基于高分辨率遥感影像的面向对象城市土地覆被分类比较研究

针对高分辨率遥感影像的城市土地覆被信息提取,根据分类目的与精度要求的不同,分别引入了优化与广义两种面向对象分类方案,并对分类的结果进行分析比较。结果表明:①优化方案的分类结果总体上要比广义方案好,前者的总体精度为86.50%,相比后者的80.50%提高了6.0%,而总体Kappa系数提高了0.0851,但是该方案效率低,可移植性差;②广义方案的分类结果虽然精度略低,但是该方案具有很强的适用性与可移植性,能够在精度可控范围内,很大程度提高分类效率,实现系统而有效的自动分类;③广义方案得到的分类结果具有一致的精度,在利用其建立城市生态模型中能够保证数据之间的系统性与鲁棒性。因此,利用优化方案能够提高分类结果的绝对精度,而广义方案对于实时精确获取城市土地覆被信息、小尺度上定量监测与评价城市化的生态后果以及有效开展城市土地规划与管理具有更重要的意义。     

Maintenance considerations for new plant

It is never too early to start planning the maintenance of new plant. From the outset, maintenance considerations should be made: a trained staff and a work force familiar with the plant, and able to operate and maintain it, is needed before production can start; management and control functions for keeping the plant in safe, efficient and profitable production also need to be established. The relationships and information flows necessary to set up proper maintenance procedures are presented.     

外源镧对不同品种黄瓜镉积累及镉化学形态的影响

采用盆栽实验研究了土壤重金属Cd（20 mg/kg）污染下,外源镧（0、10、20 mg/L LaCl3）对‘燕白’和‘津优1号’2 个品种黄瓜（Cucumis satiuus L.）生长、丙二醛含量、抗氧化酶活性及果实中的总Cd含量和形态的影响。结果表明：La提高了2 个品种叶和根的抗氧化酶（过氧化氢酶、超氧化物歧化酶和过氧化物酶）的活性,增加了2 个品种的叶、茎、根、果实干质量及植株总干质量。La对‘津优1号’植株干物质量的影响大于‘燕白’。外源La使黄瓜叶和根抗氧化酶活性升高可能是植株对Cd的抗性增强、干质量增加的生理机制之一。La减少了2 个品种果实中总Cd含量和不同形态Cd含量,但随着La质量浓度的增加,2 个品种果实总Cd含量和残渣态Cd（FR）含量表现为先降后升的趋势。外源La使黄瓜叶、茎、根和果实中的Cd含量分别降低了6.0%～10.2%、8.9%～23.5%、4.0%～29.2%和32.0%～49.8%。喷La后,单株果实的Cd含量和Cd积累量、植株Cd全量均以‘津优1号’＞‘燕白’。     

Testing a Dynamic Complex Hypothesis in the Analysis of Land Use Impact on Lake Water Quality

In this study, we proposed a dynamic complex hypothesis that the impact of land use on water quality could vary along the expansion of the buffer size, and there should be an effective buffer zone where the strongest linkage occurs between land use and water quality. The hypothesis was tested and supported by a case study carried out in four watersheds in Hanyang District, China. More specific, buffer analysis and regression model were applied for studying the impacts of land use type, area proportion of land use type, and spatial pattern of land use on water quality. We conclude that not only the proportion of land use but also the spatial pattern moderates the impact of land use on water quality. Our study indicates that the identification of the effective buffer zones can provide new information and ideas for planning and management. Moreover, this study could also partially help to explain the conflicting results on the impact of land use on water quality in buffer versus in catchments in the literatures.     

漓江秋季大型底栖动物群落结构特征分析

2009年8—9月,通过对漓江流域大型底栖动物进行详细调查,共鉴定大型底栖动物3门6纲24种,其中昆虫纲种类最多,腹足纲次之。以优势度指数大于0.02作为判别标准,判断出调查区域内全流域以及上中下游的优势种。调查结果表明:漓江大型底栖动物平均总密度与平均总生物量分别为682个/m2和152.77g/m2。两者均为下游最高、中游次之、上游最低。其Shannon-wiener多样性指数、Pielou均匀度指数和Marglef丰富度指数的平均值分别为2.37、0.61和6.01。并依照漓江上、中、下游3个江段150个采样点的数据作出丰度/生物量曲线,分析该曲线,认为漓江上游大型底栖动物群落处于未受干扰的状态;其他两个江段则均受到了轻度的干扰。