Since the mud snail Bullacta exarata was introduced for economic aquaculture in the Huanghe River(Yellow River) Delta in 2001, its quick population growth and expanded distribution make it a key-species in the interti...Since the mud snail Bullacta exarata was introduced for economic aquaculture in the Huanghe River(Yellow River) Delta in 2001, its quick population growth and expanded distribution make it a key-species in the intertidal zone of this area. This significantly contributed to the economic income of the local people, but its potential ecological impact on the benthic ecosystem remains unknown. A mesocosm study was conducted to test whether its bioturbation activities affect the microphytobenthos(MPBs;i.e., sedimentary microbes and unicellular algae)productivity and the nutrient exchange between the sediment-water interface. Our results show that the mud snail significantly impacted the dissolved oxygen(DO) flux across the sediment-water interface on the condition of normal sediment and light treatment, and significantly increased the ammonium efflux during recovery period in the defaunated sediment and dark treatment. The presence of micro-and meiofauna significantly increased the NH4-N flux in dark treatment. Whereas, in light treatment, these small animals had less effects on the DO and NH4-N flux between sediment-water interface. Our results provide better insight into the effect of the mud snail B.exarata on the ecosystem functioning via benthic fluxes.展开更多
The Huanghe River(Yellow River)Delta has a wide distribution of fine-grained soils.Fluvial alluviation,erosion,and wave loads affect the shoal area,resulting complex physical and mechanical properties to sensitive fin...The Huanghe River(Yellow River)Delta has a wide distribution of fine-grained soils.Fluvial alluviation,erosion,and wave loads affect the shoal area,resulting complex physical and mechanical properties to sensitive finegrained soil located at the river-sea boundary.The cone penetration test(CPT)is a convenient and effective in situ testing method which can accurately identify various soil parameters.Studies on undrained shear strength only roughly determine the fine content(FC)without making the FC effect clear.We studied four stations formed in different the Huanghe River Delta periods.We conducted in situ CPT and corresponding laboratory tests,examined the fine content influence on undrained shear strength(S_(u)),and determined the cone coefficient(N_(k)).The conclusions are as follows.(1)The fine content in the area exceeded 90%,and the silt content was high,accounting for more than 70%of all fine particle compositions.(2)The undrained shear strength gradually increased with depth with a maximum of approximately 250 kPa.When the silt content was lower than 60%–70%,the undrained shear strength decreased.(3)The silt and clay content influenced undrained shear strength,and the fitted f_(s)h/q_(t) function model was established,which could be applied to strata with a high fine content.The cone coefficients were between 20 and 25,and the overconsolidated soil layer had a greater cone coefficient.展开更多
基金The Strategic Priority Research Program of the Chinese Academy of Sciences under contract Nos XDA23050304 and XDA23050202the Key Research Project of Frontier Science of Chinese Academy of Sciences under contract No.QYZDB-SSWDQC041+3 种基金the Program of Ministry of Science and Technology of the People’s Republic of China under contract No.2015FY210300the National Natural Science Foundation of China under contract No.41061130543the Netherlands Organization for Scientific Research under contract No.843.10.003 as part of the NSFC-NOW “Water ways,Harbours,Estuaries and Coastal Engineering” schemethe self-deployment project of Yantai Institute of Coastal Zone Research,Chinese Academy of Sciences under contract No.YIC755021012
文摘Since the mud snail Bullacta exarata was introduced for economic aquaculture in the Huanghe River(Yellow River) Delta in 2001, its quick population growth and expanded distribution make it a key-species in the intertidal zone of this area. This significantly contributed to the economic income of the local people, but its potential ecological impact on the benthic ecosystem remains unknown. A mesocosm study was conducted to test whether its bioturbation activities affect the microphytobenthos(MPBs;i.e., sedimentary microbes and unicellular algae)productivity and the nutrient exchange between the sediment-water interface. Our results show that the mud snail significantly impacted the dissolved oxygen(DO) flux across the sediment-water interface on the condition of normal sediment and light treatment, and significantly increased the ammonium efflux during recovery period in the defaunated sediment and dark treatment. The presence of micro-and meiofauna significantly increased the NH4-N flux in dark treatment. Whereas, in light treatment, these small animals had less effects on the DO and NH4-N flux between sediment-water interface. Our results provide better insight into the effect of the mud snail B.exarata on the ecosystem functioning via benthic fluxes.
基金The National Natural Science Foundation of China under contract Nos S42177153,U2006213 and 41806075the Shandong Province Focused Research and Development Program under contract No.2019GHY112075the National Major Scientific Research Instrument Development Project under contract No.41627801.
文摘The Huanghe River(Yellow River)Delta has a wide distribution of fine-grained soils.Fluvial alluviation,erosion,and wave loads affect the shoal area,resulting complex physical and mechanical properties to sensitive finegrained soil located at the river-sea boundary.The cone penetration test(CPT)is a convenient and effective in situ testing method which can accurately identify various soil parameters.Studies on undrained shear strength only roughly determine the fine content(FC)without making the FC effect clear.We studied four stations formed in different the Huanghe River Delta periods.We conducted in situ CPT and corresponding laboratory tests,examined the fine content influence on undrained shear strength(S_(u)),and determined the cone coefficient(N_(k)).The conclusions are as follows.(1)The fine content in the area exceeded 90%,and the silt content was high,accounting for more than 70%of all fine particle compositions.(2)The undrained shear strength gradually increased with depth with a maximum of approximately 250 kPa.When the silt content was lower than 60%–70%,the undrained shear strength decreased.(3)The silt and clay content influenced undrained shear strength,and the fitted f_(s)h/q_(t) function model was established,which could be applied to strata with a high fine content.The cone coefficients were between 20 and 25,and the overconsolidated soil layer had a greater cone coefficient.
