2024 Vol. 46, No. 3
Display Method:
2024, 46(3): .
Abstract:
2024, 46(3): 1-11.
doi: 10.12284/hyxb2024014
Abstract:
Reliable assessment of the impact and risk of typhoons on coastal areas is very important for scientific resistance to typhoon disasters. China has a detailed typhoon observation record with a history of only 60 years, which makes it limited in estimating extreme wind speed with a long recurrence period and corresponding extreme wave height and tide level. The insufficient records also limits the application of data-driven models in typhoon disaster prediction. Therefore, it is necessary to construct synthetic typhoons based on the actual typhoon travel law to overcome the problem of insufficient historical observations. In this paper, 18 671 synthetic typhoons were constructed in the Northwest Pacific Ocean by using the Empirical Path Model based on kernel density estimation, and the parameters such as the start and end position, frequency of occurrence, travel speed and direction of the synthetic typhoons were statistically compared and analyzed with historical typhoons. The results show that the synthetic typhoon constructed based on the proposed method is generally consistent with the traveling characteristics of historical typhoons in the Northwest Pacific Ocean. Through the construction of these synthetic typhoons, a synthetic typhoon database with sufficient data and reliable performance can be provided for the study of extreme wave and storm surge along the coast of China.
Reliable assessment of the impact and risk of typhoons on coastal areas is very important for scientific resistance to typhoon disasters. China has a detailed typhoon observation record with a history of only 60 years, which makes it limited in estimating extreme wind speed with a long recurrence period and corresponding extreme wave height and tide level. The insufficient records also limits the application of data-driven models in typhoon disaster prediction. Therefore, it is necessary to construct synthetic typhoons based on the actual typhoon travel law to overcome the problem of insufficient historical observations. In this paper, 18 671 synthetic typhoons were constructed in the Northwest Pacific Ocean by using the Empirical Path Model based on kernel density estimation, and the parameters such as the start and end position, frequency of occurrence, travel speed and direction of the synthetic typhoons were statistically compared and analyzed with historical typhoons. The results show that the synthetic typhoon constructed based on the proposed method is generally consistent with the traveling characteristics of historical typhoons in the Northwest Pacific Ocean. Through the construction of these synthetic typhoons, a synthetic typhoon database with sufficient data and reliable performance can be provided for the study of extreme wave and storm surge along the coast of China.
2024, 46(3): 12-21.
doi: 10.12284/hyxb2024008
Abstract:
There are also obvious inter-annual variations of the North Equatorial Countercurrent (NECC) during the occurrence and development of the El Niño-Southern Oscillation (ENSO), but its changing process in hydroecological conditions and response mechanism influenced by ENSO cycle are still unclear. Taking the NECC affected area in the tropical western Pacific as the study area, this paper analyzes the characteristics of the changes of hydroecoclimatic conditions at different stages during the ENSO cycle during autumn and winter transition period from 2006 to 2022. Results reveal that there are high chlorophyll concentration bands in the NECC source area and its path, which are formed by the combined influence of nutrients carried by the NECC from its source area and the New Guinea Coastal Undercurrent. The upwelling of the Mindanao Dome also has a great influence on the nutrient supply. When El Niño events occurred, the westerly wind events in the tropical western Pacific increased, the NECC strengthened, a large amount of surface water moved eastward, the sea level in the study area decreased, the deep water recharge to the shallow layer increased, and the deep cold water rose. The jointly enhanced NECC, New Guinea Coastal Current, New Guinea Coastal Undercurrent and Mindanao Dome upwelling transport more nutrients to the sea surface from both horizontal and vertical levels, resulting in significant increases in surface chlorophyll concentration and primary organic carbon production by all types of phytoplankton. When La Niña events occurred, the changes of ecohydroclimatic conditions in the NECC affected area are almost opposite to those during El Niño events, but the degree of change is weaker than that during El Nino events. The combined weakening of the NECC, the New Guinea Coastal Undercurrent and the Mindanao Dome upwelling significantly reduce the nutrients delivered to the sea surface from the horizontal and vertical levels. The chlorophyll concentration and primary organic carbon production by all types of phytoplankton decreased significantly. This paper proposes a model of the response mechanism of the evolution of hydroecoclimatic conditions in the NECC affected area to El Niño and La Niña events, which is conducive to further analysis of the role of ENSO cycle in local ecological effects and hydroclimatic evolution. It has important significance for understanding the impact of global climate change on the material cycle.
There are also obvious inter-annual variations of the North Equatorial Countercurrent (NECC) during the occurrence and development of the El Niño-Southern Oscillation (ENSO), but its changing process in hydroecological conditions and response mechanism influenced by ENSO cycle are still unclear. Taking the NECC affected area in the tropical western Pacific as the study area, this paper analyzes the characteristics of the changes of hydroecoclimatic conditions at different stages during the ENSO cycle during autumn and winter transition period from 2006 to 2022. Results reveal that there are high chlorophyll concentration bands in the NECC source area and its path, which are formed by the combined influence of nutrients carried by the NECC from its source area and the New Guinea Coastal Undercurrent. The upwelling of the Mindanao Dome also has a great influence on the nutrient supply. When El Niño events occurred, the westerly wind events in the tropical western Pacific increased, the NECC strengthened, a large amount of surface water moved eastward, the sea level in the study area decreased, the deep water recharge to the shallow layer increased, and the deep cold water rose. The jointly enhanced NECC, New Guinea Coastal Current, New Guinea Coastal Undercurrent and Mindanao Dome upwelling transport more nutrients to the sea surface from both horizontal and vertical levels, resulting in significant increases in surface chlorophyll concentration and primary organic carbon production by all types of phytoplankton. When La Niña events occurred, the changes of ecohydroclimatic conditions in the NECC affected area are almost opposite to those during El Niño events, but the degree of change is weaker than that during El Nino events. The combined weakening of the NECC, the New Guinea Coastal Undercurrent and the Mindanao Dome upwelling significantly reduce the nutrients delivered to the sea surface from the horizontal and vertical levels. The chlorophyll concentration and primary organic carbon production by all types of phytoplankton decreased significantly. This paper proposes a model of the response mechanism of the evolution of hydroecoclimatic conditions in the NECC affected area to El Niño and La Niña events, which is conducive to further analysis of the role of ENSO cycle in local ecological effects and hydroclimatic evolution. It has important significance for understanding the impact of global climate change on the material cycle.
2024, 46(3): 22-32.
doi: 10.12284/hyxb2024004
Abstract:
Natural gas hydrates have received widespread attention due to their enormous resource potential, but previous researches have focused mostly on the passive continental margin in the northern South China Sea, while rarely on the active continental margin in the eastern South China Sea. Based on the analysis of multi-channel seismic profiles in the active continental margin area of the Manila Trench in northeast of the South China Sea, this paper identified typical gas hydrate indicators such as bottom simulating reflector, blanking zone, polarity-reversal, and fluid migration channels, such as reverse fault and mud diapir are identified in this paper. The Orogenic Belt in southwestern Taiwan is an extension of the accretionary wedge of the Manila Trench. The associated gas of mud volcano is mainly CH4 and minorly showing high nitrogen anomaly. The geochemical characteristics of the associated gas show that natural gas in this area is mainly mature hydrocarbon gas of pyrolysis origin, and is mainly the contribution of Neogene thick marine sedimentary source rock. According to the analysis, the cause is that the plate subduction brought deep hydrocarbon into the accretionary wedge and formed a high-pressure environment. The thermally generated hydrocarbon gas migrated upward along mud diapir and reverse fault. During the migration, some natural gas was gradually transformed by decomposition of microorganisms and mixed with in-situ microbial gas. The thermogenic and biogenic methane eventually mixed in the suitable stable zone to form a mixed gas hydrate reservoir dominated by thermogenic and partly biogenic. In addition, with the change of external environment and the continuous activities of subduction movement, the stability of natural gas hydrate is damaged and decomposition leakage occurs, which may cause landslide. In the further exploration and development of natural gas hydrate resources in this area, we must pay attention to the potential geological disaster risk.
Natural gas hydrates have received widespread attention due to their enormous resource potential, but previous researches have focused mostly on the passive continental margin in the northern South China Sea, while rarely on the active continental margin in the eastern South China Sea. Based on the analysis of multi-channel seismic profiles in the active continental margin area of the Manila Trench in northeast of the South China Sea, this paper identified typical gas hydrate indicators such as bottom simulating reflector, blanking zone, polarity-reversal, and fluid migration channels, such as reverse fault and mud diapir are identified in this paper. The Orogenic Belt in southwestern Taiwan is an extension of the accretionary wedge of the Manila Trench. The associated gas of mud volcano is mainly CH4 and minorly showing high nitrogen anomaly. The geochemical characteristics of the associated gas show that natural gas in this area is mainly mature hydrocarbon gas of pyrolysis origin, and is mainly the contribution of Neogene thick marine sedimentary source rock. According to the analysis, the cause is that the plate subduction brought deep hydrocarbon into the accretionary wedge and formed a high-pressure environment. The thermally generated hydrocarbon gas migrated upward along mud diapir and reverse fault. During the migration, some natural gas was gradually transformed by decomposition of microorganisms and mixed with in-situ microbial gas. The thermogenic and biogenic methane eventually mixed in the suitable stable zone to form a mixed gas hydrate reservoir dominated by thermogenic and partly biogenic. In addition, with the change of external environment and the continuous activities of subduction movement, the stability of natural gas hydrate is damaged and decomposition leakage occurs, which may cause landslide. In the further exploration and development of natural gas hydrate resources in this area, we must pay attention to the potential geological disaster risk.
2024, 46(3): 33-53.
doi: 10.12284/hyxb2023172
Abstract:
The coastal plain of Jiangsu Province is a fragile zone of water resources in Jiangsu Province, and groundwater salinization has become a serious ecological problem. In order to analyze the groundwater recharge and its salinity sources in the north flank of the Changjiang River Delta since Pleistocene, a 275 m deep well HYRD1 was deployed and the whole hole was continuously collected with easily soluble salt samples, geotechnical samples and water samples. Surface water, shallow and deep groundwater, and seawater samples were collected in the area. The hydrochemical characteristics of Well HYRD1 high-precision porewater were obtained by using soluble salt index combined with geotechnical index (water content, wet density, specific gravity). In order to analyze the groundwater recharge and its salt source since Pleistocene, Piper trilinear diagram, Gibbs diagram and ion ratio method were used in combination with δD and δ18O data and 14C data. The results show that the salinity of Well HYRD1 soil is mainly NaCl, and the percentage of saline soil is 25%. The saline soils are mainly distributed in the Qp3 aquitard, Qp2 stratum and the upper part of Qp1 stratum. The water chemistry type of porewater is Cl-Na type (only the lower section of Qp1 is HCO\begin{document}$_3^- $\end{document} ![]()
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The coastal plain of Jiangsu Province is a fragile zone of water resources in Jiangsu Province, and groundwater salinization has become a serious ecological problem. In order to analyze the groundwater recharge and its salinity sources in the north flank of the Changjiang River Delta since Pleistocene, a 275 m deep well HYRD1 was deployed and the whole hole was continuously collected with easily soluble salt samples, geotechnical samples and water samples. Surface water, shallow and deep groundwater, and seawater samples were collected in the area. The hydrochemical characteristics of Well HYRD1 high-precision porewater were obtained by using soluble salt index combined with geotechnical index (water content, wet density, specific gravity). In order to analyze the groundwater recharge and its salt source since Pleistocene, Piper trilinear diagram, Gibbs diagram and ion ratio method were used in combination with δD and δ18O data and 14C data. The results show that the salinity of Well HYRD1 soil is mainly NaCl, and the percentage of saline soil is 25%. The saline soils are mainly distributed in the Qp3 aquitard, Qp2 stratum and the upper part of Qp1 stratum. The water chemistry type of porewater is Cl-Na type (only the lower section of Qp1 is HCO
2024, 46(3): 54-65.
doi: 10.12284/hyxb2024038
Abstract:
To understand the characteristics and distribution of benthic shellfish communities in the vicinity of the Nanji Islands, we conducted bottom trawl surveys in the surrounding waters during October 2022 (autumn) and March 2023 (spring). The findings reveal that a total of 49 benthic shellfish species were captured, spanning 2 classes, 6 orders, and 17 families. During spring, the average abundance of benthic shellfish was (2 429 ± 2 038) ind./Agt, with an average biomass of (4 849.79 ± 2 513.84) g/Agt. In autumn, the average abundance was (1 149 ± 1 589) ind./Agt, with an average biomass of (4 985.30 ± 2 159.23) g/Agt. The primary dominant species comprised Turritella bacillum, Murex trapa, Tegillarca nodifera, Inquisitor jeffreysii, Bufonaria rana, Cancellaria sinensis and Trigonaphera bocageana. Notably, Turritella bacillum emerged as a dominant species in both spring and autumn, with dominance significantly surpassing that of other species. The dominance of benthic shellfish communities in this marine area appears relatively stable, with the community’s functionality and nature being primarily governed by a select few species. This study provides a reference basis for the dynamic changes in the marine ecosystem of the Nanji Islands and offers foundational data for the protection of marine ecological environments.
To understand the characteristics and distribution of benthic shellfish communities in the vicinity of the Nanji Islands, we conducted bottom trawl surveys in the surrounding waters during October 2022 (autumn) and March 2023 (spring). The findings reveal that a total of 49 benthic shellfish species were captured, spanning 2 classes, 6 orders, and 17 families. During spring, the average abundance of benthic shellfish was (2 429 ± 2 038) ind./Agt, with an average biomass of (4 849.79 ± 2 513.84) g/Agt. In autumn, the average abundance was (1 149 ± 1 589) ind./Agt, with an average biomass of (4 985.30 ± 2 159.23) g/Agt. The primary dominant species comprised Turritella bacillum, Murex trapa, Tegillarca nodifera, Inquisitor jeffreysii, Bufonaria rana, Cancellaria sinensis and Trigonaphera bocageana. Notably, Turritella bacillum emerged as a dominant species in both spring and autumn, with dominance significantly surpassing that of other species. The dominance of benthic shellfish communities in this marine area appears relatively stable, with the community’s functionality and nature being primarily governed by a select few species. This study provides a reference basis for the dynamic changes in the marine ecosystem of the Nanji Islands and offers foundational data for the protection of marine ecological environments.
2024, 46(3): 66-74.
doi: 10.12284/hyxb2024052
Abstract:
Based on the survey data of fishery resources and environment of four voyages from April 2021 to January 2022, the spatial and temporal distribution of Portunus trituberculatus and its relationship with influencing factors in the Ruian sea area were studied, including its marine dominance, community structure and resource density distribution. At the same time, generalized additive model (GAM) is used to analyze the relationship between resource density and influencing factors. The results showed that: in the Ruian sea area, P. trituberculatus is an important species (100 ≤ IRI < 1 000) in spring and summer and a dominant species (IRI ≥ 1 000) in autumn and winter. The average carapace length and body weight of P. trituberculatus ranged from 33.9 mm to 60.4 mm, and 22.9 g to 126.1 g. The carapace length and body weight of P. trituberculatus were the highest in summer and the lowest in autumn. There were significant differences between different seasons. P. trituberculatus showed negative allometric growth in spring, summer and winter (b < 3), and positive allometric growth in autumn (b > 3). The average resource density of P. trituberculatus ranged from 16.57 kg/km2 to 422.60 kg/km2, with the highest in autumn and the lowest in spring, and the average resource density in autumn was 25.5 times of that in spring. GAM analysis showed that the interpretation rate of the model was 80.2%. Season, surface water temperature, bottom water temperature, bottom salinity and surface chlorophyll a concentration had significant effects on the resource density of P. trituberculatus (p < 0.05), among which season had the greatest effect. Through this study, it provides reference for grasping the dynamic change law of P. trituberculatus resources in Ruian sea area, and further provides theoretical support for the proliferation and release of P. trituberculatus.
Based on the survey data of fishery resources and environment of four voyages from April 2021 to January 2022, the spatial and temporal distribution of Portunus trituberculatus and its relationship with influencing factors in the Ruian sea area were studied, including its marine dominance, community structure and resource density distribution. At the same time, generalized additive model (GAM) is used to analyze the relationship between resource density and influencing factors. The results showed that: in the Ruian sea area, P. trituberculatus is an important species (100 ≤ IRI < 1 000) in spring and summer and a dominant species (IRI ≥ 1 000) in autumn and winter. The average carapace length and body weight of P. trituberculatus ranged from 33.9 mm to 60.4 mm, and 22.9 g to 126.1 g. The carapace length and body weight of P. trituberculatus were the highest in summer and the lowest in autumn. There were significant differences between different seasons. P. trituberculatus showed negative allometric growth in spring, summer and winter (b < 3), and positive allometric growth in autumn (b > 3). The average resource density of P. trituberculatus ranged from 16.57 kg/km2 to 422.60 kg/km2, with the highest in autumn and the lowest in spring, and the average resource density in autumn was 25.5 times of that in spring. GAM analysis showed that the interpretation rate of the model was 80.2%. Season, surface water temperature, bottom water temperature, bottom salinity and surface chlorophyll a concentration had significant effects on the resource density of P. trituberculatus (p < 0.05), among which season had the greatest effect. Through this study, it provides reference for grasping the dynamic change law of P. trituberculatus resources in Ruian sea area, and further provides theoretical support for the proliferation and release of P. trituberculatus.
Evaluation of benthic ecological quality status in the Yalu River Estuary based on environmental DNA
2024, 46(3): 75-88.
doi: 10.12284/hyxb2024058
Abstract:
Investigating the potential for application of environmental DNA to identify benthic organisms for evaluating ecological quality status collection of 17 benthic samples from the Yalu River Estuary, environmental DNA and morphological identification and comparative analyses of the resulting ecological quality assessment indices (AMBI, BENTIX, Shannon-Wiener H', M-AMBI) were used, respectively. The results show: environmental DNA identification of organisms belonging to 10 class, 16 orders, 19 families, 20 genera and 22 species, morphological identification of organisms belonging to 9 class, 27 orders, 43 families, 55 genera and 57 species, with a total of 10 organisms; the two methods of identification yielded AMBI inter-index (R = 0.428, p = 0.043, y = 0.32x + 1.08), BENTIX inter-exponential (R = 0.430, p = 0.043, y = 0.28x + 3.59) significant consistency exists, while there was significant difference between the Shannon-Wiener H' indices; the two methods of identification yielded AMBI intergrade, M-AMBI intergrade higher similarity, 51.02%, 44.90%, respectively; the AMBI and M-AMBI grades from the two identification methods were more in line with the actual situation and evaluated the overall ecological quality status of the Yalu River Estuary as good. This study demonstrates that the identification of benthic organisms based on environmental DNA to evaluate the ecological quality status has a high potential for application in marine environmental monitoring surveys.
Investigating the potential for application of environmental DNA to identify benthic organisms for evaluating ecological quality status collection of 17 benthic samples from the Yalu River Estuary, environmental DNA and morphological identification and comparative analyses of the resulting ecological quality assessment indices (AMBI, BENTIX, Shannon-Wiener H', M-AMBI) were used, respectively. The results show: environmental DNA identification of organisms belonging to 10 class, 16 orders, 19 families, 20 genera and 22 species, morphological identification of organisms belonging to 9 class, 27 orders, 43 families, 55 genera and 57 species, with a total of 10 organisms; the two methods of identification yielded AMBI inter-index (R = 0.428, p = 0.043, y = 0.32x + 1.08), BENTIX inter-exponential (R = 0.430, p = 0.043, y = 0.28x + 3.59) significant consistency exists, while there was significant difference between the Shannon-Wiener H' indices; the two methods of identification yielded AMBI intergrade, M-AMBI intergrade higher similarity, 51.02%, 44.90%, respectively; the AMBI and M-AMBI grades from the two identification methods were more in line with the actual situation and evaluated the overall ecological quality status of the Yalu River Estuary as good. This study demonstrates that the identification of benthic organisms based on environmental DNA to evaluate the ecological quality status has a high potential for application in marine environmental monitoring surveys.
2024, 46(3): 89-97.
doi: 10.12284/hyxb2024050
Abstract:
Planktonic copepods is an important group of zooplankton. It is of great significance to study the distribution characteristics of planktonic copepods abundance and its correlation with various environmental indicators. In this study, we analyzed environmental monitoring data of Haizhou Bay, Lianyungang, Jiangsu Province, from 2003 to 2022 using generalized additive model (GAM), to investigate the spatiotemporal variation of planktonic copepods and its correlation with other sea water indicators. The results showed that the abundance of planktonic copepods varied significantly different between seasons (p < 0.01), and the mean value of copepods was greater in spring than in summer than in autumn. The spatial distribution of abundance was generally low in the artificial reef area and high in the southern coastal area. GAM analysis showed that the main influencing factors were different between seasons. The main influencing factors in spring were dissolved oxygen, chlorophyll a concentration,\begin{document}${\mathrm{SiO}}_3^- $\end{document} ![]()
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Planktonic copepods is an important group of zooplankton. It is of great significance to study the distribution characteristics of planktonic copepods abundance and its correlation with various environmental indicators. In this study, we analyzed environmental monitoring data of Haizhou Bay, Lianyungang, Jiangsu Province, from 2003 to 2022 using generalized additive model (GAM), to investigate the spatiotemporal variation of planktonic copepods and its correlation with other sea water indicators. The results showed that the abundance of planktonic copepods varied significantly different between seasons (p < 0.01), and the mean value of copepods was greater in spring than in summer than in autumn. The spatial distribution of abundance was generally low in the artificial reef area and high in the southern coastal area. GAM analysis showed that the main influencing factors were different between seasons. The main influencing factors in spring were dissolved oxygen, chlorophyll a concentration,
2024, 46(3): 98-110.
doi: 10.12284/hyxb2024042
Abstract:
In order to explore the relationship between zooplankton community structure and environmental factors in the Oujiang River Estuary, four voyages were conducted in March (winter), May (spring), August (summer) and November (autumn) in 2021 to investigate the zooplankton and other environmental factors such as sea temperature, salinity and chlorophyll a concentration in the Oujiang River Estuary sea area. The results show that 78 species of zooplankton are identified, including 16 species of larva, it belongs to 8 classes and 14 categories , with the highest number of species in summer (47 species) and the lowest number in winter (23 species). The dominant species (Y ≥ 0.02) include Calanus sinicus, Sinocalanus sinensis, Acartia pacifica, and Centropages dorsispinatus, 17 species. The average annual abundance of zooplankton is (162.95 ± 310.96) ind./m3, and the average annual biomass is (118.85 ± 62.80) mg/m3. The abundance and biomass of zooplankton are the highest in spring and the lowest in autumn. The abundance in winter is higher than that in summer, and the biomass is lower than that in summer. The average annual Shannon-Wiener diversity index (H'), Pielou evenness index (J') and Margalef richness index (D) are 1.500 ± 0.702, 0.656 ± 0.270 and 2.301 ± 1.087, respectively. Spearman correlation analysis and canonical correspondence analysis show that sea temperature, salinity, Chl a concentration and phytoplankton abundance are important environmental factors affecting the dominant abundance of zooplankton in the Oujiang River Estuary. It provides scientific reference for the study on the influence of seasonal environmental changes on zooplankton in the Oujiang River Estuary, and provides basic data and theoretical basis for the sustainable development of biological resources in the Oujiang River Estuary.
In order to explore the relationship between zooplankton community structure and environmental factors in the Oujiang River Estuary, four voyages were conducted in March (winter), May (spring), August (summer) and November (autumn) in 2021 to investigate the zooplankton and other environmental factors such as sea temperature, salinity and chlorophyll a concentration in the Oujiang River Estuary sea area. The results show that 78 species of zooplankton are identified, including 16 species of larva, it belongs to 8 classes and 14 categories , with the highest number of species in summer (47 species) and the lowest number in winter (23 species). The dominant species (Y ≥ 0.02) include Calanus sinicus, Sinocalanus sinensis, Acartia pacifica, and Centropages dorsispinatus, 17 species. The average annual abundance of zooplankton is (162.95 ± 310.96) ind./m3, and the average annual biomass is (118.85 ± 62.80) mg/m3. The abundance and biomass of zooplankton are the highest in spring and the lowest in autumn. The abundance in winter is higher than that in summer, and the biomass is lower than that in summer. The average annual Shannon-Wiener diversity index (H'), Pielou evenness index (J') and Margalef richness index (D) are 1.500 ± 0.702, 0.656 ± 0.270 and 2.301 ± 1.087, respectively. Spearman correlation analysis and canonical correspondence analysis show that sea temperature, salinity, Chl a concentration and phytoplankton abundance are important environmental factors affecting the dominant abundance of zooplankton in the Oujiang River Estuary. It provides scientific reference for the study on the influence of seasonal environmental changes on zooplankton in the Oujiang River Estuary, and provides basic data and theoretical basis for the sustainable development of biological resources in the Oujiang River Estuary.
2024, 46(3): 111-117.
doi: 10.12284/hyxb2024040
Abstract:
Spaceborne synthetic aperture radar (SAR) is able to collect observations under all kinds of weather during day and night. Such measurements have been proven to provide significant data support for the ocean dynamics study. While SAR imaging of ocean waves is a highly nonlinear process, leading the wave signal missing along the azimuth direction. The image cross-spectrum provides a way to help investigate the ocean wave features particularly for their propagation direction. In this study, we extended a recently defined parameter based on SAR image cross-spectrum and analyzed the correlation of different wave scales with the local wind speed. The range peak wavenumber (wavelength) extracted from the range spectral profile is also demonstrated at the global scale based on about 4 million SAR images. It is found that this new spectral parameter could to some extent reflect the coupling between wind and waves. The global pattern of range peak wavenumber also illustrates evident seasonality.
Spaceborne synthetic aperture radar (SAR) is able to collect observations under all kinds of weather during day and night. Such measurements have been proven to provide significant data support for the ocean dynamics study. While SAR imaging of ocean waves is a highly nonlinear process, leading the wave signal missing along the azimuth direction. The image cross-spectrum provides a way to help investigate the ocean wave features particularly for their propagation direction. In this study, we extended a recently defined parameter based on SAR image cross-spectrum and analyzed the correlation of different wave scales with the local wind speed. The range peak wavenumber (wavelength) extracted from the range spectral profile is also demonstrated at the global scale based on about 4 million SAR images. It is found that this new spectral parameter could to some extent reflect the coupling between wind and waves. The global pattern of range peak wavenumber also illustrates evident seasonality.
2024, 46(3): 118-128.
doi: 10.12284/hyxb2024054
Abstract:
The deposition fluxes of 210Po, 210Bi and 210Pb in atmosphere are the basis for the application of radionuclide tracing in the ocean. In order to reveal the spatio-temporal variation of the activity of 210Po, 210Bi and 210Pb in nearshore areas and estimate their deposition fluxes into the sea, in this paper, sampling observation and analysis of two typical areas near the East China Sea in Shanghai and Xiamen in different periods are carried out. A time series study was conducted on the the aerosol activities of 210Po, 210Pb and 210Bi in Shanghai and Xiamen from September 2016 to February 2017 and from September to November 2021, respectively. The residence time of aerosol particle was calculated based on 210Po/210Pb and 210Bi/210Pb. Deposition fluxes of three nuclides were also estimated. This paper reported the activity of 210Po, 210Bi and 210Pb in Shanghai in autumn and winter of 2016. The activity ranges of 210Po, 210Pb and 210Bi were 0.11−1.27 mBq/m3, 0.45−1.83 mBq/m3 and 1.12−6.10 mBq/m3, respectively. In the fall of 2021, the activity ranges of 210Po, 210Bi and 210Pb in Xiamen were 0.05−0.85 mBq/m3, 0.83−2.52 mBq/m3 and 0.17−1.32 mBq/m3, respectively. The aerosol activity of each nuclide in Shanghai was higher than that in Xiamen. The estimated residence time based on 210Po-210Pb and 210Bi-210Pb methods are significantly different, for example, in Shanghai area, the averaged aerosol residence time based on 210Po-210Pb method was calculated to be (94 ± 54) d, which is much higher than the result from 210Bi-210Pb method. The main reason for this difference is most likely due to the difference in the properties of the tracing isotopes we used. In this paper, based on a one-dimensional simple aerosol deposition rate model, the atmospheric deposition fluxes of 210Pb, 210Bi and 210Po over Shanghai area into the East China Sea are estimated, and their variation ranges are 0.1−26.35 Bq/(m2·d), 0.04−7.91 Bq/(m2·d) and 0.01−5.49 Bq/(m2·d), respectively. The deposition fluxes of 210Po, 210Bi and 210Pb estimated based on the model are close to the actual observed values in the study area during the same period in winter within a certain range. The feasibility of estimating the deposition flux of nuclide into the sea with a simple one dimensional aerosol deposition rate model is verified.
The deposition fluxes of 210Po, 210Bi and 210Pb in atmosphere are the basis for the application of radionuclide tracing in the ocean. In order to reveal the spatio-temporal variation of the activity of 210Po, 210Bi and 210Pb in nearshore areas and estimate their deposition fluxes into the sea, in this paper, sampling observation and analysis of two typical areas near the East China Sea in Shanghai and Xiamen in different periods are carried out. A time series study was conducted on the the aerosol activities of 210Po, 210Pb and 210Bi in Shanghai and Xiamen from September 2016 to February 2017 and from September to November 2021, respectively. The residence time of aerosol particle was calculated based on 210Po/210Pb and 210Bi/210Pb. Deposition fluxes of three nuclides were also estimated. This paper reported the activity of 210Po, 210Bi and 210Pb in Shanghai in autumn and winter of 2016. The activity ranges of 210Po, 210Pb and 210Bi were 0.11−1.27 mBq/m3, 0.45−1.83 mBq/m3 and 1.12−6.10 mBq/m3, respectively. In the fall of 2021, the activity ranges of 210Po, 210Bi and 210Pb in Xiamen were 0.05−0.85 mBq/m3, 0.83−2.52 mBq/m3 and 0.17−1.32 mBq/m3, respectively. The aerosol activity of each nuclide in Shanghai was higher than that in Xiamen. The estimated residence time based on 210Po-210Pb and 210Bi-210Pb methods are significantly different, for example, in Shanghai area, the averaged aerosol residence time based on 210Po-210Pb method was calculated to be (94 ± 54) d, which is much higher than the result from 210Bi-210Pb method. The main reason for this difference is most likely due to the difference in the properties of the tracing isotopes we used. In this paper, based on a one-dimensional simple aerosol deposition rate model, the atmospheric deposition fluxes of 210Pb, 210Bi and 210Po over Shanghai area into the East China Sea are estimated, and their variation ranges are 0.1−26.35 Bq/(m2·d), 0.04−7.91 Bq/(m2·d) and 0.01−5.49 Bq/(m2·d), respectively. The deposition fluxes of 210Po, 210Bi and 210Pb estimated based on the model are close to the actual observed values in the study area during the same period in winter within a certain range. The feasibility of estimating the deposition flux of nuclide into the sea with a simple one dimensional aerosol deposition rate model is verified.
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