From paleo to policy: partitioning the historical point and nonpoint phosphorus loads to the St. Croix River,Minnesota-Wisconsin,USA     

Mark B. Edlund  Laura D. Triplett  Mark D. Tomasek  Kathy Bartilson 《Journal of Paleolimnology》2009,41(4):679-689

Paleolimnological studies show that phosphorus (P) loads to the federally protected St. Croix River, a tributary of the Upper Mississippi River, have increased about threefold over the last century. Ongoing management efforts to protect and restore the river hinge on the question of whether the increased nutrient load results from point-source discharges or nonpoint runoff from agricultural intensification and urban expansion. Here we determine the historical contribution of point source phosphorus (P) loads to the St. Croix watershed from 1900–2000 A.D. Historical point source loads were estimated based on discharge volumes, demographics, industrial sources, wastewater technologies, and facility discharge records, where available. Sewering in the basin began in 1905, and since that time, there have been as many as 169 permitted point source dischargers basinwide, including municipal, industrial, and agricultural facilities. Early wastewater management typically discharged untreated sewage; technological advances had secondary treatment in place at most facilities by the 1960s–1970s and much of the municipal population was served by tertiary treatment by the 1990s. Peak nutrient discharges from point sources occurred in the 1960s–1970s. Detergent phosphorus bans instituted in the late 1970s for Minnesota and Wisconsin, greater use of land and groundwater effluent disposal, and improvements in treatment technology brought about decreases in P loads in the 1980s and 1990s. Point-source discharges were compared to historical total phosphorus loads estimated in a whole-basin phosphorus mass balance to calculate the historical contribution of point sources, anthropogenic nonpoint sources, and natural or background sources. We estimated 1990s point source loads at 48 t P yr⁻¹, which represents about 10% of the total phosphorus load (459 t P yr⁻¹, flow-corrected to 412 t P yr⁻¹) to the basin. Without further controls on nutrient inputs to the St. Croix River, annual flow-corrected P loads are projected to increase to 498 t P yr⁻¹ by the 2020s with point source phosphorus loading contributions at 65 t P yr⁻¹ or 13% of the total load. However, if we exclude background P loads to the St. Croix (166 t P yr⁻¹), recent nutrient loads are primarily from anthropogenic nonpoint sources. Point sources also contribute over 19% of the current and future phosphorus load that can be attributed to human activities in the watershed. Interstate and federal efforts to decrease P loading to the St. Croix River by 20% will need to target both point and nonpoint sources. This is one of eight papers dedicated to the “Recent Environmental History of the Upper Mississippi River” published in this special issue of the Journal of Paleolimnology. D.R. Engstrom served as guest editor of the special issue.  相似文献   

上海近50年气温变化与城市化发展的关系   总被引：11，自引：1，他引：10       下载免费PDF全文

曹爱丽  张浩  张艳  马蔚纯 《地球物理学报》2008,51(6):1663-1669

根据上海地区2个气象站近50年的年均气温数据,采用回归分析、滑动平均和Mann\|Kendall检验法研究上海地区气温的年代际变化与跃变,城郊温差的年际变化;采用趋势拟合与相关分析,研究城郊温差与城市人口、GDP、能源消耗量、建成区面积和住宅竣工面积等各项城市发展指标的关系.结果表明：（1）近50年来,上海地区年均气温缓慢上升,20世纪90年代后城郊温差呈锯齿状上升趋势,若以徐家汇代表城区,奉贤代表郊区,则近50年来,城郊温差增温率为0.23℃/10a.（2）1989~1990年为上海城区气温的跃变年份,而郊区的气温跃变出现在20世纪90年代中期.（3）各项城市发展指标均与上海城郊温差有着显著的相关性,表明它们与上海城市热岛的发展关系密切,其中,住宅建设是上海城市热岛最主要的驱动因素,城市人口和经济发展也具有重要影响.  相似文献   

基于模糊物元的城市化生态预警模型及应用   总被引：8，自引：0，他引：8  

符娟林  乔标 《地球科学进展》2008,23(9):990-995

根据模糊物元理论建立了城市化的生态预警模型,将警报级别分为无警、轻警、中警、重警和巨警5级,并从资源预警、生态预警和环境预警3个方面构建河西走廊城市化进程中的生态环境预警指标体系,设立了预警参照标准与预警界限、警灯、警度,对河西走廊进行了实证分析。结果发现,河西走廊及五大地市按照预警指数从大到小的顺序依次为：张掖市、武威市、金昌市、河西走廊、嘉峪关市和酒泉市。其中,河西走廊的生态用水比重、植被覆盖率、人均环境保护费用和万元产值工业SO2排放量的景气指数最高,处于重警状态;城市工业用地定额、城市居住用地定额、万元产值工业废水排放量和万元产值工业粉尘排放量的景气指数最低,均处于轻警状态;其它指标均处于中警状态。可见,相对于土地资源和环境污染因素而言,水资源和生态条件已经对河西走廊的城市化产生了较强的束缚作用。  相似文献   

共享社会经济路径下中国各省城市化水平预测     

丁小江  钟方雷  毛锦凰  宋晓谕  黄春林 《气候变化研究进展》2018,14(4):392-401

城市化水平预测与减缓及适应气候变化研究息息相关。基于国家统计局2005—2015年全国各省区城镇和乡村人口,以各省区2015年人均地区生产总值为指标进行分组,结合IPCC 5种共享社会经济路径（SSPs）的发展特征设置模型参数,运用Logistic模型预测了我国各省区2016—2050年城市化水平。结果表明,到2050年,各省区（除天津、北京、上海、西藏外）在5种典型SSPs下城市化水平收敛于75%左右。其中,SSP1、SSP3、SSP4、SSP5路径下,各省城市化水平比较趋同。而在SSP2路径下,全国总体上从东部到西部城市化程度逐渐降低,空间分布具有明显梯次递减性。5种SSPs路径下城市化速度方面,基本上呈现出中西部快而东部慢、西南快而东北慢的空间分布格局。同时,高收入省份不同路径下的城市化水平差别小,而中低收入省份的差别较大。  相似文献   

The evaluation of “social risk” due to volcanic eruptions of Vesuvius     

C. Pesaresi  M. Marta  C. Palagiano  R. Scandone 《Natural Hazards》2008,47(2):229-243

A re-evaluation of the demographic risk per number of inhabitants due to volcanic eruptions in the Vesuvius area was made on the basis of the Census data of 2001. We introduced other variables (population density and number of houses) which permit to upgrade the existing models. Using the Geographical Information Systems (GIS) and particularly ArcGIS 9.0 software we have elaborated a land use map, an urbanization map and a series of new risk maps which lead us to obtain a map of what we call “social risk” due to volcanic eruptions, derived from the combination of the data used and the overlay of the maps. We have proposed an integrated model which can be easily updated to follow the evolution of the volcanic risk in the overpopulated Vesuvius area, with the aim of supporting the planning of Civil Protection and Local Authorities, for an evacuation scenarios and the possibility of taking into account the potential infrastructural damages. This methodology can be tested in other volcanic regions.  相似文献   

Splintered networks: The colonial and contemporary waters of Jakarta     

Michelle Kooy  Karen Bakker 《Geoforum》2008,39(6):1843-1858

This paper queries the relevance of the ‘splintering urbanism’ thesis to postcolonial cities of the South, and responds to calls for the production of a decentered theory of urbanization through a case study of Jakarta. Drawing on archival and interview data, the paper demonstrates that Jakarta has, since its inception, been characterized by a high degree of differentiation of access to water supply, and of fragmentation of water supply networks. We document the origins of this fragmentation in the colonial era, and trace the legacy of the colonial constructions within the postcolonial city. Moreover, we demonstrate that the introduction of private sector management (in 1988) has not significantly disrupted, and certainly not caused, this pattern. In short, we provide evidence to support our claim that Jakarta’s water supply system is ‘splintered’ rather than ‘splintering’, and demonstrate that this phenomenon was not caused by the rise (or fall) of the ‘modern infrastructural ideal’. In order to explain this sustained fragmentation of infrastructure and access, the paper develops a conceptual framework of postcolonial governmentality that emphasizes the interrelationship between materiality, governmentality, identity, and urbanization, in particular through demonstrating how contested and evolving process of social differentiation are linked to the differentiation of water supply infrastructures and of urban spaces. Although we are wary of any simplistic comparisons between the colonial past and present, we argue that the optic of postcolonial governmentality provides a powerful lens for dissecting the power relations that continue to structure access to water supply and urban space in cities in the South.  相似文献   

Numerical Study On Cloud Lines Over An Urban Street In Tokyo     

Manabu Kanda  Yushi Inoue  Itsushi Uno 《Boundary-Layer Meteorology》2001,98(2):251-273

`Kanpachi Street Cloud (KSC)' is an unusual small-scalecumulus cloud line visible during calm summer conditions over a major street in the Tokyo metropolitanarea. In order to understand the mechanism leading to the formation of this cloud line,numerical simulations have been performed using the Regional Atmospheric Modelling System.The general characteristics of the simulated KSC agree well with observations. On alarge-scale view, the KSC can be characterized as a cumulus cloud line generated at the convergenceline of two sea breezes on the western side of Tokyo Bay, while on the microscale view, it resemblesBenard-type thermal convection modified longitudinally by wind shear.The location of the convergence line leading to the KSCformation coincides withthe Kanpachi street location, although the street itself does notmake any direct effect on the KSC formation. Additional numerical experiments were performed toidentify causes of the KSC formation in accordance with urbanization, by changing anthropogenicheat impact, land-cover and grid resolution.They confirmed that the formation of the KSC requirestwo meteorological processes at the same time:(1) the convergence of two sea breezes – the localsouth-eastern sea breeze from Tokyo Bay andan extended southern sea breeze from thePacific Ocean, respectively; (2) Forcing due to an urban heat island. It is shown that urbanization couldchange the intensity and position of the KSC through enhancement of local upward motions and changesin the near-surface horizontal pressure gradient between urban and sub-urban areas. Further,fine horizontal grid resolution is needed to be able to resolve these local thermal convection issues.  相似文献   

华北平原城市用水问题研究   总被引：11，自引：7，他引：11  

金凤君 《地理科学进展》2000,19(1):17-24

本文重点分析了华北平原地区城市化发展水平、发展趋势及其与水资源利用间的关系。得出以下主要观点 :第一 ,城市用水快速增长 ,用水结构从生产、生活并重型向生产主导型转换 ;第二 ,城市水资源供需矛盾突出 ,局部地区地下水超采严重 ;第三 ,城市用水结构存在明显 4种类型 ,即生活用水比重高—人均用水水平低、生活用水比重高—人均用水水平高、生活用水比重低—人均用水水平低、生活用水比重高—人均用水水平高四类城市 ,各类城市的未来用水需求趋势存在差异 ;第四 ,未来本地区城市化水平将进一步提高 ,经济总量进一步扩大 ,水资源供需矛盾会更加突出 ,建立更有效的城市用水机制和更广泛的区域供水网络将显得非常重要。  相似文献   

Toward an environmental justice of the rural-urban interface     

《Geoforum》2016

In this article, I make the case for an explicit extension of environmental justice research to the rural-urban interface or fringe. A more systematic exploration and synthesis of the blurred boundaries and transitional character of the interface might advance the empirical scope of environmental justice research while contributing to the environmental justice literature’s evolving treatment of space, ecology, and oppression. I subsequently synthesize previous research to outline some fringe characteristics, which signal the interface as a distinct geographical space deserving of closer attention in environmental justice studies, before proposing a few unique dimensions of injustice on the interface. In light of these new facets of rural-urban injustice, I finally outline some preliminary empirical and conceptual questions the interface might pose to environmental justice studies more broadly.  相似文献   

Four decades of urban sprawl and population growth in Teresina,Brazil     

《Applied geography (Sevenoaks, England)》2017

The expansion of medium-sized cities in Brazil has increased significantly since the 80–90's decades. In that period, most of the urbanization process was represented by the agglomeration of the population in the major metropolitan areas such as São Paulo and Rio de Janeiro. Nowadays, the rural-urban movement in Brazil is predominantly affecting cities with less than 1 million inhabitants, located particularly in the Center-West and in the Semiarid Northeast regions. The city of Teresina, the capital and largest city of the Brazilian state of Piauí, is one example that has shown an accelerated process of urban development. In this context, this paper seeks to discuss the urban sprawl of Teresina over the last four decades (1974–2014), associating its trends of urban expansion and population growth with their social and environmental implications. The results of our work indicate that urban sprawl in Teresina has been continuous over the years and getting faster in the 2010–2014 period. High demographic density areas are located mostly in peripheral zones, where the low-income population dominates. The population density varies across the city, and it is far from the standard proposed by the urban legislation. Thus, urbanization in Teresina is characterized by the sprawl of its municipal boundaries, intra-urban densification and verticalization, and an increase in population, especially in areas of low-income neighborhoods.  相似文献