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791.
Che-Chen Xu Wen-Xiang Wu Quan-Sheng Ge Yang Zhou Yu-Mei Lin Ya-Mei Li 《Mitigation and Adaptation Strategies for Global Change》2017,22(4):565-594
Rice (Oryza) is a staple food in China, and rice yield is inherently sensitive to climate change. It is of great regional and global importance to understand how and to what degree climate change will impact rice yields and to determine the adaptation options effectiveness for mitigating possible adverse impacts or for taking advantage of beneficial changes. The objectives of this study are to assess the climate change impact, the carbon dioxide (CO2) fertilization effect, and the adaptation strategy effectiveness on rice yields during future periods (2011–2099) under the newly released Representative Concentration Pathway (RCP) 4.5 scenario in the Sichuan Basin, one of the most important rice production areas of China. For this purpose, the Crop Estimation through Resource and Environment Synthesis (CERES)-Rice model was applied to conduct simulation, based on high-quality meteorological, soil and agricultural experimental data. The modeling results indicated a continuing rice reduction in the future periods. Compared to that without incorporating of increased CO2 concentration, a CO2 fertilization effect could mitigate but still not totally offset the negative climate change impacts on rice yields. Three adaptive measures, including advancing planting dates, switching to current high temperature tolerant varieties, and breeding new varieties, could effectively offset the negative climate change impacts with various degrees. Our results will not only contribute to inform regional future agricultural adaptation decisions in the Sichuan Basin but also gain insight into the mechanism of regional rice yield response to global climate change and the effectiveness of widely practiced global thereby assisting with appropriate adaptive strategies. 相似文献
792.
选择三户典型城市家庭作为研究对象,对其家庭生活污水进行调查与分析.结果表明:城市家庭生活用水类型较多,主要分为洗澡水、洗衣水、淘米水、洗漱水、洗莱水、洗碗水、厕所用水和其它用水八个类型.所调查城市家庭人均用水量为217.84L/人·d,其范围在151.51~264.00L/人·d.所调查城市家庭生活污水的pH值的范围为6.14—7.43;浊度范周为13-221.6度;TP浓度的范围为0.69—3.18mg/L;COD浓度范围为5.9—1368.8mg/L。 相似文献
793.
在城市环境目益恶化的今天,景观生态设计问题越来越受到人们的重视。此文从环境和生态的观点出发分析现代景观设计,并以中山岐江公园为例探讨景观设计与环境保护和生态主义之议题,提出景观设计创作之初应先进行环境评估,立足于环境保护和生态主义的景观设计才更具生命力。 相似文献
794.
数字水准仪DiNi11/12原理及应用中应注意的问题 总被引:2,自引:0,他引:2
本文介绍了数字水准仪的原理、特点,着重分析了对台站跨断层观测精度影响较大的几个因素,并结合台站工作实际提出了减弱这些影响的措施,实测结果表明:采取这些措施可以有效地提高测量精度. 相似文献
795.
The aphid alarm pheromone (E)-β-farnesene (EβF) is an efficient signal that warns aphids of attack by natural enemies. In this field study, eight open-top chambers (OTCs) located in Beijing, China (40°11′N, 116°24′E) with spring wheat Triticum aestivum were used to examine the response of the grain aphid Sitobion avenae to CO2 (ambient vs. double ambient) and EβF (applied zero, two, or five times each day). We experimentally tested the hypotheses that, depending on frequency of EβF release, elevated CO2 reduces the response (in terms of population density) of S. avenae to EβF, and that lower activity of acetylcholinesterase (AChE) in S. avenae may be involved in its reduced sensitivity to EβF under elevated CO2. Numbers of S. avenae declined with increased frequency of EβF application under ambient CO2 but were unaffected by EβF application under elevated CO2. Additionally, the mean relative growth rate (MRGR) and the dry material and amino acid content of S. avenae increased with elevated CO2 but declined when with EβF application. Activities of superoxide dismutase and catalase were higher in S. avenae under elevated vs. ambient CO2. Under elevated CO2, however, AChE activity remained low when S. avenae was exposed to the lower EβF frequency, while the highest AChE activity occurred in aphids exposed to the higher EβF frequency. These results indicate that aphids become insensitive to EβF under elevated CO2, perhaps because of decreased AChE activity. 相似文献
796.
Aijuan Wang Yunshan Ge Jianwei Tan Mingliang Fu Asad Naeem Shah Yan Ding Hong Zhao Bin Liang 《环境科学学报(英文版)》2011,23(3):419-426
On-road emission and fuel consumption (FC) levels for Euro III and IV buses fueled on diesel and compressed natural gas (CNG)
were compared, and emission and FC characteristics of buses were analyzed based on approximately 28,700 groups of instantaneous
data obtained in Beijing using a portable emissions measurement system (PEMS). The experimental results revealed that NOx and
PM emissions from CNG buses were decreased by 72.0% and 82.3% respectively, compared with Euro IV diesel buses. Similarly,
these emissions were reduced by 75.2% and 96.3% respectively, compared with Euro III diesel buses. In addition, CO2, CO, HC,
NOx, PM emissions and FC of Euro IV diesel buses were reduced by 26.4%, 75.2%, 73.6%, 11.4%, 79.1%, and 26.0%, respectively,
relative to Euro III diesel buses. The CO2, CO, HC, NOx, PM emissions and FC factors all decreased with bus speed increased, while
increased as bus acceleration increased. At the same time, the emission/FC rates as well as the emission/FC factors exhibited a strong
positive correlation with the vehicle specific power (VSP). They all were the lowest when VSP < 0, and then rapidly increased as VSP
increased. Furthermore, both the emission/FC rates and emission/FC factors were the highest at accelerations, higher at cruise speeds,
and the lowest at decelerations for non-idling buses. These results can provide a base reference to further estimate bus emission and FC
inventories in Beijing. 相似文献
797.
Zhihua Liu Asad Naeem Shah Yunshan Ge Yan Ding Jianwei Tan Lei Jiang Linxiao Yu Wei Zhao Chu Wang Tao Zeng 《环境科学学报(英文版)》2011,23(5):798-807
The effects of continuously regenerating diesel particulate filter (CRDPF) systems on regulated gaseous emissions, and number-size
distribution and mass of particles emanated from a diesel engine have been investigated in this study. Two CRDPF units (CRDPF-1
and CRDPF-2) with di erent specifications were separately retrofitted to the engine running with European steady-state cycle (ESC).
An electrical low pressure impactor (ELPI) was used for particle number-size distribution measurement and mass estimation. The
conversion/reduction rate (RCR) of hydrocarbons (HC) and carbon monoxide (CO) across CRDPF-1 was 83% and 96.3%, respectively.
Similarly, the RCR of HC and CO and across CRDPF-2 was 91.8% and 99.1%, respectively. The number concentration of particles
and their concentration peaks; nuclei mode, accumulation mode and total particles; and particle mass were highly reduced with the
CRDPF units. The nuclei mode particles at downstream of CRDPF-1 and CRDPF-2 decreased by 99.9% to 100% and 97.8% to 99.8%
respectively; and the particle mass reduced by 73% to 92.2% and 35.3% to 72.4%, respectively, depending on the engine conditions.
In addition, nuclei mode particles increased with the increasing of engine speed due to the heterogeneous nucleation initiated by the
higher exhaust temperature, while accumulation mode particles were higher at higher loads due to the decrease in the air-to-fuel ratio
(A/F) at higher loads. 相似文献
798.
799.
Tianzeng Chen Yongchun Liu Biwu Chu Changgeng Liu Jun Liu Yanli Ge Qingxin M Jinzhu M Hong He 《环境科学学报(英文版)》2019,31(5):256-263
Current atmospheric quality models usually underestimate the level of ambient secondary organic aerosol(SOA), one of the possible reasons is that the precursors at different concentrations may undergo different oxidation processes and further affect SOA formation. Therefore, there is a need to perform more chamber studies to disclose the influence. In this work, SOA formation over a wide range of initial precursor concentrations(tens of ppb to hundreds of ppb levels) was investigated in a 30 m3 indoor smog chamber,and mainly through the analysis of multiple generations of VOCs detected from HR-To FPTRMS to expound the difference in the oxidation process between low and high precursor concentrations. Compared to high initial concentrations, gas-phase intermediates formed at low concentrations had a higher intensity by about one order of magnitude, and the lowvolatility compounds also had a higher formation potential due to the competition between semi-volatile intermediates and precursors with oxidants. In addition, the formed SOA was more oxidized with higher f44 value(0.14 ± 0.02) and more relevant to real atmosphere than that formed at high concentrations. This work should help to deeply understand SOA formation and improve the performance of air quality models for SOA simulation. 相似文献
800.
恩诺沙星与Cu复合污染对白菜和西红柿根及芽伸长的抑制作用 总被引:1,自引:0,他引:1
抗生素恩诺沙星和重金属Cu是当今我国土壤中较常见的污染物。本研究考察了恩诺沙星与Cu复合污染对砖红壤中白菜和西红柿种子的根及芽伸长的影响,以评估恩诺沙星和Cu复合污染潜在的生态风险。结果表明,加入不同浓度的Cu时,土壤中的恩诺沙星浓度与2种作物的根伸长和芽伸长的抑制率均显著相关(P0.05);白菜的敏感性均大于西红柿;白菜和西红柿的根伸长对复合污染的生态毒性的敏感性均较芽伸长更高;与单一恩诺沙星胁迫相比,在恩诺沙星与Cu(100 mg·kg~(-1))或Cu(300 mg·kg~(-1))复合污染下,二者对白菜和西红柿的根及芽伸长抑制效应均表现为协同作用。试验结果在揭示恩诺沙星与Cu复合污染的生态毒性效应的同时,也为重金属和抗生素复合污染的生态风险评价提供科学依据。 相似文献