This study explores the differences of fish assemblages in three macrotidal estuaries of Man-gyeong River Estuary(MRE),Geum River Estuary(GRE),and Han River Esturay(HRE)with similar ranges of seasonal water temperatur...This study explores the differences of fish assemblages in three macrotidal estuaries of Man-gyeong River Estuary(MRE),Geum River Estuary(GRE),and Han River Esturay(HRE)with similar ranges of seasonal water temperature that are diked with different levels of disconnection from freshwater discharge.The distribution of major species in the three estuaries could generally be grouped into three distinctive patterns based on their cumulative distribution with respect to the salinity gradient.The MRE was geographically closer to the GRE than to the HRE,but the fish community of the MRE more closely resembled that of the HRE.Increased freshness of the water inside the dike and the limit of coastal fish to the river may have led to this result.The results provide clues to how enclosure patterns of estuarine waters could affect fish communities over a long-term period.In addition,the information may provide guidance for how a fish community may return once environmental conditions are restored.展开更多
In northeastern Japan,an area of high precipitation and mountains,beech(Fagus creanata Blume),larch(Larix kaempferi Lamb.),cedar(Cryptomeria japonica D.Don)and black locust(Robinia pseudoacacia L.)were evaluated for N...In northeastern Japan,an area of high precipitation and mountains,beech(Fagus creanata Blume),larch(Larix kaempferi Lamb.),cedar(Cryptomeria japonica D.Don)and black locust(Robinia pseudoacacia L.)were evaluated for N resorption and N isotope fractionation in preand post-abscission leaves in comparison to green leaves.The highest leaf N concentration in summer corresponded to the N-fi xing black locust,followed in decreasing order by the deciduous beech and larch and evergreen cedar.On the other hand,the lowest N resorption effi ciency corresponded to black locust and the highest to beech,in increasing order by larch and cedar.All tree species returned signifi cant amounts of N before leaf abscission;however,N isotope fractionation during leaf N resorption was only found for beech,with a depleted N isotope value from green to pre-abscission leaf.The most N,however,was resorbed from pre-abscission to post-abscission.This result may indicate thatδ15 N fractionation took place during N transformation processes,such as protein hydrolysis,when the concentration of free amino acids increased sharply.The diff erence in the type of amino acid produced by each species could have infl uenced the N isotope ratio in beech but not in the other tree species.The results of this study showed that it is possible to infer the type and timing of processes relevant to N resorption by analyzing leafδ15 N variation during senescence.展开更多
From the similarity theorem,an expression of bubble population is derived as a function of the air en-trainment rate,the turbulent kinetic energy(TKE)spectrum density and the surface tension.The bubble size spectrum t...From the similarity theorem,an expression of bubble population is derived as a function of the air en-trainment rate,the turbulent kinetic energy(TKE)spectrum density and the surface tension.The bubble size spectrum that we obtain has a dependence of a?2.5+nd on the bubble radius,in which nd is positive and dependent on the form of TKE spectrum within the viscous dissipation range.To relate the bubble population with wave parameters,an expression about the air entrainment rate is deduced by intro-ducing two statistical relations to wave breaking.The bubble population vertical distribution is also derived,based on two assumptions from two typical observation results.展开更多
基金This study was partly supported by Chung-nam National University to K-H.Choiproject PG50850 of the Korea Institute of Ocean Science and Technology(KIOST)to S.W.Hwang.
文摘This study explores the differences of fish assemblages in three macrotidal estuaries of Man-gyeong River Estuary(MRE),Geum River Estuary(GRE),and Han River Esturay(HRE)with similar ranges of seasonal water temperature that are diked with different levels of disconnection from freshwater discharge.The distribution of major species in the three estuaries could generally be grouped into three distinctive patterns based on their cumulative distribution with respect to the salinity gradient.The MRE was geographically closer to the GRE than to the HRE,but the fish community of the MRE more closely resembled that of the HRE.Increased freshness of the water inside the dike and the limit of coastal fish to the river may have led to this result.The results provide clues to how enclosure patterns of estuarine waters could affect fish communities over a long-term period.In addition,the information may provide guidance for how a fish community may return once environmental conditions are restored.
基金We thank technicians Daisuke Arai and Yoshiaki Izuka,of Yamagata University Research Forest and the students of the Watershed Preservation Laboratory,Yamagata University,for their very helpful assistance with fi eldwork.
文摘In northeastern Japan,an area of high precipitation and mountains,beech(Fagus creanata Blume),larch(Larix kaempferi Lamb.),cedar(Cryptomeria japonica D.Don)and black locust(Robinia pseudoacacia L.)were evaluated for N resorption and N isotope fractionation in preand post-abscission leaves in comparison to green leaves.The highest leaf N concentration in summer corresponded to the N-fi xing black locust,followed in decreasing order by the deciduous beech and larch and evergreen cedar.On the other hand,the lowest N resorption effi ciency corresponded to black locust and the highest to beech,in increasing order by larch and cedar.All tree species returned signifi cant amounts of N before leaf abscission;however,N isotope fractionation during leaf N resorption was only found for beech,with a depleted N isotope value from green to pre-abscission leaf.The most N,however,was resorbed from pre-abscission to post-abscission.This result may indicate thatδ15 N fractionation took place during N transformation processes,such as protein hydrolysis,when the concentration of free amino acids increased sharply.The diff erence in the type of amino acid produced by each species could have infl uenced the N isotope ratio in beech but not in the other tree species.The results of this study showed that it is possible to infer the type and timing of processes relevant to N resorption by analyzing leafδ15 N variation during senescence.
文摘From the similarity theorem,an expression of bubble population is derived as a function of the air en-trainment rate,the turbulent kinetic energy(TKE)spectrum density and the surface tension.The bubble size spectrum that we obtain has a dependence of a?2.5+nd on the bubble radius,in which nd is positive and dependent on the form of TKE spectrum within the viscous dissipation range.To relate the bubble population with wave parameters,an expression about the air entrainment rate is deduced by intro-ducing two statistical relations to wave breaking.The bubble population vertical distribution is also derived,based on two assumptions from two typical observation results.
