Salt marshes are important carbon and nutrient sinks that are threatened by climate changes and human activities.In this study,the accumulation rates of sedimentary total organic carbon(TOC),total nitrogen(TN),and tot...Salt marshes are important carbon and nutrient sinks that are threatened by climate changes and human activities.In this study,the accumulation rates of sedimentary total organic carbon(TOC),total nitrogen(TN),and total phosphorus(TP)from two cores in the Andong salt marsh,Hangzhou Bay,were investigated to determine whether TOC,TN,and TP show increasing or decreasing trends toward the present.The TOC accumulation rates at the relatively lower marsh were lower during 1990-1996(1.63-2.37 g/(cm^(2)·a))than 1997-2014(1.15-4.30 g/(cm^(2)·a)).The TN accumulation rates increased from 1990(0.14 g/(cm^(2)·a))toward 2012(0.40 g/(cm^(2)·a)),then decreased toward 2014(0.16 g/(cm^(2)·a)).The TP accumulation rates were lower during 1990-1999(0.10-0.21 mg/(cm^(2)·a)),and decreased from 2000(0.32 mg/(cm^(2)·a))toward 2014(0.15 mg/(cm^(2)·a)).The TOC accumulation rates along the relatively upper marsh during 1982-1992(1.18-3.25 g/(cm^(2)·a))were lower than during 1998-2010(2.30-4.20 g/(cm^(2)·a)),and then decreased toward 2015(2.15 g/(cm^(2)·a)).TN increased from 1982(0.18 g/(cm^(2)·a))to 2005(0.41 g/(cm^(2)·a)),then decreased toward 2015(0.22 g/(cm^(2)·a)).TP accumulation rates fluctuated within a narrow range during 1982-1997(0.21-0.41 mg/(cm^(2)·a)),increased from 1998(0.50 mg/(cm^(2)·a))to 2004(0.87 mg/(cm^(2)·a)),then decreased to 2015(0.38 mg/(cm^(2)·a)).Thus,increases in accumulation rates of TOC,TN,and TP from the 1980s to 1990s indicates that the marsh likely served as carbon and nutrient sinks,then the rates decreased during 2000-2015 due probably to the reduced sediment inputs from rivers and intensified sea level rise.展开更多
Salt marshes are among the most important coastal wetlands and provide critical ecological services,including climate regulation,biodiversity maintenance,and blue carbon sequestration.However,most salt marshes worldwi...Salt marshes are among the most important coastal wetlands and provide critical ecological services,including climate regulation,biodiversity maintenance,and blue carbon sequestration.However,most salt marshes worldwide are shrinking,owing to the effects of natural and human factors,such as climate change and artificial reclamation.Therefore,it is essential to understand the decline in the morphological processes of salt marshes,and accordingly,the likely evolution of these marshes,in order to enable measures to be taken to mitigate this decline.To this end,this study presented an extensive systematic review of the current state of morphological models and their application to salt marshes.The emergence of process-based(PB)and data-driven(DD)models has contributed to the development of morphological models.In morphodynamic simulations in PB models,multiple physical and biological factors(e.g.,the hydrodynamics of water bodies,sediment erosion,sediment deposition,and vegetation type)have been considered.The systematic review revealed that PB models have been extended to a broader interdisciplinary field.Further,most DD models are based on remote sensing database for the prediction of morphological characteristics with latent uncertainty.Compared to DD models,PB models are more transparent but can be complex and require a lot of computational power.Therefore,to make up for the shortcomings of each model,future studies could couple PB with DD models that consider vegetation,microorganisms,and benthic animals together to simulate or predict the biogeomorphology of salt marsh systems.Nevertheless,this review found that there is a lack of unified metrics to evaluate model performance,so it is important to define clear objectives,use multiple metrics,compare multiple models,incorporate uncertainty,and involve experts in the field to provide guidance in the further study.展开更多
An experiments were carried out with treatments differing in nitrogen supply （0, 5 and 15 g N/m^2） and CO2 levels （350 and 700 μmol/mol） using OTC （open top chamber） equipment to investigate the biomass of Cala...An experiments were carried out with treatments differing in nitrogen supply （0, 5 and 15 g N/m^2） and CO2 levels （350 and 700 μmol/mol） using OTC （open top chamber） equipment to investigate the biomass of Calamagrostis angustifolia and soil active carbon contents after two years. The results showed that elevated CO2 concentration increased the biomass of C. angustifolia and the magnitude of response varied with each growth period. Elevated CO2 concentration has increased aboveground biomass by 16.7% and 17.6% during the jointing and heading periods and only 3.5% and 9.4% during dough and maturity periods. The increases in belowground biomass due to CO2 elevation was 26.5%, 34.0% and 28.7% during the heading, dough and maturity periods, respectively. The responses of biomass to enhanced CO2 concentrations are differed in N levels. Both the increase of aboveground biomass and belowground biomass were greater under high level of N supply （15 g N/m^2）. Elevated CO2 concentration also increased the allocation of biomass and carbon in root. Under elevated CO2 concentration, the average values of active carbon tended to increase. The increases of soil active soil contents followed the sequence of microbial biomass carbon （10.6%） 〉 dissolved organic carbon （7.5%） 〉 labile oxidable carbon （6.6%） 〉 carbohydrate carbon （4.1%）. Stepwise regressions indicated there were significant correlations between the soil active carbon contents and plant biomass. Particularly, microbial biomass carbon, labile oxidable carbon and carbohydrate carbon were found to be correlated with belowground biomass, while dissolved organic carbon has correlation with aboveground biomass. Therefore, increased biomass was regarded as the main driving force for the increase in soil active organic carbon under elevated CO2 concentration.展开更多
Based on plant specimen data,sediment samples,photos,and sketches from 45 coastal cross-sections,and materials from two recent countrywide comprehensive investigations on Chinese coasts and is-lands,this paper deals w...Based on plant specimen data,sediment samples,photos,and sketches from 45 coastal cross-sections,and materials from two recent countrywide comprehensive investigations on Chinese coasts and is-lands,this paper deals with China’s vegetative tidal-flats:salt marshes and mangrove swamps.Thereare now 141700 acres of salt marshes and 51000 acres of mangrove swamps which together cover about30% of the mud-coast area of the country and distribute between 18°N(Southem Hainan Island)and41°N(Liaodong Bay).Over the past 45 years.about 1750000 acres of salt marshes and 49400 acres ofmangrove swamps have been reclaimed.The2.0×10~9 tons of fine sediments input by rivers into the Chinese seas form extensive tidal flats,the soil basis of coastal helophytes.Different climates result inthe diversity of vegetation.The 3～8m tidal range favors intertidal zone development.Of over 20plant species in the salt marshes,native Suaeda salsa,Phragmites australis,Aeluropus littoralis,Zoysiamaerostachys,Imperata cylindrica and展开更多
Biogenic silica （BSi） contents in the marsh plants （Phragmites australis, Scirpus mariqueter and Spartina alterniflora） and associated sediments in Chongming Island eastern intertidal flat of the Yangtze Estuary w...Biogenic silica （BSi） contents in the marsh plants （Phragmites australis, Scirpus mariqueter and Spartina alterniflora） and associated sediments in Chongming Island eastern intertidal flat of the Yangtze Estuary were determined. The BSi contents in P. australis, S. mariqueter and S. alterniflora varied from 25.78–42.74 mg/g, 5.71–19.53 mg/g and 6.71–8.92 mg/g, respectively. Over the entire growth season, P. australis and S. mariqueter were characterized by linear accumulation patterns of BSi. The aboveground biomass （leaves and culms） of the marsh plants generally contained more BSi than underground biomass （roots）. BSi contents were relatively higher in dead plant tissues than in live tissues which was probably due to the decomposition and the leaching of labile components of plant tissues such as organic carbon and nitrogen. Comparing with the habitats of S. mariqueter and S. alterniflora, the highest BSi content was recorded in sediments inhabited by P. australis, with an annual average of 15.69 mg/g. Overall, the intertidal marshes in the Yangtze Estuary may act as a net sink of BSi via plant uptake and sedimentary burial.展开更多
基金Supported by the Zhejiang University Self Program Fund for the Research of Heavy Metal Geochemical Characteristics in Sediments of Hangzhou Baythe Zhejiang University Fundamental Research Funds for the Central Universities(No.2013QNA4037)+1 种基金the National Key Research and Development Plan of China(No.2016YFC1401603)the National Natural Science Foundation of China(No.41876031)。
文摘Salt marshes are important carbon and nutrient sinks that are threatened by climate changes and human activities.In this study,the accumulation rates of sedimentary total organic carbon(TOC),total nitrogen(TN),and total phosphorus(TP)from two cores in the Andong salt marsh,Hangzhou Bay,were investigated to determine whether TOC,TN,and TP show increasing or decreasing trends toward the present.The TOC accumulation rates at the relatively lower marsh were lower during 1990-1996(1.63-2.37 g/(cm^(2)·a))than 1997-2014(1.15-4.30 g/(cm^(2)·a)).The TN accumulation rates increased from 1990(0.14 g/(cm^(2)·a))toward 2012(0.40 g/(cm^(2)·a)),then decreased toward 2014(0.16 g/(cm^(2)·a)).The TP accumulation rates were lower during 1990-1999(0.10-0.21 mg/(cm^(2)·a)),and decreased from 2000(0.32 mg/(cm^(2)·a))toward 2014(0.15 mg/(cm^(2)·a)).The TOC accumulation rates along the relatively upper marsh during 1982-1992(1.18-3.25 g/(cm^(2)·a))were lower than during 1998-2010(2.30-4.20 g/(cm^(2)·a)),and then decreased toward 2015(2.15 g/(cm^(2)·a)).TN increased from 1982(0.18 g/(cm^(2)·a))to 2005(0.41 g/(cm^(2)·a)),then decreased toward 2015(0.22 g/(cm^(2)·a)).TP accumulation rates fluctuated within a narrow range during 1982-1997(0.21-0.41 mg/(cm^(2)·a)),increased from 1998(0.50 mg/(cm^(2)·a))to 2004(0.87 mg/(cm^(2)·a)),then decreased to 2015(0.38 mg/(cm^(2)·a)).Thus,increases in accumulation rates of TOC,TN,and TP from the 1980s to 1990s indicates that the marsh likely served as carbon and nutrient sinks,then the rates decreased during 2000-2015 due probably to the reduced sediment inputs from rivers and intensified sea level rise.
基金supported by the National Natural Science Foundation of China(Grant No.U2040204)the Jiangsu Provincial Natural Science Foundation of China(Grants No.BK2020020,BK20220979,and BK20220993)the Fundamental Research Funds for the Central University(Grant No.B220202057).
文摘Salt marshes are among the most important coastal wetlands and provide critical ecological services,including climate regulation,biodiversity maintenance,and blue carbon sequestration.However,most salt marshes worldwide are shrinking,owing to the effects of natural and human factors,such as climate change and artificial reclamation.Therefore,it is essential to understand the decline in the morphological processes of salt marshes,and accordingly,the likely evolution of these marshes,in order to enable measures to be taken to mitigate this decline.To this end,this study presented an extensive systematic review of the current state of morphological models and their application to salt marshes.The emergence of process-based(PB)and data-driven(DD)models has contributed to the development of morphological models.In morphodynamic simulations in PB models,multiple physical and biological factors(e.g.,the hydrodynamics of water bodies,sediment erosion,sediment deposition,and vegetation type)have been considered.The systematic review revealed that PB models have been extended to a broader interdisciplinary field.Further,most DD models are based on remote sensing database for the prediction of morphological characteristics with latent uncertainty.Compared to DD models,PB models are more transparent but can be complex and require a lot of computational power.Therefore,to make up for the shortcomings of each model,future studies could couple PB with DD models that consider vegetation,microorganisms,and benthic animals together to simulate or predict the biogeomorphology of salt marsh systems.Nevertheless,this review found that there is a lack of unified metrics to evaluate model performance,so it is important to define clear objectives,use multiple metrics,compare multiple models,incorporate uncertainty,and involve experts in the field to provide guidance in the further study.
基金supported by the Chinese Academy of Sciences (No KZCX2-YW-309)the National Basic Research Program (973) of China (No 2004CB418507)
文摘An experiments were carried out with treatments differing in nitrogen supply （0, 5 and 15 g N/m^2） and CO2 levels （350 and 700 μmol/mol） using OTC （open top chamber） equipment to investigate the biomass of Calamagrostis angustifolia and soil active carbon contents after two years. The results showed that elevated CO2 concentration increased the biomass of C. angustifolia and the magnitude of response varied with each growth period. Elevated CO2 concentration has increased aboveground biomass by 16.7% and 17.6% during the jointing and heading periods and only 3.5% and 9.4% during dough and maturity periods. The increases in belowground biomass due to CO2 elevation was 26.5%, 34.0% and 28.7% during the heading, dough and maturity periods, respectively. The responses of biomass to enhanced CO2 concentrations are differed in N levels. Both the increase of aboveground biomass and belowground biomass were greater under high level of N supply （15 g N/m^2）. Elevated CO2 concentration also increased the allocation of biomass and carbon in root. Under elevated CO2 concentration, the average values of active carbon tended to increase. The increases of soil active soil contents followed the sequence of microbial biomass carbon （10.6%） 〉 dissolved organic carbon （7.5%） 〉 labile oxidable carbon （6.6%） 〉 carbohydrate carbon （4.1%）. Stepwise regressions indicated there were significant correlations between the soil active carbon contents and plant biomass. Particularly, microbial biomass carbon, labile oxidable carbon and carbohydrate carbon were found to be correlated with belowground biomass, while dissolved organic carbon has correlation with aboveground biomass. Therefore, increased biomass was regarded as the main driving force for the increase in soil active organic carbon under elevated CO2 concentration.
基金The project was supported by the NSFC(No.49476281)
文摘Based on plant specimen data,sediment samples,photos,and sketches from 45 coastal cross-sections,and materials from two recent countrywide comprehensive investigations on Chinese coasts and is-lands,this paper deals with China’s vegetative tidal-flats:salt marshes and mangrove swamps.Thereare now 141700 acres of salt marshes and 51000 acres of mangrove swamps which together cover about30% of the mud-coast area of the country and distribute between 18°N(Southem Hainan Island)and41°N(Liaodong Bay).Over the past 45 years.about 1750000 acres of salt marshes and 49400 acres ofmangrove swamps have been reclaimed.The2.0×10~9 tons of fine sediments input by rivers into the Chinese seas form extensive tidal flats,the soil basis of coastal helophytes.Different climates result inthe diversity of vegetation.The 3～8m tidal range favors intertidal zone development.Of over 20plant species in the salt marshes,native Suaeda salsa,Phragmites australis,Aeluropus littoralis,Zoysiamaerostachys,Imperata cylindrica and
基金supported by the National Natural Science Foundation of China (No. 40701167, 40671171)the Doctoral Program Foundation of Ministry of Education of China (No. 20070269006)the State Key Laboratory of Estuarine and Coastal Research (No. 2008KYQN01,2008KYYW07)
文摘Biogenic silica （BSi） contents in the marsh plants （Phragmites australis, Scirpus mariqueter and Spartina alterniflora） and associated sediments in Chongming Island eastern intertidal flat of the Yangtze Estuary were determined. The BSi contents in P. australis, S. mariqueter and S. alterniflora varied from 25.78–42.74 mg/g, 5.71–19.53 mg/g and 6.71–8.92 mg/g, respectively. Over the entire growth season, P. australis and S. mariqueter were characterized by linear accumulation patterns of BSi. The aboveground biomass （leaves and culms） of the marsh plants generally contained more BSi than underground biomass （roots）. BSi contents were relatively higher in dead plant tissues than in live tissues which was probably due to the decomposition and the leaching of labile components of plant tissues such as organic carbon and nitrogen. Comparing with the habitats of S. mariqueter and S. alterniflora, the highest BSi content was recorded in sediments inhabited by P. australis, with an annual average of 15.69 mg/g. Overall, the intertidal marshes in the Yangtze Estuary may act as a net sink of BSi via plant uptake and sedimentary burial.
