Building empirical equations is an effective way to link the acoustic and physical properties of sediments.These equations play an important role in the prediction of sediments sound speeds required in underwater acou...Building empirical equations is an effective way to link the acoustic and physical properties of sediments.These equations play an important role in the prediction of sediments sound speeds required in underwater acoustics.Although many empirical equations coupling acoustic and physical properties have been developed over the past few decades,further confirmation of their applicability by obtaining large amounts of data,especially for equations based on in situ acoustic measurement techniques,is required.A sediment acoustic survey in the South Yellow Sea from 2009 to 2010 revealed statistical relationships between the in situ sound speed and sediment physical properties.To improve the comparability of these relationships with existing empirical equations,the present study calculated the ratio of the in situ sediment sound speed to the bottom seawater sound speed,and established the relationships between the sound speed ratio and the mean grain size,density and porosity of the sediment.The sound speed of seawater at in situ measurement stations was calculated using a perennially averaged seawater sound speed map by an interpolation method.Moreover,empirical relations between the index of impedance and the sound speed and the physical properties were established.The results confirmed that the existing empirical equations between the in situ sound speed ratio and the density and porosity have general suitability for application.This study also considered that a multiple-parameter equation coupling the sound speed ratio to both the porosity and the mean grain size may be more useful for predicting the sound speed than an equation coupling the sound speed ratio to the mean grain size.展开更多
In recent years, natural gas hydrate has attracted increasing attention worldwide as a potential alternative energy source due to its attributes of wide distribution, large reserves, and low carbon. Since the acoustic...In recent years, natural gas hydrate has attracted increasing attention worldwide as a potential alternative energy source due to its attributes of wide distribution, large reserves, and low carbon. Since the acoustic characteristics of hydratebearing reservoirs clearly differ from those of adjacent formations, an acoustic approach, using seismic and acoustic logging, is one of the most direct, effective and widely used methods among the identification and characterization techniques for hydrate reservoir exploration. This review of research on the influence of hydrate(content and distribution) on the acoustic properties(velocity and attenuation) of sediments in the past two decades includes experimental studies based on different hydrate formation methods and measurements, as well as rock physics models. The main problems in current research are also pointed out and future prospects discussed.展开更多
围栏是一种广泛使用的草地管理措施。磷是植物生长发育不可或缺的营养元素,研究围栏管理对土壤磷含量的影响和驱动,对高寒草地生态系统修复和适应性管理具有重要意义。然而,目前缺乏系统的围栏管理对土壤磷含量的影响研究。本文基于Web ...围栏是一种广泛使用的草地管理措施。磷是植物生长发育不可或缺的营养元素,研究围栏管理对土壤磷含量的影响和驱动,对高寒草地生态系统修复和适应性管理具有重要意义。然而,目前缺乏系统的围栏管理对土壤磷含量的影响研究。本文基于Web of Science核心数据库和中国知网(CNKI)检索平台,筛选了101篇文献开展Meta分析,探究不同高寒草地土壤全磷(STP)与速效磷(SAP)含量对围栏管理措施及围栏年限(短期1~4年,中期5~8年和长期9~30年)的响应。结果表明:1)总体而言,围栏显著提升了STP、SAP、全氮(STN)、有机碳(SOC)、速效氮(SAN)和含水量(SM)(P<0.001),却导致了pH和容重显著降低(P<0.01)。2)围栏对高寒草原STP和SAP的正效应显著高于其对高寒草甸磷含量的影响(P<0.001)。3)针对围栏年限,发现中长期围栏对草甸STP具有极显著的正效应(P<0.001),同时短期围栏能够极显著促进草原STP(P<0.001),中长期围栏则会导致草原STP降低;围栏始终有利于提升SAP,且中期围栏对草原SAP的效应最大。4)围栏管理下STP、STN和SOC的效应值存在协同变化规律,且围栏对STP的效应值随气温的升高而显著增加,但土壤pH的降低促进了围栏对STP的效应值的显著增加。此外,围栏对STN与SAP的效应值呈显著正相关关系。本研究揭示了合理的围栏管理有利于提高高寒草地生态系统的土壤磷含量,结果可为高寒草地管理提供理论参考。展开更多
Atmospheric nanoparticles are crucial components contributing to fine particulate matter(PM_(2.5)),and therefore have significant effects on visibility,climate,and human health.Due to the unique role of atmospheric na...Atmospheric nanoparticles are crucial components contributing to fine particulate matter(PM_(2.5)),and therefore have significant effects on visibility,climate,and human health.Due to the unique role of atmospheric nanoparticles during the evolution process from gas-phase molecules to larger particles,a number of sophisticated experimental techniques have been developed and employed for online monitoring and characterization of the physical and chemical properties of atmospheric nanoparticles,helping us to better understand the formation and growth of new particles.In this paper,we firstly review these state-of-the-art techniques for investigating the formation and growth of atmospheric nanoparticles(e.g.,the gas-phase precursor species,molecular clusters,physicochemical properties,and chemical composition).Secondly,we present findings from recent field studies on the formation and growth of atmospheric nanoparticles,utilizing several advanced techniques.Further-more,perspectives are proposed for technique development and improvements in measuring atmospheric nanoparticles.展开更多
基金The National Natural Science Foundation of China under contract Nos 42076082,41706062 and 41676055the Director Fund of Pilot National Laboratory for Marine Science and Technology(Qingdao)under contract No.QNLM201713+1 种基金the Public Science and Technology Research Funds Projects of Ocean under contract No.201405032the Taishan Scholar Project Funding under contract No.tspd20161007。
文摘Building empirical equations is an effective way to link the acoustic and physical properties of sediments.These equations play an important role in the prediction of sediments sound speeds required in underwater acoustics.Although many empirical equations coupling acoustic and physical properties have been developed over the past few decades,further confirmation of their applicability by obtaining large amounts of data,especially for equations based on in situ acoustic measurement techniques,is required.A sediment acoustic survey in the South Yellow Sea from 2009 to 2010 revealed statistical relationships between the in situ sound speed and sediment physical properties.To improve the comparability of these relationships with existing empirical equations,the present study calculated the ratio of the in situ sediment sound speed to the bottom seawater sound speed,and established the relationships between the sound speed ratio and the mean grain size,density and porosity of the sediment.The sound speed of seawater at in situ measurement stations was calculated using a perennially averaged seawater sound speed map by an interpolation method.Moreover,empirical relations between the index of impedance and the sound speed and the physical properties were established.The results confirmed that the existing empirical equations between the in situ sound speed ratio and the density and porosity have general suitability for application.This study also considered that a multiple-parameter equation coupling the sound speed ratio to both the porosity and the mean grain size may be more useful for predicting the sound speed than an equation coupling the sound speed ratio to the mean grain size.
基金the financial support provided by the National Natural Science Foundation of China(Grant Nos.42174133 and 41676032)China Geological Survey(Grant No.DD20190234)。
文摘In recent years, natural gas hydrate has attracted increasing attention worldwide as a potential alternative energy source due to its attributes of wide distribution, large reserves, and low carbon. Since the acoustic characteristics of hydratebearing reservoirs clearly differ from those of adjacent formations, an acoustic approach, using seismic and acoustic logging, is one of the most direct, effective and widely used methods among the identification and characterization techniques for hydrate reservoir exploration. This review of research on the influence of hydrate(content and distribution) on the acoustic properties(velocity and attenuation) of sediments in the past two decades includes experimental studies based on different hydrate formation methods and measurements, as well as rock physics models. The main problems in current research are also pointed out and future prospects discussed.
文摘围栏是一种广泛使用的草地管理措施。磷是植物生长发育不可或缺的营养元素,研究围栏管理对土壤磷含量的影响和驱动,对高寒草地生态系统修复和适应性管理具有重要意义。然而,目前缺乏系统的围栏管理对土壤磷含量的影响研究。本文基于Web of Science核心数据库和中国知网(CNKI)检索平台,筛选了101篇文献开展Meta分析,探究不同高寒草地土壤全磷(STP)与速效磷(SAP)含量对围栏管理措施及围栏年限(短期1~4年,中期5~8年和长期9~30年)的响应。结果表明:1)总体而言,围栏显著提升了STP、SAP、全氮(STN)、有机碳(SOC)、速效氮(SAN)和含水量(SM)(P<0.001),却导致了pH和容重显著降低(P<0.01)。2)围栏对高寒草原STP和SAP的正效应显著高于其对高寒草甸磷含量的影响(P<0.001)。3)针对围栏年限,发现中长期围栏对草甸STP具有极显著的正效应(P<0.001),同时短期围栏能够极显著促进草原STP(P<0.001),中长期围栏则会导致草原STP降低;围栏始终有利于提升SAP,且中期围栏对草原SAP的效应最大。4)围栏管理下STP、STN和SOC的效应值存在协同变化规律,且围栏对STP的效应值随气温的升高而显著增加,但土壤pH的降低促进了围栏对STP的效应值的显著增加。此外,围栏对STN与SAP的效应值呈显著正相关关系。本研究揭示了合理的围栏管理有利于提高高寒草地生态系统的土壤磷含量,结果可为高寒草地管理提供理论参考。
基金supported by the National Key Research and Development Program of China(No.2017YFC0209500)。
文摘Atmospheric nanoparticles are crucial components contributing to fine particulate matter(PM_(2.5)),and therefore have significant effects on visibility,climate,and human health.Due to the unique role of atmospheric nanoparticles during the evolution process from gas-phase molecules to larger particles,a number of sophisticated experimental techniques have been developed and employed for online monitoring and characterization of the physical and chemical properties of atmospheric nanoparticles,helping us to better understand the formation and growth of new particles.In this paper,we firstly review these state-of-the-art techniques for investigating the formation and growth of atmospheric nanoparticles(e.g.,the gas-phase precursor species,molecular clusters,physicochemical properties,and chemical composition).Secondly,we present findings from recent field studies on the formation and growth of atmospheric nanoparticles,utilizing several advanced techniques.Further-more,perspectives are proposed for technique development and improvements in measuring atmospheric nanoparticles.
