不同土壤水分条件下添加硅对紫花苜蓿茎叶和土壤氮磷钾含量的影响

为提高植物氮磷钾利用能力,采用盆栽试验研究了不同土壤水分条件下添加硅对紫花苜蓿(Medicago sativa)茎叶和土壤氮、磷、钾含量的影响.结果表明,土壤含水量为饱和含水量的35%和80%时添加硅对紫花苜蓿生物量没有明显影响,而土壤含水量为饱和含水量的50%和65%时则显著提高了紫花苜蓿生物量(P<0.05);添加硅对紫花苜蓿茎叶内氮含量没有显著影响,但显著提高了茎叶内钾和磷含量(P<0.05);添加硅对土壤全氮、速效氮、全钾和全磷含量没有显著影响,而显著提高了土壤速效磷含量(P<0.05),显著降低了土壤速效钾含量(P<0.05).说明添加硅能够显著增加紫花苜蓿茎叶内磷和钾的积累量,刺激土壤速效磷释放,降低土壤速效钾含量.     

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Abstract

Based on the data of urban land use obtained by remote sensing interpretation from aero images in 1986 and 2004, the spatial structure of Jinan is studied in this paper with the method of Geographic Information System (GIS). According to the proportion of land for residence, industry and commerce, the urban district can be distinguished into three rings. Compared with the traditional theory of the ring structure in Western countries, they have many distinctive characteristics. The main functions of the inner ring include residence, business and banking, but the proportion of residential land (more than 50%) is considerably higher than that of the cities in Western countries. The land proportion for residence and industry in the intermediate ring is equal on the whole. The main land of the outside ring is for industrial use. From 1986 to 2004, great changes have taken place on the land proportion of different types of use. In the inner ring, the land for residential and industrial use has shrunk much while the land for commercial use has increased. In the intermediate ring, the changes of the three types of land use were not very much and the temporal variation was relatively stable. On the contrary, the structure in the outside ring varies acutely. Though most of it is also for industrial use, the proportion of residential land has increased much. The three rings can also be divided into several sectors respectively, according to the function of land use clusters. New trends and mechanisms of the changes of land use impacting the urban structure were proposed in the end of the paper.     

北京9个树种叶片滞尘量及叶面微形态解释

不同树种叶片对PM(颗粒物)的滞留能力存在较大差别,并与其表面特性密切相关. 在北京市选择空气相对清洁的植物园和污染严重的国贸桥2个地点,测定了9个常见绿化树种——白蜡、大叶黄杨、垂柳、国槐、毛白杨、玉兰、紫叶李、元宝枫和银杏的单位叶面积滞尘量及其粒径组成,并观测了各树种叶面微形态结构. 结果表明,国贸桥和北京植物园9个树种PM、PM>10、PM_2.5~10和PM_2.5平均滞留量之比分别为1.64、1.60、1.89和2.50,该比值随PM粒径减小呈增大的趋势. 环境污染会改变树木叶片表面结构与性质,从而改变其滞尘能力. 叶面沟槽深且间距大、润湿性好、气孔密度(>189 N/mm2)(以单位面积气孔数计)较大有利于滞尘;气孔密度(>217 N/mm2)更大的叶片有利于滞留PM_2.5~10. 此外,叶面绒毛数量直接影响PM_2.5滞留量,在不同污染程度下均表现为有绒毛树叶的PM_2.5滞留能力更强.      

Seasonal variations in leaf capturing of particulate matter, surface wettability and micromorphology in urban tree species

The seasonal changes in leaf particulate matter (PM) accumulation, surface wettability and micromorphology in urban tree species, including Sophora japonica (S. japonica), Platanus acerifolia (P. acerifolia) and Cedrus deodara (C. deodara), were studied during a single growing season. The three species showed distinct seasonal trends in PM accumulation, increasing from spring to autumn (or winter) even during the rainy season, but at different rates. During the study, the leaf PM retention amount of P. acerifolia, a species with ridged leaf surfaces, was significantly higher than that of S. japonica and C. deodara, species with waxy leaf surfaces. The contact angles of water droplets on leaves decreased with leaf age except on the abaxial surface of S. japonica, which remained non-wettable or highly non-wettable throughout the growing season; the decrease in the contact angle on adaxial surface of S. japonica was greater when compared with P. acerifolia and C. deodara. A significant and negative relationship existed between leaf PM retention amounts and contact angles on adaxial surface of leaves of all three species. The increase in wettability, probably caused when epicuticular wax was destroyed by mechanical and chemical abrasion, seemed to be the main factor leading to seasonal variations in leaf PM accumulation.     

不同活性物种对光催化降解水中邻苯二甲酸二甲酯动力学的贡献研究

采用光催化氧化技术对邻苯二甲酸二甲酯（DMP）进行降解研究,并在基础上考察了催化剂量,溶液pH和溶液初始浓度对降解速率的影响。且采用Langmuir-Hinshelwood动力学模型来描述DMP的光催化降解,研究表明DMP的光催化降解符合假一级动力学。系统研究了光催化降解DMP过程中不同活性物种对光催化反应速率的贡献,实验结果表明：在TiO2光催化降解DMP的过程中,？OH为主要的活性物种,其对DMP的降解速率贡献高于94%,而其它活性物种（ecb-,hvb＋,O2？-和H2O2）对光催化贡献较小。     

武夷山主峰黄岗山片区生态安全格局构建研究

生态安全格局理论为区域尺度的景观综合体生态保护修复实践提供了理论依据和技术路径。以我国东南地区重要的生态屏障——武夷山主峰黄岗山片区为例,按照识别生态源地—构建阻力面—提取生态廊道的研究框架,采用定性与定量相结合的方法,评估提取区域内生态系统服务功能极重要区,将其与自然保护地叠加生成生态源地;采用地类和地形因子对研究区设置阻力面,运用最小累积阻力模型提取生态廊道,将生态功能重要区确定为生态缓冲区,构建黄岗山片区生态安全格局。结果显示：黄岗山片区生态源地面积为5 808.80 km²,占区域面积的34.16%,占比较大,主要分布在江西省南部、福建省北部山地的交界地带;提取生态廊道共21条,长度为455.1 km,呈组团式将中部与东北部、西南部源地斑块连通起来;生态缓冲区面积为1 574.13 km²,占比为9.2%,主要分布在研究区的北部山区。研究打破省域、市域、流域界限,将研究区视为一个完整的生命共同体,充分考虑生态结构的完整性、生态过程的连通性以及生态功能的重要性,构建区域尺度点线面状的生态安全格局,可为当地实施区域一体化保护和修复提供空间指引。