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101.
本研究利用荧光区域积分法考察了在水体冻结过程中,溶解性有机物(DOM)组分中荧光物质的迁移转化.同时,利用XAD树脂,将DOM分为3个部分:疏水性有机酸(HPO-A)、过渡亲水性有机酸(TPI-A)和亲水性有机物(HPI).结果表明,在水体冻结过程中,HPO-A、TPI-A和HPI的DOC浓度在水相中逐渐增加,而在冰相中先减少后增加,并且这3种DOM组分在冰、水两相间的分配系数排序为:HPITPI-AHPOA.在水体冻结过程中,水相中HPO-A和HPI的总累计荧光强度(ΦT,n)值,以及冰相中3种DOM组分的总ΦT,n值随冻结时间的变化趋势均为先降低后升高.在水体冻结过程中,水相中3种DOM组分的类腐殖酸荧光峰发生蓝移.冻融作用导致HPO-A和HPI的荧光性降低.与HPO-A和HPI相比,TPI-A的荧光性受冻融作用的影响相对较小.此外,在4类荧光物质中,冻融作用对DOM组分中的类富里酸荧光物质和类腐殖酸荧光物质的影响较显著. 相似文献
102.
This paper presents a new optimization model for the synthesis of direct reuse/recycle water networks with data uncertainties. In this case, data uncertainties were originated from the varying parameters of the water sources and sinks, which fluctuate within a given range of values. The aim of the method is to design an optimum flexible water network (FWN) that ensures minimum fresh water consumption and yet fulfilling all process constraints and uncertain parameters. The resulting FWN also features the minimum number of pipelines, which will ease process operation and control. Due to the complexity of the problem, multistep solving method based on theorem of corner points has been developed. The FWN obtained using the proposed method also includes information on the maximum flow rate in the pipelines, which is essential for detailed network design stage. The resulting model is a mixed integer linear problem (MILP), which may be solved to obtain global optimum solution. Two case studies were used to elucidate the newly proposed method. 相似文献
103.
104.
利用协整理论和基于误差修正模型的Granger因果关系检验分析了中国能源消费、能源效率和经济增长的关系。协整检验表明这三者之间存在长期协整关系,GDP和能源消费之间存在双向因果关系,而GDP和能源效率之间不存在因果关系。进一步脉冲响应函数分析结果表明,能源消费和GDP在长期内存在较强的双向正向效应;中国GDP在长期内对能源效率将会产生较强的正向效应,而能源效率则对GDP存在微弱的负向效应。 相似文献
105.
He Feng 《中国人口.资源与环境(英文版)》2008,6(3):93-96
With the endless strengthening of the economic globalization trend, the world market gradually steps into a new turn of the market integration period. Market integration in China is always the key study field of academic communities, but it is developed late, whatever content system or methodology shall be greatly improved as expected. This paper aims at summarizing and reviewing the study on the content system and main demonstrations of market integration in order to provide theoretical guide and methodological basis for related studies. 相似文献
106.
国际粮食贸易背景下的市场整合与虚拟资源流动——以中国巴基斯坦大米市场为例 总被引:1,自引:0,他引:1
贸易自由化和区域经济一体化不仅会通过比较优势整合市场、提升效率,还会带来农产品贸易中虚拟资源的流动。以中国—巴基斯坦大米贸易为研究对象,使用两国大米贸易数据,首先检验中巴粮食市场整合程度,其次分析中巴大米贸易带来的虚拟水和虚拟土地的流动。结果表明:(1)中巴之间大米市场已经高度整合,且价格存在长期均衡,但巴基斯坦大米价格比中国波动大,其对中国大米的价格弹性为1.097;“一带一路”倡议带来了巴方大米价格7.8%的下降,增加了穷人的福利。(2)贸易带来了虚拟水土资源的流动。中国累计从巴基斯坦净进口大米354万t,相当于净进口国内52万hm2、巴基斯坦96.4万hm2耕地,以及国内34.4亿t、巴基斯坦101.7亿t水资源。中国应加大技术支持和扩散的力度,具有促进粮食安全,节约全球资源的意义。 相似文献
107.
ERIK GÓMEZ‐BAGGETHUN SARA MINGORRÍA VICTORIA REYES‐GARCÍA LAURA CALVET CARLOS MONTES 《Conservation biology》2010,24(3):721-729
Abstract: Researchers and conservation managers largely agree on the relevance of traditional ecological knowledge for natural resource management in indigenous communities, but its prevalence and role as societies modernize are contested. We analyzed the transmission of traditional knowledge among rural local people in communities linked to protected areas in Doñana, southwestern Spain. We studied changes in knowledge related to local practices in agriculture and livestock farming among 198 informants from three generations that cover the period in which the area transited from an economy strongly dependent on local ecosystem services to a market economy with intensified production systems. Our results suggest an abrupt loss of traditional agricultural knowledge related to rapid transformations and intensification of agricultural systems, but maintenance of knowledge of traditional livestock farming, an activity allowed in the protected areas that maintains strong links with local cultural identity. Our results demonstrate the potential of protected areas in protecting remaining bodies of traditional ecological knowledge in developed country settings. Nevertheless, we note that strict protection in cultural‐landscape‐dominated areas can disrupt transmission of traditional knowledge if local resource users and related practices are excluded from ecosystem management. 相似文献
108.
Integration of Case Studies on Global Change by Means of Qualitative Differential Equations 总被引:2,自引:0,他引:2
We present a novel methodology to integrate qualitative knowledge from different case studies on Global Change related issues
into a single framework. The method is based on the concept of qualitative differential equations (QDEs) which represents
a mathematically well-defined approach to investigate classes of ordinary differential equations (ODEs) used in conventional
modeling exercises. These classes are defined by common qualitative features, e.g., monotonicity, signs, etc. Using the QSIM-algorithm
it is possible to derive the set of possible solutions of all ODEs in the class. By this one can formulate a common, qualitatively
specified cause–effect scheme valid for all case studies. The scheme is validated by testing it against the actually observed
histories in the study regions with respect to their reconstruction by the corresponding QDE. The method is outlined theoretically
and exemplary applied to the problem of land-use changes due to smallholder agriculture in developing countries. It is shown
that the seven case-studies used can be described by a single cause–effect scheme which thus constitutes a pattern of Global Change. As a generally valid prerequisite for sustainability of this kind of land-use the presence of wage labor is shown to represent
a decisive factor.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
109.
Hoenicke R Davis JA Gunther A Mumley TE Abu-Saba K Taberski K 《Environmental monitoring and assessment》2003,81(1-3):15-25
The San Francisco Estuary Regional Monitoring Program (RMP) for Trace Substances is an innovative partnership among a regulatory agency, more than 70 regulated entities, and an independent scientific organization. The institutional arrangement behind the RMP has made the regulatory system increasingly responsive to emerging management needs, particularly with regard to the development of total maximum daily loads and ecosystem impairment assessment. Through multi-agency partnerships within and outside the RMP institutional structure, major information gaps for several pollutants of concern have been narrowed, resulting in a successful consensus-based regulatory approach to managing copper and nickel mass inputs into the Estuary. Short-term research efforts, based upon monitoring results, helped identify the most cost-effective control and remediation options for various bioaccumulative substances. Additionally, adaptive changes to the monitoring program documented the existence of widespread aquatic toxicity in the Estuary that is apparently due to pesticide runoff from agricultural and urban areas. One of the most important contributions of this collaborative monitoring program is the deliberate and systematic adjustment of management and research questions that serve to influence and add relevance to the overall research agenda related to San Francisco Estuary ecosystem assessment. 相似文献
110.