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Significance of dredging on sediment denitrification in Meiliang Bay,China:A year long simulation study

Journal of Environmental Sciences 2010年第1期22卷 68-75页

作者： Jicheng Zhong Chengxin Fan Lu Zhang Edward Hall Shiming Ding Bao Li Guofeng Liu State Key Laboratory of Lake Science and Environment Nanjing Institute of Geography and Limnology Chinese Academy of Sciences Nanjing 210008 China Department of Freshwater Ecology University of Vienna Althanstr 14A-1090 Vienna Austria

An experiment for studying the effects of sediment dredging on denitrification in sediments was carried out through a one-year incubation of undredged （control） and dredged cores in laboratory. dredging the upper 30 cm of sediment can significantly affect physico-chemical characteristics of sediments. Less degradation of organic matter in the dredged sediments was found during the experiment. Denitrification rates in the sediments were estimated by the acetylene blockage technique, and ranged from 21.6 to 102.7 nmol N2/（g dry weight （dw）-hr） for the undredged sediment and from 6.9 to 26.9 nmol N2/（g dw-hr） for dredged sediments. The denitrification rates in the undredged sediments were markedly higher （p 〈 0.05） than those in the dredged sediments throughout the incubation, with the exception of February 2006. The importance of various environmental factors on denitrification was assessed, which indicated that denitrification was regulated by temperature. Nitrate was probably the key factor limiting denitrification in both undredged and dredged sediments. Organic carbon played some role in determining the denitrification rates in the dredged sediments, but not in the undredged sediments. sediment dredging influenced the mineralization of organic matter and denitrification in the sediment; and therefore changed the pattern of inherent cycling of nitrogen.

关键词： sediment dredging denitrification Taihu Lake

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Environmental Science and Ecotechnology 2020年第2期2卷 1-8页

作者： Xiaochuang Li Shouliang Huo Jingtian Zhang Zhe Xiao Beidou Xi Renhui Li State Key Laboratory of Environmental Criteria and Risk Assessment Chinese Research Academy of Environmental SciencesBeijing100012PR China Key Laboratory of Algal Biology Institute of HydrobiologyChinese Academy of SciencesWuhanHubei430072PR China

In recent years,Cylindrospermopsis raciborskii blooms have been widely found worldwide.Topics dealing with the mitigation of C.raciborskii bloom is of great importance for toxins produced could threaten public health.The paper first investigated C.raciborskii dynamics over three years following sediment dredging in a shallow eutrophic Lake Dongqian(China).Based on rpoC1 gene copies,C.raciborskii bloom formed with average density of 1.30×10^(6) cells/L on July 2009.One year later after sediment dredging,C.raciborskii cell density decreased below 1.17×10^(5) cells/L or under detected limits during summer days on 2010.While two years later,the C.raciborskii bloom period was returned with markedly increased cell density reaching up to 4.15×10^(7) cells/L on October 2011,and the maximum peak density was shown at 20.3C that was much lower than reported optimal growth temperature.Inferred from Spearman correlation analysis,linear regression showed C.raciborskii density was significant and positive with pH and SD,whereas they were significant and negative with TP and DO.Multiple regression analysis further demonstrated that TN,TP,SRP,pH and DO provided the best model and explained 53.1% of the variance in C.raciborskii dynamics.The approaches managing nutrients reduction might not control C.raciborskii bloom as extremely low TN(avg.0.18 mg/L)and TP concentrations(avg.0.05 mg/L)resulted in the highest C.raciborskii cell density after sediment dredging.

关键词： Bloom control Cylindrospermopsis Environmental variables sediment dredging

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Influence of sediment dredging on Nitrogen and Phosphorus Release in Fubao Bay of Dianchi Lake,China

Influence of Sediment Dredging on Nitrogen and Phosphorus Re...

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International Research Conference of Resources Utilization and Environmental Effectiveness

作者： LI Bao ZHANG Yunqi School of Chemistry and Resources Environment Linyi Normal University

ISBN: (纸本)9781921712043

Fubao Bay lies in the northeast part of Dianchi Lake with highly polluted by contamination input from the Daqing and Haihe rivers,and hyper-eutrophication and algae blooming appeared in this bay.A laboratory experiment was carried out through a six-month incubation of undredged(control)and dredged cores to study the effect of sediment dredging on nitrogen and phosphorus release from the sediment.During the experiment,dredging the upper 30 cm layer could efficiently reduce the organic matter,microbial activity,alkaline phosphatase activity and different phosphorus forms in the sediment.The results showed that the sediment,whether dredging or undredging,was the source of NH-N and PO-P for the water.The NH-N and PO-P fluxes of the undredged sediment ranged from 245.6 to461.6 mg/m.d and 2.21 to 3.22 mg/m.d,respectively.The dredged sediment made the fluxes to decrease to 46.1 to 154.7 mg/m.dand 0.38 to 1.22 mg/m.d,respectively.The fluxes of the dredged cores were sharply lower than those of the control.dredging can be considered as a useful measure for rehabilitating the aquatic ecosystem of our study site.

关键词： sediment dredging Nutrient release phosphorus forms Dianchi Lake

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Numerical modeling of sedimentation control scenarios in the approach channel of the Nakdong River Estuary Barrage,South Korea

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International Journal of sediment Research 2016年第3期31卷 257-263页

作者： Un Ji Eun-Kyung Jang Gwonhan Kim Hydro Science and Engineering Research Institute Korea Institute of Civil Engineering and Building Technology

The effects of sedimentation reduction at the Nakdong River Estuary Barrage(NREB) in Korea were quantitatively analyzed with respect to different sediment control methods using the calibrated and validated two-dimensional model.The countermeasures of sediment dredging,sediment flushing,channel geometry change,and a combination of flushing and channel geometry change were examined for the approach channel of the NREB.The flood event and channel geometries of the 3.8 km section upstream of the NREB surveyed before and after dredging in 2007 were used for modeling conditions.As a result,the half of sediments dredged in 2007 could be eliminated naturally by floods without dredging.The numerical simulation of sediment flushing indicated that the deposition height decreased in the entire simulation section with the minimum and maximum reductions from 0.3 in to1.3 m in deposition height.The channel contraction method produced quantitatively the largest amount of sedimentation reduction and sediment flushing and dredging followed.sedimentation reduction by a combination of flushing and channel contraction was up 10%compared to the individual method of channel contraction.

关键词： Channel contraction Nakdong River Estuary Barrage sediment dredging sediment flushing sedimentation reduction

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