Environmental characteristics and phytoplankton community structure were investigated in two aquaculture areas in Dapeng Cove of Daya Bay, South China Sea, between April 2005 and June 2006. Phytoplankton abundance ran...Environmental characteristics and phytoplankton community structure were investigated in two aquaculture areas in Dapeng Cove of Daya Bay, South China Sea, between April 2005 and June 2006. Phytoplankton abundance ranged between 5.0 and 8877.5 cells/mL, with an average of 751.8 cells/mL. The seasonal cycle of phytoplankton were demonstrated by frequent oscillations, with recurrent high abundances from late spring to autumn and a peak stage in late winter. Diatoms were the predominant phytoplankton group, accounting for 93.21% of the total abundance. The next most abundant group was the dinoflagellates, which made up only 1.24% of total abundance. High concentrations of Alexandrium tamarense （Lebour） Balech with a maximum of 603.0 cells/mL were firstly recorded in this area known for high rates of paralytic shellfish poisoning （PSP） contamination. Temperatures and salinities were within the suitable values for the growth of phytoplankton, and were important in phytoplankton seasonal fluctuations. The operation of the Daya Bay Nuclear Power Station （DNPS） exerts influences on the phytoplankton community and resulted in the high abundances of toxic dinoflagellate species during the winter months. Dissolved inorganic nitrogen （DIN） and dissolved silicate （DSi） were sufficient, and rarely limited for the growth of phytoplankton. Dissolved inorganic phosphorus （DIP） was the most necessary element for phytoplankton growth. The enriched environments accelerated the growth of small diatoms, and made for the shift in predominant species from large diatom Rhizosolenia spp. to chain-forming diatoms such as Skeletonema costatum, Pseudo-nitzschia spp. and Thalassiosira subtilis.展开更多
This study aims to explore the distribution of meiofaunal abundance in relation to environmental factors in the Beibu Gulf, a natural semi-enclosed part of the South China Sea, surrounded by China and Vietnam. Meiofau...This study aims to explore the distribution of meiofaunal abundance in relation to environmental factors in the Beibu Gulf, a natural semi-enclosed part of the South China Sea, surrounded by China and Vietnam. Meiofauna and ten benthic environmental factors were determined at 27 sampling stations in the Beibu Gulf in four surveys during 2006 2007. The results show a clear geographical trend in meiofaunal abundance, water depth, salinity and clay content. The meiofaunal abundance and the clay content decreased, whereas the water depth and the salinity increased from the north to the south of the Gulf. The percentage of meiofaunal abundance in the 0 2 cm layer increased, whereas in the 2-5 cm and 5 10 cm layers it decreased from the north to the south of the Gulf. Correlation analysis show significant negative correlations between meiofaunal abundance and water depth, benthic temperature, salinity and pH, but significant positive correlations between meiofaunal abundance and dissolved oxygen, chlorophyll a and clay content.展开更多
Some studies have been made on the variation of primary productivity in the Central South ChinaSea. This paper studies comprehensively the characteristics of chlorophyll a distributions in time andspace and the primar...Some studies have been made on the variation of primary productivity in the Central South ChinaSea. This paper studies comprehensively the characteristics of chlorophyll a distributions in time andspace and the primary productivity, as well their relations to the environmental factors.Materals and methods During the comprehensive investigation in the Central South China Sea from September 1983 toDecember 1984, the distributions of chlorophyll a and primary productivity were studied. Figure 1shows the sampling stations and their range of investigation.展开更多
The corrosion behavior of Mg-Nd binary alloys in the harsh South China Sea environment was researched by scanning electron microscopy,energy-dispersive spectrometry and X-ray diffraction analysis.In order to explain t...The corrosion behavior of Mg-Nd binary alloys in the harsh South China Sea environment was researched by scanning electron microscopy,energy-dispersive spectrometry and X-ray diffraction analysis.In order to explain the corrosion mechanism,corrosion resistance was analyzed by weight loss rate and electrochemical measurement in the laboratory.With a continuous enlargement of Nd-content,Mg 12 Nd phases increased and multiplied.The weight loss rate of Mg-0.5Nd alloy was 0.0436 mg·cm^(-2)·y^(-1)(0.0837 mm·y^(-1)),whereas that of Mg-1.5Nd alloy was 0.0294 mg·cm^(-2)·y^(-1)(0.0517 mm·y^(-1))during the exposure corrosion in the South China Sea site.The mechanical strength of Mg-1.5Nd alloy was 148 MPa before the exposure in the harsh marine environment,while the residual mechanical strength was merely about 94 MPa after the exposure test.Both Mg-1.5Nd alloy and Mg-1.0Nd alloy occurred the brittle fracture,which resulted that the elongation was nearly equal to zero.The self-corrosion current density demonstrated that degradation rate of Mg-Nd binary alloys was as follows:Mg-0.5Nd>Mg-1.0Nd>Mg-1.5Nd.For the South China Sea corrosion site,a large amount of sea salts exited in the atmospheric environment.Due to the heavy rainfall and high humidity,sodium chloride in the atmospheric environment dissolved,more serious electrochemical corrosion occurred on the surface of Mg-Nd binary alloys.展开更多
This note studies the Radiolarian fossil groups since 1.2 MaBP in ODP leg 184 site 1143, the southern South China Sea (SCS). The result shows that radiolarian abundance experienced a significant variation: before 0.9 ...This note studies the Radiolarian fossil groups since 1.2 MaBP in ODP leg 184 site 1143, the southern South China Sea (SCS). The result shows that radiolarian abundance experienced a significant variation: before 0.9 MaBP it remained at the extremely low level, but increased with low extent between 0.9-0.65 Ma, which corresponded to the Mid-Pleistocene Transition stage, and it increased rapidly after 0.65 MaBP. During the whole process, the average abundance became higher and higher in each stage, and showed regularly periodic fluctuations. The obvious increase after 0.65 MaBP is inferred to result from the enhanced up-welling in this region, which was induced by the intensified monsoon circulation after the 'Mid-Pleistocene Transition'. An outstanding result of the spectral analyses is that a long oscillation of - 0.2 Ma cycle was found in the records of radiolarian abundance and complex diversity, which corresponds well to the result of other paleoceanographic indexes. This probably indicated a展开更多
为探究鸢乌贼(Sthenoteuthis oualaniensis)资源变化与海洋环境因子的关系,基于2019—2020年南海围网捕捞鸢乌贼的电子渔捞日志数据,首先分析了鸢乌贼资源的月间变动特征,之后利用结构方程模型解析海洋环境因子对其资源时空分布的影响...为探究鸢乌贼(Sthenoteuthis oualaniensis)资源变化与海洋环境因子的关系,基于2019—2020年南海围网捕捞鸢乌贼的电子渔捞日志数据,首先分析了鸢乌贼资源的月间变动特征,之后利用结构方程模型解析海洋环境因子对其资源时空分布的影响。结果表明:围网月间的平均单位捕捞努力量渔获量(Catch per unit effort,CPUE)变化趋势基本一致,年平均CPUE则为2020年大于2019年。南海鸢乌贼渔汛期为3—4月,高产区域集中在112°E—117°E、8°N—12°N,渔汛期CPUE呈现向东和向北偏移的趋势。海洋环境对鸢乌贼资源分布的综合影响系数为0.38,而海表盐度和光合有效辐射在海洋环境上的载荷量分别为0.87和0.82,两者是影响鸢乌贼资源分布的重要环境因子。所用结构方程模型为量化海洋环境因子与鸢乌贼资源分布之间的复杂关系提供了新的研究思路,可为鸢乌贼资源可持续利用和管理提供参考依据。展开更多
基金supported by the National Natural Science Foundation of China(No.40673062,40773063, U0633006)
文摘Environmental characteristics and phytoplankton community structure were investigated in two aquaculture areas in Dapeng Cove of Daya Bay, South China Sea, between April 2005 and June 2006. Phytoplankton abundance ranged between 5.0 and 8877.5 cells/mL, with an average of 751.8 cells/mL. The seasonal cycle of phytoplankton were demonstrated by frequent oscillations, with recurrent high abundances from late spring to autumn and a peak stage in late winter. Diatoms were the predominant phytoplankton group, accounting for 93.21% of the total abundance. The next most abundant group was the dinoflagellates, which made up only 1.24% of total abundance. High concentrations of Alexandrium tamarense （Lebour） Balech with a maximum of 603.0 cells/mL were firstly recorded in this area known for high rates of paralytic shellfish poisoning （PSP） contamination. Temperatures and salinities were within the suitable values for the growth of phytoplankton, and were important in phytoplankton seasonal fluctuations. The operation of the Daya Bay Nuclear Power Station （DNPS） exerts influences on the phytoplankton community and resulted in the high abundances of toxic dinoflagellate species during the winter months. Dissolved inorganic nitrogen （DIN） and dissolved silicate （DSi） were sufficient, and rarely limited for the growth of phytoplankton. Dissolved inorganic phosphorus （DIP） was the most necessary element for phytoplankton growth. The enriched environments accelerated the growth of small diatoms, and made for the shift in predominant species from large diatom Rhizosolenia spp. to chain-forming diatoms such as Skeletonema costatum, Pseudo-nitzschia spp. and Thalassiosira subtilis.
基金The part of the Chinese Offshore Investigation and Assessment Project funded by the State Oceanic Adminis-tration of China
文摘This study aims to explore the distribution of meiofaunal abundance in relation to environmental factors in the Beibu Gulf, a natural semi-enclosed part of the South China Sea, surrounded by China and Vietnam. Meiofauna and ten benthic environmental factors were determined at 27 sampling stations in the Beibu Gulf in four surveys during 2006 2007. The results show a clear geographical trend in meiofaunal abundance, water depth, salinity and clay content. The meiofaunal abundance and the clay content decreased, whereas the water depth and the salinity increased from the north to the south of the Gulf. The percentage of meiofaunal abundance in the 0 2 cm layer increased, whereas in the 2-5 cm and 5 10 cm layers it decreased from the north to the south of the Gulf. Correlation analysis show significant negative correlations between meiofaunal abundance and water depth, benthic temperature, salinity and pH, but significant positive correlations between meiofaunal abundance and dissolved oxygen, chlorophyll a and clay content.
文摘Some studies have been made on the variation of primary productivity in the Central South ChinaSea. This paper studies comprehensively the characteristics of chlorophyll a distributions in time andspace and the primary productivity, as well their relations to the environmental factors.Materals and methods During the comprehensive investigation in the Central South China Sea from September 1983 toDecember 1984, the distributions of chlorophyll a and primary productivity were studied. Figure 1shows the sampling stations and their range of investigation.
基金The authors gratefully acknowledge the Fundamental Re-search Project of Technology Program of Qingdao(No.17-1-1-76-JCH)Shandong Provincial Natural Science Foundation(ZR201910230421)the National Natural Science Foun-dation of China for Exploring Key Scientific Instrument(No.41827805)for providing support.
文摘The corrosion behavior of Mg-Nd binary alloys in the harsh South China Sea environment was researched by scanning electron microscopy,energy-dispersive spectrometry and X-ray diffraction analysis.In order to explain the corrosion mechanism,corrosion resistance was analyzed by weight loss rate and electrochemical measurement in the laboratory.With a continuous enlargement of Nd-content,Mg 12 Nd phases increased and multiplied.The weight loss rate of Mg-0.5Nd alloy was 0.0436 mg·cm^(-2)·y^(-1)(0.0837 mm·y^(-1)),whereas that of Mg-1.5Nd alloy was 0.0294 mg·cm^(-2)·y^(-1)(0.0517 mm·y^(-1))during the exposure corrosion in the South China Sea site.The mechanical strength of Mg-1.5Nd alloy was 148 MPa before the exposure in the harsh marine environment,while the residual mechanical strength was merely about 94 MPa after the exposure test.Both Mg-1.5Nd alloy and Mg-1.0Nd alloy occurred the brittle fracture,which resulted that the elongation was nearly equal to zero.The self-corrosion current density demonstrated that degradation rate of Mg-Nd binary alloys was as follows:Mg-0.5Nd>Mg-1.0Nd>Mg-1.5Nd.For the South China Sea corrosion site,a large amount of sea salts exited in the atmospheric environment.Due to the heavy rainfall and high humidity,sodium chloride in the atmospheric environment dissolved,more serious electrochemical corrosion occurred on the surface of Mg-Nd binary alloys.
基金This work was supported by the National Natural Science Foundation of China (Grant No. 49999560)the National Key Basic Research Special Foundation Project (Grant No. 2000078500)the Knowledge Innovation Project of the Chinese Academy of Sciences (Gran
文摘This note studies the Radiolarian fossil groups since 1.2 MaBP in ODP leg 184 site 1143, the southern South China Sea (SCS). The result shows that radiolarian abundance experienced a significant variation: before 0.9 MaBP it remained at the extremely low level, but increased with low extent between 0.9-0.65 Ma, which corresponded to the Mid-Pleistocene Transition stage, and it increased rapidly after 0.65 MaBP. During the whole process, the average abundance became higher and higher in each stage, and showed regularly periodic fluctuations. The obvious increase after 0.65 MaBP is inferred to result from the enhanced up-welling in this region, which was induced by the intensified monsoon circulation after the 'Mid-Pleistocene Transition'. An outstanding result of the spectral analyses is that a long oscillation of - 0.2 Ma cycle was found in the records of radiolarian abundance and complex diversity, which corresponds well to the result of other paleoceanographic indexes. This probably indicated a
文摘为探究鸢乌贼(Sthenoteuthis oualaniensis)资源变化与海洋环境因子的关系,基于2019—2020年南海围网捕捞鸢乌贼的电子渔捞日志数据,首先分析了鸢乌贼资源的月间变动特征,之后利用结构方程模型解析海洋环境因子对其资源时空分布的影响。结果表明:围网月间的平均单位捕捞努力量渔获量(Catch per unit effort,CPUE)变化趋势基本一致,年平均CPUE则为2020年大于2019年。南海鸢乌贼渔汛期为3—4月,高产区域集中在112°E—117°E、8°N—12°N,渔汛期CPUE呈现向东和向北偏移的趋势。海洋环境对鸢乌贼资源分布的综合影响系数为0.38,而海表盐度和光合有效辐射在海洋环境上的载荷量分别为0.87和0.82,两者是影响鸢乌贼资源分布的重要环境因子。所用结构方程模型为量化海洋环境因子与鸢乌贼资源分布之间的复杂关系提供了新的研究思路,可为鸢乌贼资源可持续利用和管理提供参考依据。
