关键词：
Land cover change;Dongting Lake;support vector machine;Landsat TM/OLI
摘要：
Land cover in Dongting Lake region has been faced high variations during recent decades. Therefore , there has a strong need to investigate and understand the land cover changes in Dongting Lake region between land cover types. In this study, support vector machine (SVM) classification method was employed to detect changes in land cover dynamic in Dongting Lake region using Landsat images for the year 1995, 2006 and 2015. Land cover information was classified to five categories: waterbody, wetland, built-up, cropland and forestland. Quantitative analysis , change detection matrix and land cover dynamic degree were utilized for investigating and assessing the land cover changes in Dongting Lake region. The overall accuracy (OA) and kappa coefficient of the land cover classification results were over 96% and 0.9, respectively. The results indicated that in 1995 about 11.32% of study area was covered by water-body together with 13.31% of wetland. Nearly 50% of the area was covered by cropland and remaining 2.59% was covered by built-up. During the period 1995-2015, the change rate of the waterbody was evaluated at-0.29%, at-0.67% for the wetland and at-2.47% for the built-up. On the contrary, the for-estland and cropland increased by 0.72% and 0.03%, respectively. In addition, the results of this study can provide scientific information for government to formulate policy for sustainable land use management in Dongting Lake region. Land cover change, Dongting Lake, support vector machine , Landsat TM/OLI Land cover changes affect global climate, species diversity and ecosystem balance, which can accelerate land degradation and reduce ecosystem services [1, 2]. It has become a serious environmental problem. Over the past few decades, land cover in Dongting Lake region experienced tremendous changes by natural processes, as well as anthropo-genic activities [3]. In particular, anthropogenic activities , such as reclaiming cropland from lakes and returning cropland to lakes, have become a major concern of land cover changes in Dongting Lake region [4]. Therefore, a clear understanding of the spatial and temporal changes of land cover types in the Dongting Lake region in recent two decades is important. Remote sensing has been monitoring and capturing the earth land's surface every day and night by providing spatial and temporal images over large and inaccessible area for more than six decades [5]. Therefore, remote sensing became an acknowledged technology for monitoring the land cover changes. Some optical remote sensing products, such as Moderate Images Spectrometer (MODIS), Advanced Very High-Resolution Radiometer (AVHRR), and Satellite Pour 1'Obervation de la Terre (SPOT) with resolution at 250 m to 1 km, are the very suitable data resources for studying information of earth surface [1, 6-11]. Despite short revisiting cycle and large swath width, these low-resolution products are mainly available on the detecting of large scale coarse land cover changes, but the transformation details of land cover types and its ratio remains unknown which usually occurs at a small scale. In order to settle these problems and detail monitoring earth's land cover changes, medium remote sensing satellite data, such as Landsat Thematic Mapper (TM) [12, 13], Landsat Enhanced Thematic Mapper Plus (ETM+) [7, 14] and Landsat Operational Land Im-ager (OLI) [12, 15], with resolution of 30 m but re-visiting cycle of 16 day, have been widely utilized for mapping land cover and monitoring its changes. Numerous researches have been conducted and various algorithms have been developed for detecting land cover changes especially over Dongting Lake region using remote sensing satellite technologies. Li et al. [16] employed the Geographical Information System (GIS) and Remote Sensing (RS) technologies to study the characterized long-term land cover changes in Dongting Lake region using the Landsat images from 1978, 1989, 1998. Their results indicated that land cover patterns in Dongting Lake region had been greatly altered by empoldering. Three land type had changed remarkably. The cultivated land decreased,
期刊：
Korean Journal of Chemical Engineering,2018年35(8):1636-1641 ISSN：0256-1115
通讯作者：
Zhou, Kanggen
作者机构：
[Chen, Wei; Wang, Aihe; Liu, Xing; Chen, Quanzhou; Zhang, Chun; Liu, Fang; Zhou, Kanggen] Cent S Univ, Inst Environm Sci & Engn, Sch Met & Environm, Lushan South Rd 932, Changsha 410083, Peoples R China.;[Wang, Aihe] Hunan City Univ, Sch Municipal & Mapping Engn, Yingbin East Rd 518, Yiyang 413000, Hunan, Peoples R China.
通讯机构：
[Zhou, Kanggen] C;Cent S Univ, Inst Environm Sci & Engn, Sch Met & Environm, Lushan South Rd 932, Changsha 410083, Peoples R China.
关键词：
Metal Composite Oxides;Calcium Alginate;Fluoride;Adsorption Isotherm;Adsorption Kinetic;Regeneration
摘要：
Batch experiments were conducted to study the adsorption performance of fluorine removal by the calcium alginate (SA) embedded by the composite Mg-Al-Ce oxides (SA-CMAC). The physical and chemical properties of the SA-CMAC were characterized by XRD, SEM and XPS analysis. The optimum conditions for fluoride removal were determined and the maximum adsorption capacity was 26.12mg g−1. The co-existing PO
4
3−
and CO
3
2−
anions in solution had more effect than the SO
4
2−
and NO
3
-
on the fluoride removal efficiency. The adsorption process of fluorine by SA-CMAC was attributed to ion exchange on the surface of the SA-CMAC. The experimental data fitted both the isotherms and Freundlich well, and the Freundlich model had a little higher correlation coefficient. As the rate determining step, the adsorption process could be best described by the pseudo-second order kinetic model followed by the intra-particle diffusion. The thermodynamic examination demonstrated that the fluoride adsorption on the SA-CMAC beads was reasonably spontaneous and exothermic. The reclaimed adsorbents still could adsorb 65% of the total fluoride in the solution after three cyclic processes using 0.01mol/L NaOH.
关键词：
Surface water area variation;flood inundation frequency;Dongting Lake;The Three Gorges Reservoir;remote sensing monitoring;Landsat
摘要：
Dongting Lake is the second largest freshwater lake in China, with rapid seasonal surface water area fluctuations in the middle reach of the Yangtze River and downstream from the Three Gorges Reservoir (TGR). The marked variation of the lake's surface water area is considered to have been affected by the TGR over the past decades. In this study, Landsat TM/ETM+/OLI time-series imagery data were employed to estimate the wet season total surface water area variation in South Dongting Lake and East Dongting Lake from 1988 to 2016. The surface water area was extracted from Landsat data using Modified Normalized Difference Water Index (MNDWI). The results indicated that the surface water area variation was accordant with the variation of precipitation and runoff of Xiangtan, Taojiang, Taoyuan, Shimen, Shadaoguan, Mituosi, Ouchikou and Chenglingji five hydrological stations. Most of the large surface water areas were observed during the pre-TGR period, whereas the small surface water areas were observed during the post-TGR period. Surface water area data, precipitation and runoff from the four hydrological stations (except Shimen station) all indicated downward trends, with reduction rates of 5.866 km(2).year(-1), 0.802 mm.year(-1), 3.950 10(8)m(3).year(-1), 2.834 10(8)m(3).year(-1), 0.377 10(8)m(3).year(-1), 1.282 10(8)m(3).year(-1), 2.715 10(8)m(3).year(-1) , 0.318 10(8)m(3).year(-1) and 16.114 10(8)m(3).year(-1), respectively. The results of correlation analyses indicated precipitation and water from the Yangtze river may affect the fluctuation in the surface water area to a large extent. The results of flood inundation probability analysis indicated that approximately 502.9 km(2) of the study area was in the high flood hazard zone. In addition, the results of this study can provide scientific information to understand the effect of the TGR on downstream lakes and achieve better water resources and flood hazard management in this region.
作者：
Wang Aihe;Zhou Kanggen*;Liu Xing;Liu Fang;Zhang Chun;...
期刊：
Journal of Colloid and Interface Science,2017年505:947-955 ISSN：0021-9797
通讯作者：
Zhou Kanggen
作者机构：
[Wang Aihe; Chen Quanzhou; Liu Xing; Zhou Kanggen; Liu Fang] Cent S Univ, Sch Met & Environm, Lushan South Rd 932, Changsha 410083, Hunan, Peoples R China.;[Wang Aihe; Zhang Chun] Hunan City Univ, Sch Municipal & Mapping Engn, Yingbin East Rd 518, Yiyang 413000, Hunan, Peoples R China.
通讯机构：
[Zhou Kanggen] C;Cent S Univ, Sch Met & Environm, Lushan South Rd 932, Changsha 410083, Hunan, Peoples R China.
摘要：
Studies were performed to evaluate influence of biochar addition on physico-chemical process, heavy metals transformation and bacterial community diversity during composting of sediment with agricultural wastes. Simultaneously, the relationships between those parameters including heavy metals and bacterial community compositions were evaluated by redundancy analysis (RDA). The results show that the extraction efficiency of DTPA extractable heavy metals decreased in both piles, and reduced more in pile with biochar addition about 0.1-2.96%. Biochar addition dramatically influenced the bacterial community structure during the composting process. Moreover, the bacterial community composition was significantly correlated with C/N ratio, water soluble carbon (WSC), and organic matter (OM) (P < 0.05) in pile with biochar addition; while significantly correlated with temperature, WSC, and C/N ratio in pile which was free of biochar. This study would provide some valuable information for improving the composting for disposal of river sediment with heavy metals contamination. (C) 2017 Elsevier Ltd. All rights reserved.
摘要：
This paper studied the degradation of 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) in contaminated soil under composting and natural conditions, respectively. BDE-47 residue in agricultural waste-composting pile was determined during 45-day composting. The microbial communities were determined by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE), and the relationships between the DGGE results and physico-chemical parameters were evaluated by redundancy analysis (RDA) and heatmap-clustering analysis. The results showed that the degradation rate of BDE-47 was significantly higher in agricultural waste-composting pile compared with control group, which was enhanced up to almost 15 % at the end of composting. There were different environmental factors which affected the distribution of composting bacterial and fungal communities. The bacterial community composition was more significantly affected by the addition of BDE-47 compared with other physico-chemical parameters, and BDE-47 had stronger influences on bacterial community than fungal community during the composting. Meanwhile, the most variation in distribution of fungal community was explained by pile temperature.
作者机构：
[Cao, Yijia; Shi, Haiqing; Kuang, Yonghong; Li, Canbing] Hunan Univ, Coll Elect & Informat Engn, Changsha 410082, Hunan, Peoples R China.;[Zhang, Yongjun] S China Univ Technol, Elect Power Coll, Guangzhou 510640, Guangdong, Peoples R China.;[Gao, Dan] North China Elect Power Univ, Sch Energy Power & Mech Engn, Beijing 102206, Peoples R China.;[Sun, Liang] Hunan City Univ, Municipal & Surveying Engn, Yiyang 413000, Peoples R China.
摘要：
The reductive acid leaching kinetics of synthetic cadmium-bearing zinc ferrite was investigated, and the influence of reaction temperature, sulfuric acid and hydrazine sulfate were studied. The results illustrated that an increase in the reaction temperature, initial sulfuric acid and hydrazine sulfate significantly enhanced the extraction efficiencies of cadmium, zinc and iron. The leaching kinetics were controlled by a surface chemical reaction based on a shrinking core model. The empirical equation
$$ 1 - (1 - X)^{{{\raise0.7ex\hbox{$1$} \!\mathord{\left/ {\vphantom {1 3}}\right.\kern-0pt} \!\lower0.7ex\hbox{$3$}}}} = k_{\text{r}} t $$
applied was found to fit well with the kinetics analysis; the leaching processes of cadmium, zinc and iron were similar and the activation energies were 79.9 kJ/mol, 77.9 kJ/mol and 79.7 kJ/mol, respectively. The apparent orders of cadmium-bearing zinc ferrite dissolution with respect to sulfuric acid concentration were 0.83, 0.83 and 0.84 for Cd, Zn and Fe, respectively.
摘要：
Zinc neutral leaching residue (ZNLR) from hydrometallurgical zinc smelting processing can be determined as hazardous intermediate containing considerable amounts of Cd and Zn which have great threats to the environment. The ZNLR contained approximately 35.99% Zn, 15.93% Fe and 0.26% Cd, and Cd mainly existed as ferrites in the ZNLR in this research. Reductive acid leaching of ZNLR was investigated. The effects of hydrazine sulfate concentration, initial sulfuric acid concentration, temperature, duration and liquid-to-solid ratio on the extraction of Cd, Zn and Fe were examined. The extraction efficiencies of Cd, Zn and Fe reached 90.81%, 95.83% and 94.19%, respectively when the leaching parameters were fixed as follows:hydrazine sulfate concentration, 33.3 g/L; sulfuric acid concentration, 80 g/L; temperature, 95 ℃; duration of leaching, 120 min; liquid-to-solid ratio, 10 mL/g and agitation, 400 r/min. XRD and SEM-EDS analyses of the leaching residue confirmed that lead sulfate (PbSO_4) and hydrazinium zinc sulfate((N_2H_5)_2Zn(SO_4)_2) were the main phases remaining in the reductive leaching residue.
摘要：
In this work, zinc neutral leaching residue was mechanically activated by ball-milling. The subsequent leaching behavior and kinetics of cadmium extraction in a mixed SO2-H2SO4 system were studied. Changes in the crystalline phase, lattice distortion, particle size and morphology, which were induced by mechanical activation, were also investigated. The activated samples showed different physicochemical characteristics, and cadmium extraction was found to be easier than for the un-activated samples. Under the same conditions, mechanical activation contributed to higher cadmium leaching. The cadmium extraction kinetics at 75–95°C was found to fit the shrinking core model. The raw neutral leaching residue, and the samples activated for 60 min and 120 min had a calculated activation energy of 65.02 kJ/mol, 59.45 kJ/mol and 53.46 kJ/mol, respectively. The leaching residue was characterized by ICP, XRD and SEM analysis. According to XRD analysis, the main phases in the residue were lead sulfate (PbSO4), zinc sulfide (ZnS) and cadmium sulfide (CdS).
摘要：
Enhanced reductive leaching of cadmium from zinc neutral leaching residue, along with zinc and iron, was conducted using sulfur dioxide as reductant. Cadmium mainly exists as cadmium-bearing zinc ferrite (CdxZn(1-x)Fe2O4) (x = 0~1). The influence of variables on the extraction rates of cadmium, zinc, and iron was studied. The results showed the maximum extraction of cadmium, zinc, and iron reached 99.11%, 93.43%, and 93.38% under the optimum conditions. The raw and the reductive leaching residue were characterized by XRD, ICP, and SEM-EDX analysis. Lead sulfate, zinc, and cadmium sulfide are the main phases contained in the reductive leaching residue.
期刊：
Journal of Navigation,2014年67(5):810-824 ISSN：0373-4633
通讯作者：
Cai, Changsheng
作者机构：
[Cai, Changsheng; Luo, Xiaomin] Cent S Univ, Sch Geosci & Infophys, Changsha, Hunan, Peoples R China.;[Liu, Zhizhao] Hong Kong Polytech Univ, Dept Land Surveying & Geoinformat, Hong Kong, Hong Kong, Peoples R China.;[Xiao, Qinqin] Hunan City Univ, Sch Municipal & Surveying Engn, Yiyang, Peoples R China.
通讯机构：
[Cai, Changsheng] C;Cent S Univ, Sch Geosci & Infophys, Changsha, Hunan, Peoples R China.
