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1.
湖泊富营养化评价方法及分级标准   总被引:219,自引:14,他引:205  
由于人类活动的影响 ,湖泊富营养化引起的环境问题日益突出。而目前现有的富营养化评价方法和分级标准混乱 ,因此有必要统一评价方法和分级标准 ,以便加强对湖泊的管理 ,保护湖泊生态环境  相似文献
2.
荒漠化类型划分及其数量化评价体系   总被引:32,自引:0,他引:32  
从我国荒漠化监测的实际需要出发,提出了包括气候区、外营力、土地利用类型、地表特征和荒漠化程度在内的多因素复叠式荒漠化分类体系;既可适用于小区域大比例尺的重点监测,又可适用于大区域小比例尺的宏观监测的各荒漠化类型数量化程度判定指标体系和判定方法;适用于各级行政区的荒漠化水平评价方法.  相似文献
3.
基于颗粒物浓度的沙尘天气分级标准研究   总被引:13,自引:2,他引:11  
沙尘天气在近年对我国城市空气质量造成明显影响。目前我国沙尘天气分级仍然按照气象标准 ,主要是以水平能见度进行分级。文章参考国外的有关标准 ,通过统计近年来我国沙尘天气过程中的颗粒物浓度 ,结合我国沙尘天气的发生情况和特点 ,提出了基于沙尘浓度的沙尘天气分级标准  相似文献
4.
生态监测指标选择一般过程探讨   总被引:10,自引:2,他引:8  
本文对生态监测指标体系设计的一般过程进行了详细的分析和论述。主要包括生态监测目标、生态系统所受的环境压力、生态系统模型的提出以及生态监测指标的分类。旨在为我国生态监测规划和设计进行初步的探索。  相似文献
5.
环境污染事故危险源评级方法研究   总被引:7,自引:1,他引:6  
将环境污染事故危险源分成空气污染型和水体污染型两大类,并考虑危险源自身特性和周围环境状况两个主要因素对两类危险源分别提出了评级模式,依据危险指数大小将危险源分为特大、重大、较大和一般四级;利用试点调研的63家企业的183个危险源数据,对危险源评级模式进行了参数选定和验证,证明所建议的方法和模式是可行的,可供危险源调研和建立数据库等实际工作应用。  相似文献
6.
国内外空气污染指数的现状及发展趋势   总被引:6,自引:1,他引:5       下载免费PDF全文
针对中国目前使用的空气污染指数(Air Pollution Index,API)中存在的问题,通过比较国内外空气污染指数在基本概念、级别限值和等级划分等方面的区别,结合中国的实际情况,提出了增加监测指标、提高发布效率、优化统计模型等改进意见。  相似文献
7.
国外沙漠化监测评价指标与分级标准   总被引:6,自引:0,他引:6  
利用国内外有关资料,从狭义沙漠化定义出发,介绍了联合国沙漠化监测评价指标体系、分级标准和评价方法。  相似文献
8.
Applying Satellite Imagery to Triage Assessment of Ecosystem Health   总被引:3,自引:0,他引:3  
Considerable evidence documents that certain changes in vegetation and soils result in irreversibly degraded rangeland ecosystems. We used Advanced Very High Resolution Radiometer (AVHRR) imagery to develop calibration patterns of change in the Normalized Difference Vegetation Index (NDVI) over the growing season for selected sites for which we had ground data and historical data characterizing these sites as irreversibly degraded. We used the NDVI curves for these training sites to classify and map the irreversibly degraded rangelands in southern New Mexico. We composited images into four year blocks: 1988–1991, 1989–1992, and 1990–1993. The overlap in pixels classified as irreversibly degraded ranged from 42.6% to 84.3% in year block comparisons. Quantitative data on vegetation composition and cover were collected at 13 sites within a small portion of the study area. Wide coverage reconnaissance of boundaries between vegetation types was also conducted for comparisons with year block maps. The year block 1988–1991 provided the most accurate delineation of degraded areas. The rangelands of southern New Mexico experienced above average precipitation from 1990–1993. The above average precipitation resulted in spatially variable productivity of ephemeral weedy plants on the training sites and degraded rangelands which resulted in much smaller areas classified as irreversibly degraded. We selected imagery for a single year, 1989, which was characterized by the absence of spring annual plant production in order to eliminate the confounding effect of reflectance from annual weeds. That image analysis classified more than 20% of the rangelands as irreversibly degraded because areas with shrub-grass mosaic were included in the degraded classification. The single year image included more than double the area classified as irreversibly degraded by the year blocks. AVHRR imagery can be used to make triage assessments of irreversibly degraded rangeland but such assessment requires understanding productivity patterns and variability across the landscapes of the region and careful selection of the years from which imagery is chosen.  相似文献
9.
A multi-channel continuous water toxicity monitoring system was, after confirming the systems' performance, implemented to samples of water discharged from power plants to detect and classify their toxicity using several recombinant bioluminescent bacteria. Each channel of the system is composed of a series of two mini-bioreactors to enable a continuous operation, i.e., without system interruption due to highly toxic samples. A different recombinant bacterial strain was present in each channel: DPD2540 (fabA::lux CDABE), DPD2794 (recA::luxCDABE), and TV1061 (grpE::luxCDABE), which are induced by cell membrane-, DNA-, and protein-damaging agents, respectively. GC2 (lac::luxCDABE) is a constitutive strain, whose bioluminescence is reduced by an increase in cellular toxicity. Phenol and mitomycin C (MMC) were used for evaluating the system's performance to detect toxic chemicals. These samples were injected into the second mini-bioreactor according to a step or bell-curve manner. The field samples used in this study were obtained from the water discharged from two different power plants in Korea – from a nuclear power plant and a thermo-electronic power plant, and were injected into the second mini-bioreactor to initiate the toxicity test. Each channel showed specific bioluminescent (BL) response profiles due to the toxic compounds present in the water samples. Comparing the BL signals between the standard toxic chemical samples and discharged water samples, the equivalent toxicity of the field water could be estimated. Finally, it was proved that this novel continuous toxicity monitoring system can be used as an alternative tool for the quick monitoring and control of water quality, as well as aid in the setting up of a new monitoring strategy to protect the source of tap water and in the prevention of polluted water discharge.  相似文献
10.
Watershed-Based Survey Designs   总被引:2,自引:0,他引:2  
Watershed-based sampling design and assessment tools help serve the multiple goals for water quality monitoring required under the Clean Water Act, including assessment of regional conditions to meet Section 305(b), identification of impaired water bodies or watersheds to meet Section 303(d), and development of empirical relationships between causes or sources of impairment and biological responses. Creation of GIS databases for hydrography, hydrologically corrected digital elevation models, and hydrologic derivatives such as watershed boundaries and upstream–downstream topology of subcatchments would provide a consistent seamless nationwide framework for these designs. The elements of a watershed-based sample framework can be represented either as a continuous infinite set defined by points along a linear stream network, or as a discrete set of watershed polygons. Watershed-based designs can be developed with existing probabilistic survey methods, including the use of unequal probability weighting, stratification, and two-stage frames for sampling. Case studies for monitoring of Atlantic Coastal Plain streams, West Virginia wadeable streams, and coastal Oregon streams illustrate three different approaches for selecting sites for watershed-based survey designs.  相似文献
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