Spatial variations in daily average CO2 concentrations above wetland surface of Xianghai National Nature Reserve, China

Horizontal and vertical variations of daily average CO2 concentration above the wetland surface were studied in Xianghai National Nature Reserve of China in August, 2000. The primary purpose was to study spatial distribution characteristics of CO2 concentration on the four levels of height(0.1 m, 0.6 m, 1.2 m and 2 m) and compare the differences of CO2 concentration under different land covers. Results showed that daily average CO2 concentration above wetland surface in Xianghai National Natural Reserve was lower than that above other wetlands in northeast China as well as the worldwide average, suggesting that Xianghai wetland absorbed CO2 in August and acted as“sink” of CO2. The horizontal variations on the four levels of height along the latitude were distinct, and had the changing tendency of“decreasing after increasing” with the increase of height. The areas with obvious variations were consistent on different levels of height,and those with the highest variations appeared above surface of shore, sloping field, Typha wetland and Phragmites wetland; the vertical variations were greatly different, with the higher variations in Phragmites wetland and Typha wetland, and the lands near the shore and the sloping field with the lower variations. Spatial variations of daily average CO2 concentrations above wet!and surface were affected by surface qualities and land covers.     

大连城市环境评价与城市发展定量研究

通过对大连城市环境系统的考察,设立了完整的评价指标体系,运用模糊优选理论建立模糊评价模型,对大连城市环境进行了定量研究,并结合经济和城市化情况进行了分析。研究结果表明:城市环境质量总体上是在逐年提高的,但从2002年以来发展较为平缓。经济和城市化情况有较大发展,但仍有不足之处。     

海水环境下玻璃纤维增强复合材料力学性能演化规律研究

目的 研究海水环境下海流能发电机组叶片用玻璃纤维复合材料力学性能的变化规律.方法 在实验室内通过海水浸泡试验、拉伸试验、弯曲试验以及剪切试验,测定叶片用玻璃纤维树脂基复合材料的吸水特性,以及在人工海水介质中各项力学性能参数的演变规律.结果 随着浸泡时间的增加,玻璃纤维树脂基复合材料吸水率先逐步增大、后趋于稳定,总吸水率约0.075％.抗拉强度呈先降低、后提高、又降低的趋势,抗拉强度最高可超过1100 MPa,最小值约为940 MPa.弹性模量和弯曲强度呈逐渐降低的趋势,弹性模量降幅约9.5％,弯曲强度降幅约为30％.弯曲模量变化起伏不定,变化幅度在15％以内.材料剪切强度呈先增大、后降低的趋势,最小值为189 MPa,较初始值高10 MPa.剪切模量呈先降低、后提高的现象,在浸泡28 d时,剪切模量最小,为16.4 GPa.结论 玻璃纤维增强树脂基复合材料经过长期海水浸泡后,拉伸及抗剪切性能略有降低,但降幅不大,抗弯性能下降明显,需要在叶片结构设计和强度计算时,充分考虑抗弯性能衰减的负面影响.     

重庆大气可吸入颗粒物中多环芳烃的分析测定

本文报告了重庆大气可吸入颗粒物(IP)中多环芳烃(PAH)的分析测定方法和结果.用GC-MS定性和定量分析了重庆IP中的PAH;研究了IP中PAH的种类和分布情况;确认重庆IP中存在甲基多环芳烃(MePAH)、约占33%;颗粒大小分布表明,约有98%PAH存在于小于3μm的颗粒中.     

云南蒙自县新建小区室内空气污染调查及防治措施探讨

对蒙自县新建小区11户33个点室内环境空气中的游离甲醛、氨、苯进行了监测，游离甲醛和苯均超过标准。对有害物质的来源、危害及防治进行了讨论。     

北京市二个主要工业区汞污染及其来源的初步研究

为了调查北京市汞污染状况及其来源，选择二个主要工业区石景山区和朝阳区为研究对象．共采集表层土壤２６个，剖面样品４个，对照土壤样品４个，并且在冬季采集降雪样品和枯叶样品，分析汞含量．结果表明，燃煤烟尘排放的汞是北京市汞的主要来源，汽车尾气和化工厂泄漏可使局部汞含量增高，表层土壤中汞含量为００７—２７５ｍｇ／ｋｇ．土壤剖面中的汞含量在０—１００ｃｍ土层中均较高，其含量与土壤有机质和碳酸盐含量正相关．降雪中汞在０７—３７ｍｇ／Ｌ之间，明显高于背景值，其中大部分吸附在颗粒物上．枯叶中汞主要是从土壤吸收，并且有可能被雨水淋溶出来．     

活性污泥法的多变量最优控制Ⅰ.基础理论与DO浓度对运行费用的影响

在现有的关于活性污泥法最优控制研究的基础上，首次提出了以两个最重要的控制参数污泥排放量和溶解氧浓度（ＤＯ）为控制变量、以出水水质为约束条件、以运行费用为性能指标的活性污泥法多变量最优控制的研究问题，并着重进行了基础研究．首先建立了最优控制所必要的基本状态方程与性能指标的泛函表达式．然后通过计算研究了在满足同一出水质量前提下控制不同的ＤＯ浓度时所需要的运行费用．结果表明，ＤＯ为０９ｍｇ／Ｌ时所需运行费用最少，这与主张应当维持ＤＯ浓度大于２ｍｇ／Ｌ的传统观点相比相差甚远；衰减速率常数Ｋｄ不受ＤＯ影响的假设也不合理．     

4-氯苯酚在水溶液中的光化学反应(Ⅱ)反应的动力学研究

研究了在模拟太阳光和紫外光作用下，４－氯苯酚的光反应动力学，研究表明，紫外光的作用更为显。４－ＣＰ的反应速率与４－ＣＰ起始浓度、ｐＨ值，金属离子浓度、富里酸浓度等因素有关，通入空气，能够加速４－ＣＰ降解。     

兰州西固工业区夏季光化学烟雾污染的气象条件

通过对兰州西固工业区光化学烟雾污染规律与气象条件的关系的研究表明,在高空槽后的低空弱高压控制下,西固区出现高的臭氧浓度值,此时大气层结稳定,风很小,天气晴朗,但中午有浓重烟雾,臭氧浓度峰值在中午出现。该区盆地内形成的光化学烟雾烟团水平面积达几十公里,臭氧浓度的日变化取决于太阳总辐射和大气边界层的日变化。     

First-trimester prenatal diagnosis of severe alpha-thalassemia

By means of chorion biopsy together with restriction endonuclease analysis of fetal DNA, first trimester diagnoses were successfully made in 33 fetuses at risk for Bart's hydrops fetalis. Seven pregnancies with Hb H or hydrops fetalis were therapeutically terminated before 4 months of gestation. Of the 26 pregnancies intended to continue, 18 have come to term with normal deliveries; one with threatened abortion was terminated at the end of the first trimester and, seven are progresssing normally.