Several studies focused on nutrients have shown that land use and management practices have a strong influence on stream chemistry. Much less is known about the relationship between heavy metal concentrations in strea...Several studies focused on nutrients have shown that land use and management practices have a strong influence on stream chemistry. Much less is known about the relationship between heavy metal concentrations in stream water and land use. We compared the variability of trace element concentrations in the stream of a catchment exposed to different types of management practices and land use. This is a small catchment with previous agricultural diffuse and accidental pollution mainly due to the spreading of slurry. The agricultural land was reforested in July 1998. The concentrations of Fe, Mn, Cu and Zn in dissolved phase from surface water samples collected at the catchment outlet were determined over a period of approximately six years. The results suggest that dissolved metal concentrations, especially Cu and Mn, are controlled by the land use and management practices. The median concentrations of studied metals were the highest in the agricultural period. It was also during this period when they all presented the highest concentration peaks, coinciding with a time of heavy application of manure to the soil. Dissolved Fe and Mn showed high dependence of flow rate, whereas Cu and Zn concentrations seemed to be independent of flow.展开更多
This paper emphatically introduces the general situation, financial evaluation and competitive edge of both Xiangjiaba and Xiluodu hydropower stations, and briefs the preparatory works of Wudongde and Baihetan hydropo...This paper emphatically introduces the general situation, financial evaluation and competitive edge of both Xiangjiaba and Xiluodu hydropower stations, and briefs the preparatory works of Wudongde and Baihetan hydropower stations.展开更多
Boulder block ramps are river engineering structures used to stabilise river beds. Block ramps provide a semi-natural and aesthetically pleasing solution to certain river engineering problems in mountain streams. When...Boulder block ramps are river engineering structures used to stabilise river beds. Block ramps provide a semi-natural and aesthetically pleasing solution to certain river engineering problems in mountain streams. When constructing block ramps,one can use the dissipative behaviour of large macroroughness elements randomly placed on the river bed to enhance fish migration in an upstream direction thus, in this sense, meeting the requirements of the EU Water Framework Directive. Block ramps are often designed and constructed to replace damaged drop hydraulic structures in the channels of mountain streams. This paper investigates the resilience of a particular block ramp placed in the Krzczonówka stream(Polish Carpathians) in terms of the engineering design function and its durability against damaging. A hydrodynamic analysis of a block ramp is presented before and after a flood event that changed the configuration of the blocks. The seminatural unstructured hydraulic structure was built on the Krzczonowka stream to protect gas pipes which are located beneath it. As a result of several floods, the boulder block chute described in this paper was damaged, and some boulders were dislodged and transported downstream. Our post-flood investigations of bathymetry and velocity revealed that even damaged boulder blocks, removed from the chute and displaced downstream of the structure, still provide significant energy dissipation of the flowing water. The novel of our paper is for the first time showing very detailed analysis of unstructured block ramp hydrodynamics parameters done in the field.Also the novel finding of our investigations shows that before and after the flood event the unstructured block ramp structure, is still fish friendly in terms of hydrodynamics.展开更多
Recent improvements to sewerage systems have meant that the relative contribution of point sources of pollution to the overall pollutant loads of streams has decreased markedly. Consequently, the potential increase in...Recent improvements to sewerage systems have meant that the relative contribution of point sources of pollution to the overall pollutant loads of streams has decreased markedly. Consequently, the potential increase in non-point source pollution means that it may be necessary to focus more on pollution loads from non-point sources in the future. This study examined pollution loads from non-point sources in streams flowing through forested areas. In addition, the relationship between runoff and pollution loads was also clarified. The small streams in the Tohoku University Botanical Gardens, in Sendai city, Japan, were sampled during a dry weather period and their water quality parameters were characterized. Chemical Oxygen Demand （COD） concentration increased with distance downstream, possibly because the soils in downstream areas contained high amounts of organic matter. Conversely, the concentration of nitrate nitrogen （NO3-N） decreased with distance downstream, probably because upstream soils were generally in an oxidized state while those further downstream were reduced. COD concentration increased with air temperature, while NO3-N levels decreased with an increase in air temperatures.展开更多
The true freshwater crabs(Crustacea,Decapoda,Brachyura) are highly adapted to life in freshwater and complete their life cycle entirely independently of sea water.All true freshwater crabs exhibit direct development a...The true freshwater crabs(Crustacea,Decapoda,Brachyura) are highly adapted to life in freshwater and complete their life cycle entirely independently of sea water.All true freshwater crabs exhibit direct development and lack the free-living larval forms(zoea and megalopa) typical of most other brachyurans.After a prolonged embryonic period(during which they pass through the typical brachyuran larval forms embryologically) the eggs of true freshwater crabs hatch to produce juvenile(hatchling) crabs.We provide here the first report and description of the continuous record of embryonic development from egg-laying up to hatching in the Chinese true freshwater crab Sinopotamon yangtsekiense Bott,1967(Potamoidea,Potamidae).Direct development(complete secondary embryonization) in S.yangtsekiense was observed to take 77 days and to include an additional embryonic phase(termed here the egg-juvenile-crab) that occurs in the embryo between the imprisoned megalopa and the newly-emerged juvenile(hatchling) crab.This is significant because the only other freshwater crab whose embryonic development has been studied in detail is Potamon fluviatilis(Potamidae) which takes 45-47 days and involves only nine embryonic stages.展开更多
This study expands on recent reports that direct development in the Chinese potamid freshwater crab Sinopotamon yangtsekiense involves the completion of all brachyuran larval stages (nauplius, zoea, and megalopa) insi...This study expands on recent reports that direct development in the Chinese potamid freshwater crab Sinopotamon yangtsekiense involves the completion of all brachyuran larval stages (nauplius, zoea, and megalopa) inside the egg case during embryonic development. Detailed studies of embryonic development in this species revealed the presence of an additional larval stage (the egg-juvenile) between the megalopa and the free-living hatchling crab. We described and compared the appendages of the head, thorax, and abdomen of the egg-juvenile with those of the hatchling crab in S. yangtsekiense. Significant differences were found between most of the appendages of these two stages with a soft exoskeleton in the egg-juvenile, no joint articulation, a slimmer appearance, and a lack of setae when compared with the newly emerged free-living hatchling crab. These modifications of the appendages are related to the confinement within the egg case of the egg-megalopa and egg-juvenile during direct development, and the need for the free-living hatchling freshwater crab to move, feed, and respire. In marine crabs, the megalopa gives rise to the first crab stage whereas in freshwater crabs the egg-juvenile follows the megalopa and immediately precedes the free-living first crab stage.展开更多
Hydropower development in China is concentrated in the country's western regions.Among all the rivers in China,the lower course of the Jinsha River contains the richest hydro-energy resource,and therefore,4 mammot...Hydropower development in China is concentrated in the country's western regions.Among all the rivers in China,the lower course of the Jinsha River contains the richest hydro-energy resource,and therefore,4 mammoth hydropower plants are under construction on this particular section of the river at Wudongde,Baihetan,Xiluodu,and Xiangjiaba.The water-blocking structures of the hydropower facilities at Wudongde,Baihetan and Xiluodu are all arch dams of around 300 m high.In view of changes in the geological conditions at the foundation of the Xiluodu dam on the riverbed after excavation started,the designs of expanding foundation surface excavation and dovetailing the dam body and foundation rock on both upstream and downstream sides were introduced,allowing the arch dam and foundation to fit each other and improving the stress conditions of the dam body and foundation.By dividing the dam body into various concrete sections,the dynamic properties of concrete were adequately adjusted to the distribution of stress in the dam body.In addition,the use of the most optimal concrete material and mixture ratio allowed thermodynamics of concrete to satisfy the requirements of the strength,durability,temperature control and crack prevention of the concrete.Moreover,rigorous temperature control measures were introduced to prevent harmful cracking,thus enhancing the integrity of the arch dam.Furthermore,sophisticated construction machinery,scientific testing methods,and sound construction techniques were employed to ensure the uniformity and reliability of concrete placement.The "Digital Dam" for the Xiluodu project,which is based on the theory of total life cycle,has supplied strong support for construction process control and decision-making.展开更多
文摘Several studies focused on nutrients have shown that land use and management practices have a strong influence on stream chemistry. Much less is known about the relationship between heavy metal concentrations in stream water and land use. We compared the variability of trace element concentrations in the stream of a catchment exposed to different types of management practices and land use. This is a small catchment with previous agricultural diffuse and accidental pollution mainly due to the spreading of slurry. The agricultural land was reforested in July 1998. The concentrations of Fe, Mn, Cu and Zn in dissolved phase from surface water samples collected at the catchment outlet were determined over a period of approximately six years. The results suggest that dissolved metal concentrations, especially Cu and Mn, are controlled by the land use and management practices. The median concentrations of studied metals were the highest in the agricultural period. It was also during this period when they all presented the highest concentration peaks, coinciding with a time of heavy application of manure to the soil. Dissolved Fe and Mn showed high dependence of flow rate, whereas Cu and Zn concentrations seemed to be independent of flow.
文摘This paper emphatically introduces the general situation, financial evaluation and competitive edge of both Xiangjiaba and Xiluodu hydropower stations, and briefs the preparatory works of Wudongde and Baihetan hydropower stations.
基金financed by the Ministry of Science and Higher Education of the Republic of Poland: 1. Cracow University of Technology, Faculty of Civil Engineering: L4/106/2018/DS, L4/107/2018/DS and L4/585/2018/DS-M. 2. University of Agriculture in Krakow: BM2313/KIWi G/2018
文摘Boulder block ramps are river engineering structures used to stabilise river beds. Block ramps provide a semi-natural and aesthetically pleasing solution to certain river engineering problems in mountain streams. When constructing block ramps,one can use the dissipative behaviour of large macroroughness elements randomly placed on the river bed to enhance fish migration in an upstream direction thus, in this sense, meeting the requirements of the EU Water Framework Directive. Block ramps are often designed and constructed to replace damaged drop hydraulic structures in the channels of mountain streams. This paper investigates the resilience of a particular block ramp placed in the Krzczonówka stream(Polish Carpathians) in terms of the engineering design function and its durability against damaging. A hydrodynamic analysis of a block ramp is presented before and after a flood event that changed the configuration of the blocks. The seminatural unstructured hydraulic structure was built on the Krzczonowka stream to protect gas pipes which are located beneath it. As a result of several floods, the boulder block chute described in this paper was damaged, and some boulders were dislodged and transported downstream. Our post-flood investigations of bathymetry and velocity revealed that even damaged boulder blocks, removed from the chute and displaced downstream of the structure, still provide significant energy dissipation of the flowing water. The novel of our paper is for the first time showing very detailed analysis of unstructured block ramp hydrodynamics parameters done in the field.Also the novel finding of our investigations shows that before and after the flood event the unstructured block ramp structure, is still fish friendly in terms of hydrodynamics.
文摘Recent improvements to sewerage systems have meant that the relative contribution of point sources of pollution to the overall pollutant loads of streams has decreased markedly. Consequently, the potential increase in non-point source pollution means that it may be necessary to focus more on pollution loads from non-point sources in the future. This study examined pollution loads from non-point sources in streams flowing through forested areas. In addition, the relationship between runoff and pollution loads was also clarified. The small streams in the Tohoku University Botanical Gardens, in Sendai city, Japan, were sampled during a dry weather period and their water quality parameters were characterized. Chemical Oxygen Demand （COD） concentration increased with distance downstream, possibly because the soils in downstream areas contained high amounts of organic matter. Conversely, the concentration of nitrate nitrogen （NO3-N） decreased with distance downstream, probably because upstream soils were generally in an oxidized state while those further downstream were reduced. COD concentration increased with air temperature, while NO3-N levels decreased with an increase in air temperatures.
基金Supported by the Shanghai Leading Academic Discipline Project(No.S30701)the Leading Academic Discipline Project of Shanghai Municipal Education Commission(No.J50701)
文摘The true freshwater crabs(Crustacea,Decapoda,Brachyura) are highly adapted to life in freshwater and complete their life cycle entirely independently of sea water.All true freshwater crabs exhibit direct development and lack the free-living larval forms(zoea and megalopa) typical of most other brachyurans.After a prolonged embryonic period(during which they pass through the typical brachyuran larval forms embryologically) the eggs of true freshwater crabs hatch to produce juvenile(hatchling) crabs.We provide here the first report and description of the continuous record of embryonic development from egg-laying up to hatching in the Chinese true freshwater crab Sinopotamon yangtsekiense Bott,1967(Potamoidea,Potamidae).Direct development(complete secondary embryonization) in S.yangtsekiense was observed to take 77 days and to include an additional embryonic phase(termed here the egg-juvenile-crab) that occurs in the embryo between the imprisoned megalopa and the newly-emerged juvenile(hatchling) crab.This is significant because the only other freshwater crab whose embryonic development has been studied in detail is Potamon fluviatilis(Potamidae) which takes 45-47 days and involves only nine embryonic stages.
基金Supported by the Leading Academic Discipline Project of Shanghai Municipal Education Commission(No.J50701)
文摘This study expands on recent reports that direct development in the Chinese potamid freshwater crab Sinopotamon yangtsekiense involves the completion of all brachyuran larval stages (nauplius, zoea, and megalopa) inside the egg case during embryonic development. Detailed studies of embryonic development in this species revealed the presence of an additional larval stage (the egg-juvenile) between the megalopa and the free-living hatchling crab. We described and compared the appendages of the head, thorax, and abdomen of the egg-juvenile with those of the hatchling crab in S. yangtsekiense. Significant differences were found between most of the appendages of these two stages with a soft exoskeleton in the egg-juvenile, no joint articulation, a slimmer appearance, and a lack of setae when compared with the newly emerged free-living hatchling crab. These modifications of the appendages are related to the confinement within the egg case of the egg-megalopa and egg-juvenile during direct development, and the need for the free-living hatchling freshwater crab to move, feed, and respire. In marine crabs, the megalopa gives rise to the first crab stage whereas in freshwater crabs the egg-juvenile follows the megalopa and immediately precedes the free-living first crab stage.
文摘Hydropower development in China is concentrated in the country's western regions.Among all the rivers in China,the lower course of the Jinsha River contains the richest hydro-energy resource,and therefore,4 mammoth hydropower plants are under construction on this particular section of the river at Wudongde,Baihetan,Xiluodu,and Xiangjiaba.The water-blocking structures of the hydropower facilities at Wudongde,Baihetan and Xiluodu are all arch dams of around 300 m high.In view of changes in the geological conditions at the foundation of the Xiluodu dam on the riverbed after excavation started,the designs of expanding foundation surface excavation and dovetailing the dam body and foundation rock on both upstream and downstream sides were introduced,allowing the arch dam and foundation to fit each other and improving the stress conditions of the dam body and foundation.By dividing the dam body into various concrete sections,the dynamic properties of concrete were adequately adjusted to the distribution of stress in the dam body.In addition,the use of the most optimal concrete material and mixture ratio allowed thermodynamics of concrete to satisfy the requirements of the strength,durability,temperature control and crack prevention of the concrete.Moreover,rigorous temperature control measures were introduced to prevent harmful cracking,thus enhancing the integrity of the arch dam.Furthermore,sophisticated construction machinery,scientific testing methods,and sound construction techniques were employed to ensure the uniformity and reliability of concrete placement.The "Digital Dam" for the Xiluodu project,which is based on the theory of total life cycle,has supplied strong support for construction process control and decision-making.
