新疆CDM项目的开发状况与前景分析

随着世界经济的进一步发展,能源的需求量持续增加,CO2的排放量还将持续增长.温室气体排放带来的气候变暖问题会进一步加剧。清洁发展机制(CDM)是在《京都议定书》框架下,发达国家与发展中国家就碳减排进行合作的重要机制.发展中国家通过CDM可以获得实现节能减排的资金援助和先进技术,促进国家的经济发展和环境的可持续发展。就新疆CDM项目的发展状况、国际碳市场的前景,以及新疆CDM项目开发存在的问题和解决方法方面进行了探讨。     

我国农村劳动力流动性就业计量问题研究

改革开放30年来,上亿农村劳动力实现了向城镇非农产业大规模转移,而我国沿袭至今的劳动就业统计制度突出的缺陷是将三部分人--在农村从事纯农的农民,在城镇从事非农工作但户口在农村的农民工,游移于乡城间"亦工亦农"的农村劳动力--排除于劳动统计计量之外.不解决这部分劳动力就业的统计计量的问题,则很难准确回答"中国的失业率究竟有多高?".为此,确定严格的、便于与国际接轨的劳动就业标准,从而构建我国统一的、规范的劳动就业市场至关重要.本文着重探讨了游移于农村与城市之间、就业岗位、就业时间不固定的农村劳动力就业、失业不充分的计量问题.作者在对国内外就业和失业定义和计量标准进行比较和评价基础上,结合我国实情提出了以法定劳动力年工时为核心的劳动力流动性就业的调查和计量方法,并通过调查案例证实了它的有效性与可行性.     

Residues and dynamics of pymetrozine in rice field ecosystem

The fate of pymetrozine was studied in rice field ecosystem, and a simple and reliable analytical method for determination of pymetrozine in soil, rice straw, paddy water and brown rice was developed. Pymetrozine residues were extracted from samples, cleaned up by solid phase extraction (SPE) and then determined by high-performance liquid chromatography electrospray ionization tandem mass spectrometry (LC-ESI-MS-MS). The average recovery was 81.2-88.1% from soil, 83.4-88.6% from rice straw, 87.3-94.1% from paddy water and 82.9-85.3% from brown rice. The relative standard deviation (RSD) was less than 15%. The limits of detection (LODs) of pymetrozine calculated as a sample concentration were 0.0003 mg kg⁻¹ (mg L⁻¹) for soil and paddy water, 0.001 mg kg⁻¹ for brown rice and rice straw. The results of kinetics study of pymetrozine residue showed that pymetrozine degradation in water, soil, and rice straw coincided with C = 0.194e^−0.986t, C = 0.044e^−0.099t, and C = 0.988e^−0.780t, respectively; the half-lives were about 0.70 d, 7.0 d and 0.89 d, respectively. The degradation rate of pymetrozine in water was the fastest, followed by rice straw. The highest final pymetrozine residues in brown rice were 0.01 mg kg⁻¹, which was lower than the EU’s upper limit of 0.02 mg kg⁻¹ in rice. Therefore, a dosage of 300-600 g a.i.hm⁻² was recommended, which could be considered as safe to human beings and animals.     

Seasonal change of PCDDs/PCDFs/DL-PCBs in the water of Ayase River, Japan: pollution sources and their contributions to TEQ

In Japan, Ayase River is one of the most polluted rivers by PCDDs, PCDFs and dioxin-like PCBs, which are referred to as dioxins in this paper. The water samples of the river were collected once per month for a year, and dioxins were analyzed to examine the dioxin sources and their contributions to toxic equivalent (TEQ). The WHO-2006 TEQs ranged from 0.26 to 7.0 pg-TEQ L⁻¹ and the average was 2.7 pg-TEQ L⁻¹; eight of 12 samples exceeded the environmental quality standard in Japan (1.0 pg-TEQ L⁻¹). The TEQ value was high during the irrigation period from May to August. The most part of the dioxins in the river water existed in suspended solids (SS) and it seemed that the river received water with highly-dioxin-contaminated SS in the irrigation period. The homologue profiles of the water samples suggested that the dioxins were influenced by pentachlorophenol (PCP) and chlornitrofen (CNP) formulations which were widely used as herbicides for the paddy fields in Japan. According to TEQ apportionment estimated by using indicative congeners, the TEQ was mainly contributed by PCP. Moreover, it was also shown that the TEQ contributions of PCP and CNP formulations increased along with the increase of the total TEQ and the TEQ contribution was dominated by these herbicides during the irrigation period. Therefore, it was concluded that the herbicides-originated dioxins run off from the paddy fields into the river during the irrigation period and increased the dioxins level in the river water. The result from the principal component analysis was consistent with these conclusions.     

Polychlorinated dibenzo-p-dioxins, dibenzofurans, and dioxin-like polychlorinated biphenyls in rice straw smoke and their origins in Japan

Polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and dioxin-like polychlorinated biphenyls (DL-PCBs) contained in the smoke generated from rice straw burning in post-harvest paddy fields in Japan were analyzed to determine their congener profiles. Both the apportionment of toxic equivalent (TEQ) by using indicative congeners and the comparison of the homolog profiles showed that the PCDDs/PCDFs/DL-PCBs present in the rice-straw smoke were greatly influenced by those present as impurities in pentachlorophenol (PCP) and chlornitrofen (CNP, 4-nitrophenyl-2,4,6-trichlorophenyl ether) formulations that had been widely used as herbicides in paddy fields in Japan. Further, in order to investigate the effects of paddy-field soil on the PCDDs/PCDFs/DL-PCBs present in rice-straw smoke, PCDD/PCDF/DL-PCB homolog profiles of rice straw, rice-straw smoke and paddy-field soil were compared. Rice-straw smoke was generated by burning rice straw on a stainless-steel tray in a laboratory. The results suggested that the herbicides-originated PCDDs/PCDFs/DL-PCBs and the atmospheric PCDDs/PCDFs/DL-PCBs contributed predominantly to the presence of PCDDs/PCDFs/DL-PCBs in the rice-straw smoke while the contribution of PCDDs/PCDFs/DL-PCBs formed during rice straw burning was relatively minimal. The major sources of the PCDDs/PCDFs/DL-PCBs found in the rice-straw smoke were attributed primarily to the paddy-field soil adhered to the rice straw surface and secondarily to the air taken by the rice straw. The principal component analysis supported these conclusions. It is concluded that rice straw burning at paddy fields acts as a driving force in the transfer of PCDDs/PCDFs/DL-PCBs from paddy-field soil to the atmosphere.     

壁面粗糙度对旋风分离器内流场影响的数值模拟

利用计算流体动力学软件FLUENT6.2.16对壁面粗糙度不同的旋风分离器内流场进行了数值模拟,得到了切向速度、轴向速度、径向速度和静压力分布规律。旋风分离器内的切向速度随着壁面粗糙度的增大而明显减小;轴向速度没有明显的规律性变化,只在上部筒体涡核区轴向速度增加,削弱了涡核区滞留现象;在流场大部分区域径向速度随粗糙度的...     

漓江上游植被覆盖度时空变化对地表热场影响

自20世纪80年代以来,桂林漓江由于上游森林遭受破坏出现水生态环境快速恶化的趋势。地表热场的时空变化直接影响森林蒸散及水文效应。因此,对漓江上游1989~2006年5景TM/ETM+卫星图像,利用归一化植被指数反演植被覆盖度,利用单窗算法反演地表温度,提出归一化温度使不同时相地表热场具有可比性,分析植被覆盖度时空变化对地表热场的影响。结果表明,在空间上,地表温度随植被覆盖度的增加而降低,在植被覆盖度很高或很低时,这种影响相对变弱;在时间上,漓江上游1989~2000年植被中、高度覆盖面积从96.1%逐年下降到65.9%,导致归一化地表温度数值较高的像元比例相应增加;2000~2006年植被中、高度覆盖面积逐渐恢复上升到90.8%,但仍略低于1989年,使得归一化地表温度数值较高的像元比例相应减少。植被覆盖可以有效地降低漓江上游地表温度     

高压输电线路跨越建筑物工频电场研究

当高压输电线路跨越或邻近建筑物时,线路下方区域工频电场会发生不同程度的畸变,此时,传统的二维模型已无法正确描述该情况时线路下方工频电场的分布。利用自编仿真软件进行模拟,并结合实测数据,研究和分析高压输电线路跨越或邻近建筑物时线路下方的工频电场分布和变化趋势。     

断裂构造对斜坡应力场影响的数值模拟及成灾机理研究

断裂构造及活动强度对斜坡体的应力场分布具有重要的影响。采用基于强度折减法的有限元法,分别以正断层和逆断层与斜坡体的组合关系为例,剖析了断裂构造对斜坡体应力场的影响及成灾机理,揭示了含有断层的斜坡体塑性区的贯通过程。研究表明,包含断层的斜坡体在应力分布特征及斜坡变形破坏机理方面与无断层的斜坡体有较大差别:含断层的斜坡体在坡面和断层面附近的最大主应力迹线与坡面或断层面相平行,在天然状态下,塑性区同时出现在坡脚和断层面后方,随着折减系数的增大,塑性区分别从坡脚和断层面后方向坡体深部和上部发展,直至断层面前后两个塑性区相贯通,坡体发生破坏,并且对坡体变形破坏的影响程度以逆断层最强,其次为正断层,断层不活动时较弱。     

低纬高原大气电场特征及其在预警中的应用

通过对2006年7月- 2007年6月云南地闪定位网探测资料和玉溪大气电场仪资料分析,研究了高原晴天大气电场和雷暴天气过程的电场演变特征.结果表明:高原晴天大气电场具有明显的日变化和月变化特征.低纬高原地区雷暴云具有偶极性和三极性两种结构,但大多数雷暴具有偶极性电荷结构,不同电荷结构的雷暴云的放电特征不同,偶极性时主要为负地闪,地闪活动较活跃;三极性时主要是正地闪,地闪活动较少.根据雷暴云近地面电场变化特征,探讨了大气电场仪预警地闪的方法,首次提出极性变化预警法,其命中率和提前预警时间都明显优于阈值预警法.