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Recreational impact was measured on eight beaches in Glen Canyon National Recreation Area and 15 beaches in Grand Canyon National Park using permanently located transects and plots. Recreational impact indices included densities of human trash and charcoal and a measure of sand discoloration due to charcoal. Significant increases in the indices occurred on several Glen Canyon beaches over a seven-month period. Sand discoloration became significantly higher over all Glen Canyon beaches during the same time period. All indices were significantly higher in Glen Canyon than on similar Grand Canyon beaches. These differences are probably due to differences in: (a) level of impacts tolerated by the respective management regimes and, (b) in the number of user days among the two National Park Service administrative units. Management alternatives are presented for reversing the present trends of recreational impact on Glen Canyon beaches. 相似文献
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阳离子染料废水的脱色方法及其机理的研究 总被引:18,自引:2,他引:18
本文以阳离子染料碱性品红为代表,采用PFAS混凝剂对其水溶液进行脱色处理,在处理过程加入适量的十二烷基苯磺酸钠做助剂,脱色率最高可达99%以上。本文还研究pH值及盐效应对脱色率的影响。脱色机理的研究结果表明:阳离子染料在水溶液中与十二烷基苯磺酸钠之间发生化学作用,靠氢键及静电键结合,使原来带正电荷的阳离子染料粒子转变为带负电荷的粒子,再与带正电荷的PFAS混凝剂的胶体作用产生絮凝沉淀。 相似文献
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Reflective features of Norway spruce have been studied as a part of a multi‐level experiment in order to assess and to develop methods for early forecasting of forest damages by remote sensing. Discoloration and histological changes were investigated by high resolution reflectance spectroscopy and true‐color image interpretation of histological cuts, respectively. Major changes of reflectances were detected in the visible spectral range 480–680 nm depending on degree of tree's damages and/or needle discoloration. Related histological changes depending on degree of tree's damage were hypertrophy of chloroplasts, plasmolysis and partial loss of compartmentalization. Development and use of several highly sensitive channels with narrow bandwidths between 480 and 680 nm, e.g. 480, 550, 680, 760 nm, for early assessment of forest damages by remote sensing could be recommended. 相似文献
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Smith AH Pinkard EA Stone C Battaglia M Mohammed CL 《Environmental monitoring and assessment》2005,111(1-3):243-256
Fungal pathogens, browsing mammals, birds, insects, nutrient deficiencies, drought, frost and waterlogging are all damaging
agents to plantation species. The subsequent loss in leaf tissue or reduced photosynthetic potential can reduce growth and
potentially lead to tree death. The Crown Damage Index (CDI) was developed in Australia to quantify damage in young eucalypt
plantations. The accuracy and precision of assessing damage at a tree level were determined to ensure the reliability, objectivity
and repeatability of the CDI method. Nine assessors, with varying levels of experience, estimated damage on three plots of
fifty trees each, to obtain an understanding of the subjectivity of assessing damage caused by insects (e.g. Chrysophtharta spp.) and fungal pathogens (e.g. Mycosphaerella spp.) on Eucalyptus globulus. Damage levels were measured by destructive sampling to enable direct comparisons between estimates and damage levels to
be made. The most experienced assessors provided the most repeatable estimates and were generally the most accurate. The incidence
of foliar necrosis was the least subjective measure while defoliation was the most subjective and the least accurate of the
indices measured. All assessors, regardless of experience, were able to predict the Crown Damage Index (a combined index of
all damage classes) to within 12% of measured damage levels. 相似文献
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膨胀石墨对活性艳红X-3B染料的吸附脱色 总被引:2,自引:0,他引:2
研究了以膨胀石墨(250 mL/g)为吸附剂,对活性艳红X-3B染料的吸附脱色作用,探讨了影响吸附的因素,结果表明:膨胀石墨对活性艳红X-3B染料的吸附率高,当膨胀石墨用量适当时,低初始浓度、低pH值有利于活性艳红X-3B染料的吸附脱色,温度高低对活性艳红X-3B染料的吸附脱色无明显影响。 相似文献
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Dynamic behaviors of hydroxyl (OH) radical generation and consumption in photo-Fenton oxidation process were investigated by measuring OH radical concentration during the discoloration of azo-dye Orange II. The effects of operating parameters for photo-Fenton discoloration, i.e. dosages of H2O2 and Fe, initial dye concentration, solution pH and UV irradiation, on the generation and consumption of OH radicals playing the main role in advanced oxidation processes were extensively studied. The scavenger probe or trapping technique in which coumarin is scavenger of OH radical was applied to estimate OH radical concentration in the photoreactor during the photo-Fenton discoloration process. The OH radical generation was enhanced with increasing the dosages of Fenton regents, H2O2 and Fe. At the initial stage of photo-Fenton discoloration of Orange II, the OH radical concentration rapidly increased (Phase-I) and the OH radical concentration decreased after reaching of OH radical concentration at maximum value (Phase-II). The decrease in OH radical concentration started when the complete discoloration of Orange II was nearly achieved and the H2O2 concentration became rather low. The dynamic behavior of OH radical concentration during the discoloration of Orange II was found to be strongly linked with the change in H2O2 concentration. The generation of OH radical was maximum at solution pH of 3.0 and decreased with an increase of solution pH. The OH radical generation rate in the Fenton Process was rather slower than that in the photo-Fenton process. 相似文献
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Bussotti F Gerosa G Cenni E Cozzi A Ferretti M Bettini D Nibbi R 《Environmental monitoring and assessment》2003,85(3):221-238
This study examines defoliation and discoloration findings collected throughout the Italian Level I network between 1997 and 2000. Prior to this period no Quality Assurance procedures had been implemented, so that earlier findings cannot be considered reliable. The aim of the study is to compare differentindices used in reporting findings, in order to determine the full potential and limitations of each. In international surveys,findings are normally expressed in terms of individual trees presenting a defoliation level greater than 2 %; this criterion,however, has been challenged since it is not based on scientificevidence. By analysing the distribution of defoliation values(grouped in 5% classes) relating to the main species (Fagus sylvatica, Quercus pubescens, Quercus cerris, Picea abies), the study examines the behaviour of statistical indices such as the median, the mode and the mean. Instead of using the traditional 25% threshold to determine the part of the population with the highest defoliation values, a procedureis suggested whereby a different threshold can be determined foreach species. It is established based on the 90° percentile of cumulative defoliation values recorded over the four-year period. Each index used to report findings possessesits own information potential, and the findings may at times appear contradictory. The use of a combined defoliation and discoloration index (Ilce = Lacking Crown Equivalent Index) is also proposed, but the results obtained do not differin substance from the results relating to defoliation alone. Thefunctional limitations of this index are due mainly to the way the data are collected: for this reason suggestions are made onhow to improve the procedure in future surveys. 相似文献