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Impacts of the large amount of sand mining on riverbed morphology and tidal dynamics in lower reaches and delta of the dongjiang river

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Journal of Geographical Sciences 2007年第2期17卷 197-211页

作者： JIA Liangwen LUO Zhangren YANG Qingshu OU Shuying LEI Yaping Coastal Ocean Research Center Sun Yat-sen University Guangzhou 510275 China Institute of Estuarine and Coastal Research Sun Yat-sen University Guangzhou 510275 China

The sand dredging and its impacts on riverbed evolution and tidal dynamic change in the lower reaches and delta of the dongjiang river are examined in this paper. The large amount of sand, totally 3.32 billion m^3 from 1980 to 2002, was mined from the riverbeds of the lower reaches and delta of the dongjiang river. Increasing of the channel capacity, lowering of the average riverbed elevation, deepening of the water depth and decreasing of the longitudinal riverbed gradient are the main effects on the riverbed evolution brought by the large amount of sand dredging. Under the strong sand dredging and associated significant riverbed deformation, the notable changes of the tidal dynamic in the lower reaches and delta of the dongjiang river occurred, including：（1）in the upper reaches of the dongjiang river delta and lower reaches of the dongjiang river, tidal level dropped apparently, tidal range widened, flood tidal duration became longer, amplitudes for major tidal components became bigger and tidal dynamics intensified; （2） tidal wave spread faster; and （3） the limits of the tidal level, tidal current and salt water moved upstream.

关键词： dongjiang river sand mining tide

Sources and transport of organic carbon from the dongjiang river to the Humen outlet of the Pearl river, southern China

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Journal of Geographical Sciences 2014年第1期24卷 143-158页

作者： FU Yingchun TANG Congguo LI Jun ZHAO Yaolong ZHONG Wei ZENG Xiantie School of Geography South China Normal University Guangzhou 510631 China State Key Laboratory of Environmental Geochemistry Institute of Geochemistry CAS Guiyang 550002China Tianjin Key Laboratory of Water Resources and Environment Tianjin Normal University Tianjin 300387China

Transport of organic carbon via rivers to estuary is a significant geochemical proc- ess in the global carbon cycle. This paper presents bulk total organic carbon （TOC） from the dongjiang catchment to the adjacent Humen outlet, and discusses the applicability of 613C and ratio of carbon to nitrogen （C/N） as indicators for sources of organic matter in the surface sediments. Survey results showed that organic carbon concentration in summer were higher than in the winter. An elevated trend of TOC occurred along the river to the Humen outlet in both surveys, and the highest mean values of dissolved and particular organic carbon （DOC-279 μmol L-1 and POC-163μmol L-1） were observed in the urban deltaic region in summer flood flow. Winter samples had a wide range of b＇13C and C/N （5-3C -24.6%o to -30.0%o, C/N 4-13）, and summer ones varied slightly （8-3C -24.2%o to -27.6%0, C/N 6-18）. As results suggest that POC in the three zones of upstream-delta-outlet dominantly came from riverbank soil, phytoplankton and agricultural C3 plants in winter, whereas main sources were from the riverbank and mangrove soil in summer. Moreover, anthropogenic sewage inputs had 11% and 7% contribution to POC in the deltaic and outlet. Transport accompanied with seasonal freshwater variation, phytoplankton production and degradation, and removal be- havior caused variation of organic carbon concentration. The results also discovered that TOC export bulk in dongjiang was approximately one quarter of Humen flux in the dry flow, and anthropogenic activity significantly impacted the river export contribution.

关键词： dongjiang river Humen outlet total organic carbon flux δ13C C/N

Investigation and Risk Assessment of Alien Invasive Plants in Riparian Zone of dongjiang river

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Agricultural Science & Technology 2011年第12期12卷 1897-1904页

作者：付岚赵鸣飞龚玲刘全儒北京师范大学生命科学学院北京100875

[Objective] The aim was to conduct investigation and risk assessment of the alien invasive plants in riparian zone of dongjiang river.[Method] The field survey was carried out by the combination methods of sampling plots investigation and route survey,and the whole dongjiang river was covered.52 sampling points were set in the main streams,and 87 sampling points in tributaries streams,624 quadrats were set in total;multi-index comprehensive evaluation method was adopted for the risk assessment with 6 first-level indexes and 25 second-level indexes.[Result] Through the investigation on the riparian zone of dongjiang river for 2 years,51 species of alien invasive plants were found,belonging to 17 families and 38 *** risk level assessment results of these 51 species showed that 18 species,such as Ageratum conyzoides,belonged to high-level risk with over 60 points;26 species,such as Chenopodium ambrosioides,were between 30 and 60 points which belonged to middle-level risk;7 species,such as Paspalum dilatatum,with less than 30 points belonged to low-level risk.[Conclusion] Basic data on the protection,water environmental management and functional zoning of riparian zone of dongjiang river were provided.

关键词： Alien invasive plants dongjiang river Risk assessment Multi-index comprehensive evaluation

A Study on the impact of sand extraction on riverbed evolution in lower reaches and delta of the dongjiang river

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A Study on the impact of sand extraction on riverbed evoluti...

Advanced purification of filtered water by aerobic IBAC

海洋地质、矿产资源与环境学术研讨会

作者： Ren Jie ( Centre for Coastal Ocean Science and Tecnogy, Guangzhou 510275, China)

The large amount of sand, totally 3.32 billion m3 from 1980 to 2002, was mined from the riverbeds of lower reaches and delta of the dongjiang river. The sand dredging impacts obviously on riverbed evolution and tidal dynamic change in lower reaches and delta of the dongjiang river. Under the strong sand dredging and associated significant riverbed deformation, the notable changes of the tidal dynamic in lower reaches and delta of the dongjiang river occurred ,which include: (1) in the upper reach of the dongjiang river delta and lower reaches of the dongjiang river, tidal level dropped apparently, tidal range widened, flood tidal duration became longer, amplitudes for major tidal components became bigger and tidal dynamic intensified;(2) tidal wave spread faster;(3) the limits of the tidal level, tidal current and salt water moved upstream.

关键词： dongjiang river sand mining headcut

来源： cnki会议评论

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Journal of Harbin Institute of Technology(New Series) 2007年第1期14卷 29-32页

作者：马放秦松岩黄鹏单羿 School of Municipal and Environmental Engineering Harbin Institute of Technology Joint Research Centre for Water and Wastewater Treatment Technology Department of Civil and Structural Engineering Hong Kong Polytechnic University

Conventional water purified processes have low removal efficiencies for low concentrations of ammonia nitrogen, nitrite nitrogen and micro-pollutants. The efficiency and mechanisms of a novel immobilized biological activated carbon (IBAC) process to remove those pollutants from treated potable water was investigated. Operated at a hydraulic retention time of 24 minutes, the IBAC process achieved ammonia nitrogen, nitrite nitrogen and organic micro-pollutants (measured as COD equivalent) removal efficiencies of 95%, 96% and 37%, respectively. A GC/MS analysis of the organic micro-pollutants revealed that the initial 24 organic compounds in the in-coming water were reduced to 7 after the IBAC treatment. The organic micro-pollutant removal efficiency decreased with decreasing in-coming concentrations. Pollutant reduction in the IBAC process was achieved by a rapid physical adsorption on the activated carbon, which effectively retained the pollutants in the system despite the short hydraulic retention time, followed by a slower biological enzymatic degradation of the pollutants.

关键词： dongjiang river IBAC GAC ammonia and nitrite nitrogen removal