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Effect of different treatments on electrokinetic remediation of Zn, Pb and Cd from a contaminated calcareous soil

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Chinese Journal of Chemical Engineering 2021年第10期34卷 255-265页

作者： Hossein Beyrami National Salinity research center Agricultural ResearchEducation and Extension OrganizationYazdIran

Electrokinetic remediation is a promising method to decontamination of the heavy metals from *** this paper,the remediation of a contaminated calcareous soil with Zn,Cd and Pb sampled from around Zanjan province of Iran,was investigated using electrokinetic *** this paper,the soil contain a high concentration of Zn(1400 mg·kg^(-1)),Cd(15 mg·kg^(-1))and Pb(250 mg·kg^(-1)).Electrokinetic decontamination consists of two series of experiments as follows:(1)the effect of five treatments including the use of distilled water,acetic acid and EDTA electrolyte solutions,and approaching anodes systems,and the circulation flow of electrolyte at two different voltage gradient(i.e.1.33 and 2.66 V·cm^(-1)),and(2)the effect of moisture content(saturated,FC and 0.7 FC,FC indicated soil moisture at "Field Capacity")with a voltage gradient of 1.33 V·cm^(-1).After applying electric current for 5 days,the results of experiments indicated that the removal efficiency of heavy metals can be increased by raising the voltage *** this matter,the highest remediation can be observed among different treatments in EDTA(Ethylene diamine tetra acetic acid)treatment(40.11%,43.10%and 24.7%for Zn,Cd and Pb,respectively).Moreover,the heavy metals removal at the saturated moisture was at the highest level so that 32.62%cadmium,31.33%zinc and 18.82%lead being removed after 120 h of electric current *** decreasing moisture to 0.7 FC,the removal percentage for the three heavy metals obtained 20.97%,18.44%and 12.25%,***,Cd had the highest removal,and Zn and Pb were next among the three heavy metals in question.

关键词： Decontamination Soil moisture Voltage gradient Cadmium Lead Zinc

Undrained response of reconstituted clay to cyclic pure principal stress rotation

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Journal of Central South University 2015年第1期22卷 280-289页

作者：严佳佳周建龚晓南曹洋 research center of coastal and Urban Geotechnical Engineering Zhejiang University

A series of monotonic and rotational shearing tests are carried out on reconstituted clay using a hollow cylinder apparatus under undrained condition. In the rotational shearing tests, the principal stress axes rotate cyclically with the magnitudes of the principal stresses keeping constant. The anisotropy of the reconstituted clay is analyzed from the monotonic shearing tests. Obvious pore pressure is induced by the principal stress rotation alone even with shear stress q0=5 k Pa. Strain components also accumulate with increasing the number of cycles and increases suddenly at the onset of failure. The deviatoric shear strain of 7.5% can be taken as the failure criterion for clay subjected to the pure cyclic principal stress rotation. The intermediate principal stress parameter b plays a significant role in the development of pore pressure and strain. Specimens are weakened by cyclic rotational shearing as the shear modulus decreases with increasing the number of cycles, and the shear modulus reduces more quickly with larger b. Clear deviation between the directions of the principal plastic strain increment and the principal stress is observed during pure principal stress rotation. Both the coaxial and non-coaxial plastic mechanisms should be taken into consideration to simulate the deformation behavior of clay under pure principal stress rotation. The mechanism of the soil response to the pure principal stress rotation is discussed based on the experimental observations.

关键词： clay principal stress rotation intermediate principal stress undrained behavior

Near-bed sediment transport in a heavily modified coastal plain estuary

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International Journal of Sediment research 2014年第2期29卷 232-245页

作者： Gao-feng LIU Jia-xue WU Yuan-ye WANG Shanghai Estuarine and coastal Science research center The center for coastal Ocean Science and Technology research School of Marine SciencesSun Yat-sen University

Numerous estuaries of the world have been strongly modified by human *** interferences can make great adjustments of not only sediment transport processes,but also the collective behavior of the *** paper provides a typical case of a heavily modified coastal plain estuary of Sheyang on the China coast,where a sluice barrage was built in 1956 to stop the intrusions of storm surges and saline *** sets of instrumented tripods were simultaneously deployed along a cross-shore transect to continuously observe near-bed flow currents and sediment *** in-situ surveys lasted over a spring and neap tide cycle when a strong wind event occurred in the neap *** of flows and sediment transport between tide-dominated and wind-dominated conditions demonstrated the important role of episodic wind events in flows and sediment *** wind-induced currents,bottom stresses,and sediment transport rates were significantly greater when wind was present than corresponding quantities induced by the *** long-shore sediment transport induced by winds exceeds the cross-shore component,especially near the river mouth *** results indicate the noticeable importance of wave-dominated coastal processes in shaping topographic features.A regime shift of estuarine evolution under highly intense human forcing occurs from fluvial to marine *** finding suggests that the management strategy of the estuarine system should focus on the restoration of estuarine processes,rather than the present focus on inhibition of marine dynamics.

关键词： Estuarine dynamics Sediment transport Strong wind event Anthropogenic effects

Soil Organic Carbon Pools Under Switchgrass Grown as a Bioenergy Crop Compared to Other Conventional Crops

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Pedosphere 2013年第4期23卷 409-416页

作者： F.G.DOU F.M.HONS W.R.OCUMPAUGH J.C.READ M.A.HUSSEY J.P.MUIR Texas A&M AgriLife research &extension center at Beaumont Department of Soil and Crop Sciences Texas A&M University Texas A&M AgriLife research Station at Beeville Texas A&M AgriLife research and extension center at Dallas Texas A&M AgriLife research and extension center at Stephenville

Switchgrass （Panicum virgaturn L.） has been proposed as a sustainable bioenergy crop because of its high yield potential, adap- tation to marginal sites, and tolerance to water and nutrient limitations. A better understanding of the potential effects of biomass energy crop production practices on soil biological properties and organic matter dynamics is critical to its production. Our objective was to evaluate changes in C pools under a warm-season perennial switchgrass in different soils compared to typically-grown crops col- lected at College Station, Dallas, and Stephenville, TX in February 2001. Sampling depths were 0-5, 5-15, and 15-30 cm. Switchgrass increased soil organic C （SOC）, soil microbial biomass C （SMBC）, mineralizable C, and particulate organic matter C （POM-C） com- pared to conventional cropping systems. Soil C concentrations were in the order： long-term coastal bermudagrass [Cynodon dactylon （L.） Pers.] 〉 switchgrass or kleingrass （Panicum coloratura L.） planted in 1992 〉 switchgrass 1997 〉 conventional cropping systems. Soil C concentrations tended to increase with increasing clay content. Greater microbial biomass C followed the order of Dallas 〉 College Station 〉 Stephenville, and ranged from approximately 180 mg C kg-1 soil at Stephenville to 1 900 mg C kg-1 soil at Dallas. Particulate organic C was more sensitive than other fractions to management, increasing as much as 6-fold under long-term coastal bermudagrass compared to conventional cropping systems. Our study indicated that conversion of conventional cropping systems into switchgrass production can sequestrate more SOC and improve soil biological properties in the southern USA.

关键词： cropping systems particulate organic C perennial grasses soil microbial biomass C soil mineralizable C

Morphological Evolution and Its Response to the Navigational Improvements in the North Passage,Yangtze Estuary

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China Ocean Engineering 2007年第4期21卷 611-624页

作者：刘杰陈吉余徐志扬乐嘉海 State Key Laboratory of Estuarine and coastal research East China Normal University Shanghai Estuarine and coastal Science research center

By use of bathymetric chart, recent change of the riverbed in the North Passage of the Yangtze Estuary has been studied in this paper. The main channel of the upper, middle and lower （section） in the North Passage has been successively eroded and its groin field significantly deposited. At the same time, sediment has been deposited on the entrance region. Erosion and deposition had responded rapidly to the construction of the regulation engineering. There was about one year duration of lagging between erosion in the deep channel and the construction of the regulation engineering. The siltation lag of time in the groin field varied with the initial depth, but the average deposited thickness was about 0.5 m per year. Volumetric analysis demonstrates that there is a increasing trend of siltation in the North Passage after 2002, because of the difference in duration and quantity between erosion in the deep channel and deposition in the groin field. The water volume of the North Passage was reduced by =9% （280 million m^3） between 2002 and 2006. Sediment budget reveals that the main sediment deposited in the North Passage takes its source from the river and the ocean. The decreasing water volume was attributable to shoaling in the groin field. Its triggering factors for increased sedimentation are the navigational improvements（jetties and groins） after 1998, which altered the passage boundary and destroyed the equilibrium state on the average ebb and flood sediment fluxes. The establishment of a stable estuary is attributed to a reduction in depth of the groin field. The forecast on the sediment deposition quantity and continuous infilling time in the groin system is about 325 × 10^6m^3 and 6 - 7 years, respectively.

关键词： Yangtze Estuary North Passage navigational improvements bathymetric data

Heavy metal pollution in tidal zones of Bohai Bay using the dated sediment cores

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Journal of Environmental Sciences 2006年第3期18卷 610-615页

作者： QIN Yan-wen MENG Wei ZHENG Bing-hui SU Yi-bin River and coastal Environment research center Chinese Research Academy of Environmental Sciences Beijing 100012 China

Three sediment cores were collected in November 2003 from Dagu estuary to Qikou estuary. The main polluted heavy metals in the sediment of tidal zones for the Bohai Bay have been found by analyzing the relationship among the contents of heavy metals, the contents of geochemical elements （Fe, AI and Mn） and the size of grain. The dominating contaminative elements in tidal sediments of Bohai Bay are Pb, Zn and Cd. Their contents are higher than the corresponding upper limit of environmental background values and they have very faint correlation with the corresponding contents of geochemical elements and the size of grain, indicating the anthropogenic enrichment. Especially, the preliminary study on the pollution sources and the history of heavy metals in the Dagu estuary has been done using the dated results. The contamination by Zn and Cd also started in the middle 1950s, while the contamination by Pb appeared in the early 1940s. The pollution by Zn and Cd mainly originate from sewage discharge, while the pollution by Pb has many sources, like atmosphere deposition and industrial discharRe.

关键词： Bohai Bay tidal zone the dated sediment core heavy metal pollution

Toxic effects of fluoranthene and copper on marine diatom Phaeodactylum tricornutum

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Journal of Environmental Sciences 2008年第11期20卷 1363-1372页

作者： WANG Liping ZHENG Binghui River and coastal Environment research center Chinese Research Academy of Environmental Sciences Beijing 100012 China

To investigate the effects of polycyclic aromatic hydrocarbons (PAHs) and metals on the population reproduction,antioxidative defense system and cell ultrastructure of the marine diatom,fluoranthene and Cu2+ were selected to test their toxicity to Phaeodactylum tricorntum,in the *** results indicated that both fluoranthene and Cu2+ inhibited population reproduction of *** the algal cells were exposed to fluoranthene or Cu2+ for 72 h,ultrastructure damage in the cells was observed un...

关键词： marine diatom polycyclic aromatic hydrocarbons (PAHs) heavy metals transmission electron microscope (TEM)

Heavy metal pollution in Tianjin Bohai Bay,China

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Journal of Environmental Sciences 2008年第7期20卷 814-819页

作者： MENG Wei QIN Yanwen ZHENG Binghui River and coastal Environment research center Chinese Research Academy of Environmental SciencesBeijing 100012China

The contamination levels and distribution characters of heavy metals in coastal waters and sediments from Tianjin Bohai Bay,China were *** and Zn were found as the main heavy metal pollutants in the coastal waters of the *** levels of Pb and Zn appeared especially near the estuary,indicating that river discharge was the main pollution ***,atmospheric deposition resulted in Pb contamination in the middle of the *** of data for the period 1987-2004 indicated that Pb pol...

关键词： heavy metals pollution Tianjin Bohai Bay China

Development of a skill assessment tool for the Korea operational oceanographic system

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Acta Oceanologica Sinica 2013年第9期32卷 74-81页

作者： CHO Kyoung-Ho CHOI Jin-Yong JEONG Sang-Hun CHOI Jung-Woon KWON Jae-Il PARK Kwang-Soon coastal Disaster research center Korea Institute of Ocean Science and Technology

A standard skill assessment （SA） tool was developed and implemented to evaluate the performance of op- erational forecast models in the Korea operational oceanographic system. The SA tool provided a robust way to assess model skill in the system by comparing predictions and observations, and involved the com- putation of multiple skill metrics including correlation and error skills. User- and system-based acceptance criteria of skill metrics were applied to determine whether predictions were acceptable for the system. To achieve this, the tool produced a time series comparison plot, a skill score table, and an advanced sum- marized diagram to effectively demonstrate the multiple skill scores. Moreover, the SA was conducted to evaluate both atmospheric and hydrodynamic forecast variables. For the atmospheric variables, acceptable error criteria were preferable to acceptable correlation criteria over short timescales, since the mean square error overwhelmed the observation variance. Conversely, for the hydrodynamic variables, acceptable root mean square percentage error （e.g., perms） criteria were preferable to acceptable error （e.g., erms） criteria owing to the spatially variable tidal intensity around the Korean Peninsula. Furthermore, the SA indicated that predetermined acceptance error criteria were appropriate to satisfy a target central frequency （fc） for which errors fell within the specified limits （i.e., the .fc equals 70%）.

关键词： skill assessment tool operational forecast system Korea operational oceanographic system