城市三维景观格局时空分异特征研究——以大连市中山区为例   总被引：3，自引：1，他引：2  

杨俊  国安东  席建超  葛全胜  李雪铭 《地理学报》2017,72(4):646-656

以大连市中山区2003年、2013年城市三维建筑数据为基础,选取三维景观指标,运用ArcGIS空间分析方法从多个角度来研究城市10年间建筑景观格局时空分异特征。结果表明：① 大连市中山区建筑加权平均高度和体积分别增加7.87 m、277.25×10⁴ m³;地块覆盖率减少了16.27%,容积率增加了20.67%,反映出城市水平和垂直空间分别呈收缩、扩展的态势。② 中山区城市天际线起伏差异明显,东—西方向呈逐渐增高的趋势,南—北方向呈“北部高峰,中部和南部平缓”格局。城市高层建筑主要集中于城市的西北部,且2013年建筑最高点中心裕景比2003年宏进大厦高140 m。③ 建筑覆盖率和容积率在空间分布上差异明显,低和极低覆盖率与容积率地块所占比例大,分别增加了8.3%、-4.33%;高和极高覆盖率与容积率地块所占比例少,且集中分布在青泥洼桥和人民路街道。④ 2003年超高层建筑在空间分布上呈“聚集—离散”状态,即在距离660 m尺度范围内呈聚集状态,大于660 m时呈离散分布,其他三种建筑类型在空间上都呈一定的聚集分布状态;2013年4种不同类型建筑在空间分布上都呈现一定的聚集分布状态,聚集程度为：超高层建筑>低层建筑>多层建筑>高层建筑。  相似文献   

北京市密云区农业土壤重金属元素地球化学特征及生态风险评价   总被引：3，自引：0，他引：3  

段续川  李苹  黄勇  林赟  袁国礼  罗先熔 《现代地质》2018,32(1):95

在北京市密云区西南部农业区系统地采集了1 065件表层土壤样品,对其中Ni、V、Cr、As、Cd、Pb、Zn、Hg 8种重金属元素的含量开展了测试分析。采用多元统计分析法及空间分析法,阐明了这些重金属元素的地球平均化学分布特征,并探讨了其可能的主要来源。结果表明,8种重金属元素主要分为3类：第一类为Ni、V、Cr、As,其含量低于北京地区背景值,其分布主要受成土母质等自然因素的影响;第二类为Cd、Pb、Zn,其平均含量高于背景值,且居民区含量最高。除继承成土母质外,此类元素的分布特征受人为活动影响较大,其中Cd受人为活动影响的程度明显高于Pb和Zn;第三类为Hg,推断大气沉降为影响Hg分布的主要因素。主要采用Hakanson法评价了土壤中重金属的生态风险,结果表明该地区潜在生态危害指数较低。  相似文献   

宁夏固原市原州区高氟地区氟对人体健康的影响   总被引：1，自引：0，他引：1  

邰苏日嘎拉  李永春  周文辉  王永亮  陈国栋  苏日力格  张祥 《岩矿测试》2021,(6):919-929

近年来随着人们生活质量的提升,对健康的关注度也不断提高,氟中毒性地方病越来越受到人们的重视。在关注氟污染源分析及暴露途径研究的同时,开展氟暴露途径评价健康风险研究也十分必要。据调查,固原市原州区彭堡镇地区表层土壤氟含量高于当地区域背景值,本文针对当地存在氟超标导致地方病的实际情况,重点采集了固原市原州区彭堡镇地区表层土壤、地层岩石、农作物、地下水等样品,主要采用电感耦合等离子体发射光谱法（ICP-OES）、原子荧光光谱法（AFS）等分析方法对相关元素进行分析测试,研究固原市原州区彭堡镇高氟区氟超标对人体健康的影响,并运用健康风险评价模型对人体健康风险进行评价。评价结果表明：谷物和蔬菜氟暴露途径健康风险指数HQ<1,没有非致癌风险。当地人体氟暴露风险主要途径为饮用地下水摄入,相关的健康风险指数HQ>1,这表明通过饮用氟超标的地下水,可能具有潜在的非致癌风险。年度总健康风险为1.69×10^-8,低于国际辐射防护委员会（ICRP）建议的最大可接受年健康风险水平5.0×10^-5,属于人类可接受的风险水平。根据氟健康风险评价结果,本文提出该地区饮用水安全性方面还需多给予关注。  相似文献   

河套灌区耕地-荒地-海子系统间不同类型水分运移转化          下载免费PDF全文

王国帅  史海滨  李仙岳  闫建文  郭珈玮  李正中 《水科学进展》2021,31(6):832-842

为了探明耕地-荒地-海子系统中不同类型水分的运移转化规律,在2018-2019年典型时期对系统内具有代表性的采样点进行水样采集,分析了不同时期内不同水体的δ¹⁸O变化特征,并利用二端元混合模型和土壤水动力学方法计算了不同类型水分转化贡献率。结果发现：①在灌溉期,82%的灌溉水储存于1 m土体中,18%的灌溉水通过渗漏补给了耕地地下水,渠系灌溉水通过地下侧向径流给耕地地下水贡献了76%。②灌溉水和降雨对耕地地下水平均贡献率为94%和6%;耕地地下水和降雨对荒地地下水的平均贡献率为71%和29%;荒地地下水和降雨对海子的平均贡献率为43%和57%。③渠系灌溉水通过侧向径流贡献给耕地地下水的水量基本全部迁移给了荒地地下水,地下水迁移转化是由渠系水侧向径流触发的。④灌后5 d,耕荒地交界土层0~40 cm存在饱和-非饱和侧向补给;灌后15 d和30 d,耕地和耕荒地交界处的地下水向根区40~60 cm、土层80 cm以及100 cm补给水分;灌后30 d,耕地中的灌溉水水分消失。⑤在非灌溉期,荒地地下水和海子耗水较多,应给海子补给水分。  相似文献   

含矿区小流域生境质量评估方法——以宝兴河流域锅巴岩矿山为例     

许小龙  杨星辰  魏瑞龙  程先琼  叶成名  王俪璇  眭天波 《地质力学学报》2021,27(3):400-408

为了探究小流域背景下的地质工程活动对生境质量的影响评估方法,文章以宝兴河流域为例,利用遥感技术对流域内的重点工程锅巴岩矿山的土地利用变化情况进行了信息提取,并采用InVEST模型定量评估了生境质量。结果表明:锅巴岩矿山的土地利用类型主要由林地向裸地转变,林地面积占比减少15.11%,裸地的面积占比增加12.30%;锅巴岩矿山的生境质量指数从0.9234下降到0.8618,标准差从0.2389增加到0.3134,生境质量低等级面积占比增加4.84%,表明矿山区域整体的生境质量有所下降,但变化不明显;锅巴岩矿山的生境退化强的区域面积占比增加3.40%,生境退化指数由0.0113增加到0.0159,表明矿区生境有所退化但不明显。由此可见,含矿区小流域的生境质量虽受人类活动干扰,但如果采取合理开采方法,科学优化土地利用格局,有效地进行生态修复,对环境的影响可以控制在较低水平。   相似文献   

Overprinting porphyry‐type veinlets on the intrusive rocks and phreatomagmatic breccias in the Southwest prospect,southwestern Sto. Tomas II (Philex), Baguio District,Philippines     

Avriel Venis L. Cirineo  Akira Imai  Ryohei Takahashi  Redempta P. Baluda  Noel C. Oliveros  Victor B. Maglambayan  Roy Ronald C. Luis  Maria Lourdes M. Faustino  Jacky Almadin 《Resource Geology》2021,71(1):1-40

The Southwest prospect is located at the southwestern periphery of the Sto. Tomas II porphyry copper–gold deposit in the Baguio District, northwestern Luzon, Philippines. The Southwest prospect hosts a copper‐gold mineralization related to a complex of porphyry intrusions, breccia facies, and overlapping porphyry‐type veinlets emplaced within the basement Pugo metavolcanics rocks and conglomerates of the Zigzag Formation. The occurrences of porphyry‐type veinlets and potassic alteration hosted in the complex are thought to be indications of the presence of blind porphyry deposits within the Sto. Tomas II vicinity. The complex is composed of at least four broadly mineralogically similar dioritic intrusive rocks that vary in texture and alteration type and intensity. These intrusions were accompanied with at least five breccia facies that were formed by the explosive brecciation, induced by the magmatic–hydrothermal processes and phreatomagmatic activities during the emplacement of the various intrusions. Hydrothermal alteration assemblages consisting of potassic, chlorite–magnetite, propylitic and sericite–chlorite alteration, and contemporaneous veinlet types were developed on the host rocks. Elevated copper and gold grades correspond to (a) chalcopyrite–bornite assemblage in the potassic alteration in the syn‐mineralization early‐mineralization diorite (EMD) and contemporaneous veinlets and (b) chalcopyrite‐rich mineralization associated with the chalcopyrite–magnetite–chlorite–actinolite±sericite veinlets contemporaneous with the chlorite–magnetite alteration. Erratic remarkable concentrations of gold were also present in the late‐mineralization Late Diorite (LD). High X_Mg of calcic amphiboles (>0.60) in the intrusive rocks indicate that the magmas have been oxidizing since the early stages of crystallization, while a gap in the composition of Al between the rim and the cores of the calcic amphiboles in the EMD and LD indicate decompression at some point during the crystallization of these intrusive rocks. Fluid inclusion microthermometry suggests the trapping of immiscible fluids that formed the potassic alteration, associated ore mineralization, and sheeted quartz veinlets. The corresponding formation conditions of the shallower and deeper quartz veinlets were estimated at pressures of 50 and 30 MPa and temperatures of 554 and 436°C at depths of 1.9 and 1.1 km. Temperature data from the chlorite indicate that the chalcopyrite‐rich mineralization associated with the chlorite–magnetite alteration was formed at a much lower temperature (ca. 290°C) than the potassic alteration. Evidence from the vein offsetting matrix suggests multiple intrusions within the EMD, despite the K‐Ar ages of the potassic alteration in EMD and hornblende in the LD of about the same age at 3.5 ± 0.3 Ma. The K‐Ar age of the potassic alteration was likely to be thermally reset as a result of the overprinting hydrothermal alteration. The constrained K‐Ar ages also indicate earlier formed intrusive rocks in the Southwest prospect, possibly coeval to the earliest “dark diorite” intrusion in the Sto. Tomas II deposit. In addition, the range of δ³⁴S of sulfide minerals from +1.8‰ to +5.1‰ in the Southwest prospect closely overlaps with the rest of the porphyry copper and epithermal deposits in the Sto. Tomas II deposit and its vicinity. This indicates that the sulfides may have formed from a homogeneous source of the porphyry copper deposits and epithermal deposits in the Sto. Tomas II orebody and its vicinity. The evidence presented in this work proves that the porphyry copper‐type veinlets and the adjacent potassic alteration in the Southwest prospect are formed earlier and at a shallower level in contrast with the other porphyry deposits in the Baguio District.  相似文献   

Glacier shrinkage and negative mass balance in the Chilean Lake District (40°S) / Rétrécissement glaciaire et bilan massique négatif dans la Région des Lacs du Chili (40°S)     

《水文科学杂志》2013,58(6)

Abstract

Ice-capped volcanoes of the Chilean Lake District have shown significant glacier retreat during recent decades, probably in response to tropospheric warming and precipitation decrease. Volcán Mocho-Choshuenco (39°55′S, 72°02′W) is one of the main active volcanoes in this part of the country. A mass balance programme was initiated on its southeastern glacier in 2003, in view of its representative conditions as an ice body that is presumably not affected by current volcanic activity. The glaciers of this volcano have been retreating and shrinking in recent decades; by 2003 there had been a reduction of 40% of the original area of 28.4 km² in 1976. A maximum decrease of area was observed in the most recently analysed period, a rate of 0.45 km² year^-1 between 1987 and 2003. The glacier average net mass balance of 2003/04 yielded ?0.88 m w.e. (water equivalent) per year (±0.18), with an average net accumulation and ablation of 2.59 and ?3.47 m w.e. per year, respectively. This is the first direct measurement of glacier mass balance in southern Chile, where very little is known about glacier variations and glacier–volcano interactions.  相似文献   

Testing the model of oblique transpression with oblique extrusion in two natural cases: Steps and consequences     

《Journal of Structural Geology》2013

Kinematic models of various types of transpression have been used to explain fabric features and strain in many natural deformation studies. Here, a mathematical model that encompasses all monoclinic and triclinic transpressional deformations including triclinic deformation with inclined simple shear (ϕ) and/or inclined extrusion orientations (υ) can be tested using a step-by-step approach with available field evidence. Two cases are presented. The first case from the Wabigoon–Quetico boundary in the Archean Superior Province utilizes both fabric orientation and quantified strain data. The best fit of the field evidence to the model indicates that deformation likely took place along subvertical shear zones via transpression with subhorizontal simple shear (ϕ = 0–20°) and variable inclined extrusion direction (extrusion can be either east or west and υ typically indicates extrusion orientations between 0 and 50° from vertical). The second case of the South Iberian shear zone has fabric orientation data, but no quantifiable strain possibilities. The best fit of the field evidence to the model indicates that deformation likely took place along a moderately inclined shear zone via transpression with subhorizontal simple shear (ϕ = 0–20°) and variable inclined extrusion direction (υ values between 0° and 80° from the true dip of the shear zone). Using this protocol in other examples of natural deformation will allow further constraints to be applied to kinematic models.  相似文献   

灰色关联度分析法在北京通州区地裂缝灾害危险性评价中的应用     

刘德成  靳小平  周自梁 《中国地质灾害与防治学报》2010,21(3):73-76

地裂缝是地质灾害中的地面变形灾害之一,是直接或间接地恶化环境、降低环境质量、危害人类和生物圈发展的地质事件。本文介绍了利用灰色关联度分析法对地裂缝灾害危险性进行评价,并系统阐述了灰色关联度分析法的评价方法与模型,旨在为城市规划和防灾减灾提供科学依据。文中以北京市通州区为例,对北京市通州区地裂缝现状进行了说明并对其进行了成因分析,选取了灾害发育强度、地质条件和水文地质条件三项因子共六个评价指标,然后对评价指标进行权重计算评定地裂缝的危险性等级,并绘制区划图。根据区划的结果,划分地裂缝中度易发区、轻度易发区、微度易发区以及非易发区。  相似文献   

保育滨海湿地 实现持续发展   总被引：1，自引：0，他引：1  

许昱辉 《湿地科学与管理》2012,8(2):60-62

滨海新区是天津市东部重点建设的经济区域,沿海有大量湿地,对当地的生态环境起着重要的调节作用。随着滨海新区的开发建设,该区的湿地面临着如何保护等实际问题。本文从生态学的角度就目前滨海新区的湿地生态功能、经济价值和社会价值进行了评述,并就目前该区域面临的主要问题及如何合理有序地开发与保护提出建议,旨在使滨海新区的自然、经济、社会协调统一发展。  相似文献