River regulation,decline of ecological resources,and potential for restoration in a semi-arid lands river in the western USA   总被引：7，自引：0，他引：7  

F.?Richard?HauerEmail author  Mark?S.?Lorang 《Aquatic Sciences - Research Across Boundaries》2004,66(4):388-401

  相似文献   

Economic and political drivers of environmental impact shifting between countries     

《Global Environmental Change》2023

There is mounting evidence that major improvements in environmental quality in high-income countries over the past decades may have been achieved to a large degree through relocation of environmental impacts of consumption to other, usually poorer countries. While political and academic debates on appropriate policy interventions to address this challenge are gaining ground, we still know rather little about the drivers of international environmental impact shifting, other than international trade flows per se. We address this issue by focusing on the effects of economic inequality and political factors. We argue that income inequality between and within countries as well as variation in political institutions, environmental clauses in preferential trade agreements (PTAs), and participation in international environmental treaties could be important drivers or mitigators of environmental impact shifting between countries. We use novel panel data on five types of environmental impact flows between country dyads (187 countries, 1990–2015) to assess these arguments. We find that richer countries and countries with higher domestic economic equality tend to be the “outsourcers”, and poorer, domestically more unequal countries the “insourcers” of environmental impacts. Discrepancies in democracy levels aggravate the outsourcing from more equal to more unequal societies. In turn, environmental clauses in PTAs have a mitigating effect on environmental impact shifting, but participation in international environmental agreements has no such effect. Our findings highlight the need for green economy policies that reduce environmental footprints of consumption not only within high-income democracies, but also make their global supply chains more sustainable.  相似文献   

Impacts of – and farmers’ adaptation to – land allocation policies in the north central uplands of Vietnam     

Rikke Folving Ginzburg  Thomas Theis Nielsen 《Geografisk tidskrift / udgivet af Bestyrelsen for Det Kongelige danske geografiske selskab》2018,118(1):36-55

A series of policies on land tenure have been implemented in Vietnam following the doi moi restructuring. This study assesses the impacts of these policies, the extent to which they have had intended effects and coping strategies adopted by farmers. Data were collected in five upland villages in Nghe An Province, North Central Vietnam. The intended effects of the land allocation policies were poverty alleviation, intensification of agriculture, agricultural modernization and forest protection. The policies implemented to achieve these goals include changes in land allocation, purportedly to increase land tenure security. However, the policies have been implemented in a very uneven manner and the effects differ widely due to differences in the local contexts in which they have been implemented. In general, farmers perceive the impacts of policies as adverse and have attempted to cope with their impact in a variety of ways. The paper argues that land allocation policies have: (1) decreased the amount of land available, (2) not improved land tenure security and (3) had a limited impact on farming practices. The differences between the five villages are great, demonstrating the very different results produced by national policies depending on the specific implementation modality and the local context.  相似文献   

Fish protein recovered using ph shifting method and its physicochemical properties     

Choi  J. Yeung Kim  Jinx-Soo 《中国海洋大学学报(英文版)》2005,4(3):224-228

The solubility of meat protein of croaker and jack mackerel was significantly affected by pH shifting. The protein yield of alkali-aided processing is higher than those of conventional and acid-aided processing. The addition of sarcoplasmic protein increases the breaking force and deformation value. The breaking force of recovered protein gel from alkali-aided processing is decreased by the addition of NaCI. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis （SDS-PAGE） revealed that fish protein of alkali is similar to that at pH7.0. Alkali-aided processing for recovering fish protein is a valuable method for increasing the utilization of frozen and pelagic fishes and for making kamaboko products.  相似文献   

砂旋复花的防风固沙作用   总被引：4，自引：0，他引：4  

韩广 《中国沙漠》1995,15(3):273-277

砂旋复花是一种沙生先锋多年生草本植物,营养繁殖能力极强,能很好地适应恶劣的流沙环境。研究结果表明,砂旋复花群聚的防风固沙作用非常突出,作为一种优良固抄植物,值得在北方沙区大力推广。  相似文献   

晚更新世末至公元前7世纪的黄河流向和黄河三角洲   总被引：17，自引：3，他引：14  

薛春汀  周永青  朱雄华 《海洋学报》2004,26(1):48-61

大约距今9600～8500a黄河在苏北北部入黄海.黄河口与其南侧的长江口相距100多千米.两条大河巨大数量的入海泥砂形成了黄河-长江复合三角洲.根据南黄海西部全新世海相沉积物厚度变化、苏北响水县陈家巷QCA孔沉积序列、阜宁以南、泰州以北里下河洼地早全新世沉积序列及苏北沿岸砂脊的物质组成判断,距今8500a左右黄河向北流注入渤海,距今8500～7000 a海面上升过程中没有形成黄河水下三角洲,距今7 000 a黄河三角洲又开始形成.  相似文献   

有限元直接迭代算法   总被引：10，自引：1，他引：9  

陈小斌 《物探化探计算技术》1999,21(2):165-171

本文提出了有限元直接迭代算法。推导出了直接迭代格式的统一公式,并给出了几种网格剖分方式下的有限元直接迭代格式的具体形式,讨论了各剖分方式的优劣。编程实现了该算法并进行了实例验证  相似文献   

地质图件的数字化仪数据采集原理及程序设计     

石骁騑  朱焰 《物探化探计算技术》2000,22(1):73-77

由于计算机在地质研究中的大量运用,传统地质图件的数字化成为目前许多应用的主要 数据来源。作者在文章中主要讨论利用数字化仪输入地质图件的基本原理,数据转换以及坐标变换的核心技术和在Ｗｉｎｄｏｗｓ环境下,如何用Ｖｉｓｕａｌ Ｂａｓｉｃ６．０开发数字化仪通信程序。最后给出了一个简单的数字化仪通信实验程序。  相似文献   

草原与荒漠交界地区流沙的固定——以沙坡头铁路防护体系旱路固沙为例   总被引：3，自引：2，他引：1  

刘家琼 《中国沙漠》2002,22(5):495-498

在年降水量200~ 300mm左右的草原与荒漠交界地区,无灌溉条件下的流沙固定不仅是可能的,亦是非常成功的。以包兰铁路沙坡头铁路人工植被的建立为例,年平均降水量仅186.2mm,在扎设草方格辅助措施下,栽植固沙植物,成功地从根本上解决了流沙固定问题。油蒿是特别优良的固沙植物,天然更新能力强,并能形成群落,又能稳定相当长时期。理应成为该地区流沙固定的首选。  相似文献   

半干旱地区流动沙地土壤湿度变异及其对降水的依赖   总被引：23，自引：4，他引：19  

何志斌  赵文智 《中国沙漠》2002,22(4):359-362

应用半干旱区科尔沁沙地1983- 1990年5~ 10月份土壤湿度定点观测资料,对流动沙地土壤湿度的时空变异及其与降水关系进行了研究。结果表明:半干旱区科尔沁沙地,在0~ 300cm的垂直剖面上,以20cm作为一个层次,流动沙地土壤湿度多年平均值变化于3.25%~ 3.47%,层次间无显著差异。在时间序列土壤湿度存在年内和年际变异,5月份的土壤湿度与6~ 10月份存在显著差异,但6~ 10月份之间土壤湿度差异不显著。年际间降水量变化于243.3~ 567.1mm (变异系数9505%)之间,流动沙地土壤湿度变化于3.10%~ 3.69% (变异系数18.68%)之间。0~ 40cm土壤湿度与前月降水量不显著相关,但40~ 300cm土壤湿度与前月降水量显著相关,当月降水量与各层土壤湿度均显著相关。  相似文献