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681.
682.
Guixiang Zhang Xitao Liu Ke Sun Ye Zhao Chunye Lin 《Frontiers of Environmental Science & Engineering in China》2010,4(4):421-429
Batch sorption experiments were conducted to evaluate the sorption behavior of tetracycline (TC, H3L) on sediments and soils in the presence and absence of cadmium (Cd), as affected by pH and properties of sediments and soils.
The results indicated stronger nonlinearity and higher capacity of TC sorption on sediments than on soils. Sorption of TC
also strongly depended on environmental factors and sediment/soil properties. Lower pH facilitated TC sorption through a cation
exchange mechanism, which also took place at pH values above 5.5, where TC existed as a zwitterion (H2L0) or anions (HL− and L2−). When pH was above 7, however, ligand-promoted dissolution of TC might occur due to TC weakening the Al-O bond of aluminum
oxide and the Fe-O bond of iron oxide. Natural organic matter (NOM) plays a more important role in TC sorption than cation
exchange capacity (CEC) and clay contents. The presence of Cd (II) increased TC sorption on both sediments and soils, which
resulted from the decrease of equilibrium solution pH caused by Cd2+ exchange with H+ ions of sediment/soil surfaces. The increase of TC sorption was also related to the formation of TC-Cd complexes, where Cd2+ acted as a bridge between the sediment/soil and TC. 相似文献
683.
Tertiary marsupial records are very scarce in Asia. A new peradectine marsupial, Junggaroperadectes burqinensis gen. et sp. nov., is reported from the Early Oligocene Keziletuogayi Formation in the Burqin region, Xinjiang, China. This
new species is based on a single right upper M2. The tooth possesses a straight centrocrista, a characteristic of peradectines.
Its main cusps lean buccally, with the paracone being smaller and lower than the metacone. The conules and stylar cusps are
weakly developed. These characters distinguish J. burqinensis from Euro-American Tertiary peradectines, but they also imply a close phylogenetic relationship to Siamoperadectes and Sinoperadectes, two Asian Early Miocene peradectines. 相似文献
684.
685.
脱氮硫杆菌自养反硝化及其影响因素研究进展 总被引:1,自引:0,他引:1
简要回顾了近几十年来利用脱氮硫杆菌进行自养反硝化及其影响因素方面的研究成果,阐述了接种脱氮硫杆菌的自养反硝化系统的应用范围和主要影响因素的研究现状。其中对一些与自养反硝化应用及其影响因素相关的重要问题、近年来研究的热点问题,如硫磺颗粒粒径影响、硫磺/石灰石的体积比、进水硫化物/硝酸盐的摩尔比、水力停留时间、有毒物质的影响以及脱氮动力学模型的建立进行了重点分析。指出了利用脱氮硫杆菌进行自养反硝化目前存在的一些技术方面的问题及其解决途径,并对其今后的发展趋势和应用前景进行了展望。 相似文献
686.
687.
Assessment of source water contamination by estrogenic disrupting compounds in China 总被引:2,自引:0,他引:2
Weiwei Jiang Ye Yan Mei M Donghong Wang Qian Luo Zijian Wang Senthil Kumaran Satyanarayanan 《环境科学学报(英文版)》2012,24(2):320-328
Detection of estrogenic disrupting compounds (EDCs) in drinking waters around China has led to rising concerns about health risks associated with these compounds. There is, however, a paucity of studies on the occurrence and identification of the main compounds responsible for this pollution in the source waters. To fill this void, we screened estrogenic activities of 23 source water samples from six main river systems in China, using a recombinant two-hybrid yeast assay. All sample extracts induced significant estrogenic activity, with E2 equivalents (EEQ) of raw water ranging from 0.08 to 2.40 ng/L. Additionally, 16 samples were selected for chemical analysis by gas chromatography-mass spectrometry. The EDCs of most concern, including estrone (E1), 17βup-estradiol (E2), 17αup-ethinylestradiol (EE2), estriol (E3), diethylstilbestrol (DES), estradiol valerate (EV), 4-t-octylphenol (4-t-OP), 4-nonylphenols (4-NP) and bisphenol A (BPA), were determined at concentrations of up to 2.98, 1.07, 2.67, 4.37, 2.52, 1.96, 89.52, 280.19 and 710.65 ng/L, respectively. Causality analysis, involving comparison of EEQ values from yeast assay and chemical analysis identified E2, EE2 and 4-NP as the main responsible compounds, accounting for the whole estrogenic activities (39.74% to 96.68%). The proposed approach using both chemical analysis and yeast assay could be used for the identification and evaluation of EDCs in source waters of China. 相似文献
688.
Influence of soil type and genotype on Cd bioavailability and uptake by rice and implications for food safety 总被引:7,自引:0,他引:7
Cadmium (Cd) entering the human body via the food chain is of increasing concern. This study investigates the effects of soil type and genotype on variations in the Cd concentrations of different organs of nine rice plants grown on two types of soils with two Cd levels. Cd concentrations in nine rice cultivars varied significantly with genotype and soil type (P < 0.01). The Cd concentration was higher in red paddy soil (RP) than in yellow clayey paddy soil (YP). The average Cd concentrations of different organs in three rice types were indica > hybrid > japonica for the Cd treatments and controls. The polished grain concentration in YP and RP soils had a range of 0.055-0.23 mg/kg and 0.13-0.36 mg/kg in the Cd treatment, respectively. Two rice cultivars in YP soil and five rice cultivars in RP soil exceeded the concentration limits in the Chinese Food Hygiene Standard (0.2 mg/kg). The Cd concentrations in roots, stems, and leaves were all significantly and positively correlated to that in polished grain in a single test. The Cd concentrations in polished grain were positively and significantly (P < 0.01) correlated with the calculated transfer factors of stem to grain and leaf to grain Cd transfer. The results indicated that the variations of Cd concentration in grain were related to Cd uptake and the remobilization of Cd from stem and leaf to grain. Also, the cultivars with a strong tendency for Cd-accumulation should be avoided in paddy soil with low soil pH and low organic matter content to reduce the risks to human health from high Cd levels in rice. 相似文献
689.
吴烨 《中国ISO14000认证》2012,(6):49-51
本文从有特色的环境工程专业构成要素出发,在知识体系构成、教学切入点等方面将相关专业的内涵共同与外沿问题渗透,修订专业培养方案,改革教学课程与实践,使专业培养的人才具有煤田、地质与环境特色,属于国家急需与紧缺型人才。 相似文献
690.
合同能源管理是一种基于市场运作的节能激励机制,自引入中国以来,通过示范、引导和推广,服务范围已经扩展到工业、建筑、交通三大领域。十多年来,中国合同能源管理模式不断得到创新,国家政策的扶持力度越来越大,资金来源逐步多元化,有力地促进了节能服务产业的迅速发展,将成为"十二五"节能减排的新机遇。与此同时,合同能源管理业面临着融资难、激励机制不健全等问题。 相似文献