为了探讨南极磷虾主要渔场捕捞群体集群及单位捕捞努力量渔获量(catch per unit fishing effort,CPUE)空间特征,基于2018—2019渔季中国渔船南极磷虾商业捕捞渔捞日志数据,对南极磷虾主要渔场捕捞群体的集群形态、集群中心深度和集群水...为了探讨南极磷虾主要渔场捕捞群体集群及单位捕捞努力量渔获量(catch per unit fishing effort,CPUE)空间特征,基于2018—2019渔季中国渔船南极磷虾商业捕捞渔捞日志数据,对南极磷虾主要渔场捕捞群体的集群形态、集群中心深度和集群水温等特征进行了分析,并探讨其对CPUE的影响。结果显示,在0.1°×0.2°统计单元中,南极磷虾捕捞群体在南奥克尼群岛(South Orkney Islands)附近海域主要为带状集群,平均集群中心深度为20.00~50.00 m,平均集群水温为0.01~0.50℃,平均CPUE为20.01~40.00 t·h^(-1);在南设得兰群岛(South Shetland Islands)北部海域主要呈散点状集群,其比例高达97.78%,平均集群中心深度为20.00~50.00 m,平均集群水温为-0.99~-0.50℃,平均CPUE为5.18~20.00 t·h^(-1);在布兰斯菲尔德海峡(Bransfield Strait)南极磷虾散点状和带状集群比例相近,分别为55.54%和44.46%,平均集群中心深度为50.10~100.00 m,平均集群水温为-1.99~-1.50℃,平均CPUE为20.01~40.01 t·h^(-1)。多元回归分析结果显示,集群形态和集群中心深度对CPUE均有较大影响(P<0.05),而集群水温对CPUE影响不显著(P=0.284)。研究结果可为深入掌握南极磷虾渔场与快速选择合适捕捞的磷虾集群提供参考,并为进一步研究渔场形成机制提供基础数据。展开更多
The aggregation and deposition of carbon nanotubes（CNTs） determines their transport and fate in natural waters.Therefore,the aggregation kinetics of humic-acid treated multi-walled carbon nanotubes（HA-MWCNTs） was ...The aggregation and deposition of carbon nanotubes（CNTs） determines their transport and fate in natural waters.Therefore,the aggregation kinetics of humic-acid treated multi-walled carbon nanotubes（HA-MWCNTs） was investigated by time-resolved dynamic light scattering in NaCl and CaCl_2 electrolyte solutions.Increased ionic strength induced HA-MWCNT aggregation due to the less negative zeta potential and the reduced electrostatic repulsion.The critical coagulation concentration（CCC） values of HA-MWCNTs were 80 mmol/L in NaCl and 1.3 mmol/L in CaCl_2 electrolyte,showing that Ca^（2＋） causes more serious aggregation than Na~＋.The aggregation behavior of HA-MWCNTs was consistent with Derjaguin-Landau-Verwey-Overbeek theory.The deposition kinetics of HA-MWCNTs was measured by the optical absorbance at 800 ran.The critical deposition concentrations for HA-MWCNT in NaCl and CaCl_2 solutions were close to the CCC values,therefore the rate of deposition cannot be increased by changing the ionic strength in the diffusion-limited aggregation regime.The deposition process was correlated to the aggregation since larger aggregates increased gravitational deposition and decreased random Brownian diffusion.HA-MWCNTs hydrodynamic diameters were evaluated at 5,15 and 25℃.Higher temperature caused faster aggregation due to the reduced electrostatic repulsion and increased random Brownian motion and collision frequency.HA-MWCNTs aggregate faster at higher temperature in either NaCl or CaCl_2electrolyte due to the decreased electrostatic repulsion and increased random Brownian motion.Our results suggest that CNT aggregation and deposition are two correlated processes governed by the electrolyte,and CNT transport is favored at low ionic strength and low temperature.展开更多
用扫描电子显微镜对聚苯乙烯 b 聚丙烯酸 (PS b PAA)嵌段共聚物在水中自组装形貌进行了观察。结果表明 :外界环境和制样方法能够影响聚合物的自组装和聚集情况。 0℃时 ,PS38 b PAA2 10 胶束聚集形成纺锤状结构。而在临界条件下 ,缓慢...用扫描电子显微镜对聚苯乙烯 b 聚丙烯酸 (PS b PAA)嵌段共聚物在水中自组装形貌进行了观察。结果表明 :外界环境和制样方法能够影响聚合物的自组装和聚集情况。 0℃时 ,PS38 b PAA2 10 胶束聚集形成纺锤状结构。而在临界条件下 ,缓慢改变体系冷冻 解冻循环次数 ,则会得到这些纺锤结构的花状聚集体。展开更多
基金supported by the National Natural Science Foundation of China(Nos.41303079 and 21377070)the State Kay Laboratory of Pollution Control and Resource Reuse(Nos.,PCRRF13010 and PCRRF14010)the Project Sponsored by the Scientific Research Foundation for the Returned Overseas Chinese Scholars,State Education Ministry of China
文摘The aggregation and deposition of carbon nanotubes（CNTs） determines their transport and fate in natural waters.Therefore,the aggregation kinetics of humic-acid treated multi-walled carbon nanotubes（HA-MWCNTs） was investigated by time-resolved dynamic light scattering in NaCl and CaCl_2 electrolyte solutions.Increased ionic strength induced HA-MWCNT aggregation due to the less negative zeta potential and the reduced electrostatic repulsion.The critical coagulation concentration（CCC） values of HA-MWCNTs were 80 mmol/L in NaCl and 1.3 mmol/L in CaCl_2 electrolyte,showing that Ca^（2＋） causes more serious aggregation than Na~＋.The aggregation behavior of HA-MWCNTs was consistent with Derjaguin-Landau-Verwey-Overbeek theory.The deposition kinetics of HA-MWCNTs was measured by the optical absorbance at 800 ran.The critical deposition concentrations for HA-MWCNT in NaCl and CaCl_2 solutions were close to the CCC values,therefore the rate of deposition cannot be increased by changing the ionic strength in the diffusion-limited aggregation regime.The deposition process was correlated to the aggregation since larger aggregates increased gravitational deposition and decreased random Brownian diffusion.HA-MWCNTs hydrodynamic diameters were evaluated at 5,15 and 25℃.Higher temperature caused faster aggregation due to the reduced electrostatic repulsion and increased random Brownian motion and collision frequency.HA-MWCNTs aggregate faster at higher temperature in either NaCl or CaCl_2electrolyte due to the decreased electrostatic repulsion and increased random Brownian motion.Our results suggest that CNT aggregation and deposition are two correlated processes governed by the electrolyte,and CNT transport is favored at low ionic strength and low temperature.
