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31.
Various approaches have been used to classify large geographical areas into smaller regions of similar water quality or extrapolate
water-quality data from a few streams to other unmonitored streams. A combination of some of the strengths of existing techniques
is used to develop a new approach for these purposes. In this new approach, referred to here as SPARTA (SPAtial Regression-Tree
Analysis), environmental characteristics for each monitored stream are first quantified using a Geographic Information System
(GIS) and then regression-tree analysis is used to determine which characteristics are most statistically important in describing
the distribution of a specific water-quality constituent. GIS coverages of only the most statistically significant environmental
characteristics are then used to subdivide the area of interest into relatively homogeneous environmental water-quality zones.
Results from the regression-tree analysis not only define the most important environmental characteristics, but also describe
how to subdivide the coverage of the specific characteristic (for example, areas with <26% or ≥26% soil clay content). The
resulting regionalization scheme is customized for each water-quality constituent based on the environmental characteristics
most statistically related to that constituent. SPARTA was used to delineate areas of similar phosphorus, nitrogen, and sediment
concentrations (by including land-use characteristics) and areas of similar potential water quality (by excluding land-use
characteristics). The SPARTA approach reduced the variability in water-quality concentrations (phosphorus, total nitrogen,
Kjeldahl nitrogen, and suspended sediment) within similarly classified zones from that obtained using the US Environmental
Protection Agency's nutrient ecoregions. 相似文献
32.
以沈阳某污水处理厂的进水水质为例,用SPSS软件对COD和BOD进行回归分析。结果表明,COD和BOD之间具有线性关系,其一元线性回归方程为COD=35.76+2.26*BOD。利用该回归方程测算BOD,对预测值和实际值进行t检验,发现两者之间不存在显著性差异,从而表明利用回归方程测算BOD方便快速,有助于生产运行管理。 相似文献
33.
A. Ronza S. Flez R. M. Darbra S. Carol J. A. Vílchez J. Casal 《Journal of Loss Prevention in the Process Industries》2003,16(6):551-560
The historical analysis of 828 accidents in port areas, which have been selected from a database, has been used to identify the sequences of the accidents. Processing these data has allowed the event trees and the probability of the various accident scenarios to be determined. By using these event trees and figures detailing the frequency of the events that initiated the accidents, as taken from various authors, the frequency of the accidents has been determined. 相似文献
34.
邱运亮 《湖南环境生物职业技术学院学报》2002,8(4):247-250
花卉无土栽培是在土壤栽培的基础上发展起来的现代农业高新技术,本文作者经多年来的无土栽培试验,根据当地条件,改良了霍格兰和阿农(Hogagland&Arnon)配方,改良配方效果显示:无土栽培的花卉其叶色浓艳,叶绿素含量较有土栽培一般高10~20%;黄枯叶较土壤栽培少60~80%左右,耗水量、病虫害较土壤栽培分别少40~60%、75~100﹪,且无杂草,可观期延长. 相似文献
35.
Peggy?Gunkel Estelle?Roth Bernard?FabreEmail author 《Environmental Chemistry Letters》2003,1(1):92-97
Agricultural practices can lead to copper accumulation in soils and at high concentration it can become toxic for plants.
One common toxic effect of copper on plants is a decrease of crop yield. Here, we studied 1) the crop yield of maize grown
on plots of a soil intentionally enriched with copper sulphate and 2) the possible relationship between the copper concentration
in chemical soil fractions and the maize crop yield. Anthropogenic copper is mainly bound to manganese oxides, to iron oxides
and to the organic matter. Maize (Zea maize L.) was grown on outdoor experimental plots. The crop yield was evaluated for three development stages: the 6–10 leaf stage,
the female flowering stage and the maturity stage, 2, 4 and 6 years after the soil copper enrichment. Strong crop yield reductions,
proving a toxic effect of copper on maize growth were noted 2 years after the copper input at the maturity stage and 4 years
after the copper input at the 6–10 leaf stage. Variations in maize crop yield are described with linear multiple regression
equations including the variable copper content in soil, and other variables when needed such as soil pH, soil organic carbon
level and the climatic variables, the precipitation rate and the ambient temperature. The crop yield study at the 6–10 leaf
stage and at the female flowering stage does not provide significant regression equations, while the crop yield study at the
maturity stage does. Request variables for the models are the total copper content or the copper bound to the organic matter
and the meteorological data.
Electronic Publication 相似文献
36.
秋色叶树种在园林造景中的应用 总被引:3,自引:0,他引:3
秋色叶树种是园林造景中重要的观赏树种之一,我国秋色叶树木资源十分丰富,开发利用秋色叶树木资源对我国园林建设具有重要意义.作者分析了秋色叶树种内涵,主要树种的性状、特征、观赏价值及在我国自然秋色景观中的应用等,初步探讨了它们在城市园林造景中应用方式、应用前景,提出了秋色叶树种选择应用的原则及应注意的问题. 相似文献
37.
Fire and Green-Tree Retention in Conservation of Red-Listed and Rare Deadwood-Dependent Beetles in Finnish Boreal Forests 总被引:1,自引:0,他引:1
Abstract: Habitat loss, fragmentation, and declining habitat quality have created an extinction debt in boreal forests, which could be partly reversed by deliberately improving the habitat quality in managed areas outside reserves. We studied the effects of green-tree retention and controlled burning on red-listed and rare, deadwood-dependent (saproxylic) beetles in a large-scale field experiment in eastern Finland. Our factorial study design included 24 sites dominated by Scots pine ( Pinus sylvestris L.) and with three levels of green-tree retention (0, 10, and 50 m3 /ha) and uncut controls. Twelve of the 24 sites were burned in 2001. We sampled beetles with 10 flight-intercept traps on each site during the years 2000–2002 (i.e., 1 pretreatment and 2 post-treatment years). A total sample of 153,449 individuals representing 1,160 beetle species yielded 2,107 specimens of 84 red-listed or rare saproxylic species. The richness of these species was higher on the burned than on the unburned sites, and higher levels of green-tree retention promoted species richness, but there were clear differences between the years. The richness of red-listed and rare saproxylic species increased in the first post-treatment year, evidently due to the treatments, continued to increase on the burned sites in the second post-treatment year, but decreased on the unburned sites. Our results showed that the living conditions of many red-listed and rare saproxylic species could be improved significantly with rather simple alterations to forest management methods. Controlled burning with high levels of green-tree retention creates resources for many saproxylic species, but increasing the levels of green-tree retention in unburned areas can also be beneficial. 相似文献
38.
袋装控释铁肥压根法矫治桃树黄叶病的效果 总被引:1,自引:1,他引:0
本文介绍了袋装控释铁肥压根法矫治桃树缺铁黄叶病的效果。该法具有大幅度增加叶绿素含量.提高果实产量,改善果实品质,降低矫治成本,安全可靠,效果好的特点。 相似文献
39.
Based on hourly measurements of NOx NO2 and O3 and meteorological data, an ordinary least squares (OLS) model and a first-order autocorrelation (AR) model were developed to analyse the regression and prediction of NOx and NO2 concentrations in London. Primary emissions and wind speed are the most important factors influencing NOx concentrations; in addition to these two, reaction of NO with O3 is also a major factor influencing NO2 concentrations. The AR model resulted in high correlation coefficients (R > 0.95) for the NOx and NO2 regression based on a whole year's data, and is capable of predicting NO2 (R = 0.83) and NOx (R = 0.65) concentrations when the explanatory variables were available. The analysis of the structure of regression models by Principal Component Analysis (PCA) indicates that the regression models are stable. The results of the OLS model indicate that there was an exceptional NO2 source, other than primary emission and reaction of NO with O3, in the air pollution episode in London in December 1991. 相似文献
40.