2017 Vol. 39, No. 2
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2017, 39(2): .
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2017, 39(2): .
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2017, 39(2): 1-15.
doi: 10.3969/j.issn.0253-4193.2017.02.001
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In this paper, with the digitized data of 1950s and 1970s and measured date of 2012, model grids were designed. Considering the effects of runoff, tide and wind stress, a 3D numerical model of Changjiang Estuary was built to simulate and analyze the tide, residual water transport, water flux and split ratio in bifurcations and the effects of river regime changes on them. The changes of the maximum tidal range occurs mainly in the North Branch, the tidal range of middle reaches of the North Branch decreased from 1950s to 1970s, and increased from 1970s to 2012.In 1950s, the residual water transport was greater in the North Channel than in the South Channel,transported toward the upper reaches in the lower reaches of the North Branch and its value was low in the upper reaches of the North Branch. In 1970s, the residual water transport was greater in the South Channel than in the North Channel, transported toward the lower reaches in the upper reaches of the North Branch and its value was low in the lower reaches of the North Branch. In 2012, the residual transport was equivalent in the North Channel and the South Channel,transported toward the upper reaches in the North Branch. The flood, ebb and net water split ratio during spring and neap tide in the North and South Branch, and the North and South Channel in the three times was given and the reason of change was analyzed based on the change of river regime.
In this paper, with the digitized data of 1950s and 1970s and measured date of 2012, model grids were designed. Considering the effects of runoff, tide and wind stress, a 3D numerical model of Changjiang Estuary was built to simulate and analyze the tide, residual water transport, water flux and split ratio in bifurcations and the effects of river regime changes on them. The changes of the maximum tidal range occurs mainly in the North Branch, the tidal range of middle reaches of the North Branch decreased from 1950s to 1970s, and increased from 1970s to 2012.In 1950s, the residual water transport was greater in the North Channel than in the South Channel,transported toward the upper reaches in the lower reaches of the North Branch and its value was low in the upper reaches of the North Branch. In 1970s, the residual water transport was greater in the South Channel than in the North Channel, transported toward the lower reaches in the upper reaches of the North Branch and its value was low in the lower reaches of the North Branch. In 2012, the residual transport was equivalent in the North Channel and the South Channel,transported toward the upper reaches in the North Branch. The flood, ebb and net water split ratio during spring and neap tide in the North and South Branch, and the North and South Channel in the three times was given and the reason of change was analyzed based on the change of river regime.
2017, 39(2): 16-28.
doi: 10.3969/j.issn.0253-4193.2017.02.002
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Eddy properties in the Northwestern Pacific Ocean are studied from 22 years of AVISO altimeter data using a SLA-based eddy identification approach. 3 841 cyclones and 2 836 anticyclones with lifetimes that exceed 30 days are detected during the 22-year period, and there is a preference for cyclones for most of lifetimes and propagation distances. Most mesoscale eddies propagate westward, the westward eddies are distributed everywhere of the area, as well as the eastward eddies occur mainly along Kuroshio Current and in Kuroshio Extension. Eddies exist principally in the latitude band of 15°-30°N, especial in the region near Kuroshio Current. The cyclones prefer to occur in the northern and southern of the area, while anticyclones mainly occur in the Subtropical Countercurrent. There are higher EKE, eddy amplitudes and eddy radii in The Kuroshio Extension of 30°-35°N. Cyclones and anticyclones occur more often in spring than in other seasons. The interannual variability of eddies activities is not obvious, the number of eddies generated every year are distributed in the range of 270-330. The comparison of the monthly variations of the numbers of eddies with Multivariate ENSO Index (MEI) shows that the eddy activities of Northwestern Pacific Ocean do not directly related with the ENSO phenomena.
Eddy properties in the Northwestern Pacific Ocean are studied from 22 years of AVISO altimeter data using a SLA-based eddy identification approach. 3 841 cyclones and 2 836 anticyclones with lifetimes that exceed 30 days are detected during the 22-year period, and there is a preference for cyclones for most of lifetimes and propagation distances. Most mesoscale eddies propagate westward, the westward eddies are distributed everywhere of the area, as well as the eastward eddies occur mainly along Kuroshio Current and in Kuroshio Extension. Eddies exist principally in the latitude band of 15°-30°N, especial in the region near Kuroshio Current. The cyclones prefer to occur in the northern and southern of the area, while anticyclones mainly occur in the Subtropical Countercurrent. There are higher EKE, eddy amplitudes and eddy radii in The Kuroshio Extension of 30°-35°N. Cyclones and anticyclones occur more often in spring than in other seasons. The interannual variability of eddies activities is not obvious, the number of eddies generated every year are distributed in the range of 270-330. The comparison of the monthly variations of the numbers of eddies with Multivariate ENSO Index (MEI) shows that the eddy activities of Northwestern Pacific Ocean do not directly related with the ENSO phenomena.
2017, 39(2): 29-38.
doi: 10.3969/j.issn.0253-4193.2017.02.003
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Ensemble Optimal Interpolation (EnOI) assimilation of HY-2 satellite altimetry data into SWAN(Simulating Waves Nearshore) model was applied into wave simulating and forecasting of typhoon "Lipee". The results showed that the assimilation of EnOI combined with HY-2 satellite altimeter wave data could improve the accuracy of initial field. The accuracy of the bias of the initial field could be improved by 15%, and the RMSE of it could be improved by 14%. The bias and RMSE of forecasting both decreased at different levels. The accuracy of the forecasting field could be improved most in the first 24 hours, and the values of bias and RMSE were decreased by 12% and 13%. Conclusion of these experiments can provide information for wave forecasting and simulation, and can strength the use of HY-2 satellite altimetry data into practice.
Ensemble Optimal Interpolation (EnOI) assimilation of HY-2 satellite altimetry data into SWAN(Simulating Waves Nearshore) model was applied into wave simulating and forecasting of typhoon "Lipee". The results showed that the assimilation of EnOI combined with HY-2 satellite altimeter wave data could improve the accuracy of initial field. The accuracy of the bias of the initial field could be improved by 15%, and the RMSE of it could be improved by 14%. The bias and RMSE of forecasting both decreased at different levels. The accuracy of the forecasting field could be improved most in the first 24 hours, and the values of bias and RMSE were decreased by 12% and 13%. Conclusion of these experiments can provide information for wave forecasting and simulation, and can strength the use of HY-2 satellite altimetry data into practice.
2017, 39(2): 39-52.
doi: 10.3969/j.issn.0253-4193.2017.02.004
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Stable carbon and nitrogen isotopes were used to distinguish sources of suspended particulate organic matter in the Daya Bay in summer 2015. Our results showed that the values of δ13CPOC and δ15NPN ranged from -25.7‰ to -17.4‰ and from -6.3 to 10.4‰, with averages of -20.2‰ and 8.2‰, respectively. The spatial variation of δ13CPOC and δ15NPN reflected the effect of different sources of organic matter. The high POC, PN, δ13CPOC and δ15NPN were observed around Xizhou Island, indicating a phytoplankton bloom. The high POC, PN, δ15NPN, but low δ13CPOC occurred around the Fanhe Habour in the northeastern bay, pointing to the contribution of riverine/estuarine organic matter. Meanwhile, the low values of δ13CPOC and δ15NPN were observed in the north coastal areas, reflecting the input of terrigenous organic matter and anthropogenic wastes. Based on the mass balance of δ13CPOC and δ15NPN, the contribution of autochthonous, terrigenous and riverine/estuarine organic matter were estimated as 70%, 13% and 17% respectively. The particulate organic matter in the Daya Bay in summer was dominated by marine autochthonous source. The contents of autochthonous organic matter showed a decrease from the inner to the mouth of the bay, corresponding to the decrease of primary productivity. The riverine/estuarine organic matter showed high contents in the northeastern bay. However, distribution of terrigenous organic matter showed different patterns in the surface and bottom layers. The low contents of terrigenous organic matter in surface waters were observed in the central bay, while they increased from the inner to the mouth of the bay in the bottom. The spatial distribution of terrigenous organic matter in the Daya Bay was regulated by the offshore distance, the Pearl river diluted water and the coastal upwelling along the eastern part of Guangdong province.
Stable carbon and nitrogen isotopes were used to distinguish sources of suspended particulate organic matter in the Daya Bay in summer 2015. Our results showed that the values of δ13CPOC and δ15NPN ranged from -25.7‰ to -17.4‰ and from -6.3 to 10.4‰, with averages of -20.2‰ and 8.2‰, respectively. The spatial variation of δ13CPOC and δ15NPN reflected the effect of different sources of organic matter. The high POC, PN, δ13CPOC and δ15NPN were observed around Xizhou Island, indicating a phytoplankton bloom. The high POC, PN, δ15NPN, but low δ13CPOC occurred around the Fanhe Habour in the northeastern bay, pointing to the contribution of riverine/estuarine organic matter. Meanwhile, the low values of δ13CPOC and δ15NPN were observed in the north coastal areas, reflecting the input of terrigenous organic matter and anthropogenic wastes. Based on the mass balance of δ13CPOC and δ15NPN, the contribution of autochthonous, terrigenous and riverine/estuarine organic matter were estimated as 70%, 13% and 17% respectively. The particulate organic matter in the Daya Bay in summer was dominated by marine autochthonous source. The contents of autochthonous organic matter showed a decrease from the inner to the mouth of the bay, corresponding to the decrease of primary productivity. The riverine/estuarine organic matter showed high contents in the northeastern bay. However, distribution of terrigenous organic matter showed different patterns in the surface and bottom layers. The low contents of terrigenous organic matter in surface waters were observed in the central bay, while they increased from the inner to the mouth of the bay in the bottom. The spatial distribution of terrigenous organic matter in the Daya Bay was regulated by the offshore distance, the Pearl river diluted water and the coastal upwelling along the eastern part of Guangdong province.
2017, 39(2): 53-61.
doi: 10.3969/j.issn.0253-4193.2017.02.005
Abstract:
Surface sediments were analyzed in order to demonstrate the distribution and transformation of terrestrial organic matter in the Bohai Sea and Yellow Sea. Organic carbon ranged at 0.03%-1.02% in the surface sediments, in which low in the estuary of Yellow River and higher in areas off the estuaries of Yellow Sea and Shuangtaizi River, as well as higher in the central North Yellow Sea and central South Yellow Sea. δ13C of organic carbon ranged at -21.55‰ and -24.28‰, indicating both terrestrial and oceanic sources of organic carbon, and the oceanic source increased from near shore to off shore areas. Long chain fatty acids, long chain alcohols and terrestrial sterols existed higher in the estuaries, a little lower in the rivers, and rapidly decreased from estuary to the central Bohai Sea, suggesting significant riverine inputs. Meanwhile, the free lipids absolutely dominated by almost 100% in estuaries, and saponified lipids primarily contributed by >50% and a little mineral associated lipids accounted for <5% in the central Bohai Sea and Bohai Strait. The degradation of terrestrial lipids was significant from estuaries to central Bohai Sea and Bohai Strait, and the lipids were transformed in younger stage. Both organic carbon and terrestrial lipids highly accumulated in the fine-clay areas of central North Yellow Sea and central South Yellow Sea, but the terrestrial organic carbon contributed in minor ratio to total organic carbon. Saponified lipids accounted for >50% and mineral associated lipids <10% to total lipids, which implied a middle transformation of terrestrial organic carbon in fine-clay areas of central North Yellow Sea and central South Yellow Sea.
Surface sediments were analyzed in order to demonstrate the distribution and transformation of terrestrial organic matter in the Bohai Sea and Yellow Sea. Organic carbon ranged at 0.03%-1.02% in the surface sediments, in which low in the estuary of Yellow River and higher in areas off the estuaries of Yellow Sea and Shuangtaizi River, as well as higher in the central North Yellow Sea and central South Yellow Sea. δ13C of organic carbon ranged at -21.55‰ and -24.28‰, indicating both terrestrial and oceanic sources of organic carbon, and the oceanic source increased from near shore to off shore areas. Long chain fatty acids, long chain alcohols and terrestrial sterols existed higher in the estuaries, a little lower in the rivers, and rapidly decreased from estuary to the central Bohai Sea, suggesting significant riverine inputs. Meanwhile, the free lipids absolutely dominated by almost 100% in estuaries, and saponified lipids primarily contributed by >50% and a little mineral associated lipids accounted for <5% in the central Bohai Sea and Bohai Strait. The degradation of terrestrial lipids was significant from estuaries to central Bohai Sea and Bohai Strait, and the lipids were transformed in younger stage. Both organic carbon and terrestrial lipids highly accumulated in the fine-clay areas of central North Yellow Sea and central South Yellow Sea, but the terrestrial organic carbon contributed in minor ratio to total organic carbon. Saponified lipids accounted for >50% and mineral associated lipids <10% to total lipids, which implied a middle transformation of terrestrial organic carbon in fine-clay areas of central North Yellow Sea and central South Yellow Sea.
2017, 39(2): 62-71.
doi: 10.3969/j.issn.0253-4193.2017.02.006
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Dosidicus gigas is one of the most important oceanic fishing objects. It is useful for learning the ecological habitat and increasing the fishing efficiency to study the spatial distribution of D. gigas. We used the fishing data as main variable and sea surface temperature (SST), sea surface height (SSH), sea surface salinity (SSS) and concentration of Chlorophyll a (Chl a) as co-variables by cokriging to analyze the spatial distribution of D. gigas abundance. The fishing data was selected from June to September during 2003 to 2012 provided by the Chinese squid-jigging technology group. To solve the weight of four different environmental factors in cokriging, they were transferred to the value between 0 and 1, then combined by principle component analysis as a single comprehensive co-variable. The relative test was taken between catch per unite fishing effort (CPUE) and the co-variable. Mean error (ME), root mean square error (RMSE) and root mean standardized squared error (RMSSE) were used to assess the predicting results to examine this method. The study results showed that (1) the comprehensive environmental factors from June to September had significant correlation with CPUE, (2) The ME were 0.002 6 and 0.002 5 respectively in June and July, which indicated that the average predicted results were higher than the objected data. However ME were -0.007 8 and -0.000 2 in August and September respectively, indicting the predicting accuracy were better and the average predicted results were lower than the objected data. The precision in June was the best, and it was lower in August. The RMSSE values in June and July were less than 1, suggesting over-valuating their uncertainty. This also indicated there were bias on the predicting precision and accuracy. In a word, from the view of ME, RMSE and RMSSE, the predicted data had a certain reliability.
Dosidicus gigas is one of the most important oceanic fishing objects. It is useful for learning the ecological habitat and increasing the fishing efficiency to study the spatial distribution of D. gigas. We used the fishing data as main variable and sea surface temperature (SST), sea surface height (SSH), sea surface salinity (SSS) and concentration of Chlorophyll a (Chl a) as co-variables by cokriging to analyze the spatial distribution of D. gigas abundance. The fishing data was selected from June to September during 2003 to 2012 provided by the Chinese squid-jigging technology group. To solve the weight of four different environmental factors in cokriging, they were transferred to the value between 0 and 1, then combined by principle component analysis as a single comprehensive co-variable. The relative test was taken between catch per unite fishing effort (CPUE) and the co-variable. Mean error (ME), root mean square error (RMSE) and root mean standardized squared error (RMSSE) were used to assess the predicting results to examine this method. The study results showed that (1) the comprehensive environmental factors from June to September had significant correlation with CPUE, (2) The ME were 0.002 6 and 0.002 5 respectively in June and July, which indicated that the average predicted results were higher than the objected data. However ME were -0.007 8 and -0.000 2 in August and September respectively, indicting the predicting accuracy were better and the average predicted results were lower than the objected data. The precision in June was the best, and it was lower in August. The RMSSE values in June and July were less than 1, suggesting over-valuating their uncertainty. This also indicated there were bias on the predicting precision and accuracy. In a word, from the view of ME, RMSE and RMSSE, the predicted data had a certain reliability.
2017, 39(2): 72-85.
doi: 10.3969/j.issn.0253-4193.2017.02.007
Abstract:
The evolution characteristics of the anabranched estuary and their ecological effects are important issues of current estuarine and coastal research. The North Branch is one of the first order bifurcations of Yangtze Estuary. Its evolution would have profound effects on regional ecological and environmental conditions. In this study, we expounded the evolution characteristics of the North Branch of Yangtze Estuary in last 30 years, based on the pre-existing results and also the remote sensing image analysis. Together with the recent ecological investigation in the water area, their corresponding effects on species diversity were discussed thoroughly. The results proved that the prominent feature of the evolution was that the middle and upper segments of the North Branch got narrowed significantly, while the lower segment was less narrowed and still had a funnel shape. A large number of reclamations taken place in the middle and upper areas were responsible for this. With the changes of river regime, the water depth, channel volume and the split ratio of water of the North Branch decreased, while the split ratio of sediment went up. These had contributed to the intensive saltwater intrusions into the North Branch, and also the increased risks of the sediment and saltwater spilling into the South Branch. The North Branch evolution altered the salinity conditions of the water, which led to the dominant biomes appeared to be those adapted to the high salinity and brackish water. Furthermore, the variations of the water depth, hydrodynamic and sediment concentration of the water could also have effects on the biomes. However, at present, the North Branch was still an important habitat and nursery area for many biomes, such as the benthic macroinvertebrates, the fishes and so on, and still had higher biodiversity. As a consequence, we need to sustain the ecosystem structure and functions of the area to ensure the sustainable development of the region. We also need a comprehensive analysis on the basis of effective monitoring in the future to reveal the evolution trends of the North Branch and their corresponding effects.
The evolution characteristics of the anabranched estuary and their ecological effects are important issues of current estuarine and coastal research. The North Branch is one of the first order bifurcations of Yangtze Estuary. Its evolution would have profound effects on regional ecological and environmental conditions. In this study, we expounded the evolution characteristics of the North Branch of Yangtze Estuary in last 30 years, based on the pre-existing results and also the remote sensing image analysis. Together with the recent ecological investigation in the water area, their corresponding effects on species diversity were discussed thoroughly. The results proved that the prominent feature of the evolution was that the middle and upper segments of the North Branch got narrowed significantly, while the lower segment was less narrowed and still had a funnel shape. A large number of reclamations taken place in the middle and upper areas were responsible for this. With the changes of river regime, the water depth, channel volume and the split ratio of water of the North Branch decreased, while the split ratio of sediment went up. These had contributed to the intensive saltwater intrusions into the North Branch, and also the increased risks of the sediment and saltwater spilling into the South Branch. The North Branch evolution altered the salinity conditions of the water, which led to the dominant biomes appeared to be those adapted to the high salinity and brackish water. Furthermore, the variations of the water depth, hydrodynamic and sediment concentration of the water could also have effects on the biomes. However, at present, the North Branch was still an important habitat and nursery area for many biomes, such as the benthic macroinvertebrates, the fishes and so on, and still had higher biodiversity. As a consequence, we need to sustain the ecosystem structure and functions of the area to ensure the sustainable development of the region. We also need a comprehensive analysis on the basis of effective monitoring in the future to reveal the evolution trends of the North Branch and their corresponding effects.
2017, 39(2): 86-95.
doi: 10.3969/j.issn.0253-4193.2017.02.008
Abstract:
The partial mitochondrial cytochrome oxidase Ⅰ gene (CO Ⅰ) sequences of 18 Buccinoidea species were employed to evaluate the phylogenetic relationships of the family Buccinidae at the intra- and suprafamilial level. Within the family, the buccinids formed four clades:Clade Ⅰ includes Japelion latus, Buccinum koreana, Buccinum yokomaruae, Voluthapa perryi, Neptunea cumingi, Lirabuccinum musculus and Japeuthria cingulata;Clade Ⅱ includes Antillophos monsecourorum and Nassaria acuminata; Clade Ⅲ includes Cantharus melanostoma and Engina lanceolata; Clade Ⅳ includes Siphonalia spadicea and Euthria lubrica. This result generally agrees with the previous subfamilial assignments based on morphological data. The monophyly of Buccinidae was interrupted by insertion of Nassariids, Olivids and Babyloniids. Babyloniidae, previously considered as a subfamily of Buccinidae, is now treated as an independent family. The present study confirmed this assignment. The genera Nassaria and Antillophos clustered together with nassariids closer than with other buccinids, indicating that they have very close relationship with Nassariidae, this result is consistent with that of recently published molecular study.
The partial mitochondrial cytochrome oxidase Ⅰ gene (CO Ⅰ) sequences of 18 Buccinoidea species were employed to evaluate the phylogenetic relationships of the family Buccinidae at the intra- and suprafamilial level. Within the family, the buccinids formed four clades:Clade Ⅰ includes Japelion latus, Buccinum koreana, Buccinum yokomaruae, Voluthapa perryi, Neptunea cumingi, Lirabuccinum musculus and Japeuthria cingulata;Clade Ⅱ includes Antillophos monsecourorum and Nassaria acuminata; Clade Ⅲ includes Cantharus melanostoma and Engina lanceolata; Clade Ⅳ includes Siphonalia spadicea and Euthria lubrica. This result generally agrees with the previous subfamilial assignments based on morphological data. The monophyly of Buccinidae was interrupted by insertion of Nassariids, Olivids and Babyloniids. Babyloniidae, previously considered as a subfamily of Buccinidae, is now treated as an independent family. The present study confirmed this assignment. The genera Nassaria and Antillophos clustered together with nassariids closer than with other buccinids, indicating that they have very close relationship with Nassariidae, this result is consistent with that of recently published molecular study.
2017, 39(2): 96-104.
doi: 10.3969/j.issn.0253-4193.2017.02.009
Abstract:
To explore the molecular structure and functional characteristics of LAP3 gene and its role in the process of growth and development, full length cDNA of LAP3 in Meretrix meretrix(Mm-LAP3)was cloned by rapid amplification of cDNA ends technique(RACE), then the bioinformatics and expression profiles in different adult tissues and developmental stages of larvae were analyzed. The results showed that the full length cDNA of Mm-LAP3 gene was 2 037 bp, containing a complete 1 254 bp ORF encoding 417 amino acids. There were two functional domains of Mm-LAP3 protein (Peptidase_M17 and N-terminal). The result of Q-RT-PCR indicated that Mm-LAP3 expressed in six tissues and ten developmental stages, but the expression of foot was significantly higher than other tissues. The expression of Mm-LAP3 gradually increased with the process of the development, and showed the highest in D-shaped larvae stage, and then the expression decreased, which suggested that Mm-LAP3 may be involved in the formation of certain organs in early developmental stages.
To explore the molecular structure and functional characteristics of LAP3 gene and its role in the process of growth and development, full length cDNA of LAP3 in Meretrix meretrix(Mm-LAP3)was cloned by rapid amplification of cDNA ends technique(RACE), then the bioinformatics and expression profiles in different adult tissues and developmental stages of larvae were analyzed. The results showed that the full length cDNA of Mm-LAP3 gene was 2 037 bp, containing a complete 1 254 bp ORF encoding 417 amino acids. There were two functional domains of Mm-LAP3 protein (Peptidase_M17 and N-terminal). The result of Q-RT-PCR indicated that Mm-LAP3 expressed in six tissues and ten developmental stages, but the expression of foot was significantly higher than other tissues. The expression of Mm-LAP3 gradually increased with the process of the development, and showed the highest in D-shaped larvae stage, and then the expression decreased, which suggested that Mm-LAP3 may be involved in the formation of certain organs in early developmental stages.
2017, 39(2): 105-111.
doi: 10.3969/j.issn.0253-4193.2017.02.010
Abstract:
Physical experiments were carried out in a wave flume to examine the geometric characteristics of limiting gravity waves propagating in shallow water. Several random wave trains varying height and peak frequency were generated using JONSWAP spectra. Three bottom slopes (1/15, 1/30, 1/45) were installed in the wave flume and the influence of slope bottoms were also considered. Limiting waves were captured from the measured wave trains and the geometric characteristics of its waveform were analyzed. It is found that in the range of bottom slope adopted in this experiment both initial wave heights and local water depth have significant influence on the limiting characteristics of shallow water waves. With the influence of these factors, the geometric of extreme waves are developed. The bottom slopes effect to the limiting steepness and skewness could be neglected, however, it has obvious influence to the limiting wave asymmetry. It will show a more severe asymmetry when waves are on a steeper bottom. Furthermore, the empirical formulae regarding the relationships between geometric characteristics and the local nondimensional wave height were derived.
Physical experiments were carried out in a wave flume to examine the geometric characteristics of limiting gravity waves propagating in shallow water. Several random wave trains varying height and peak frequency were generated using JONSWAP spectra. Three bottom slopes (1/15, 1/30, 1/45) were installed in the wave flume and the influence of slope bottoms were also considered. Limiting waves were captured from the measured wave trains and the geometric characteristics of its waveform were analyzed. It is found that in the range of bottom slope adopted in this experiment both initial wave heights and local water depth have significant influence on the limiting characteristics of shallow water waves. With the influence of these factors, the geometric of extreme waves are developed. The bottom slopes effect to the limiting steepness and skewness could be neglected, however, it has obvious influence to the limiting wave asymmetry. It will show a more severe asymmetry when waves are on a steeper bottom. Furthermore, the empirical formulae regarding the relationships between geometric characteristics and the local nondimensional wave height were derived.
2017, 39(2): 112-119.
doi: 10.3969/j.issn.0253-4193.2017.02.011
Abstract:
Green-tide events occurred in the Yellow Sea successively in recent years. The marine macrophyte Ulva prolifera is the dominant green-tide-forming seaweed. It is necessary to study the nitrogen contents in the algal tissue, which contributes to knowing the uptake and assimilation of nitrate by Ulva prolifera. In this study, the method of salicylic acid-concentrated sulfuric acid colorimetry was employed to investigate the nitrate contents in Ulva prolifera. The influenced factors, including sample pretreatment, the amount of chromogenic reagent addition and the selection of performance curve, were examined and optimized during the determinations. The detection limit, precision and accuracy of this method were also established simultaneously. Our results indicated that this method was applicable for the fast examination of the nitrate contents in the algal tissue.
Green-tide events occurred in the Yellow Sea successively in recent years. The marine macrophyte Ulva prolifera is the dominant green-tide-forming seaweed. It is necessary to study the nitrogen contents in the algal tissue, which contributes to knowing the uptake and assimilation of nitrate by Ulva prolifera. In this study, the method of salicylic acid-concentrated sulfuric acid colorimetry was employed to investigate the nitrate contents in Ulva prolifera. The influenced factors, including sample pretreatment, the amount of chromogenic reagent addition and the selection of performance curve, were examined and optimized during the determinations. The detection limit, precision and accuracy of this method were also established simultaneously. Our results indicated that this method was applicable for the fast examination of the nitrate contents in the algal tissue.
2017, 39(2): 120-128.
doi: 10.3969/j.issn.0253-4193.2017.02.012
Abstract:
Tuna is a commercially important species in the Western-Central Pacific. The skipjack (Katsuwonus pelamis) yield accounts for about 50% of total production. In this study, differences in the distribution of fishing grounds and the relationship between CPUE (Catch Per Unit Effort) and ENSO (El Niño Southern Oscillation) index are discussed through the temporal and spatial analysis of top 10 fishing areas based on the tuna purse seine catches in Western-Central Pacific (20°S-20°N, 120°E-155°W) and ENSO SSTA (sea surface temperature anomaly) data of Niño 3.4 region (5°S-5°N, 120°-170°W) collected from 1995 to 2010. The result indicated that the top 10 high yield fishing areas distributed mainly in 5°S-5°N, 130°-175°W region, which account for almost 47.5% in total production. Among them, four fishing areas like 5°-0°S,155°-160°E; 0°-5°N, 130°-135°E; 0°-5°N, 135°-140°E and 5°-0°S, 160°-165°E all have more than 10% of the top 10 high yield fishing areas' production, which are the important skipjack production areas in the Western-Central Pacific. High yield fishing areas are easily affected by SST (sea surface temperature) which are eastward distributed in 155°-180°E region during El Niño events, and westward distributed in 130°-160°E region during La Niña events.
Tuna is a commercially important species in the Western-Central Pacific. The skipjack (Katsuwonus pelamis) yield accounts for about 50% of total production. In this study, differences in the distribution of fishing grounds and the relationship between CPUE (Catch Per Unit Effort) and ENSO (El Niño Southern Oscillation) index are discussed through the temporal and spatial analysis of top 10 fishing areas based on the tuna purse seine catches in Western-Central Pacific (20°S-20°N, 120°E-155°W) and ENSO SSTA (sea surface temperature anomaly) data of Niño 3.4 region (5°S-5°N, 120°-170°W) collected from 1995 to 2010. The result indicated that the top 10 high yield fishing areas distributed mainly in 5°S-5°N, 130°-175°W region, which account for almost 47.5% in total production. Among them, four fishing areas like 5°-0°S,155°-160°E; 0°-5°N, 130°-135°E; 0°-5°N, 135°-140°E and 5°-0°S, 160°-165°E all have more than 10% of the top 10 high yield fishing areas' production, which are the important skipjack production areas in the Western-Central Pacific. High yield fishing areas are easily affected by SST (sea surface temperature) which are eastward distributed in 155°-180°E region during El Niño events, and westward distributed in 130°-160°E region during La Niña events.
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