The Lake Tian E Zhou(TEZ,an oxbow lake)was formed during the rerouting of the Changjiang River in 1972,with strong influences from the main river channel and flood events.Herein,a sediment core was collected from the ...The Lake Tian E Zhou(TEZ,an oxbow lake)was formed during the rerouting of the Changjiang River in 1972,with strong influences from the main river channel and flood events.Herein,a sediment core was collected from the Lake TEZ for the measurements of carbon isotopes and biomarkers,including stable carbon isotopes(δ13C),radiocarbon composition(?14C),and lignin phenols,as well as lead-210 to reconstruct recent heavy flood events over the past 70 years.At the 24–26 cm interval,the sediment contained the highest OC%,TN%,and lignin phenols content,as well as significantly depleted 13C but enriched 14C,corresponding to the extreme flood event in 1998.In addition,statistics from t-test showed that lignin phenols normalized to OC(Λ8),the concentration of 3,5-dihydroxy benzoic acid(3,5-BD),and the ratio of p-hydroxy benzophenone to total hydroxyl phenols(PHB/HP)were all significantly different between the layers containing flood deposits and the layers deposited under normal non-flood conditions(p<0.05).These results indicate that the later three parameters are highly related to flood events and can be used as compelling proxies,along with sediment chronology,for hydrological changes and storm/flood events in the river basin and coastal marine environments.展开更多
The assessment of the ecosystem health of urban rivers and lakes is the scientific basis for their management and ecological restoration.This study developed a three-level indicator system for its assessment.The resul...The assessment of the ecosystem health of urban rivers and lakes is the scientific basis for their management and ecological restoration.This study developed a three-level indicator system for its assessment.The results indicated that:Zhonghai and Nanhai are in the state of transition from unhealthy to critical state and all the other lakes are in unhealthy states.Water environmental quality,structure and function of the aquatic ecosystem,and the structure of waterfront areas were the constraints.Nanhai was ranked as poor and the others were all ranked as very poor.However,the ecological environment of Zhonghai and Nanhai were better than the others,the sums of the degree of membership to the healthy state and critical state were all close to 0.6.and the restorations of these lakes were moderate.The sums of the degree of membership to the healthy state and critical state of the other lakes were under 0.3,as it was difficult to restore these lakes.Some suggestions on scientific management and ecological restoration of the six lakes were proposed:①To control non-point pollution and to improve the water quality of six lakes and the water entering into these lakes;②To improve the hydrological conditions of six lakes;③To rehabilitate the aquatic ecosystem and waterfront areas.展开更多
基金The National Natural Science Foundation of China under contract Nos 41021064,41276081 and 41606211the 111 Project under contract No.B08022the Scientific Research Fund of Second Institute of Oceanography,MNR under contract No.JG1806
文摘The Lake Tian E Zhou(TEZ,an oxbow lake)was formed during the rerouting of the Changjiang River in 1972,with strong influences from the main river channel and flood events.Herein,a sediment core was collected from the Lake TEZ for the measurements of carbon isotopes and biomarkers,including stable carbon isotopes(δ13C),radiocarbon composition(?14C),and lignin phenols,as well as lead-210 to reconstruct recent heavy flood events over the past 70 years.At the 24–26 cm interval,the sediment contained the highest OC%,TN%,and lignin phenols content,as well as significantly depleted 13C but enriched 14C,corresponding to the extreme flood event in 1998.In addition,statistics from t-test showed that lignin phenols normalized to OC(Λ8),the concentration of 3,5-dihydroxy benzoic acid(3,5-BD),and the ratio of p-hydroxy benzophenone to total hydroxyl phenols(PHB/HP)were all significantly different between the layers containing flood deposits and the layers deposited under normal non-flood conditions(p<0.05).These results indicate that the later three parameters are highly related to flood events and can be used as compelling proxies,along with sediment chronology,for hydrological changes and storm/flood events in the river basin and coastal marine environments.
基金This study was supported by the National Basic Research Program of China(Grant No.2006CB403403)Key Program of the National Natural Science Foundation of China(Grant No.50238020)。
文摘The assessment of the ecosystem health of urban rivers and lakes is the scientific basis for their management and ecological restoration.This study developed a three-level indicator system for its assessment.The results indicated that:Zhonghai and Nanhai are in the state of transition from unhealthy to critical state and all the other lakes are in unhealthy states.Water environmental quality,structure and function of the aquatic ecosystem,and the structure of waterfront areas were the constraints.Nanhai was ranked as poor and the others were all ranked as very poor.However,the ecological environment of Zhonghai and Nanhai were better than the others,the sums of the degree of membership to the healthy state and critical state were all close to 0.6.and the restorations of these lakes were moderate.The sums of the degree of membership to the healthy state and critical state of the other lakes were under 0.3,as it was difficult to restore these lakes.Some suggestions on scientific management and ecological restoration of the six lakes were proposed:①To control non-point pollution and to improve the water quality of six lakes and the water entering into these lakes;②To improve the hydrological conditions of six lakes;③To rehabilitate the aquatic ecosystem and waterfront areas.
