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451.
Agricultural Productivity Changes Induced by the Sloping Land Conversion Program: An Analysis of Wuqi County in the Loess Plateau Region 总被引:3,自引:0,他引:3
This paper examines the agricultural productivity change induced by the Sloping Land Conversion Program (SLCP) using the Malmquist
index method and household data collected from Wuqi. We find that during the period of 1998–2004, the total factor productivity
(TFP) grew by 15.8%. While numerous households suffered a TFP decline, the majority of them experienced a large gain. By decomposing
the TFP, we further show that its increase is due exclusively to the improvement of technical efficiency rather than to technological
change. To validate these findings and put them in perspective, we also estimated the TFP change with county-level aggregate
data. It is revealed that driven by technological change and scale efficiency, the TFP grew slightly during the period of
1992–1998. Because of the tremendous cropland reduction and production mode shift caused by implementing the SLCP, the TFP
declined substantially during the first three years of the program; due to continued improvement of technical efficiency;
however, its growth accelerated later. Altogether, our evidence consistently suggests that implementing the SLCP has contributed
to the agricultural TFP growth in the longer term and that the efficiency improvement has resulted mainly from the increased
public expenditures for extension services and diffusion of technical knowledge. Wuqi’s experience proves that it is possible
to achieve environmental conservation and increase productivity simultaneously, even when facing a cropland reduction and
production mode alternation. 相似文献
452.
Development Potentials and Policy Options of Biomass in China 总被引:7,自引:0,他引:7
Biomass, one of the most important renewable energies, is playing and will continue to play an important role in the future
energy structure of the world. This article aims to analyze the position and role, assess the resource availability, discuss
the geographic distribution, market scale and industry development, and present the policy options of biomass in China. The
resource availability and geographical distribution of biomass byproducts are assessed in terms of crop residues, manure,
forest and wood biomass byproducts, municipal waste and wastewater. The position of biomass use for power generation is just
next to hydropower among types of renewable energy in China. The potential quantity of all biomass byproducts energy in 2004
is 3511 Mtce (Mtce is the abbreviation of million tons of coal equivalents and 1 Mtce is equal to106 tce.), while the acquirable quantity is 460 Mtce. Biomass energy plays a critical role in rural regions of China. The geographical
distribution and quantity of biomass byproducts resources depends mainly on the relationship between ecological zones and
climate conditions. Our estimation shows that the total quantity of crop residues, manure, forest and wood biomass byproducts,
municipal waste and wastewater resources are 728, 3926, 2175, 155 and 48240 Mt (million tons), respectively. Crop residues
come mainly from the provinces of Henan, Shandong, Heilongjiang, Jilin and Sichuan. All manure is mainly located in the provinces
of Henan, Shandong, Sichuan, Hebei and Hunan. Forest and wood biomass byproducts are mainly produced in the provinces or autonomous
regions of Tibet, Sichuan, Yunnan, Heilongjiang and Inner Mongolia, while most of municipal waste mainly comes from Guangdong,
Shandong, Heilongjiang, Hubei and Jiangsu. Most of wastewater is largely discharged from advanced provinces like Guangdong,
Jiangsu, Zhejiang, Shandong and Henan. Biomass byproducts’ energy distribution also varies from province to province in China.
Based on the analysis of the market scale and industry development, the article argues that China’s biomass energy industry
is still at a very early stage of development and that Feed-in Tariffs (FIT) might be the best policy option for China to
promote its development of biomass energy. A successful enforcement of FIT in China needs some policy combination of special
capital subsidies, R&D funding, tax incentives and pricing. 相似文献
453.
The coastal landscapes in southwestern Korea include a diverse array of tidal wetlands and salt marshes. These coastal zones
link the ecological functions of marine tidal wetlands and freshwater ecosystems with terrestrial ecosystems. They are rich
in biological diversity and play important roles in sustaining ecological health and processing environmental pollutants.
Korean tidal wetlands are particularly important as nurseries for economically important fishes and habitats for migratory
birds. Diking, draining, tourism, and conversion to agricultural and urban uses have adversely affected Korean tidal wetlands.
Recent large development projects have contributed to further losses. Environmental impact assessments conducted for projects
affecting tidal wetlands and their surrounding landscapes should be customized for application to these special settings.
Adequate environmental impact assessments will include classification of hydrogeomorphic units and consideration of their
responses to biological and environmental stressors. As is true worldwide, Korean laws and regulations are changing to be
more favorable to the conservation and protection of tidal wetlands. More public education needs to be done at the local level
to build support for tidal wetland conservation. Some key public education points include the role of tidal wetlands in maintaining
healthy fish populations and reducing impacts of nonpoint source pollution. There is also a need to develop procedures for
integrating economic and environmental objectives within the overall context of sustainable management and land uses. 相似文献
454.
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456.
There is increasing concern that agricultural intensification in China has greatly increased N2O emissions due to rapidly increased fertilizer use. By linking a spatial database of precipitation, synthetic fertilizer N input, cropping rotation and area via GIS, a precipitation-rectified emission factor of N2O for upland croplands and water regime-specific emission factors for irrigated rice paddies were adopted to estimate annual synthetic fertilizer N-induced direct N2O emissions (FIE-N2O) from Chinese croplands during 1980-2000. Annual FIE-N2O was estimated to be 115.7 Gg N2O-N year−1 in the 1980s and 210.5 Gg N2O-N year−1 in the 1990s, with an annual increasing rate of 9.14 Gg N2O-N year−1 over the period 1980-2000. Upland croplands contributed most to the national total of FIE-N2O, accounting for 79% in 1980 and 92% in 2000. Approximately 65% of the FIE-N2O emitted in eastern and southern central China. 相似文献
457.
A competitive indirect enzyme-linked immunoassay for lead ion measurement using mAbs against the lead-DTPA complex 总被引:1,自引:0,他引:1
Jun-jian Xiang Hong Wang Bin Liu Chang-wei Guo 《Environmental pollution (Barking, Essex : 1987)》2010,158(5):1376-314
Immunoassays for quantitative measurement of environmental heavy metals offer several advantages over other traditional methods. To develop an immunoassay for lead, Balb/c mice were immunized with a lead-chelate-protein conjugate to allow maximum exposure of the metal to the immune system. Three stable hybridoma cell lines were obtained through spleen cells fusion with Sp2/0 cells. One cell line, 2A11D11, produced mAbs with preferential selectivity and sensitivity for Pb-DTPA than DTPA, exhibiting an affinity constant of 3.34 ± 0.24 × 109 M−1. Cross reactivity (CR) with other metals were below 1%, except for Fe(III) with a CR less than 5%. This quantitative indirect ELISA for the lead ion was used to detect environmental lead content in local water sources; importantly, the results from the immunoassay were in excellent agreement with those from ICP-MS. Development of immunoassays for metal ions may thus facilitate the detection and regulation of environmental pollution. 相似文献
458.
废弃中药渣催化热解制取生物油的研究 总被引:1,自引:0,他引:1
利用热重分析仪(TGA)对植物类中药渣的热解特性进行了研究,用Coats-Redfern积分法计算了其热解动力学参数,得出中药渣热解反应符合一级反应动力学方程,其活化能较低,为36.0kJ/mol。考察了热解温度对气体、液体、固体产物的影响,在723K时,液体产物生物油产率最高,为39%。以介孔分子筛SBA-15以及分别负载Al、Sn、Ni、Cu和Mg的SBA-15作为催化剂,研究催化热解对气体、液体、固体产率及生物油组分的影响。研究表明,Al-SBA-15的催化效果较好,液体产率最高,为36%;采用元素分析仪和热值测定仪,得到用Al-SBA-15作为催化剂时生物油的氧质量分数最低,低位热值最高。用GC/MS对生物油组分的分析结果表明,添加Al-SBA-15后,热解产物中脂肪族和芳香族化合物增加,而含氧化合物减少。 相似文献
459.
以68台燃油锅炉(≤10~MW)NOx排放实测数据为基础,通过统计分析方法,研究了NOx的排放特征;通过对比分析,探讨了我国燃油锅炉NOx排放控制与管理现状,讨论了进一步加强我国燃油锅炉NOx排放管理控制的可能性与可行性,并提出了相应的管理控制建议。结果表明,NOx平均排放浓度为318.2mg/m^3,基于燃料消耗量的平均排放因子为4.4kg/t,基于燃料发热量的平均排放因子为102.8ng/J,基于燃料氮含量的平均排放因子为2.1mg/mg;建议采取分阶段控制的方式,逐步提高NOx排放限制,从而实现控源减排目标。 相似文献
460.
中性红在柚子皮上的吸附机制研究 总被引:2,自引:0,他引:2
采用柚子皮作为生物吸附材料吸附去除中性红。研究了中性红的初始浓度、吸附时间及反应温度对吸附效果的影响。结果表明,当中性红溶液从100 mg/L升高到250 mg/L时,反应95 min后,柚子皮对中性红的吸附量从16.80 mg/g增加到40.00mg/g。中性红在柚子皮上的吸附在60 min内基本上可以达到平衡,且柚子皮对中性红的吸附过程为放热过程;二级吸附动力学方程能更好地描述中性红在柚子皮上的吸附行为;中性红在柚子皮孔隙中的扩散不是唯一的吸附速率控制步骤,这个吸附过程可能受多个步骤共同控制;柚子皮对中性红的吸附是自发吸附,Langmuir、Freundlich和Temkin吸附等温式能很好地拟合柚子皮对中性红的吸附过程,拟合相关系数分别达到了0.991 8、0.993 4、0.989 0。 相似文献