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1.
亚洲地区的流域—海岸相互作用：APN近期研究动态   总被引：1，自引：0，他引：1  
高抒 《地球科学进展》2006,21(7):680-686
在亚洲地区,不同流域的海岸带所接受的淡水、沉积物、营养物质和污染物质入海通量有着很大的差异。入海通量的特征受到流域人类活动的强烈影响,如水坝建设和化肥的大量施用。气候和海平面的变化也起了一定的作用。流域—海岸相互作用的特点是,入海物质通量的变化将导致流域、河口以及邻近水域的地貌、环境和生态系统的改变。在流域—海岸系统不断变化的情况下,为了改进流域—海岸系统开发的管理策略,应进行以下调查和研究工作：①在现场监测和观察的基础上,定量地描述上述变化;②了解引起上述变化的过程和机制;③发展预测未来变化的趋势和幅度的新方法、新技术;④将所获结果应用于流域—海岸系统的开发和管理实践。为了确定本研究领域今后10年的资助方向,APN (Asian Pacific Network for Global Change Research)召集了相关的学术研讨会。按照APN的部署,笔者负责完成了“流域—海岸相互作用”领域的研究课题建议,本文是这份文件的简要总结。  相似文献   

2.
This paper examines a case study regarding a site in the Murge karst (Apulia, southern Italy) where, in the course of time, anthropogenic activity has caused significant damage to the natural landscape and environment, also in terms of loss of human lives. The study site comprises the city of Bari and the neighbouring towns, belonging to the same catchment basin, which is characterised by a low-relief karst very rich in natural cavities and dry valleys, the latter locally called lame. From the second half of the 1500s until today, in the whole area, short rainfall storms (lasting less than 6 h) with disastrous and mortal consequences have been recorded many times. In the last decades, human activities, such as urbanization, stone clearing for agricultural purposes, quarrying and deforestation induced severe changes in the karst landscape causing the modification of the surficial and underground drainage. In particular, an examination is made of the factors causing the complete destruction of the “di Maso” Park on the night between 22 and 23 October 2005, in consequence of a high-intensity rainfall (152.6 mm in a 6-h period) accompanied by flash flooding. Finally, the need for a better understanding of natural processes and patterns in karst areas, and the interactions with human activities through to the development of environmental management systems ensuring further steps towards sustainable development is remarked.  相似文献   

3.
Two short cores of late Holocene, low tidal, estuarine sediment from the sheltered fringes of the Auckland's Waitemata Harbor, New Zealand, record the following changes through time since human colonization: an abrupt decline and disappearance of marine molluscs, a major decline and virtual disappearance of ostracods, an abrupt decline in calcareous foraminifera (mostlyAmmonia spp.), a rapid increase, in abundance of agglutinated foraminifera, large diatoms, and freshwater thecamoebians, and an increase in sedimentation rate, but no consistent trend in change of grain size. The up-core foraminiferal changes mimic their present day up-estuary zonation, which correlates strongly with decreasing salinity and pH. In both localities the faunal changes can be correlated with the documented local land-use history and increased freshwater runoff over time. At the head of the Waitemata Harbor, in Lucas Creek estuary, three phases of foraminiferal faunal change occurred: minor changes during initial Polynesian forest clearance (1500–1800 AD), a major change in early European times (1840–1870 AD) with clearance of most of the remaining native forest, and another small change in very, recent times (∼1990s) with urbanization in the Lucas Creek catchment. On the eastern, seaward fringes of the Waitemata Harbor, in the smaller Tamaki Estuary, no faunal changes occurred in association with complete forest clearance and establishment of pastoral farming in Polynesian and early European times (before 1950s). Major foraminiferal and other faunal changes occurred in the late European period (1960s–1970s) coincident with the onset of major urbanization spreading throughout the Tamaki catchment. Our results suggest increased freshwater runoff is the major culprit for many of the observed biotic changes in the urbanized estuaries of New Zealand.  相似文献   

4.
Three small sequential Saddle Mountains flows, occupying similar areas on the Columbia Plateau, were erupted over a short interval of time. In the Lewiston Basin area the middle flow of the trio (Lapwai) has intermediate mineralogy and lies on a straight mixing line between the other two flows for virtually all twenty-five elements analyzed. Systematic changes in the ratios of incompatible elements demonstrate that these relationships are a result of magma mixing rather than either crystal fractionation or variable degrees of partial melting. The Lapwai flow has a composition approximately midway between the two homogeneous end members and is itself relatively homogeneous. This implies efficient mixing between equal amounts of Asotin and Wilbur Creek magmas and suggests that mixing was completed in a magma reservoir prior to eruption. The Wilbur Creek and Asotin end members have isotopic features which are believed to result from different degrees of assimilation of crustal material by magma derived from an enriched mantle source (Carlson 1984). The mixing processes described here cannot be related to that earlier mantle/crust mixing process.  相似文献   

5.
Steelmaking-coal waste rock placed in mountain catchments in the Elk Valley, British Columbia, Canada, drain constituents of interest (CIs) to surface water downgradient of the waste rock dumps. The role of groundwater in transporting CIs in the headwaters of mountain catchments is not well understood. This study characterizes the physical hydrogeology of a portion of a 10-km2 headwater catchment (West Line Creek) downgradient of a 2.7-km2 waste rock dump placed over a natural headwater valley-bottom groundwater system. The study site was instrumented with 13 monitoring wells. Drill core samples were collected to determine subsurface lithology and geotechnical properties. The groundwater system was characterized using field testing and water-level monitoring. The valley-bottom sediments were composed of unconsolidated glacial and meltwater successions (<64 m thick) deposited as a series of cut and fill structures overlying shale bedrock. An unconfined basal alluvial aquifer located above fractured bedrock was identified as the primary conduit for groundwater flow toward Line Creek (650 m from the toe of the dump). Discharge through the basal alluvial aquifer was estimated using the geometric mean hydraulic conductivity (±1 standard deviation). These calculations suggest groundwater discharge could account for approximately 15% (ranging from 2 to 60%) of the total water discharged from the watershed. The residence time from the base of the waste rock dump to Line Creek was estimated at <3 years. The groundwater system was defined as a snowmelt (i.e., nival) regime dominated by direct recharge (percolation of precipitation) across the catchment.  相似文献   

6.
Saline seepage zone development and hence dryland salinity is a major environmental problem which many arid to semiarid landscapes in Australia are experiencing. Due to the geological complexity of the regional aquifer system and the heterogeneous nature of the local groundwater system, each groundwater seepage zone in the Spicers Creek catchment, central west, New South Wales, Australia possesses different mechanisms which control its development. Saline seepage zones have formed adjacent to a fault zone, and two experimental sites were established through these groundwater discharge zones to understand geochemical processes which have led to the development of soil sodicity, gully erosion and the flushing of salts into the surface water systems. Seepage zone groundwaters contain a distinctive geochemical signature with elevated concentrations of Na, Cl, HCO3, Ca, Sr, B, As and Li. The mixing of deep saline groundwaters together with ion exchange processes lead to a distinctive seepage zone groundwater chemistry being developed. Altering the landscape features within this rural groundwater system has developed water toxicity for crops, soil sodicity leading to land degradation, and waterlogging problems.  相似文献   

7.
Many coastal ecosystems are undergoing anthropogenic stress from large increases in population and urbanization. In many regions changes in freshwater and material inputs to the coastal zone are altering the biogeochemical and biological capacities of ecosystems. Despite increased watershed inputs, large tidal volumes and flushing indicative of macrotidal estuaries can modulate the fate of introduced materials masking some of the symptoms of eutrophication. The Land Use Coastal Ecosystem Study (LU-CES) examined linkages between land use and environmental properties of Malind and Okatee Creeks in South Carolina from 2001 to 2004. The objectives of this particular study were to assess the hydrography of the two macrotidal creek ecosystems, explore differences in dissolved oxygen (DO), and develop a better understanding of the variations in primary and benthic secondary production in southeastern creek ecosystems. Depth, pH, salinity, and DO were reduced and more variable in Malind Creek than in Okatee Creek, although both creeks had strong semidiurnal frequencies in salinity time signatures. While time series analyses of DO saturation in Malind Creek revealed a dominant semidiurnal pattern, Okatee Creek had a distinctly diel DO pattern. The strongly semidiurnal fluctuations in DO and reduced flushing time indicated that biological processes were not fast enough to influence DO in Malind Creek. The Okatee Creek system had a much greater storage volume, a wider marsh, and a dominant 25-h DO frequency. These attributes contributed to an estimated 8–10 times more phytoplankton-based carbon in Okatee Creek and twice the annual benthic production. As expected from their proximity to the upland, low surface area, and high organic content, both ecosystems were net heterotrophic. This fundamental understanding of tidal creek hydrography is being used to help define linkages among differential watershed land uses, flushing characteristics, and levels of biological production in coastal ecosystems of the southeastern United States.  相似文献   

8.
青藏高原环境变化对全球变化的响应及其适应对策   总被引：48，自引：0，他引：48  
青藏高原的环境变化对全球变化具有敏感响应和强烈影响。青藏高原的现代环境与地表过程相互作用,引起包括冰冻圈和水资源以及生态系统等方面的一系列变化,对高原本身以及周边地区的人类生存环境和经济社会发展产生重大影响。作为国际研究的热点地区,青藏高原环境变化研究目前出现三个新的科学动向：关注关键地区的关键科学问题的系统研究;关注以现代地表过程为核心的监测研究;关注全球变化影响下的圈层相互作用研究。本项目的研究对青藏高原环境变化科学的发展、国际科学前沿的贡献以及服务于社会经济发展,都具有十分重要的意义。通过项目的研究将揭示青藏高原隆升到现代地貌与环境格局过程中所出现的重大构造事件和环境事件;重建不同区域、不同时间尺度的气候环境变化序列并揭示其时空分布特征;阐明青藏高原冰冻圈、湖泊和主要生态系统与土地覆被在不同气候条件下的变化特征;揭示青藏高原环境变化与地表过程对全球变化的响应特点和高原热力与动力过程对不同气候系统变化的影响。本项目将在高原南北典型区域利用地貌学与沉积学手段,研究青藏高原现代地貌与环境格局的形成过程;利用湖芯、冰芯、树木年轮等手段,研究青藏高原过去环境变化的特征事件、区域分异及其与全球变化的联系;利用冰川、冻土、积雪的时空变化,结合对高原特殊大气边界层的观测,研究青藏高原冰冻圈变化与能量水分循环过程;从冰川、湖泊、大气的监测入手,结合模式方法,研究青藏高原环境变化的机制;利用生态系统碳的源—汇变化,研究青藏高原生态系统对环境变化的响应;综合研究全球变化背景下青藏高原环境变化与水资源变化所产生的区域效应和适应对策。  相似文献   

9.
Jiang, S., Liu, X., Sun, J., Yuan, L., Sun, L. & Wang, Y. 2011: A multi‐proxy sediment record of late Holocene and recent climate change from a lake near Ny‐Ålesund, Svalbard. Boreas, Vol. 40, pp. 468–480. 10.1111/j.1502‐3885.2010.00198.x. ISSN 0300‐9483 The Arctic constitutes a unique and important environment with a significant role in the dynamics and evolution of the earth system. Arctic lake sediments, which accumulate slowly over time, contain abundant information about the biological communities that lived within the water body, as well as in the surrounding catchment. In this study, we collected a sediment core from Ny‐Ålesund, Svalbard, performed multi‐proxy analyses on sediment pigments, mineral magnetic susceptibility, various sediment quality (i. e. organic matter content, CaCO3 content, carbon and nitrogen isotope), and diatom composition, and reconstructed the history of ecosystem responses to environmental variations, especially regarding aquatic productivity and lake catchment surface processes. Ny‐Ålesund has undergone distinct ecological and climatic changes. During the Little Ice Age, the cold climate was unfavourable for the growth of lake algae, and therefore the lake primary productivity declined. After about AD 1890 and during the 20th century, the warming climate and reduced ice cover led to rapid lithological change and growth of lake algae, enhanced lake primary productivity, and increased input of nutrients derived from increased chemical weathering into the lake. The lake ecosystem on Ny‐Ålesund has had rapid responses to climatic and environmental changes in the Arctic.  相似文献   

10.
A sediment core from Chuna Lake (Kola Peninsula, northwest Russia) was studied for pollen, diatoms and sediment chemistry in order to infer post‐glacial environmental changes and to investigate responses of the lake ecosystem to these changes. The past pH and dissolved organic carbon (DOC) of the lake were inferred using diatom‐based transfer functions. Between 9000 and 4200 cal. yr BP, slow natural acidification and major changes in the diatom flora occurred in Chuna Lake. These correlated with changes in regional pollen, the arrival of trees in the catchment, changes in erosion, sediment organic content and DOC. During the past 4200 yr diatom‐based proxies showed no clear response to changes in vegetation and erosion, as autochthonous ecological processes became more important than external climate influences during the late Holocene. The pollen stratigraphy reflects the major climate patterns of the central Kola Peninsula during the Holocene, i.e. a climate optimum between 9000 and 5400/5000 cal. yr BP when climate was warm and dry, and gradual climate cooling and an increase in moisture during the past 5400/5000 yr. This agrees with the occurrence of the north–south humidity gradient in Fennoscandia during the Holocene. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

11.
This is the first of a series of articles presenting the results of a multi-proxy investigation aimed at reconstructing changes in the ecosystem and climate of Whitrig Bog, SE Scotland, during the last glacial-inter-glacial transition (Devensian Lateglacial, c . 14–10 ka BP). We present here the results from sediment lithology, chemistry, pollen, and plant macrofossil analyses. These data are used to infer the nature of the local catchment soils and both local and regional terrestrial vegetation. The interstadial period ( c . 13–11 ka BP) is characterized by a successional sequence developing from a landscape with bare, poorly developed minerogenic soils supporting a sparse herbaceous flora into open birch woodland with juniper scrub and stable organic soils. At c . 11 ka BP the Younger Dryas climatic cooling event caused an abrupt reversion to an open herbaceous arctic/alpine flora (e.g. macrofossil evidence of Silene furcata and Oxyria digyna ) and high levels of minerogenic erosion into the basin, indicating environmental response to a cold Arctic climate. In addition to this Younger Dryas climatic reversal, two lesser reversion episodes occurred earlier during the interstadial. The more pronounced of the two, late in the intersladial, is characterized by high levels of erosion and a change from birch/juniper woodland to an open herbaceous flora. The older oscillation occurs approximately mid-way through the interstadial sequence and is marked by similar pollen changes, albeit shorter lived and more subtle.  相似文献   

12.
Long‐term fluctuations in lake‐water optical properties were examined using a Holocene sediment sequence and multi‐proxy palaeolimnological approach in Lake Einstaken, Nordaustlandet, Svalbard. UV‐absorbance of sedimentary cladoceran remains provided information on underwater UV exposure and changes in lake‐catchment coupling processes were inferred from sediment geochemistry. In addition, aquatic community succession was used as an indicator for lake‐water bio‐optical properties and a Holocene record of sun activity (sunspots) was utilized to evaluate long‐term solar forcing. The results indicated that the UV‐absorbance of cladoceran remains was highest (i.e. maximum UV‐induced pigmentation) for a short period during the early Holocene and for several millennia during the mid‐Holocene. Sun activity was high during these time intervals, probably impacting the UV intensities, but it is probable that the amount of UV‐attenuating compounds (e.g. dissolved organic carbon (DOC)) also significantly affected the underwater UV environment and were low during high UV exposure. Benthic autotrophic communities also responded to the millennial changes in lake‐water optical properties. UV‐resistant Nostoc cyanobacterial colonies were established during the mid‐Holocene, indicative of high underwater UV intensities, and Fontinalis mosses thrived during the early Holocene, indicating a highly transparent water column. The results further suggested that underwater UV exposure decreased during the late Holocene, which is probably attributable to increased DOC and decreased solar forcing. Owing to the location of Lake Einstaken and its catchment in the periglacial barren landscape of the polar desert, the fluctuations of bio‐optical lake‐water properties were apparently forced by postglacial environmental processes and Holocene climate development. These factors controlled sea shoreline proximity, water discharge, ice‐cover duration and littoral‐benthic primary production and further affected the underwater UV environment. Although the role of solar forcing cannot be underestimated, the current record emphasizes the role of climate‐mediated lake‐catchment interactions in impacting bio‐optical properties and UV exposure of high arctic aquatic systems.  相似文献   

13.
济南岩溶泉域泉群区水化学与环境同位素研究   总被引：6，自引：0，他引：6  
殷秀兰  王庆兵  凤蔚 《地质学报》2017,91(7):1651-1660
本文通过对济南岩溶泉域排泄区地下水样品的分析,采用主要离子(Cl、NO_3、Mg、Ca、HCO_3、SO_4)、微量元素(Br、Ba、Sr)、氢氧同位素(~2H和~(18)O)、硫同位素(~(34)S)等示踪因子的综合研究方法,结合岩溶泉域实际水文地质条件,揭示了济南泉水的水文地球化学特征、枯丰期水化学动态和环境同位素特征,确定了泉水在枯、丰水期不同的补给来源及补给途径。研究显示,泉群区出流的泉水可以分为三组,黑虎泉出流的路径是经奥陶系灰岩直接出流,趵突泉是经奥陶系灰岩与第四系沉积层出流地表,而五龙潭泉、珍珠泉和53号井则是在灰岩和侵入岩体的接触地带及第四系沉积层较薄弱处涌出地表;在丰水期地下水是混合补给,包括来自奥陶系岩溶水直接补给和硅酸盐岩裂隙水的间接补给,而在枯水期地下水主要由奥陶系岩溶水直接补给;泉群区地下水中的S主要来源于燃煤,而且有不断增加的趋势。  相似文献   

14.
Kuskonook Creek, an example of a debris flow analysis   总被引：1，自引：0，他引：1  
Two debris flows occurred on Kuskonook Creek in British Columbia, Canada, in August and September 2004. The initiation factors included a major forest fire in the catchment in 2003, in association with relatively small rainfall events and the accumulation of sediment in the creek channels since the last large debris flow event. Previous regional studies and morphometric comparisons with other similar catchments indicate that Kuskonook Creek has characteristics predisposed to debris flows, even without the affects of a forest fire. Based on the investigations and analyses, a magnitude/frequency relationship for future debris events on Kuskonook Creek was developed, and this information was used to carry out a partial risk assessment. It is suggested that for design purposes, a 1/50-year return period and the corresponding debris flow magnitude of 15,000 m3 would provide conservative protection to the users of the provincial highway at the mouth of the creek.  相似文献   

15.
The Dog Creek archaeological site (NcVi‐3), located in the northern Yukon, provides evidence of complex site transformational processes related to microclimatic conditions occurring since the mid‐Holocene. Geoarchaeological research at Dog Creek sought to interpret site formation processes in order to understand the relationship between surficial artifacts, buried artifacts, and stratified sediments. It also attempted to reconstruct the periglacial processes that were active in transforming the site and their relationships to microclimatic conditions. Sedimentology and fabric analysis show that artifacts were buried by solifluction and disturbed by frost heave and cryoturbation. Radiocarbon dating and pollen analysis demonstrated that solifluction took place approximately 5200–2000 years ago when a spruce forest existed at the site. This evidence suggests an onset of cooling conditions that continues to the present. After the mid‐Holocene, the spruce treeline began to move south toward its present position. © 2001 John Wiley & Sons, Inc.  相似文献   

16.
Concentrations of Fe, Mn, Cu, Zn, U and Pb, and stable Pb isotopes 206Pb, 207Pb and 208Pb were measured via inductively coupled plasma mass spectrometry in sediments, water and freshwater mussels (Velesunio angasi) from two catchments in the Alligator Rivers Region, Australia. Sediment U and Pb concentrations were higher in Magela Creek downstream than upstream of the Ranger U mine due to the mineralised nature of the catchment and potential local input of sediment from the mine site. Water metal concentrations were highest in Georgetown Creek, which is a tributary of Magela Creek and part drains the Ranger mine site, but there was little difference in concentrations between the Magela Creek upstream and downstream sites. Metal concentrations in mussels collected immediately upstream and downstream of the mine site also showed little difference, whereas Pb isotope ratios displayed a very distinct pattern. The 206Pb/207Pb and 208Pb/207Pb isotope ratios were more uranogenic downstream than upstream of the site and also more uranogenic than ratios measured in Sandy Billabong, a reference billabong in a catchment not influenced by U mineralisation. Isotope ratios were also more uranogenic in younger mussels, potentially due to the increasing footprint of the mine site over the past decade. The most uranogenic ratios were found in mussels from Georgetown Creek and at a site approximately 2 km downstream. At Mudginberri Billabong, approximately 12 km downstream of the Ranger mine, the relative contribution of uranogenic Pb to the total Pb concentration in mussels was small and overwhelmed by the input of industrial Pb with a Broken Hill type Pb signature. Whereas metal uptake by and thus concentrations in mussel flesh are influenced by water chemistry, mussel condition and metabolic rates, Pb isotope ratios are independent of these factors and provide a powerful means of source apportionment of contaminants in mussels and waterways, in particular in an U mining environment.  相似文献   

17.
The Jerrabattgulla Creek basalts are in the upper catchment of the Shoalhaven River of southeastern New South Wales. The basalts erupted into a narrow, north-draining valley and modified the local drainage system, re-routing the paleo-Jerrabattgulla Creek, preserving a series of sub-basaltic quartzose gravels with silcretes in the paleovalley. The paleovalley indicates that a north-flowing drainage existed in this place in the Miocene. The high-relief, narrow valley has preserved a volcanic stratigraphy allowing the magmatic evolution of this small lava field to be determined. The lavas have a large compositional range from olivine nephelinite through to quartz tholeiite, which is unusual in such a small lava field. They represent three distinct magma batches, most likely from an amphibole–apatite metasomatised sub-continental lithospheric mantle, and underwent fractional crystallisation of olivine, clinopyroxene and plagioclase and assimilated upper crust. The lava field underwent temporal change from dominantly alkaline, to mixed alkaline and subalkaline, to dominantly alkaline magmatism over the course of its evolution.  相似文献   

18.
Precisely how Upper Palaeolithic human ecology was shaped by changing climate during the Pleniglacial remains a matter of debate, for while this generally cold period is now understood to include complex and often rapid flux in climate, there are still considerable difficulties in resolving climatic variations at particular times and places — derived from various lines of proxy evidence — with the high-resolution proxy record of temperature changes from oxygen isotope analysis of the Greenland ice-cores.In this paper we apply the methodology of large-scale flotation to newly excavated contexts from the Upper Palaeolithic (Gravettian) site of Dolní V?stonice II, Czech Republic, to explore the potential of charcoal — as a natural archive of environmental information — to offer information on environmental change towards the end of the middle pleniglacial during Oxygen Isotope Stage 3, between c. 32,500 and 31,200 Cal yr BP. The results of an analysis of ring widths and other anatomical features — interpreted alongside micromorphological data — indicate that this charcoal may capture a higher-resolution record of the changing climatic conditions during which humans were first expanding into these hitherto marginal ecologies and, consequently, shed new light upon the complexity of the lifeways that enabled them to do so.  相似文献   

19.
《Quaternary Science Reviews》2003,22(5-7):569-580
A composite varve-dated 11.4 m long sediment sequence from Lake Holzmaar, situated in the Eifel region of western Germany, was investigated for total organic matter content, total nitrogen content and stable organic carbon isotopes. Mean time resolution is 75 years for TN and 14 years for δ13Corg. On millennial time scales primary production of lacustrine algae strongly depends on the delivery of nutrients from the catchment. The respective carbon isotope record is characterized by marked variations of δ13Corg ranging from −36.0‰ to −27.0‰ and includes a number of pronounced shifts. Reactions of the lacustrine system and the catchment to changes of environmental parameters, e.g. runoff, solar radiation and temperature, induce changes of algal associations and of lacustrine primary production which are reflected in the sediments as carbon isotope variations. Clear evidence of ecosystem reorganizations is detected by the carbon isotope record around 14,200, 10,400, 9600, 5500, 2700, 1700 and 900 varve years BP. In particular, the Holocene events of 9600, around 5500 and 2700 are interpreted as the expression of massive changes of the climate system. The steady rise of δ13Corg values during the mid-Holocene is interpreted as a continuous climatic amelioration reaching an optimum around 6500 varve years BP. Rapid and large changes of δ13Corg values from 2700 varve years BP to the present indicate major disturbances in the catchment area. These are most probably related to deforestation or reforestation and runoff changes, presumably in conjunction with human impact. Carbon isotopes, thus, characterize the Holzmaar ecosystem in time revealing lacustrine palaeoproductivity as well as providing palaeoenvironmental and palaeoclimatic information.  相似文献   

20.
Kevin Grove 《Geoforum》2009,40(2):207-216
The growing field of urban political ecology (UPE) has greatly advanced understandings of the socio-ecological transformations through which urban economies and environments are produced. However, this field has thus far failed to fully consider subjective (and subject-forming) dimensions of urban environmental struggle. I argue that this can be overcome through bringing urban political ecology into conversation with both post-structural political ecology and critical geopolitics. Bridging these literatures focuses attention on practices of socio-ecological exclusion and attachment through which environmental subjectivities are formed. This argument is drawn out through a case study of the politics of local economic development and conservation within the watershed of the Big Darby Creek near Columbus, Ohio. This struggle was driven by a preservationist movement that coalesced around a shared understanding of socio-ecological hybridity as a source of metaphysical insecurity. Hybridity appears here as a site of political and ethical struggle over social and ecological exclusions produced in the pursuit of security. This case study demonstrates a paradox of environmental politics: the non-human is at once a site of constituent possibilities for identity and subjectivity as well as forces which seek to foreclose this radical openness. Recognizing the paradoxical nature of environmental struggle allows for a more complex and nuanced account of the multifarious forces that shape the formation of environmental subjectivities.  相似文献   

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