排序方式: 共有58条查询结果,搜索用时 31 毫秒
31.
Zhao Zhang Fulu Tao Juan Du Peijun Shi Deyong Yu Yaobin Meng Yu Sun 《Journal of environmental management》2010,91(12):2483-2490
Surface water quality and its natural and anthropogenic controls in the Xiangjiang River were investigated using multivariate statistical approaches and a comprehensive observation dataset collected from 2004 to 2008. Cluster analysis (CA) grouped the 15 different sampling stations into five clusters with similar hydrochemistry characteristics and pollution levels. Four principal components (PCs), nutrients, heavy metals, natural components, and organic components, were extracted from the entire dataset. Comparison of the different regional characteristics of these four PCs revealed a decreasing trend for heavy metals and an increasing trend for organic factor on an annual scale, and the seasonal trend was only observed for natural factor. We also conducted analysis of variance (ANOVA) in combination with principal component analysis (PCA) to quantify the relative contribution of spatial and temporal variations to each of the four PCs. The results revealed that 62% of the contributions from the spatial sites were responsible for variations in heavy metals, while 83% of the contributions from the sampling time were responsible for natural variations observed. However, no significant spatial or temporal contributions were found to be responsible for the nutrient and organic variations. Finally, some suggestions regarding water management were put forward based on the current status and future trends of surface water quality in the Xiangjiang River. 相似文献
32.
Eurico C.Oliveira Yaobin Qi 《Ambio-人类环境杂志》2003,32(6):403-405
巴西某地区的第一部综合性的海藻植物志于1957年由Joly出版,该植物志描述并解释了105个分类单位.20年后,liveira和Berchez重新调查了该地区,只发现了69个分类单位,褐藻数量显著减少.1991年在三个物种丰度最大的研究站进行的另一次调查中,发现有同样的减少趋势,而且没有发现褐藻的存在.生物多样性的这种减少归因于污染的增加.这里我们列举了1998~1999年进行的一次新的调查结果.这次调查显示20世纪50年代记录的某些物种得到了恢复,其中包括7种褐藻.物种数的这一增长被认为是当地政府作出的减少污染的努力以及一个海底污水终端建成的结果. 相似文献
33.
静态混凝破乳吸附法处理乳化废液 总被引:4,自引:0,他引:4
乳化废液在静态混凝破乳分离装置中,加入混凝破乳剂PAC2g/L、助凝剂PAM(8%)2ml/L、混凝6min,静态分离1h,出水清沏透明,油含量小于10mg/L。再经煤渣灰吸附处理,出水油含量小于3mg/L,CODcr<300mg/L,pH:7~8。混凝絮渣经酸溶后,可回收95%以上的油品,此方法已在实际中应用。 相似文献
34.
Contribution of black carbon to nonlinearity of sorption and desorption of acetochlor on sediment 总被引:2,自引:1,他引:1
Jianqiu Liu Yaobin Zhang Hong Chen Yazhi Zhao Xie Quan 《Frontiers of Environmental Science & Engineering in China》2009,3(1):69-74
In order to investigate the contribution of various black carbon (BC) contents to nonlinearity of sorption and desorption
isotherms for acetochlor on sediment, equilibrium sorption and desorption isotherms were determined to measure sorption and
desorption of acetochlor in sediment amended with various amounts of BC. In this paper, two types of BC referred to as BC400
and BC500 were prepared at 400°C and 500°C, respectively. Higher preparation temperature facilitated the formation of micropores
on BC to enhance its sorption capacity. Increase of the BC content obviously increased the sorption amount and reduced the
desorption amount for acetochlor. When the BC500 contents in total organic carbon (TOC) increased from 0 to 60%, Freundlich
sorption coefficient (K
f) increased from 4.07 to 35.74, and desorption hysteresis became gradually obvious.When the content of BC in TOC was lower
than 23%, the sorption isotherm had a significant linear correlation (p = 50.05). In case of desorption, a significant nonlinear change could be observed when the content of BC was up to 13%. Increase
of BC content in the sediment would result in shifting the sorption-desorption isotherms from linearity to nonlinearity, which
indicated that contribution of BC to nonlinear adsorption fraction became gradually remarkable. 相似文献
35.
Jianqiu LIU Yaobin ZHANG Hong CHEN Yazhi ZHAO Xie QUAN 《Frontiers of Environmental Science & Engineering》2009,3(1):69-74
In order to investigate the contribution of various black carbon (BC) contents to nonlinearity of sorption and desorption isotherms for acetochlor on sediment, equilibrium sorption and desorption isotherms were determined to measure sorption and desorption of acetochlor in sediment amended with various amounts of BC. In this paper, two types of BC referred to as BC400 and BC500 were prepared at 400°C and 500°C, respectively. Higher preparation temperature facilitated the formation of micropores on BC to enhance its sorption capacity. Increase of the BC content obviously increased the sorption amount and reduced the desorption amount for acetochlor. When the BC500 contents in total organic carbon (TOC) increased from 0 to 60%, Freundlich sorption coefficient (K f) increased from 4.07 to 35.74, and desorption hysteresis became gradually obvious.When the content of BC in TOC was lower than 23%, the sorption isotherm had a significant linear correlation (p = 50.05). In case of desorption, a significant nonlinear change could be observed when the content of BC was up to 13%. Increase of BC content in the sediment would result in shifting the sorption-desorption isotherms from linearity to nonlinearity, which indicated that contribution of BC to nonlinear adsorption fraction became gradually remarkable. 相似文献
36.
37.
Aoshuang Jing Tao Liu Xie Quan Shuo Chen Yaobin Zhang 《Frontiers of Environmental Science & Engineering》2019,13(5):69
38.
不同光强下光催化降解对氯苯甲酸钠动力学 总被引:10,自引:0,他引:10
以对氯苯甲酸钠为模型污染物,研究了不同光强条件下的光催化降解动力学.结果表明对氯苯甲酸钠的光催化降解动力学可以用Langmuir-Hinshelwood模式来描述,但其中的动力学参数与光强有关.速率常数kr随入射光强的升高而增加,而表观吸附常数Ks却随入射光强的升高而降低.kr和Ks-1近似与光强呈幂函数的关系.说明提高光强虽然可以增加光催化降解速率但会降低其能量利用效率,如何使用低光强照射可能是提高光催化氧化反应器能量利用效率的重要因素之一. 相似文献
39.
Kinetic study and modeling on photocatalytic degradation of para-chlorobenzoate at different light intensities 总被引:4,自引:0,他引:4
Meng Y Huang X Wu Y Wang X Qian Y 《Environmental pollution (Barking, Essex : 1987)》2002,117(2):307-313
In order to clarify the dependence of apparent adsorption constant Ks in the Langmuir-Hinshelwood (L-H) model on the incident light intensity, photocatalytic degradation kinetic characteristics were experimentally investigated at different light intensities using para-chlorobenzoate (4-CBA) as a model compound. In all cases 4-CBA initial degradation rates showed dependence on 4-CBA initial concentration, which can be described by the L-H model. However, the adsorption constant Ks and rate constant kr obviously varied with light intensity. To account for the experimental finding, slight modification of the classic kinetic model developed by Turchi and Ollis was tentatively proposed by assuming insufficiency of H2O/OH- available for photo-activated holes' scavenging. Such a kinetic model predicts that both k(r) and Ks(-1) are linearly proportional to the square root of the intensity in a rather large intensity range. The validity of the modified model was proved by fitting it to the experimental data. 相似文献
40.
作为一种广谱性抗生素,磺胺甲恶唑(SMX)在常规城市污水生物处理过程中去除率较低,仍需要发展高效的去除方法。为此,通过原位溶剂热生长法,在碳毡上合成Cu-Co双金属氢氧化物(CuCo-BH)非均相催化剂,且在此基础上开展了类芬顿催化剂催化降解SMX的研究。对催化剂的SEM、TEM、XPS和XRD表征结果表明,CuCo-BH在碳毡上异向生长并呈棒状结构,宽度为40~115 nm,最大长度可达650 nm。在生长温度为105 ℃、反应时间为5 h的条件下,制备得到性能较好的CuCo-BH催化剂,在pH=7、H2O2=50 mmol·L−1、反应时间60 min的条件下,对初始浓度为50 mg·L−1的SMX去除率达到100%;在SMX=3 mg·L−1、H2O2=15 mmol·L−1、pH=7、反应时间为30 min的条件下,催化剂重复使用5次,SMX的去除率仍高于94%。·OH和${\rm{O}}_2^{ \cdot - }$ 的淬灭实验以及电子顺磁共振波谱仪(ESR)的测定分析结果表明,·OH对SMX的降解起到了关键的作用。以上研究结果可为SMX在污水深度处理中的高效去除提供一种新的方法。 相似文献