西太平洋Y3海山对营养盐的影响及其生态环境效应     

马骏  宋金明  李学刚  袁华茂  李宁  段丽琴  王启栋 《地学前缘》2020,27(4):322-331

作为大洋典型地貌特征的海山,其邻近的海洋生境并不被人熟知。依据2014年冬季对热带西太平洋Y3海山及其邻近海域的综合调查,首次探讨了该海山区海水中营养盐的分布特征及其与生态环境的耦合关系。结果表明Y3海山区是典型的热带寡营养海域。在50~125 m的深度,温跃层和高盐区双重作用对底部高浓度营养盐向上输送的阻碍,是导致真光层上部营养盐浓度较低的重要原因;同时,浮游植物和异养细菌的消耗也加剧了该区域营养盐的缺乏。Y3海山突出的地形地貌对营养盐的分布产生重要的影响,海山对流经的海流产生阻碍,形成上升流,使底部高浓度的营养盐突破温跃层和高盐区的阻碍向上输送,从而使海山周围营养盐的平均浓度高于远离海山的海域。相关性分析显示,Y3海山区真光层中营养盐浓度与温度、盐度、叶绿素a浓度和异养细菌丰度分别呈负相关、正相关、负相关(除NO₂-N外)和负相关关系。海山区特殊的营养盐分布及其与生态环境的耦合是其成为一种独特的大洋生态系统的重要因素。  相似文献   

城镇化与生态环境耦合的动态模拟——研究进展与展望     

崔学刚  方创琳  刘海猛  刘晓菲  李咏红 《地理学报(英文版)》2020,30(2):333-352

Urbanization and eco-environment coupling is a research hotspot.Dynamic simulation of urbanization and eco-environment coupling needs to be improved because the processes of coupling are complex and statistical methods are limited.Systems science and cross-scale coupling allow us to define the coupled urbanization and eco-environment system as an open complex giant system with multiple feedback loops.We review the current state of dynamic simulation of urbanization and eco-environment coupling and find that:(1)The use of dynamic simulation is an increasing trend,the relevant theory is being developed,and modeling processes are being improved;(2)Dynamic simulation technology has become diversified,refined,intelligent and integrated;(3)Simulation is mainly performed for three aspects of the coupling,multiple regions and multiple elements,local coupling and telecoupling,and regional synergy.However,we also found some shortcomings:(1)Basic theories are inadequately developed and insufficiently integrated;(2)The methods of unifying systems and sharing data are behind the times;(3)Coupling relations and the dynamic characteristics of the main driving elements are not fully understood or completely identified.Additionally,simulation of telecoupling does not quantify parameters and is not systemically unified,and therefore cannot be used to represent spatial synergy.In the future,we must promote communication between research networks,technology integration and data sharing to identify the processes governing change in coupled relations and in the main driving elements in urban agglomerations.Finally,we must build decision support systems to plan and ensure regional sustainable urbanization.  相似文献   

基于广义回归神经网络的全球表层海水1°×1°二氧化碳分压数据推演     

钟国荣  李学刚  曲宝晓  王彦俊  袁华茂  宋金明 《海洋学报》2020,42(10):70-79

表层海水二氧化碳分压是评估海洋碳源汇强度的关键参数，但其实测数据较少、时空分布极不均匀，导致二氧化碳交换通量的估算有很大的不确定性，海洋源汇特征就不能确切获取。为了解决这个难题，在收集的表层大洋二氧化碳地图(Surface Ocean CO₂ Atlas，SOCAT)实测数据集基础上，运用广义回归神经网络建立二氧化碳分压与经纬度、时间、温度、盐度和叶绿素浓度间的非线性关系，构建了1998?2018年间全球1°×1°经纬度的表层海水二氧化碳分压格点数据，其标准误差为16.93 μatm，平均相对误差为2.97%，优于现有研究中的前反馈神经网络、自组织映射神经网络和机器学习算法等方法。根据构建的数据所绘制的全球表层海水二氧化碳分压的分布与现有研究有较好的一致性。  相似文献   

Exploring the database of a soil environmental survey using a geo-self-organizing map: A pilot study     

Liao  Xiaoyong  Tao  Huan  Gong  Xuegang  Li  You 《地理学报(英文版)》2019,29(10):1610-1624

A model integrating geo-information and self-organizing map (SOM) for exploring the database of soil environmental surveys was established. The dataset of 5 heavy metals (As, Cd, Cr, Hg, and Pb) was built by the regular grid sampling in Hechi, Guangxi Zhuang Autonomous Region in southern China. Auxiliary datasets were collected throughout the study area to help interpret the potential causes of pollution. The main findings are as follows: (1) Soil samples of 5 elements exhibited strong variation and high skewness. High pollution risk existed in the case study area, especially Hg and Cd. (2) As and Pb had a similar topo-logical distribution pattern, meaning they behaved similarly in the soil environment. Cr had behaviours in soil different from those of the other 4 elements. (3) From the U-matrix of SOM networks, 3 levels of SEQ were identified, and 11 high risk areas of soil heavy metal-contaminated were found throughout the study area, which were basically near rivers, factories, and ore zones. (4) The variations of contamination index (CI) followed the trend of construction land (1.353) > forestland (1.267) > cropland (1.175) > grassland (1.056), which suggest that decision makers should focus more on the problem of soil pollution surrounding industrial and mining enterprises and farmland.

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冀东峪耳崖金矿区闪长岩脉地球化学特征及其地质意义     

杨爱雪  孙德有  侯雪刚  王久良  张继林  李临位 《吉林大学学报(地球科学版)》2021,51(2):416-428

冀东地区位于华北板块北缘燕山造山带东部,矿产资源丰富,是中国金矿的主要产地之一,尤其是热液型金矿。峪耳崖金矿床是冀东众多热液型金矿床的典型代表,金矿主体赋存于侏罗纪峪耳崖花岗岩体内,少部分赋存于侵入花岗岩体的侏罗纪闪长岩脉中。闪长岩脉元素地球化学分析显示：w（SiO₂）为51.99%~61.88%、Mg^#值为0.37~0.64,w（Na₂O+K₂O）为5.07%~8.89%,A/NK为1.37~2.26,A/CNK为0.73~0.96,属准铝质高钾钙碱性系列;富集轻稀土元素和大离子亲石元素Rb、Ba、K、Sr,亏损重稀土元素和高场强元素Nb、Ta、Ti。锆石原位Hf同位素测试表明,ε_Hf（t）为负值,介于-16.5~-6.5之间。综合研究认为：峪耳崖金矿区侏罗纪闪长岩浆源于俯冲流体交代的富集岩石圈地幔,岩浆上侵过程中受到华北板块古老下地壳物质的有限混染;成矿期闪长岩浆为金成矿提供了部分物质来源;峪耳崖金矿区闪长岩脉形成于古太平洋板块向欧亚大陆俯冲的动力学背景。  相似文献   

氮与磷的增加对海水无机碳体系影响的实验模拟研究     

张乃星  宋金明  贺志鹏  李学刚  袁华茂  李宁 《海洋科学集刊》2007,(48):67-76

海洋碳循环是全球变化研究中的重要领域,它不仅在很大程度上决定了全球气温乃至全球气候的变化趋势,而且还是海洋生态系持续发展的基础,它决定着了海洋生态环境变化的走向。众所周知，碳(C)在海洋中以无机态和有机态的形式存在,在海气系统中,大于98%的C以溶解无机碳(DIC)形式存在于水体中(Zeebe et al,2001)其对海洋碳循环的影响至关重要。 氮(N)和磷(P)等营养盐对维持海洋生态系的正常运转起着至关重要的作用。但是，由于近年来人类生产、生活污水的排放以及滩涂和沿岸水域养殖区的长期施肥,它们也作为近岸海区的主要污染物而导致近海海洋生态环境的日益恶化,影响并改变了一些海域的生态结构。如在胶州湾,由于营养盐浓度及结构发生了变化导致该湾地区浮游植物数量和优势种组成的变化(沈志良,2002)近年来,在海洋沿岸带的河口、海湾等水体较浅的透光层内,以孔石莼等绿藻为主要代表的大型海藻开始泛滥,形成大型海藻的水华。海洋生态环境的改变,必然将导致海洋碳循环的变化,从长时间尺度来看也会影响到全球的气候和气温变化。目前,对营养盐与水生藻类之间的响应关系研究已有大量的报道(王勇等,2002；刘媛等，2004；张文俊等，2004)但对于营养盐与海水无机碳体系之间的耦合作用报道甚少。在海洋环境中、C N P作为主要的生源要素,其变化相互影响,并与海水中所存有的海洋生物密切相关。探讨海水中C-N-P的相互耦合关系对于研究海洋生态环境演变过程及效应,阐明海洋碳循环过程的深层次机理,揭示在过量N P作用富营养化条件下,C的迁移转化行为有重要的科学意义和实际价值。本文作者初步研究了模拟条件下C-N-P的相互关系。  相似文献   

北部湾三维潮流场数值研究(英文)     

刘学刚  叶安乐 《中国海洋大学学报(自然科学版)》1988,(4)

本文对北部湾三维潮波进行了数值研究,并将所得结果与现有观测资料作了比较。通过比较发现两者相当一致。文中还绘制了M_2和K_1分潮的同潮图,并对其作了讨论。可以断定,北部湾的日潮优势是由日潮共振所引起的。M_2和K_1分潮流的水平分布表明,强流区位于它们各自的蜕化无潮点附近。还讨论了分潮流的铅直结构,可以看出这种结构十分接近实际分潮流场的特征。  相似文献   

长江口沉积物-水界面砷的迁移转化机制与微生物调控分析     

张玉婷  段丽琴  宋金明  张乃星  尹美玲  李学刚  袁华茂 《地学前缘》2022,29(4):144-155

为探析长江口沉积物-水界面砷的迁移转化机制,本文分析了2019年夏季长江口4个站位上覆水和间隙水中总As浓度及形态的剖面变化特征,耦合氧化还原敏感元素(Fe、Mn和S)的剖面变化剖析了沉积物-水界面砷循环的Fe-Mn-S控制机制,同时结合砷相关功能基因探讨了沉积物-水界面砷迁移转化的微生物调控过程,估算了沉积物-水界面总As的扩散通量。结果表明,除A7-4站位外,长江口其他3个站位间隙水总As以As³⁺为主要存在形态,且总As浓度均在上覆水中为最低值(0.748~1.57 μg·L^-1),而在间隙水中随着深度增加而逐渐增加并在6~9 cm深度达到峰值(7.14~26.9 μg·L^-1)。间隙水总As及As³⁺浓度的剖面变化趋势与溶解态Fe²⁺、Mn²⁺相似,其均在中间层出现高值,说明沉积物Fe/Mn还原带砷的释放可能是随固相Fe(Ⅲ)或Mn(Ⅳ)的还原而转移到间隙水中的。氧化层和Fe/Mn还原带过渡区间隙水砷浓度与砷异化还原菌功能基因arrA和arsC丰度存在对应关系(除A1-3站外),说明砷异化还原菌将溶解As⁵⁺或固相As⁵⁺还原为溶解As³⁺可能是该过渡层砷迁移转化的另一重要过程。硫酸盐还原带的间隙水总As和As³⁺浓度降低,但由于间隙水的低S^2-浓度不利于砷硫化物生成,因此深层间隙水砷可能与铁硫矿物结合而被移除。底层环境氧化还原条件是影响沉积物-水界面砷迁移转化的重要因素,随底层水DO浓度的降低,砷迁移转化更倾向于微生物还原控制。长江口沉积物-水界面总As的扩散通量为1.18×10^-7~2.07×10^-7 μmol·cm^-2·s^-1,均表现为沉积物间隙水中总As向上覆水释放,即沉积物是研究区域水体总As的来源之一。  相似文献   

中国旅游科技创新的时空结构、重心轨迹及其影响因素研究     

周成  冯学钢  张旭红 《世界地理研究》2022,31(2):418-427

旅游产业是充满众多科技创新与成果转化的社会经济部门。以我国旅游产业相关发明专利、旅游收入、风景名胜区、高校学生数等为分析依据,基于地理集中指数、动态变动指数、空间重心模型和灰色关联分析等方法,对各省区2006—2017年旅游科技创新的时空结构、重心轨迹及其影响因素等进行实证研究。结果表明：时间上,我国旅游科技创新整体上呈波动上升的发展态势,2013年后地理集中度指数开始持续下降;空间上,旅游科技创新在我国呈东高西低、南高北低的分布格局。此外,旅游科技创新的空间重心位于我国华东地区,并呈先由北向南、再由东向西的移动轨迹。最后,科技创新产出、旅游经济水平、科技经费投入、经济宏观环境、科技创新服务、旅游资源禀赋等要素指标均对我国旅游科技创新产生一定影响,但影响程度具有差异。  相似文献   

Evaluation on tourism ecological security in nature heritage sites —Case of Kanas nature reserve of Xinjiang, China     

Xuling Liu  Zhaoping Yang  Feng Di  Xuegang Chen 《中国地理科学(英文版)》2009,19(3):265-273

The nature heritages are the precious legacy of nature with outstanding scientific and aesthetic value. They are quite different from other common ecotourism areas, because of its original and unique system, sensitive and vulnerable landscape, and peripheral cultural features. Therefore, the tourism development in the nature heritage sites should be on the premise of ecological security. The evaluation index system of tourism ecological security in nature heritage sites was constructed in this article by AHP and Delphi methods, including nature ecological security, landscape visual security and local culture ecological security, and the security thresholds of indices were also established. In the indices’ weights of the evaluation model, the nature ecological security ranked the highest, followed by tourist landscape visual security and culture ecological security, which reflected the influence degree of the limited factor to tourism ecological security. Then, this paper carried out an empirical study of Kanas of Xinjiang Uygur Autonomous Region, China, which has the potential to be the World Nature Heritage. On the basis of the data attained from survey and observation on the spot, as well as questionnaire answered by tourists and local communities, the ecological security status in Kanas was evaluated. The result showed that the status of Kanas tourism ecological security was better, but there had some limiting factors. Lastly, effective measures were put forward to ensure its ecological security. Foundation item: Under the auspices of National Natural Science Foundation of China (No. 40671057), Knowledge Innovation Programs of Chinese Academy of Sciences (No. KZCX3-SW-355)  相似文献