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1.
In order to study the sedimentary environment characteristics of the Late Paleozoic in Kala area of Western Sichuan Province, the authors have conducted the petrological and geochemical analyses of the widely distributed silicate in Qiongyi Formation of Lower Carboniferous and Kawenggou Formation of Upper Permian. The results show that the silicate in the study area belongs to the pure siliceous rocks, with a continuous supply of land-based materials during the deposition process. The average Al/(Al+Fe+Mn) ratio is 0.62, and the silicate shows a biogenic origin by the Al-Fe-Mn diagram. The ratios of Al2O3/ (Al2O3+ Fe2O3), Th/U, Th/Sc, (La/Ce)N and (La/Yb)N and tectonic environment discriminant diagram demonstrate that the silicate developed in a shallow-slope depesitional environment in the continental margin. The Ceanom value is -0.04 to 0.07, and it gradually increases from the Carboniferous to the Permian period, indicating the water body is in an anoxic environment with gradually increasing reducibility. The Garz--Litang basin opened in the Carboniferous period, in accordance with the regional geological evolution, and it continued to expand during the Permian period, with the gradually increasing depth of the seawater within the sedimentary basins.  相似文献   
2.
陈莹  赵辉 《海洋学研究》2021,39(3):84-94
本文使用2003年1月—2019年12月MODIS遥感数据,结合海表温度、风速分析南海中西部叶绿素质量浓度分布特征和影响因素。结果显示南海中西部叶绿素质量浓度分布存在时空变化。EOF分解表明,EOF1可能反映台风等极端天气对叶绿素的影响;而EOF2 和EOF3均反映了夏季沿岸上升流对叶绿素分布的影响。相关分析表明南海中西部叶绿素质量浓度与海面风场呈正相关(r=0.87,p<0.01),与海表温度呈负相关(r=-0.59,p<0.05)。夏季在西南季风影响下越南东南沿海形成上升流,导致该区浮游植物旺发、叶绿素质量浓度升高;冬季受强东北季风影响,研究区海洋上层混合作用强烈,营养盐供应增加,促进了浮游植物生长,叶绿素质量浓度高于其他季节。  相似文献   
3.
高铁站被视为拉动城市经济增长的新型空间,研究其周边产业结构对指导高铁站区的开发具有重要意义。本文选取了全国范围内9个不同区位、不同等级的高铁站为研究对象,以高铁站周边3000 m范围内10类产业的POI信息作为研究数据,通过Ripley's K函数、核密度估计和产业指数等方法探索不同区位下高铁站区的产业结构特征。研究发现:① 当高铁站的等级规模相同时,高铁站距离城市中心越远,站区内产业POI总数一般就越少。其中,购物服务、餐饮服务、生活服务和公司企业4类产业的POI数量显著高于其他产业。② 所有高铁站区的产业在1500 m的观测距离内均呈现出显著的集聚分布特征。其中,中心站产业集聚程度的变化较为平缓,城区站产业集聚程度最高,变化幅度也更大,而新城站的规律特征不明显。③ 中心站的产业集聚区域主要分布在高铁站周边0~2500 m的范围内,城区站的产业集聚现象在500~2500 m范围内较为明显,而新城站的产业集聚区域则集中在0~1500 m、2000~3000 m的范围以内。④ 基本服务产业和衍生服务产业主要集中于内圈层和中间圈层,相关服务产业则主要分布在中间圈层和外圈层,各圈层内产业复合特征明显,且高铁站越远离城市中心,其对产业的辐射作用越弱,产业衰减趋势也越明显。基于以上结论,本文认为未来高铁站区的产业开发更应关注土地开发集约化和产业发展复合化。  相似文献   
4.
三江源地区美丽中国建设存在的问题、成功案例与启示   总被引:1,自引:0,他引:1  
杨建平  康韵婕  唐凡  秦彧 《冰川冻土》2021,43(5):1551-1559
长江、黄河与澜沧江源区(简称三江源区)是中华与亚洲“水塔”,是我国重要的生态安全屏障与水安全保障,是三大河流域经济带的共有源地,稳藏固疆的战略要地,美丽中国建设的战略高地。掌握该地区美丽中国建设进程,发现存在的问题,及时总结典型成功案例,有助于更好建设美丽高原,服务生态文明建设与社会经济高质量发展的全国战略部署。就建设内容与进程看,目前三江源区整体仍处于物质建设阶段,除畜牧业外,缺乏其他产业,忽视文化建设,美丽缺少内涵、不可持续;就建设成效而言,美丽乡村与美丽城镇工程建设成绩显著,但配套设施严重滞后,以及游牧文化与聚落文化的冲突,美丽仍流于形式;尽管存在这些问题,但亦涌现了若干成功案例,“岗龙模式”和“甘达模式”尤为典型,为三江源其他地区美丽中国建设提供了样板与发展启示:(1)找准优势资源,最大化资源潜力、实现经济“美”是高原美丽中国建设成功的物质基础;(2)领导人/团队/致富带头人是高原美丽中国建设成功的关键核心;(3)产业与因地制宜的运作机制是高原美丽中国建设可持续的强大支撑与必由之路;(4)不断探索永远走在发展路上是美丽中国建设成功的坚实动力。  相似文献   
5.
Zhejiang Province, located in the Yangtze River Delta region, is representative of China's economically developed areas. It enjoys superior natural conditions and a long history of agriculture, and is a comprehensive agricultural area with integrated development of agriculture, forestry, animal husbandry and fishery. It has nurtured the farming culture represented by Hemudu culture and Liangzhu culture, which have given rise to numerous precious Agricultural Heritage Systems. At present, Zhejiang Province has three of the world’s Globally Important Agricultural Heritage Systems (GIAHS) and 12 China Nationally Important Agricultural Heritage Systems (China-NIAHS), so it not only has the largest number of heritages in China, but it has also attained remarkable achievements in heritage conservation. Taking Zhejiang Province as an example in combination with the rural revitalization strategy, this paper summarizes the achievements in the protection of Important Agricultural Heritage Systems (IAHS) in Zhejiang Province during the past 15 years from the aspects of increasing farmers’ income, cultural Inheritance and industrial upgrading, as well as the conservation experiences in government promotion, community initiative, enterprise participation, technology driving and social linkage. Further, in view of the problems that exist in the current heritage protection,such as imperfect management of heritage sites, low participation of community residents, lack of special protection funds, and imperfect provincial management system,the following countermeasures and suggestions are put forward: (1) Improve the management mechanism for the conservation and development of Agricultural Heritage Systems; (2) Develop regional public branding of agricultural products in Agricultural Heritage System sites; (3) Increase the Agricultural Heritage System science education as well as cultural and creative product development; (4) Carry out the evaluation and recognition of IAHS at the provincial level; and (5) Provide substantial support and input to the conservation and utilization of IAHS. This study can provide some guidance for the conservation of IAHS in Zhejiang Province and it provides important reference for IAHS in the economically developed areas in China.  相似文献   
6.
邵晨晨 《探矿工程》2021,48(6):102-108
上海某国际金融大厦深大基坑项目北侧紧邻运营轨道交通8号线区间隧道,最近处仅7.87 m,南侧与现有世博共同管沟净距2.0~3.0 m,基坑变形控制要求高,周边环境敏感。同时,本项目位于黄浦江畔,场地浅层为典型的淤泥质软土地层,下部为富含承压水粉(砂)土层,且微承压水层与第一、第二承压水层互为连通,止水帷幕无法隔断承压水层,地质条件复杂。设计采用分坑施工、被动区加固、预应力伺服钢支撑系统、抽灌一体化降水方案、超深地下连续墙、跟踪注浆、型钢垫层等技术方案。实测结果表明,区间隧道的最大变形6.52 mm,共同管沟的最大变形15.3 mm,其最大变形均满足变形控制要求,确保了运营区间隧道和共同管沟的安全。  相似文献   
7.
Systematic variations in atmospheric heat exchange, surface residence time, and groundwater influx across montane stream networks commonly produce an increasing stream temperature trend with decreasing elevation. However, complex stream temperature profiles that differ from this common longitudinal trend also exist, suggesting that stream temperatures may be influenced by complex interactions among hydrologic and atmospheric processes. Lakes within stream networks form one potential source of temperature profile complexity due to the spatially variable contribution of lake-sourced water to stream flow. We investigated temperature profile complexity in a multi-season stream temperature dataset collected across a montane stream network containing many alpine lakes. This investigation was performed by making comparisons between multiple statistical models that used different combinations of stream and lake characteristics to represent specific hypotheses for the controls on stream temperature. The compared models included a set of models which used a topographically derived estimate of the hydrologic influence of lakes to separate and quantify the effects of stream elevation and lake source-water contributions to longitudinal stream temperature patterns. This source-water mixing model provided a parsimonious explanation for complex stream-network temperature patterns in the summer and autumn, and this approach may be further applicable to other systems where stream temperatures are influenced by multiple water sources. Simpler models that discounted lake effects were more optimal during the winter and spring, suggesting that complex patterns in stream temperature profiles may emerge and subside temporally, across seasons, in response to diversity of water temperatures from different sources.  相似文献   
8.
The 33 086 ha mixed land use Fall Creek watershed in upstate New York is part of the Great Lakes drainage system. Results from more than 3500 water samples are available in a data set that compiles flow data and measurements of various water quality analytes collected between 1972 and 1995 in all seasons and under all flow regimes in Fall Creek and its tributaries. Data is freely accessible at https://ecommons.cornell.edu/handle/1813/8148 and includes measurements of suspended solids, pH, alkalinity, calcium, magnesium, potassium, sodium, chloride, nitrate nitrogen (NO3-N), sulphate sulphur (SO4-S), phosphorus (P) fractions molybdate reactive P (MRP) and total dissolved P (TDP), percent P in sediment, and ammonium nitrogen (NH4-N). Methods, sub-watershed areas, and coordinates for sampling sites are also included. The work represented in this data set has made important scientific contributions to understanding of hydrological and biogeochemical processes that influence loading in mixed use watersheds and that have an impact on algal productivity in receiving water bodies. In addition, the work has been foundational for important regulatory and management decisions in the region.  相似文献   
9.
Macrophyte community diversity and composition respond to ecosystem conservation and local environmental factors. In this study, we developed a multidimensional diversity framework for macrophyte communities, including the taxonomic and functional alpha and beta diversity. We used the framework to explore the relationships among water level regimes and these diversity parameters in a case study of China's Baiyangdian Lake. Analysis of indicators of hydrologic alteration divided the water level from 1959 to 2019 into four regimes (dry, <6.42 m; low, 6.42–7.23 m; medium, 7.23–8.19 m; high, >8.19 m). Alpha and beta diversity were significantly higher in the medium regime than in the low and high regimes. Redundancy analysis indicated that the maximum water depth significantly affected taxonomic alpha diversity, and total nitrogen (TN) and chemical oxygen demand (COD) concentration significantly affected functional alpha diversity, respectively. Mantel tests showed that TN, Secchi depth (SD), and water depth in the high water level regime significantly increased the total beta diversity and turnover components. TN was the main factor that increased total taxonomic beta diversity. Water level regime mainly influenced interspecific relationships by changing the TN and COD concentration. The water level should be maintained between the medium and high water level regimes to promote restoration of the macrophyte community and improve ecosystem stability. The biodiversity evaluation framework would provide a deeper insight into the hydrological process management for restoration of aquatic macrophyte communities in shallow lakes.  相似文献   
10.
利用福建重力台网7套gPhone重力仪的连续观测资料,对不同震中距和震级地震的同震响应特征及重力仪映震的最大震中距进行分析。结果表明:1)福建重力台网的映震效能受震级和震中距影响,从映震能力来看,泉州台优于莆田台,厦门台优于福州台,漳州台和龙岩台优于南平台;2)福建重力台网的仪器稳定性好和灵敏度高,与CMG-3ESP 120S地震计相比,重力仪具有较宽的地震频带,其同震响应持续时间与波幅呈高度正相关性;3)福建重力台网仪器映震的最大震中距(Δ)与震级(MS)存在对应关系,具体公式为MS=-0.218(logΔ)3+2.056(logΔ)2-4.594logΔ+6.459。  相似文献   
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