Well preserved Early Cambrian small individual megascopic carbonaceous algal fossils have been found from the Chengjiang Biota. This paper deals with the new megascopic algal fossils in the Early Cambrian also from Ch...Well preserved Early Cambrian small individual megascopic carbonaceous algal fossils have been found from the Chengjiang Biota. This paper deals with the new megascopic algal fossils in the Early Cambrian also from Chengjiang Biota at Ercai Village, Haikou, Kunming, Yunnan, southwest China. Two new taxa, Longfengshania cordata sp. nov. and Plantulaformis sinensis gen. et sp. nov. are described here in detail. These new findings show that the Chengjiang Biota is high in species diversity of fossil algae and might offer new evidence for a better understanding of the Cambrian explosive biological evolution. Moreover, the fossils described here might belong to the megaalgal fossils according to detailed morphological study on the relationships of Longfengshania. Additionally, the occurrence of Longfengshania in the early Cambrian and the Neoproterozoic probably indicates a wide ecological tolerance and flexibility and apparently reflects its evolutionary conservation and a high degree of inherent genetic stability.展开更多
This paper, with NOAA/AHHRR data for 2 years, discusses the expanding path and extent of suspended sediment from the Changjiang River, and the relationship between the suspended sediment expanding and coastal current ...This paper, with NOAA/AHHRR data for 2 years, discusses the expanding path and extent of suspended sediment from the Changjiang River, and the relationship between the suspended sediment expanding and coastal current systems by analyzing the thermal infrared imagery with the sediment imagery, which is acquired by correlating the atmosphere corrected AVHRR imagery with in-situ suspended sediment data. The coastal current systems affecting the sediment dispersal mainly include: the Taiwan Warm Current (TWC), the Huanghai Sea Mixed Water (HSMW), North Jiangsu near-shore current, and Zhejiang near-shore current etc. In winter, the current systems are stable. Their distribution affects the sediment from north Jiangsu expanding toward the Changjiang estuary in some degree .The front between Zhejiang coastal current and TWC blocks the expanding of sediment toward the sea. In the flood season, apart from the limitation by coastal current systems, the spatial and temporal distribution of suspended sediment is also affected by the runoff, which shows as the jet stream and fresh water. Spring and autumn are the transitional periods of the forming of expanding patterns of flood season and winter respectively. In addition, the re-suspended sediment caused by the wind wave may make the expanding range of near-shore sediment larger.展开更多
Based on analyzing the limit of Ziolkowski's bubble oscillation formulation,a new model with various physical factors is established to simulate air gun signatures fo marine seismic exploration.The practical effects ...Based on analyzing the limit of Ziolkowski's bubble oscillation formulation,a new model with various physical factors is established to simulate air gun signatures fo marine seismic exploration.The practical effects of physical factors,such as heat transfe across the bubble wall,air gun port throttling,vertical rise of the bubble,fluid viscosity,and the existence of the air gun body were all taken into account in the new model.Compared with Ziolkowski's model,the signatures simulated by the new model,with small peak amplitude and rapid decay of bubble oscillation,are more consistent with actual signatures The experiment analysis indicates:(1)gun port throttling controls the peak amplitude of ai gun pulse;(2)since the hydrostatic pressure decreases when the bubble rises,the bubble oscillation period changes;(3)heat transfer and fluid viscosity are the main factors tha explain the bubble oscillation damping.展开更多
The form in which a metal exists strongly influences its mobility and thus, the effects on the environment. Operational methods of speciation analysis, such as the use of sequential extraction procedures, are commonly...The form in which a metal exists strongly influences its mobility and thus, the effects on the environment. Operational methods of speciation analysis, such as the use of sequential extraction procedures, are commonly applied. The Dongting Lake, the second largest fresh-water lake in China, contains three China wetlands of international importance, the East Dongting Lake, South Dongting Lake, and West Dongting Lake. In this work, an optimized BCR sequential extraction procedure was used to assess the environmental risk of Cd, Cr, Cu, Ni, Pb and Zn in contaminated sediment of the Dongting Lake. The procedure was evaluated by using a certified reference material, BCR701. The results of the partitioning study indicated that in the lake sediments, more easily mobilized forms (acid exchangeable) were predominant for Cd, particularly in the samples from the East Dongting Lake. In contrast, the largest amount of Pb was associated with the iron and manganese oxide fractions and Cu, Zn, Cr, and Ni analyzed were mainly distributed in residual phase at an average percentage greater than 60% of the total metals. The potential risk to the lake's water contamination was highest in the East Dongting Lake based on the calculated contamination factors. On the other hand, the total metal content was determined as well by inductively coupled plasma and mass spectrometry (ICP-MS) and assessed by using geo-accumulation index. The assessment results using geo-accumulation index were compared with the information on metal speciation. Both were correspondent with each other.展开更多
Estuaries and coasts are conjunctions of four spheres (atmosphere, lithosphere, hydrosphere and biosphere) and important matter and energy convergence/divergence zones, where developed economy, dense population and hi...Estuaries and coasts are conjunctions of four spheres (atmosphere, lithosphere, hydrosphere and biosphere) and important matter and energy convergence/divergence zones, where developed economy, dense population and highly intensive exploitation induce adverse environmental changes and serious destruction of resources, which have great impacts on coastal sustainable development, especially as the highly intensive development in river basins has direct and pronounced effects on estuaries and their adjacent coasts. In the new century, China’s estuaries and coast are faced with four main challenges: sharp decrease of sediment discharge into the sea, rapid increase of pollution matter into the sea, loss of coastal wetland, and the impacts of global sea level rise on the coastal lowlands of China. Therefore, it is undoubtedly very important and urgent to carry out studies on estuarine and coastal environmental changes, in order to resolve the issue of national sustainable development, especially that of rational use of coastal zone resources.展开更多
We investigated the foraging area of three individuals (1 female and 2 males) of Rousettus leschenaulti (Chiroptera,Pteropodidae) in suburban Haikou City, Hainan Province, South China from November 2005 to January 200...We investigated the foraging area of three individuals (1 female and 2 males) of Rousettus leschenaulti (Chiroptera,Pteropodidae) in suburban Haikou City, Hainan Province, South China from November 2005 to January 2006 using radio telemetry.These animals left the daytime roosting sites about 90 min after sunset with no significant difference in departure time betweenthe male and female bats. The average active times were 391.8 min for males and 533.7 min for the female, respectively.By reconstructing 93 radio-telemetry recording positions, we found that the long axis of foraging area of the bats ranged from7.45 to 11.70 km. The foraging area of the female (3867 ha) was larger than that of the males (1138 ha), and there was overlapbetween the foraging areas of different individuals. These bats usually kept the same flight routes across a few successive daysfrom the daytime roosting site to the foraging areas. Our findings suggested that female R. leschenaulti may explore a larger foragingarea than males. No obvious territorial behaviors were observed in our studied area.展开更多
Relocation of the Yellow River estuary has significant impacts on not only terrestrial environment and human activities, but also sedimentary and ecological environments in coastal seas. The responses of regional geoc...Relocation of the Yellow River estuary has significant impacts on not only terrestrial environment and human activities, but also sedimentary and ecological environments in coastal seas. The responses of regional geochemical characteristics to the relocation event, however, have not been well studied. In the present study, we performed detailed geochemical elemental analyses of a sediment core from the northern Yellow Sea and studied their geochemical responses to the 1855AD relocation of the Yellow River estuary. The results show that TOC/TN, Co/A1203, Cr/A1203, Ni/A1203 and Se/A1203 ratios all decreased abruptly after 1855 AD, and similar decreases are observed in the sediments of the mud area southwest off the Cheju Island. These abrupt changes are very likely caused by the changes in source materials due to the relocation of the Yellow River estuary from the southern Yellow Sea to the Bohai Sea, which the corresponding decreasing trends caused by the changes in main source materials from those transported by the Liaohe River, the Haihe River and the Luanhe River to those by the Yellow River. Because the events have precise ages recorded in historical archives, these obvious changes in elemental geochemistry of sediments can be used to calibrate age models of related coastal sea sediments.展开更多
Reclamation is one of the fastest-growing land use type developed in coastal areas and has caused degradation and loss of coastal wetlands as well as serious environmental problems. This paper was aimed at monitoring ...Reclamation is one of the fastest-growing land use type developed in coastal areas and has caused degradation and loss of coastal wetlands as well as serious environmental problems. This paper was aimed at monitoring the spatiotemporal patterns of coastal wetlands and reclamation in the Yangtze Estuary during the 1960s and 2015. Satellite images obtained from 1980 to 2015 and topography maps of the 1960 s were employed to extract changes of reclamation and coastal wetlands. Area-weight centroids were calculated to identify the movement trend of reclamation and coastal wetlands. The results show that from the 1960 s to 2015, the net area of natural wetlands declined by 574.3 km^2, while man-made wetlands and reclamation increased by 553.6 and 543.9 km^2, respectively. During the five study phases, the fastest areal change rate natural wetlands was –13.3 km^2/yr in the period of 1990–2000, and that of man-made areas was 24.7 km^2/yr in the same period, and the areal change rate of reclamation was 27.6 km^2/yr in the period of 2000–2010. Conversion of coastal wetlands mainly occurred in the Chongming Island, Changshu City and the east coast of Shanghai Municipality. Reclamation was common across coastal areas, and was mainly attributed to settlement and man-made wetlands in the Chongming Island, Lianyungang City and the east coast of Shanghai Municipality. Natural wetlands turned into farmlands and settlement, and man-made wetlands gained from reclamation of farmlands. The centroid of natural wetlands generally moved towards the sea, man-made wetlands expanded equally in all directions and inland, and the centroid of reclamation migrated toward Shanghai Municipality. Sea level rise, erosion-deposition changes, and reclamation activities together determine the dynamics of the Yangtze Estuary wetlands. However, reclamation activities for construction of ports, industries and aquaculture are the key causes for the dynamics. The results from this study on the dynamics of coastal wetlands and reclamation are valuable for local government to put forward sustainable land use and land development plans.展开更多
Data taken in the two large-scale ocean investigations in China in winter 1959 and 1982 are used to analyze the residual current off the Changjiang (Yangtze) River mouth in this paper. The current in wintertime off th...Data taken in the two large-scale ocean investigations in China in winter 1959 and 1982 are used to analyze the residual current off the Changjiang (Yangtze) River mouth in this paper. The current in wintertime off the river mouth consist of the Changjiang runoff, wind-driven current, coastal current, density-driven current and Taiwan Warm Current (TWC). The TWC occurs in wintertime off the mouth. The surface TWC reaches only to the east side of Dinghai, then turns southeastward. The bottom TWC can flow to the area off the Changjiang mouth along west slop of the submerged river valley (SRV) and to the area off the Subei coast. The simulated currents by 3D model are basically consistent with the observed currents, although the model was run with climatological forces and the observations was done in episodic time manner.展开更多
With the combination of historical data, field observations and satellite remotely sensed images (Landsat TM/ ETM+ and CBERS), changes in Huanghe (Yellow) River estuary since 1996 when artificial Chahe distributary wa...With the combination of historical data, field observations and satellite remotely sensed images (Landsat TM/ ETM+ and CBERS), changes in Huanghe (Yellow) River estuary since 1996 when artificial Chahe distributary was built up were studied, mainly including water and sediment discharge from the river, tides, tidal currents, suspended sediment diffusion, coastline changes and seabed development. During following six and half years (up to the end of 2002), runoff and sediment loads into the river mouth declined dramatically. At the beginning of the re-routing, abundant sediment loads from the river filled up nearshore shallow water areas so that the newborn delta prograded quickly. With rapid decrease of sediment loads transported to the estuary, the delta retrograded. In 1997, subaerial tip of the abandoned delta receded 1.5km; its annual mean recession rate was about 150 m in following years. In addition, marine dynamic condition near the artificial outlet had also changed. Under the interaction of ocean and river flow, most of incoming sediment loads deposited in the vicin- ity of the outlet. Seabed erosion occurred at the subaqueous delta front. Between 1999 and 2002, erosion thick- ness averaged at 0.3 m in the subaqueous delta of 585.5 km2.展开更多
文摘Well preserved Early Cambrian small individual megascopic carbonaceous algal fossils have been found from the Chengjiang Biota. This paper deals with the new megascopic algal fossils in the Early Cambrian also from Chengjiang Biota at Ercai Village, Haikou, Kunming, Yunnan, southwest China. Two new taxa, Longfengshania cordata sp. nov. and Plantulaformis sinensis gen. et sp. nov. are described here in detail. These new findings show that the Chengjiang Biota is high in species diversity of fossil algae and might offer new evidence for a better understanding of the Cambrian explosive biological evolution. Moreover, the fossils described here might belong to the megaalgal fossils according to detailed morphological study on the relationships of Longfengshania. Additionally, the occurrence of Longfengshania in the early Cambrian and the Neoproterozoic probably indicates a wide ecological tolerance and flexibility and apparently reflects its evolutionary conservation and a high degree of inherent genetic stability.
文摘This paper, with NOAA/AHHRR data for 2 years, discusses the expanding path and extent of suspended sediment from the Changjiang River, and the relationship between the suspended sediment expanding and coastal current systems by analyzing the thermal infrared imagery with the sediment imagery, which is acquired by correlating the atmosphere corrected AVHRR imagery with in-situ suspended sediment data. The coastal current systems affecting the sediment dispersal mainly include: the Taiwan Warm Current (TWC), the Huanghai Sea Mixed Water (HSMW), North Jiangsu near-shore current, and Zhejiang near-shore current etc. In winter, the current systems are stable. Their distribution affects the sediment from north Jiangsu expanding toward the Changjiang estuary in some degree .The front between Zhejiang coastal current and TWC blocks the expanding of sediment toward the sea. In the flood season, apart from the limitation by coastal current systems, the spatial and temporal distribution of suspended sediment is also affected by the runoff, which shows as the jet stream and fresh water. Spring and autumn are the transitional periods of the forming of expanding patterns of flood season and winter respectively. In addition, the re-suspended sediment caused by the wind wave may make the expanding range of near-shore sediment larger.
基金supported by the National 973 Program(Grant No.2007CB209608)National 863 Program(Grant No.2007AA06Z218)
文摘Based on analyzing the limit of Ziolkowski's bubble oscillation formulation,a new model with various physical factors is established to simulate air gun signatures fo marine seismic exploration.The practical effects of physical factors,such as heat transfe across the bubble wall,air gun port throttling,vertical rise of the bubble,fluid viscosity,and the existence of the air gun body were all taken into account in the new model.Compared with Ziolkowski's model,the signatures simulated by the new model,with small peak amplitude and rapid decay of bubble oscillation,are more consistent with actual signatures The experiment analysis indicates:(1)gun port throttling controls the peak amplitude of ai gun pulse;(2)since the hydrostatic pressure decreases when the bubble rises,the bubble oscillation period changes;(3)heat transfer and fluid viscosity are the main factors tha explain the bubble oscillation damping.
基金Supported by science and technology foundation project of Xi’an Shiyou University (No. Z06098)China Geological Survey (No. 200314200021)
文摘The form in which a metal exists strongly influences its mobility and thus, the effects on the environment. Operational methods of speciation analysis, such as the use of sequential extraction procedures, are commonly applied. The Dongting Lake, the second largest fresh-water lake in China, contains three China wetlands of international importance, the East Dongting Lake, South Dongting Lake, and West Dongting Lake. In this work, an optimized BCR sequential extraction procedure was used to assess the environmental risk of Cd, Cr, Cu, Ni, Pb and Zn in contaminated sediment of the Dongting Lake. The procedure was evaluated by using a certified reference material, BCR701. The results of the partitioning study indicated that in the lake sediments, more easily mobilized forms (acid exchangeable) were predominant for Cd, particularly in the samples from the East Dongting Lake. In contrast, the largest amount of Pb was associated with the iron and manganese oxide fractions and Cu, Zn, Cr, and Ni analyzed were mainly distributed in residual phase at an average percentage greater than 60% of the total metals. The potential risk to the lake's water contamination was highest in the East Dongting Lake based on the calculated contamination factors. On the other hand, the total metal content was determined as well by inductively coupled plasma and mass spectrometry (ICP-MS) and assessed by using geo-accumulation index. The assessment results using geo-accumulation index were compared with the information on metal speciation. Both were correspondent with each other.
文摘Estuaries and coasts are conjunctions of four spheres (atmosphere, lithosphere, hydrosphere and biosphere) and important matter and energy convergence/divergence zones, where developed economy, dense population and highly intensive exploitation induce adverse environmental changes and serious destruction of resources, which have great impacts on coastal sustainable development, especially as the highly intensive development in river basins has direct and pronounced effects on estuaries and their adjacent coasts. In the new century, China’s estuaries and coast are faced with four main challenges: sharp decrease of sediment discharge into the sea, rapid increase of pollution matter into the sea, loss of coastal wetland, and the impacts of global sea level rise on the coastal lowlands of China. Therefore, it is undoubtedly very important and urgent to carry out studies on estuarine and coastal environmental changes, in order to resolve the issue of national sustainable development, especially that of rational use of coastal zone resources.
基金funded by the National Natural Science Foundation of China (30800119)Doctoral Fund of Ministry of Education of China (200802001011)Youth Scholar grant of Northeast Normal University for Z.H. Tang (120401044)
文摘We investigated the foraging area of three individuals (1 female and 2 males) of Rousettus leschenaulti (Chiroptera,Pteropodidae) in suburban Haikou City, Hainan Province, South China from November 2005 to January 2006 using radio telemetry.These animals left the daytime roosting sites about 90 min after sunset with no significant difference in departure time betweenthe male and female bats. The average active times were 391.8 min for males and 533.7 min for the female, respectively.By reconstructing 93 radio-telemetry recording positions, we found that the long axis of foraging area of the bats ranged from7.45 to 11.70 km. The foraging area of the female (3867 ha) was larger than that of the males (1138 ha), and there was overlapbetween the foraging areas of different individuals. These bats usually kept the same flight routes across a few successive daysfrom the daytime roosting site to the foraging areas. Our findings suggested that female R. leschenaulti may explore a larger foragingarea than males. No obvious territorial behaviors were observed in our studied area.
基金supported by the National Basic Research Program of China(2010CB428902)National Natural Science Foundation of China(40876088)
文摘Relocation of the Yellow River estuary has significant impacts on not only terrestrial environment and human activities, but also sedimentary and ecological environments in coastal seas. The responses of regional geochemical characteristics to the relocation event, however, have not been well studied. In the present study, we performed detailed geochemical elemental analyses of a sediment core from the northern Yellow Sea and studied their geochemical responses to the 1855AD relocation of the Yellow River estuary. The results show that TOC/TN, Co/A1203, Cr/A1203, Ni/A1203 and Se/A1203 ratios all decreased abruptly after 1855 AD, and similar decreases are observed in the sediments of the mud area southwest off the Cheju Island. These abrupt changes are very likely caused by the changes in source materials due to the relocation of the Yellow River estuary from the southern Yellow Sea to the Bohai Sea, which the corresponding decreasing trends caused by the changes in main source materials from those transported by the Liaohe River, the Haihe River and the Luanhe River to those by the Yellow River. Because the events have precise ages recorded in historical archives, these obvious changes in elemental geochemistry of sediments can be used to calibrate age models of related coastal sea sediments.
基金Under the auspices of National Program on Key Basic Research Project(No.2013CB430401)
文摘Reclamation is one of the fastest-growing land use type developed in coastal areas and has caused degradation and loss of coastal wetlands as well as serious environmental problems. This paper was aimed at monitoring the spatiotemporal patterns of coastal wetlands and reclamation in the Yangtze Estuary during the 1960s and 2015. Satellite images obtained from 1980 to 2015 and topography maps of the 1960 s were employed to extract changes of reclamation and coastal wetlands. Area-weight centroids were calculated to identify the movement trend of reclamation and coastal wetlands. The results show that from the 1960 s to 2015, the net area of natural wetlands declined by 574.3 km^2, while man-made wetlands and reclamation increased by 553.6 and 543.9 km^2, respectively. During the five study phases, the fastest areal change rate natural wetlands was –13.3 km^2/yr in the period of 1990–2000, and that of man-made areas was 24.7 km^2/yr in the same period, and the areal change rate of reclamation was 27.6 km^2/yr in the period of 2000–2010. Conversion of coastal wetlands mainly occurred in the Chongming Island, Changshu City and the east coast of Shanghai Municipality. Reclamation was common across coastal areas, and was mainly attributed to settlement and man-made wetlands in the Chongming Island, Lianyungang City and the east coast of Shanghai Municipality. Natural wetlands turned into farmlands and settlement, and man-made wetlands gained from reclamation of farmlands. The centroid of natural wetlands generally moved towards the sea, man-made wetlands expanded equally in all directions and inland, and the centroid of reclamation migrated toward Shanghai Municipality. Sea level rise, erosion-deposition changes, and reclamation activities together determine the dynamics of the Yangtze Estuary wetlands. However, reclamation activities for construction of ports, industries and aquaculture are the key causes for the dynamics. The results from this study on the dynamics of coastal wetlands and reclamation are valuable for local government to put forward sustainable land use and land development plans.
文摘Data taken in the two large-scale ocean investigations in China in winter 1959 and 1982 are used to analyze the residual current off the Changjiang (Yangtze) River mouth in this paper. The current in wintertime off the river mouth consist of the Changjiang runoff, wind-driven current, coastal current, density-driven current and Taiwan Warm Current (TWC). The TWC occurs in wintertime off the mouth. The surface TWC reaches only to the east side of Dinghai, then turns southeastward. The bottom TWC can flow to the area off the Changjiang mouth along west slop of the submerged river valley (SRV) and to the area off the Subei coast. The simulated currents by 3D model are basically consistent with the observed currents, although the model was run with climatological forces and the observations was done in episodic time manner.
基金The work was supported by the National High-tech Research and Development Program of China (863 Program, No. AA633010-05) and key project of Natural Science Foundation of China (No. 50339050)
文摘With the combination of historical data, field observations and satellite remotely sensed images (Landsat TM/ ETM+ and CBERS), changes in Huanghe (Yellow) River estuary since 1996 when artificial Chahe distributary was built up were studied, mainly including water and sediment discharge from the river, tides, tidal currents, suspended sediment diffusion, coastline changes and seabed development. During following six and half years (up to the end of 2002), runoff and sediment loads into the river mouth declined dramatically. At the beginning of the re-routing, abundant sediment loads from the river filled up nearshore shallow water areas so that the newborn delta prograded quickly. With rapid decrease of sediment loads transported to the estuary, the delta retrograded. In 1997, subaerial tip of the abandoned delta receded 1.5km; its annual mean recession rate was about 150 m in following years. In addition, marine dynamic condition near the artificial outlet had also changed. Under the interaction of ocean and river flow, most of incoming sediment loads deposited in the vicin- ity of the outlet. Seabed erosion occurred at the subaqueous delta front. Between 1999 and 2002, erosion thick- ness averaged at 0.3 m in the subaqueous delta of 585.5 km2.