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1.
Knowledge of recreational use patterns, preferences and opinions of beach users can be useful in developing beaches in such a way as to ensure quality recreational experiences. This paper investigated, by means of questionnaire survey, a) the factors influencing human beach choice on three beaches with different levels of development and b) whether respondents on the different beaches considered different characteristics important on an ideal beach. By means of multiple discriminant analysis, visitors could be classified according to the beaches they were interviewed on, based solely on the different reasons given for visiting the beach as well as on the characteristics they considered important on a beach.Although factors relating to level of beach development were the most important in influencing beach choice on highly developed King's Beach and undeveloped Sardinia Bay, traditional/historical, socio-economic factors and accessibility (all unrelated to beach development) were more important on semi-developed Joorst Park, visited by people of a lower-socio-economic level. These people considered Joorst Park underdeveloped but were prevented by socio-economic restraints from visiting a beach of their choice, eg King's Beach. The highly and semi-developed beaches were visited for their facilities, social activities and accessibility. The undeveloped beach was visited for experiencing nature, peace and quiet, its few people and because dogs were allowed there. In addition, respondents' opinions were obtained on litter, additional facilities, preferred distances between groups on the beach and in the surf and whether dogs and off-road vehicles should be allowed on beaches. More basic facilities (toilets and refuse bins) were considered necessary on all beaches, especially on the semi-developed beach. Beyond a minimal level of amenities, additional comforts were undesired by users on the undeveloped beach and limited funds should rather be used to upgrade and improve beaches such as Joorst Park, that are already developed to attract people with greater demands for a wider range of facilities. However, beaches with different levels of development are necessary to cater for people who desire different recreational experiences. Limiting beach access beyond a certain number of visitors seems to be unpopular with the public.  相似文献   

2.
甘肃省是我国泥石流地质灾害最为严重的4大省份之一。据统计,全省发育有泥石流沟6 260条,这些泥石流沟大部分集中在东部地区,河西地区较少。泥石流强烈发育的陇南、甘南山区,地势高差多在1 000m以上,山坡坡度≥30°。区内地质构造复杂,地震活动频繁,广泛分布黄土、泥岩、千枚岩、页岩等软弱易滑岩土体,为泥石流发育提供了必要的地形条件和岩土条件,降雨和地震及人类活动是诱发因素。长期以来,频繁发生的泥石流地质灾害已给甘肃人民的生命财产和工农业生产建设带来了严重威胁和危害,造成约3 715人死亡,直接经济损失几十亿。其中,2010年8月8日,舟曲发生的特大泥石流地质灾害震惊世界,泥石流地质灾害已严重困扰和和制约着甘肃省的国民经济发展和广大人民群众的正常生活。因此,应通过科学规划人类活动,采取必要的工程措施制约泥石流地质灾害的发生,减轻泥石流地质灾害造成的损失。  相似文献   

3.
对沈阳煤田采空区地面沉陷、地下水污染和土壤重金属污染问题展开了深入的调查分析研究.结果表明:沈南煤田矿区各沉陷区面积为3.85~17.19km2,沈北煤田矿区各沉陷区面积为0.21~4.89km2.研究区地下水污染从山前地带到平原地区逐渐加重.东部山前地带工业不发达,污染较少;北部和南部地区地下水埋藏较深,污染源较少,不易造成污染,整体污染较轻;西部工业发达,污染源较多,地下水污染较重.沈阳市区土壤重金属污染较为普遍,以铁西区原工厂区为中心形成面积性污染,中心城区及于洪工业区存在Se、Zn、Pb、Hg高浓度区.  相似文献   

4.
《China Geology》2021,4(4):585-592
This study aims to comprehensively assess the environmental risks of microplastics in the Yellow River, achieving the following results through comprehensive research. The average microplastic abundances in the river waters and sediments are 5358–654000 n/m3 and 43.57–615 items/kg, respectively, and there are fewer microplastics in water samples than in sediments. Microplastics in the study area can be divided into five types according to their occurrence morphologies, namely fragments, foams, films, fibers, and particles. The most widely distributed pollution types in sediments include debris, fibers, and particles. In contrast, fibers are the dominant type in water samples, accounting for 68.18% –98.93%. The chemical components of the microplastics include polyethylene, polypropylene, polystyrene, polyethylene terephthalate, and polyvinyl chloride. The microplastics are in four colors, with white accounting for a higher proportion. The grain size of the microplastics in tributaries or lakes of the Yellow River is less than 2 mm, which makes them liable to enter organisms for enrichment. Furthermore, the sources of the microplastics are closely related to agricultural and industrial production and biological activities in habitats and exhibit seasonal and hydrological characteristics. The microplastics in the study area show the adsorption of metals and nonmetals to different degrees, which increases the pollution risks of heavy metals combined with microplastics. In addition, microplastics can accumulate in organisms in the Yellow River and cause physical, biochemical, and other damage to aquatic organisms, thus further posing carcinogenic risks to human beings. Therefore, it is necessary to study, monitor, and control the pollution and effects of microplastics in the Yellow River, in order to provide theoretical references for the control of pollution and ecological risk of microplastics in the river.©2021 China Geology Editorial Office.  相似文献   

5.
贵阳观山湖区至白云区地下水有机污染现状与防治对策   总被引:2,自引:2,他引:0  
文章按水文地质条件将全区划分为12个地下水系统,并选择43组控制性水点分丰枯两季进行有机样品采集和测试,在此基础上对研究区地下水中有机污染物的检出、超标、分布及来源均进行了分析。结果显示,参评的86组地下水样品中,有32组检出有机污染物;27种参评有机组分中,10种有机组分存在不同程度的检出,其中,三氯甲烷检出25次,检出率29.07%,其余组分检出率均低于5%;仅有1,2二氯丙烷超标1次,超标率低;区内地下水有机污染物检出浓度较低,超标率低,处于轻度污染阶段;12个系统中,有9个系统发现有机物污染物检出;检出点多分布于工矿企业的下游地段,排污河渠两侧;污染物多来源于中小型工矿企业,以污染物通过落水洞、天窗等进入含水层为主要污染途径;地下水系统排泄区的近源污染多发,危害程度大。针对上述污染特征,提出加强对中小企业污染源的集中管理,加大污水管网建设力度等对策建议。   相似文献   

6.
Sediment avalanche from delta ramp is one of the significant development mechanisms for a turbidite system in a lacustrine basin. To advance our understanding of deep-water sedimentary processes in a lacustrine delta ramp, delta-fed turbidites in the Eocene Dongying depression of the Bohai Bay Basin were studied using core data, 3-D seismic data and well log data. Sandy debris flows, muddy debris flows, mud flows, turbidity currents, slides, sandy slumps and muddy slumps were interpreted based on the identification of lithofacies. Data indicates that deep-water sedimentary processes in the study area were dominated by debris flows and slumps, which accounted for ~68% and 25% (in thickness) of total gravity flow deposits, respectively; turbidity-current deposits only accounted for ~5%. Mapping of turbidites showed that most were deposited after short-distance transportation (<20 km), restricted by the scale of deep-water areas and local topography. Channels, depositional lobes, debris flow tongues, muddy turbiditic sheets, slides and slumps were identified in a delta-fed ramp system. Slides and slumps were dominant at the base of slopes or at the hanging walls of growth faults with strong tectonic activity. Channels and depositional lobes developed in gentle, low-lying areas, where sediments were transported longer distances. Sand-rich sediment supply, short-distance transportation and local topography were crucial factors that controlled sedimentation of this ramp system. Channels generally lacked levees and only produced scattered sandstones because of possible hydroplaning of debris flow and unstable waterways. In addition to lobes, debris flow tongues could also be developed in front of channels. These findings have significant implications for hydrocarbon exploration of deep-water sandstone fed by deltas in a lacustrine basin.  相似文献   

7.
马荣  石建省 《地球学报》2011,32(5):611-622
传统的多元统计法难以定量化表征不同污染源对单个样本点的影响,本文引入了一种新的方法——模糊因子分析法.将该方法应用于洛阳市地下水污染来源解析研究,通过模糊聚类和因子分析对研究区样品进行分类,探明主要的污染源类型及其对整个研究区和单个样品点的污染贡献率.计算结果表明:洛阳市浅层地下水主要有以下四个污染源:基岩风化、加工制...  相似文献   

8.
THE CARBONATE FRACTION OF BEACH AND DUNE SANDS   总被引:1,自引:0,他引:1  
The sand size carbonate fractions of beach and dune sands from the southeastern U.S. Atlantic coast were investigated from the standpoint of mineralogy, roundness and size distribution. The carbonate fractions of beach-dune sands used in this study range in abundance from less than 1% to over 40% and average about 10%. Calcium carbonate is least abundant in Georgia beaches and increases slightly to the north and greatly to the south. The size distribution of the carbonate fraction is similar to that of the non-carbonate fraction since both have been distributed by the same processes. The variable flat shape of calcareous fragments causes the carbonate fraction to be usually coarser and more poorly sorted than the acid insoluble residues of the samples. No regional relationship between roundness and wave energies was found in sand size materials although field observations indicate high energies strikingly round gravel sized calcareous fragments. There is some tendency for angularity to increase with decreasing grain size in the sand sizes as with quartz grains. The mineralogy of beach sand carbonate fractions is characterized by the almost total absence of high My calcite. Aragonite is the dominant mineral.  相似文献   

9.
Pollution load and contamination levels of phthalate esters (PAEs) in agricultural soils throughout China were studied in this work. The usage amount and residual rates of plastic film were the main factors explaining the variation among regions and leading to higher pollution load and contamination levels in agricultural big provinces. However, higher pollution loads and contamination levels frequently occurred under non-recycling than recycling scenarios during calculation. Extremely high loads (more than 10 kg/ha/year) of PAEs were estimated in five areas including Beijing city, Tibet, Liaoning Province, Jilin Province and Fujian Province and the high contamination levels in agricultural soil were presented in these places with more than 4.0 mg/kg under non-recycling scenarios. The predicted concentrations of PAEs in soils exceed the target value for soils from Netherlands (ΣPAEs = 0.1 mg/kg), indicating very high contamination of most Chinese agricultural soils. Significant differences in estimation results after plastic film utilization suggest that decreasing plastic film residue after application is an effective measure to control PAE pollution in soils. However, the comparison between contamination levels of PAEs estimated by the model and the previous detections of PAEs pollution levels in agricultural soils showed that there were presented wide range of PAE sources indicated to agricultural soils.  相似文献   

10.
Sandy beaches are characterised by heterogeneously distributed food sources both in time and space. The major energy supply is derived from marine subsidies in the form of beach-cast macrophyte wrack. Wrack patches are short-lived, and their position on the beaches varies with tidal and seasonal cycles as well as weather conditions. Little is known about how sandy beach inhabitants orient themselves towards, and colonise, wrack patches. In a series of field studies on islands off Vancouver Island (British Columbia, Canada), colonisation patterns of wrack patches by beach fleas and sand hoppers (Amphipoda: Talitridae), the most abundant macrofaunal detritivores, were studied. As indicated by colonisation of experimental patches of wrack and wrack surrogates that were either visible or buried in the sand, beach fleas (Traskorchestia traskiana) rely on olfactory cues for locating freshly deposited wrack patches in their patchy and dynamic habitat. Dense colonisation of freshly deposited algal wrack generally occurred within less than 1 h but depended upon the tidal height of wrack patches. Beach flea density in freshly deposited wrack patches increased with increasing tidal height. By contrast, sand hoppers (Megalorchestia californiana) colonised freshly deposited wrack patches in densities that decreased with tidal height. Discussing these interspecific differences, we provide a primer for future detailed studies on transport of matter along the marine–terrestrial gradient of sand beaches.  相似文献   

11.
四川康定城市地震地质及地质灾害风险评价   总被引:1,自引:0,他引:1       下载免费PDF全文
四川康定处于鲜水河、龙门山及安宁河三条地震带的"Y"字形交汇部位,境内地震活动频繁,地震基本烈度达IX度。康定城区位于鲜水河断裂南东段的雅拉河-康定断裂,城区几乎处于康定断裂的次级断层围限之中,断裂发育,岩体破碎,在降雨、地震和人类经济活动的影响下,地质灾害十分发育。康定城发育地质灾害25处,其中滑坡14处,崩塌3处,泥石流5处,不稳定斜坡3处。地质灾害多沿城区河流两岸斜坡和支沟分布,对城区居民的生命财产安全构成巨大的威胁,一旦发生强烈地震及其产生的次生地质灾害,将对康定城市带来灾难性的毁坏。近年来随着城镇化建设速度的加快,城市规模不断扩大,城市容量空前扩张,加之活动断裂活动性增加,城市安全风险增大,正确合理规划城市规模,科学地开展城市环境地质调查,制定有效的减灾防灾预案是确保城市安全的重要方法。  相似文献   

12.
Uppermost Tortonian to lower Messinian temperate carbonates crop out in the Agua Amarga Basin (SE Spain). They consist of four units. The lower three units can be tentatively assigned to the lowstand systems tract of a fourth-order sequence, constituting in turn the lowstand (‘megatrough unit’), transgressive (‘breccia unit’) and highstand (‘bedded unit’) stages of a higher-order cycle. All these materials were deposited in a small pull-apart basin related to the sinistral Carboneras strike-slip fault system. The best represented is the bedded unit (up to 25 m thick), which consists of bioclastic, bryozoan/bivalve-dominated calcarenites/calcirudites with abundant fragments of echinoids, barnacles, benthic foraminifers, coralline algae, brachiopods and solitary corals. Facies trends within this unit are roughly arranged in an E-W direction, with the coastline to the north of the basin. The depositional model is that of a gentle ramp with prograding beaches and shoals in its higher parts. Seaward of the shoals was the ‘factory area’, where most organisms lived and maximum carbonate production took place. From this area some of the skeletons were washed landwards by waves and/or currents during storms and incorporated into the shoals and beaches, and others moved downslope along the ramp as mass-flows, accumulating to form the ‘fan-bedded zone’. The factory-area and fan-bedded sediments intercalate five well-defined, thick beds of calcarenites/fine-grained calcirudites. They show bar morphologies (single or amalgamated), or make up sand-waves with very consistent tabular cross-bedding pointing landwards. These beds formed in a very shallow, wave/current-influenced, coastal environment. The bars and sand waves in the fan-bedded zone developed during lowstands, while those located higher up in the ramp interbedded with the factory facies are related to transgressive stages. Prograding beaches, shoals, factory facies and fan-bedded layers developed during the highstands. Net skeletal production occurred mainly during the highstands. Sediment-accretion values of these sediments are similar to those of present and ancient shallow-marine, temperate carbonates considering that the whole bedded unit was deposited in a 100 000-year interval (equivalent to the short eccentricity cycle). The five cycles inside the bedded unit would therefore correspond to the c. 20 000-year precession cycles of the Milankovitch band.  相似文献   

13.
聂拉木县冲堆普2002年泥石流成因分析及防治对策   总被引:7,自引:3,他引:4  
陈晓清  崔鹏  杨忠  齐永青 《冰川冻土》2006,28(5):776-781
聂拉木县冲堆普于2002年5月23日和6月29日先后两次暴发了大规模泥石流灾害,导致下游的水电站、中尼公路、农牧业生产、通讯设施等遭受严重破坏,总共损失约750余万元,给地方社会经济造成了严重的影响.通过对上游的考察和气象资料分析,查清了灾害的形成原因是冲堆普上游冰川融水和嘉龙湖局部溃决所诱发.这是一种多因子共同作用的新型泥石流类型,不同于以往的冰川融水型泥石流和冰湖溃决型泥石流.针对泥石流的危害,提出了防治措施,包括软性措施和硬性措施.  相似文献   

14.
Everybody wants clean water for drinking, bathing and other domestic uses, but not everybody appreciates the fact that our own actions are often the worst enemy in achieving that goal. Ground water is one of the most misused and misunderstood resources. Because ground water and its movement, and consequently also its pollution, is hidden from view beneath the land surface, the seriousness of ground-water pollution problems has not been recognized until recently. The sources of ground-water pollution are many and varied because in addition to natural processes practically every type of facility or structure installed by man and each and every one of his activities may eventually contribute to ground-water quality problems. The quality of ground water is most commonly affected by waste disposal. Other major sources result from agricultural activities and ground-water development. In addition to these three major categories, there are other potential sources of pollution, such as mining, spills, leakage from underground pipes and tanks, and road salting. All of these activities can generate pollutants which eventually may enter the ground-water systems and slowly begin to move through the subsurface environment. Once under the ground, the pollutants are hidden from view and the existence of ground-water pollution becomes evident only if they reemerge on the surface or in water wells. When this occurs, it is almost too late to do anything about it. The effects of pollution may remain in the aquifers for years, decades, or centuries, because the residence time (turnover) of ground water is very slow. Ground-water pollution may even result in aquifers or parts of quifers being damaged beyond repair.  相似文献   

15.
Morphologies of placer platinum group minerals (PGM) are more variable and resistant to modification during transport than placer gold grains. This study documents morphological evolution of PGM placer grains during up to 120 km of transport in beach placers after river transport from inferred sources up to 200 km inland. PGM morphological changes are calibrated with changes in morphology of associated placer gold. Most of the PGM are Pt-Fe alloy and have been fed into the beach placer system from a large river at the western end of the beaches on the south coast of New Zealand. The incoming fluvial PGM suite includes Os, Ir and Ru alloys which may have been derived from distal ophiolitic sources. More proximal sources have Ural-Alaskan affinities and these contributed cooperite and braggite, or sperrylite, locally, as well as Pt-Fe alloy grains. Some PGM may have been recycled through Cretaceous-Quaternary fluvial sediments before entering the modern placer system. Recycled placer PGM grains have also been derived from elevated Quaternary beaches near the coastline. PGM grains entering beach placers have rough surfaces, with remnants of crystal faces, and these evolve to smooth flakes with progressive long-shore transport. PGM flakes have slightly thickened rims caused by impacts by saltating sand on windy beaches, and the most distal beach placers contain flakes with incipient toroidal shapes. These PGM incipient toroids are poorly developed compared to accompanying well-formed toroidal gold that has developed in nearly all beach placers, including those on elevated Quaternary beaches. Typical PGM and gold placer grain size decreases with increasing distance of transport, from fluvial grain size of 400–1,000 to ~200 microns on the most distal beaches, accompanied by eastward loss of equant PGM grains and associated increase in proportion of flakes. Although net transport distance is ~120 km in the beach placer complex, frequent aeolian transport of grains from beach to dunes and subsequent recycling by storm surges substantially increased total transport distance in a dynamic windy tectonic environment.  相似文献   

16.
长江上游国土资源,生态环境与灾害防治   总被引:1,自引:0,他引:1       下载免费PDF全文
长江上游干流流经青、藏、川、滇、鄂、渝6省市,支流涉及甘肃、陕西、贵州3省,流域面积为105.4×104km2,人口1.55亿,占全国国土面积的11.1%.长江上游地区经济发展相对落后,人均国民收入低,少数民族众多,与中下游经济发达地区差距很大.但上游地区蕴藏着巨大的经济开发潜能,丰富的水力和矿产等自然资源,以及农、林、牧等物产,对中下游地区经济发展有着巨大的支援作用.同时,由于自然地理上的相关性,又使上游地区的开发治理,对中下游地区的生态环境和可持续发展有着至关重要的作用.目前,长江上游森林植被大量减少,水源涵养能力下降,水土流失加剧:泥石流、滑坡、崩塌等地质灾害严重,旱、洪灾害频发;沿江大量排放废气、废水、污水,使大气和水体严重污染.随着上游地区生态环境的日益恶化,给中下游地区带来严重危害,河道、湖泊、水库淤积加速,洪涝灾害频繁发生,造成中下游地区经济建设和人民生命财产的重大损失.因此,必须尽快对长江上游地区进行全面综合治理,尽快开展新一轮国土资源大调查,制定各种自然资源的合理开发利用和保护方案;控制沿江污染源的排放,建立大气和水体污染监测系统;运用高新技术,建立上游重点地带地壳形变的动态监测和预警系统,防治地质灾害;充分利用上游地区丰富的水力资源,兴建多级水利设施,对地表水实施人工的时空控制,消除旱、洪灾害.  相似文献   

17.
寺儿沟流域位于甘肃省兰州市西固区,历史上曾发生过大规模泥石流,造成重大人员伤亡和财产损失。文章基于野外调查和遥感解译,结合已有文献成果和室内测试,研究寺儿沟泥石流物源特征及影响因素,采用FLO-2D软件模拟分析泥石流的危险性。研究结果表明:寺儿沟以黏性泥石流为主,表现为低频活动,目前处于衰退期;寺儿沟流域内物源丰富,可分为坡面型物源、崩滑型物源、沟道型物源和人为型物源共4种,其中崩滑型、沟道型物源控制了泥石流的暴发规模;而一次性冲出量的大小主要取决于泥石流起动时崩滑体的发育程度,崩滑体越发育,一次性冲出量越大,泥石流规模越大;在临界降雨条件下,寺儿沟将会暴发泥石流,中—高危险区集中于流通区,严重威胁冲沟内构筑物如兰西高铁、环城高速等安全运营。当遭遇极端强降雨时,寺儿沟将暴发更大规模泥石流。因此,有必要进一步研究极端天气条件下泥石流的危险性,为区内泥石流的防灾减灾提供地质依据。  相似文献   

18.
依据2006—2009年间采集的区内1092件浅层地下水无机分析和现场测试数据,采用地统计学分析方法,分析了黄河下游冲积平原地下水中砷的空间变异特征及在人类活动影响下的污染现状。全区26.65%的样品砷含量超过饮用水标准,超标区域面积占全区总面积的17.3%。浅层地下水中砷的统计特征表明砷的离散程度和变异系数均较高;空间变异特征显示砷在空间上的分布各向异性,砷含量分布差异与地下水流向关系不密切,不同浓度的分布主要受原生条件和污染源的影响;区内约7%的浅层地下水样品砷的浓度由人类活动影响形成,其中12%的砷污染样品源于养殖场砷污染,养殖场内浅层地下水砷检出率、超标率均为全区的2倍;砷污染源包括农村分散养殖场牲畜废弃物排放、含砷农药的施用、工业污水的不达标排放等。  相似文献   

19.
Heavy metal pollution of soils has become a major concern in China as a consequence of rapid urbanization and industrialization in recent years. However, the evaluation on soil heavy metal pollution in Shenyang, the largest heavy industrial base city in China, has not yet been conducted. In this study, accumulation, chemical speciation, and vertical distribution Cu, Zn, Pb and Cd in soils were studied and pollution condition was assessed in Tiexi Industrial District of Shenyang, the largest and oldest industrial zone in Northeastern China. The results showed that in topsoil, the average concentration of total Cu, Zn, Pb, and Cd was 209.06, 599.92, 470.19 and 8.59 mg kg−1, respectively, much higher than the national threshold limit. The values of pollution index and integrated pollution index showed that the pollution level was Cd > Cu > Zn > Pb, and Cd, Cu and Zn belong to heavy pollution level. The residual, Fe and Mn oxide-bound, and organic-bound species accounted for about 90%, while carbonate-bound and exchangeable species accounted for about 10%. This study indicates that the soils in the industrial zone were widely and extremely polluted by multi-heavy metals as a result of long-term industrial activities.  相似文献   

20.
The ecological significance of algal and seagrass wrack subsidies has been well-documented for exposed-coast sandy beaches but is relatively unstudied in lower-energy and mixed-sediment beaches. In marine nearshore environments where beaches are fringed with riparian vegetation, the potential for reciprocal subsidies between marine and terrestrial ecosystems exists. Within the marine-terrestrial ecotone, upper intertidal “wrack zones” accumulate organic debris from algae, seagrass, and terrestrial plant sources and provide food and shelter for many organisms. Human modification also occurs within this ecotone, particularly in the form of armoring structures for bank stabilization that physically disrupt the connectivity between ecosystems. We conducted detailed wrack and log surveys in spring and fall over 3 years at 29 armored–unarmored beach pairs in Puget Sound, WA, USA. Armoring lowered the elevation of the interface between marine and terrestrial ecosystems and narrowed the width of the intertidal transition zone. Armored beaches had substantially less wrack overall and a lower proportion of terrestrial plant material, while marine riparian zones (especially trees overhanging the beach) were an important source of wrack to unarmored beaches. Armored beaches also had far fewer logs in this transition zone. Thus, they lacked biogenic habitat provided by logs and riparian wrack as well as the organic input used by wrack consumers. Results such as these that demonstrate armoring-associated loss of connectivity across the marine-terrestrial ecotone may be useful in informing conservation, restoration, and management actions.  相似文献   

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