In this paper, the discussion is concentrated on the properties of the polluted sediments and the combination of clean-up and disposal process for the upper layer heavily polluted sediments with good flowability. Base...In this paper, the discussion is concentrated on the properties of the polluted sediments and the combination of clean-up and disposal process for the upper layer heavily polluted sediments with good flowability. Based on the systematic analyses of various clean-up processes, a suitable engineering process has been evaluated and recommended. The process has been applied to the river reclamation in Yangpu District of Shanghai City, China. An improved centrifuge is used for dewatering the dredged sludge, which plays an important role in the combination of clean-up and disposal process. The assessment of the engineering process shows its environmental and technical economy feasibility, which is much better than that of traditional dredging-disposal processes.展开更多
In order to explore a technology for producing organic fertilizer by composting urban forest litter and river sediment passivated by fly ash, an experiment was conducted to study dynamic changes of several parameters ...In order to explore a technology for producing organic fertilizer by composting urban forest litter and river sediment passivated by fly ash, an experiment was conducted to study dynamic changes of several parameters including temperature, pH, organic matter, C/N and germination index （GI） during high-temperature composting of urban forest litter and river sediment at five different proportions （1：1 （Ⅰ）, 1：2 （Ⅱ）, 1：3 （Ⅲ）, 2：1 （Ⅳ） and 3：1 （Ⅴ））. Results showed that the temperature and pH increased first and then decreased; at the proportion of 3：1, the temperature increased rapidly and the high-temperature duration was longest （5 d）; at the end of the composting, all the treatments reached the decomposed status, the pH ranged from 7.47 to 8.87, and the organic matter content was reduced by 36%, 38%, 42%, 33% and 29%, respectively, indicating that increasing the proportion of urban forest litter was conducive to reducing the loss of organic matter. Due to low C/N ratio of river sediment, increasing the proportion of urban forest litter was helpful to improve the efficiency of composting. The GI of treatments I, IV and V reached 80% on day 26, 18 and 19 respectively, but the GI of treatments II and III did not reach this level until the end of composting. Considering the quality of fertilizer and efficiency of composting for large-scale production, the proportion between urban forest litter and river sediment is suitable to be set as 3：1 for production of organic fertilizer.展开更多
Microbial communities in sediment are an important indicator linking to environmental pollution in urban river systems.However,how the diversity and structure of bacterial communities in sediments from an urban river ...Microbial communities in sediment are an important indicator linking to environmental pollution in urban river systems.However,how the diversity and structure of bacterial communities in sediments from an urban river network respond to different environmental factors has not been well studied.The goal of this study was to understand the patterns of bacterial communities in sediments from a highly dense urbanized river network in the lower Yangtze River Delta by Illumina MiSeq sequencing.The correlations between bacterial communities,the environmental gradient and geographical distance were analyzed by redundancy analysis(RDA)and network methods.The diversity and richness of bacterial community in sediments increased from upstream to downstream consistently with the accumulation of nutrient in the urban river network.Bacterial community composition and structure showed obvious spatial changes,leading to two distinct groups,which were significantly related to the characteristics of nutrient and heavy metal in sediments.Humic substance,available nitrogen,available phosphorus,Zn,Cu,Hg and As were selected as the key environmental factors shaping the bacterial community in sediments based on RDA.The co-occurrence patterns of bacterial networks showed that positive interaction between bacterial communities increased but the connectivity among bacterial genera and stability of sediment ecosystem reduced under a higher content of nutrient and heavy metal in average.The sensitive and ubiquitous taxa with an overproportional response to key environmental factors were detected as indicator species,which provided a novel method for the prediction of the pollution risk of sediment in an urban river network.展开更多
In view of the seriously-polluted water and broken eco-waterscapes in the Qiusuo Brook on campus of China Three Gorges University,this paper proposed the ecological restoration concept and mode of campus river accordi...In view of the seriously-polluted water and broken eco-waterscapes in the Qiusuo Brook on campus of China Three Gorges University,this paper proposed the ecological restoration concept and mode of campus river according to field investigation and monitoring results,i.e. "reduce exogenous pollution—restore sediment microorganism—build intensified plant filter strip—build river water ecosystem and optimize landscapes—maintain ecological river course".In addition to introducing the design concept and principle of this mode,this paper specified the concrete projects such as sewage interception and water supplement,restoration of sediment microorganism,restoration of water plants,ecological restoration of embankment etc.,and also gave planar layouts and sketches of some projects,in order to provide references for the researches and practices of campus river ecological restoration in China Three Gorges University and other similar projects.展开更多
A typical fiver in Yangzhou City was used to study the effects of artificial aeration, eco-brick cover, biological packing cover, and low-sited plant floating beds on the release of heavy metals from urban river sedim...A typical fiver in Yangzhou City was used to study the effects of artificial aeration, eco-brick cover, biological packing cover, and low-sited plant floating beds on the release of heavy metals from urban river sediments. This work showed that 1） the Cr release rate was decreased by 50.3%-89.6%, with an average of 59.3%, thereby reducing the Cr pollution load to the overlying water by 36.6%-82.7%, with an average of 53.3%; 2） the Zn release rate was reduced by 21.0%-88.9%, with an average of 42.3%, and the Zn pollution load of the overlying water was reduced by 38.0%-67.1%, with an average of 55.0%; 3） the Cu release rate was reduced by 27.5%-91.0%, with an average of 55.3%, and the Cu load of the overlying water was reduced by 57.1%-83.7%, with an average of 71.7%; 4） the Pb release rate was reduced by 11.8%- 79.3%, with an average of 41.2%, and the Pb pollution load of the overlying water was reduced by -1.3%-70.7%, with an average of 29.8%. We also found that the effects of in situ biological treatments on the release of heavy metals were affected by the extent of sediment disturbance. For integrated applications, high-disturbance treatments should be combined with low-disturbance treatments to reduce the explosive release of pollutants caused by sediment disturbance during the treatment operation to achieve better overall treatment effects.展开更多
文摘In this paper, the discussion is concentrated on the properties of the polluted sediments and the combination of clean-up and disposal process for the upper layer heavily polluted sediments with good flowability. Based on the systematic analyses of various clean-up processes, a suitable engineering process has been evaluated and recommended. The process has been applied to the river reclamation in Yangpu District of Shanghai City, China. An improved centrifuge is used for dewatering the dredged sludge, which plays an important role in the combination of clean-up and disposal process. The assessment of the engineering process shows its environmental and technical economy feasibility, which is much better than that of traditional dredging-disposal processes.
基金Supported by National Spark Program of China(2010GA781004)Shenzhen Science and Technology Plan Project(CXZZ20140422142833835,CXZZ20150527171538718,GCZX2015051514435234)~~
文摘In order to explore a technology for producing organic fertilizer by composting urban forest litter and river sediment passivated by fly ash, an experiment was conducted to study dynamic changes of several parameters including temperature, pH, organic matter, C/N and germination index （GI） during high-temperature composting of urban forest litter and river sediment at five different proportions （1：1 （Ⅰ）, 1：2 （Ⅱ）, 1：3 （Ⅲ）, 2：1 （Ⅳ） and 3：1 （Ⅴ））. Results showed that the temperature and pH increased first and then decreased; at the proportion of 3：1, the temperature increased rapidly and the high-temperature duration was longest （5 d）; at the end of the composting, all the treatments reached the decomposed status, the pH ranged from 7.47 to 8.87, and the organic matter content was reduced by 36%, 38%, 42%, 33% and 29%, respectively, indicating that increasing the proportion of urban forest litter was conducive to reducing the loss of organic matter. Due to low C/N ratio of river sediment, increasing the proportion of urban forest litter was helpful to improve the efficiency of composting. The GI of treatments I, IV and V reached 80% on day 26, 18 and 19 respectively, but the GI of treatments II and III did not reach this level until the end of composting. Considering the quality of fertilizer and efficiency of composting for large-scale production, the proportion between urban forest litter and river sediment is suitable to be set as 3：1 for production of organic fertilizer.
基金the National Water Pollution Control and Treatment Science and Technology Major Project of China(No.2017ZX07205)the China Postdoctoral Science Foundation(No.2017M620801)+1 种基金National Natural Science Foundation of China(Grant No.41702262)Zhejiang Provincial Natural Science Foundation of China(No.LY17D060004).
文摘Microbial communities in sediment are an important indicator linking to environmental pollution in urban river systems.However,how the diversity and structure of bacterial communities in sediments from an urban river network respond to different environmental factors has not been well studied.The goal of this study was to understand the patterns of bacterial communities in sediments from a highly dense urbanized river network in the lower Yangtze River Delta by Illumina MiSeq sequencing.The correlations between bacterial communities,the environmental gradient and geographical distance were analyzed by redundancy analysis(RDA)and network methods.The diversity and richness of bacterial community in sediments increased from upstream to downstream consistently with the accumulation of nutrient in the urban river network.Bacterial community composition and structure showed obvious spatial changes,leading to two distinct groups,which were significantly related to the characteristics of nutrient and heavy metal in sediments.Humic substance,available nitrogen,available phosphorus,Zn,Cu,Hg and As were selected as the key environmental factors shaping the bacterial community in sediments based on RDA.The co-occurrence patterns of bacterial networks showed that positive interaction between bacterial communities increased but the connectivity among bacterial genera and stability of sediment ecosystem reduced under a higher content of nutrient and heavy metal in average.The sensitive and ubiquitous taxa with an overproportional response to key environmental factors were detected as indicator species,which provided a novel method for the prediction of the pollution risk of sediment in an urban river network.
基金Sponsored by Science Fund of China Three Gorges University(KJ2011B028)National Science Foundation for Young Scientists of China(41401586)
文摘In view of the seriously-polluted water and broken eco-waterscapes in the Qiusuo Brook on campus of China Three Gorges University,this paper proposed the ecological restoration concept and mode of campus river according to field investigation and monitoring results,i.e. "reduce exogenous pollution—restore sediment microorganism—build intensified plant filter strip—build river water ecosystem and optimize landscapes—maintain ecological river course".In addition to introducing the design concept and principle of this mode,this paper specified the concrete projects such as sewage interception and water supplement,restoration of sediment microorganism,restoration of water plants,ecological restoration of embankment etc.,and also gave planar layouts and sketches of some projects,in order to provide references for the researches and practices of campus river ecological restoration in China Three Gorges University and other similar projects.
基金This research was supported by the the National Natural Science Foundation of China （Grant No. 71273254）.
文摘A typical fiver in Yangzhou City was used to study the effects of artificial aeration, eco-brick cover, biological packing cover, and low-sited plant floating beds on the release of heavy metals from urban river sediments. This work showed that 1） the Cr release rate was decreased by 50.3%-89.6%, with an average of 59.3%, thereby reducing the Cr pollution load to the overlying water by 36.6%-82.7%, with an average of 53.3%; 2） the Zn release rate was reduced by 21.0%-88.9%, with an average of 42.3%, and the Zn pollution load of the overlying water was reduced by 38.0%-67.1%, with an average of 55.0%; 3） the Cu release rate was reduced by 27.5%-91.0%, with an average of 55.3%, and the Cu load of the overlying water was reduced by 57.1%-83.7%, with an average of 71.7%; 4） the Pb release rate was reduced by 11.8%- 79.3%, with an average of 41.2%, and the Pb pollution load of the overlying water was reduced by -1.3%-70.7%, with an average of 29.8%. We also found that the effects of in situ biological treatments on the release of heavy metals were affected by the extent of sediment disturbance. For integrated applications, high-disturbance treatments should be combined with low-disturbance treatments to reduce the explosive release of pollutants caused by sediment disturbance during the treatment operation to achieve better overall treatment effects.
