourier transform infra-red spectroscopy (FTIR). Ester and ketone terminals were formed in all the three methods, but lactone and hydrofuranic structures were observed only in degradation by UV irradiation. NMR spectrum reveals that cyclization of ENR has occurred during degradation by periodic acid. At lower periodic acid concentration, degradation takes place only via C=C cleavage, but at higher concentration, the attack to the epoxide groups becomes more prominent. Potassium permanganate has attacked both the double bonds and epoxide groups. On the other hands, epoxide group was not affected during degradation by UV irradiation, which cleaved only the C=C bonds.