壳聚糖对酸性染料的吸附性能

在不同的壳聚糖浓度、pH和温度条件下，采用分光光度法测得吸附后的染料浓度，得到了壳聚糖对酸性染料的最佳吸附条件，即在固定染料浓度和体积的情况下，壳聚糖的投入量在500mg、pH值为6、温度为室温、吸附时间为2h左右条件下吸附最佳，其结果将为利用壳聚糖处理印染废水提供一定的理论根据。     

壳聚糖处理印染废水的研究

在不同的壳聚糖浓度、pH和温度条件下，采用分光光度法测得吸附后染料的浓度，得到了壳聚糖对染料的最佳吸附条件，结果为：壳聚糖的投入量在红3B为2％，兰2BG和黄3GE为3％时，pH8．4在碱性范围内，温度为50℃效果最佳。其结果将为壳聚糖在印染废水处理提供一定的理论基础。     

不同分子量壳聚糖锌配合物对尿素的吸附行为研究

研究了壳聚糖-Zn配合物对尿素的吸附行为和壳聚糖分子量对尿素吸附性能的影响.正交试验结果表明,壳聚糖-Zn对尿素的吸附最佳组合为A<,5>B<,4>C<,3>D<,4>,即尿素溶液的初始浓度为3.5mg/mL,反应温度为55℃,pH值为4.5,反应时间为7h时,壳聚糖-Zn对尿素的吸附量达到最大值260.414mg/g.在同一条件下,壳聚糖分子量对壳聚糖-Zn吸附尿素能力影响的大小顺序为50kDa＞10kDa＞5kDa.     

壳聚糖对小麦期叶中营养物质含量的影响

在不同壳聚糖浓度和时间条件下对小麦种子进行处理,通过小麦萌发后期叶中游离氨基酸、蛋白质、叶绿素和可溶性糖含量的变化,从而得出壳聚糖处理小麦种子的最佳条件为:浓度8g/L、浸种时间10h,其结果将对小麦生产提供理论基础.     

壳聚糖改性膨润土对邻苯二甲酸二乙酯的吸附研究

以膨润土为载体,壳聚糖为改性剂,制备了壳聚糖-膨润土复合吸附剂,研究了其吸附效果。实验结果表明:pH值为4~6.8,复合吸附剂用量为2.5 g,温度为25℃,吸附时间为10 min,初始浓度为20 mg/L的邻苯二甲酸二乙酯(DEP)废水去除率可达到59%。相对于原土,改性膨润土吸附效果有明显提高。     

壳聚糖吸附处理废水的研究进展

壳聚糖吸附处理废水的研究包括其对废水吸附性能和吸附机理的研究两个方面。壳聚糖表现出了良好的吸附废水中重金属离子、染料分子和其它易引起变异物质的能力;壳聚糖对金属离子和染料的吸附机理模型研究理论意义重大,它将进一步推动壳聚糖的实际工程应用。     

干旱胁迫下壳聚糖对花生幼苗生理特性的影响

为了研究壳聚糖对花生幼苗抗旱言的影响,以花生品种“花育23号”为材料,在干旱胁迫下,用不同浓度的壳聚糖溶雍处理花生幼苗,连续处理5d后测定叶绿素、可溶性蛋白、MDA和脯氨酸的含量变化。结果表明,花生幼苗在干旱条件下喷施壳聚糖与蒸馏水相比,在干旱第10天叶绿素含量提高了42．2％,MDA含量降低了36．2％;在干旱第6天,可溶性蛋白含量提高了129．0％;在干旱第8天,脯氨酸含量提高了257．0％。喷施壳聚糖溶液的最适宜浓度为0．10g／L,喷施该浓度壳聚糖可促进植物生长,增强抗旱性。     

壳聚糖处理对大豆幼苗生理指标的影响

以“齐黄28”大豆种子为试验材料,研究不同质量浓度的壳聚糖溶液对大豆幼苗生理指标的影响.结果表明,壳聚糖对大豆幼苗的生长具有促进作用,促进作用的大小因壳聚糖浓度不同而表现出较大差异.在一定范围内随壳聚糖溶液浓度的升高,大豆幼苗的可溶性糖、可溶性蛋白质、叶绿素含量和株高均有所提高.当壳聚糖质量浓度为4g/L时,对各项指标的促进作用最明显,为最适壳聚糖浓度,但随着壳聚糖溶液处理浓度的进一步加大,则对大豆幼苗表现出一定的抑制作用.     

酸改性壳聚糖载体对漆酶的固定化

利用有机酸改性壳聚糖和交联法制备酸化壳聚糖载体,然后用改性壳聚糖载体固定漆酶。结果表明,甲酸、酒石酸改性壳聚糖的最适条件是壳聚糖与酸的量比分别为100/1(g/mol)、100/0.5(g/mol),戊二醛的浓度分别为1%、2%,缓冲溶液的pH分别为4.4、3.6,反应时间分别为3h、4.5h。两种酸改性的壳聚糖用于漆酶的固定,其酶活都有所提高,尤其用酒石酸改性的壳聚糖载体的效果最好,其酶活提高了57%。     

干旱胁迫下壳聚糖对玉米幼苗保护酶的影响

干旱条件下,采用喷洒不同浓度的壳聚糖溶液处理玉米幼苗,测定其过氧化氢酶(CAT)、过氧化物酶(POD)、超氧化物歧化酶(SOD)保护酶活性。结果表明,壳聚糖溶液处理的玉米幼苗保护酶活性较对照组均有一定程度提高,说明干旱胁迫下壳聚糖溶液处理玉米幼苗有利于其生长,为壳聚糖溶液处理玉米幼苗抵抗干旱胁迫的影响提供了理论依据。     

AN APPLICATION RUNOFF MODEL STRATEGY FOR UNGAGED WATERSHEDS1

ABSTRACT: Mathematical models for predicting watershed surface flow responses are available, most of which are elaborate nonlinear numerical surface and channel flow models linked with infiltration models. Such models may be used to make predictions for ungaged areas, assuming an acceptable fitting of the model to the topography and roughness of the real system. For some application purposes, these models are impractical because of their complexity and expensive computer solutions. A procedure is developed that uses a complex model of an ungaged area to derive a simpler parametric nonlinear system model for repetitious simulation with input sequences. The predicted flow outputs are obtained with the simpler model at significant savings of money and time. The procedures for constructing a complex kinematic model of a 40 acre (161,880 m²) reference watershed and deriving the simpler system model are outlined. The results of predictions from both models are compared with a selected set of measured events, all having essentially the same initial conditions. Peak discharges ranged from 3 to 118 ft³/sec (0.085 to 3.34 m³/sec), which includes the largest event of record. The inherent limitations of lumped systems models are demonstrated, including the bias caused by their inability to model infiltration losses after rainfall ceases. Computer costs and times for the models were compared. The derived simple model has a cost advantage when repeated use of a model is required. Such an applications hydrologic model has an engineering tradeoff of reduced accuracy, and lumping bias, but is more economical for certain design purposes.     

Conversion of temperate forests into heaths: Role of ecosystem disturbance and ericaceous plants

Fire and logging in nutrient-poor temperate forests with certain ericaceous understory plants may convert the forests into heaths. The process of disturbance-induced heath formation is documented by using examples ofCalluna in western Europe,Kalmia in Newfoundland, andGaultheria (salal) in coastal British Columbia. In a cool, temperate climate, rapid vegetative growth ofCalluna, Kalmia, and salal following disturbance results in increasing organic accumulation (paludification), nutrient sequestration, soil acidification, and allelochemicals. These are thought to be the main reasons to conifer regeneration failure in disturbed habitats. If continuation in forest is a land-use objective, then temperate forests with an ericaceous understory should not be logged unless effective silvicultural methods are devised to control the ericaceous plants and restore forest regeneration. Preharvest vegetation control may be considered as an option. Failure to control the understory plants may lead to a long-term vegetation shift, from forest to heathland, particularly in nutrient-poor sites. Successful methods of controllingKalmia andGaultheria, however, have yet to be developed. While theKalmia- andGaultheria- dominated heathlands are undesirable in Canada and the Pacific Northwest, a wide range ofCalluna heathlands of western Europe are being conserved as natural and seminatural vegetation.     

Using Paleo Reconstructions to Improve Streamflow Forecast Lead Time in the Western United States

In water stressed regions, water managers are exploring new horizons that would help in long‐range streamflow forecasts. Oceanic‐atmospheric oscillations have been shown to influence streamflow variability. In this study, long‐lead time streamflow forecasts are made using a multiclass kernel‐based data‐driven support vector machine (SVM) model. The extended streamflow records based on tree ring reconstructions were used to provide a longer time series data. Reconstructed data were used from 1658 to 1952 and the instrumental record was used from 1953 to 2007. Reconstructions for oceanic‐atmospheric oscillations included the El Niño‐Southern Oscillation, Pacific Decadal Oscillation, Atlantic Multidecadal Oscillation, and North Atlantic Oscillation. Streamflow forecasts using all four oscillations were made with one‐year to five‐year lead times for 21 gages in the western United States. This is the first study that uses both instrumental and reconstructed data of oscillations in SVM model to improve streamflow forecast lead time. SVM model was able to provide “satisfactory” to “very good” forecasts with one‐ to five‐year lead time for the selected gages. The use of all the oscillation indices helped in achieving better predictability compared to using individual oscillations. The SVM modeling results are better when compared with multiple linear regression model forecasts. The findings are statistical in nature and are expected to be useful for long‐term water resources planning and management.     

Urban ecological systems: scientific foundations and a decade of progress

Urban ecological studies, including focus on cities, suburbs, and exurbs, while having deep roots in the early to mid 20th century, have burgeoned in the last several decades. We use the state factor approach to highlight the role of important aspects of climate, substrate, organisms, relief, and time in differentiating urban from non-urban areas, and for determining heterogeneity within spatially extensive metropolitan areas. In addition to reviewing key findings relevant to each state factor, we note the emergence of tentative "urban syndromes" concerning soils, streams, wildlife and plants, and homogenization of certain ecosystem functions, such as soil organic carbon dynamics. We note the utility of the ecosystem approach, the human ecosystem framework, and watersheds as integrative tools to tie information about multiple state factors together. The organismal component of urban complexes includes the social organization of the human population, and we review key modes by which human populations within urban areas are differentiated, and how such differentiation affects environmentally relevant actions. Emerging syntheses in land change science and ecological urban design are also summarized. The multifaceted frameworks and the growing urban knowledge base do however identify some pressing research needs.     

Neighbourhood characteristics and urban gardens in the Toledo metropolitan area: staffing and voluntarism,food production,infrastructure, and sustainability practices

Urban gardens are important sources of sustenance for communities with limited access to food. Hence, this study focuses on food production in gardens in the Toledo metropolitan area in Northwest Ohio. We administered surveys to 150 garden managers from November 2014 to February 2015 in our attempt to better understand how neighbourhood racial composition and poverty levels are related to staffing and voluntarism, food production and distribution, the development of infrastructure, and the adoption of sustainability practices in urban gardens. The results from 30 gardens are presented in this paper. We used Geographic Information Systems to map the gardens and overlay the map with 2010 census data so that we could conduct demographic analyses of the neighbourhoods in which the gardens were located. Though the gardens were small – two acres or less – up to 46 varieties of food were grown in a single garden. Gardens also operated on small budgets. Food from the gardens was gifted or shared with friends, family, and neighbourhood residents. Gardens in predominantly minority neighbourhoods tended to have fewer institutional partners, less garden infrastructure, and had adopted fewer sustainable practices than gardens in predominantly White neighbourhoods. Nonetheless, residents of predominantly minority and high-poverty neighbourhoods participated in garden activities and influenced garden operations. Volunteering and staffing were racialised and gendered.     

Predicting deer-vehicle collisions in an urban area

Collisions with deer and other large animals are increasing, and the resulting economic costs and risks to public safety have made mitigation measures a priority for both city and wildlife managers. We created landscape models to describe and predict deer-vehicle collision (DVCs) within the City of Edmonton, Alberta. Models based on roadside characteristics revealed that DVCs occurred frequently where roadside vegetation was both denser and more diverse, and that DVCs were more likely to occur when the groomed width of roadside right-of-ways was smaller. No DVCs occurred where the width of the vegetation-free or manicured roadside buffer was greater than 40 m. Landscape-based models showed that DVCs were more likely in more heterogeneous landscapes where road densities were lower and speed limits were higher, and where non-forested vegetation such as farmland was in closer proximity to larger tracts of forest. These models can help wildlife and transportation managers to identify locations of high collision frequency for mitigation. Modifying certain landscape and roadside habitats can be an effective way to reduce deer-vehicle collisions.     

BIOLOGICAL INDICATORS AND BIOLOGICAL EFFECTS OF ESTUARINE/COASTAL POLLUTION1

ABSTRACT: Sustained interest in and concern about the health status of the aquatic environment has resulted in extensive research focused on (1) effects of pollution on survival, growth, and reproduction of resource species at all life stages; (2) diseases of fish and shellfish, as they may be related to pollution and as they may serve as indicators of environmental stress; and (3) contaminant body burdens in fish and shellfish - their effects on the aquatic animals and their potential effects on humans. Effects, lethal and sublethal, of pollutants on life history stages of fish and shellfish have been documented, as have impacts on local stocks in badly degraded habitats, but as yet there has been no adequate quantitative demonstration of effects on entire aquatic species - probably because of the difficulty in sorting out relative effects of the many environmental factors that influence abundance. Sublethal effects, especially those that result in disease, have been examined intensively, and some diseases and disease syndromes have been associated statistically with pollution. Other pollution indicators (biochemical, physiological, genetic, behavioral, and ecological) have also received some attention, as have body burdens of contaminants in aquatic species. Research, especially that conducted during the past decade, has done much to clarify the many pathways and toxic effects of contaminants on aquatic animals, and has also helped to identify mechanisms for survival of fish and shellfish in the presence of environmental changes caused by human activities.     

Biodiversity and biotechnology

The maintenance of biodiversity is urged from many quarters and on grounds ranging from aesthetic considerations to its usefulness, particularly for biotechnology. But regardless of the grounds for preserving biodiversity, writers are generally in agreement that it should be preserved. But, in examining the various references biodiversity, such as species diversity, genetic diversity, and habitat diversity, it is apparent that we cannot aim to preserve biodiversityas such, since there are a number of conflicts in any such undertaking. In preserving one aspect of biodiversity, we damage another aspect. Five arguments which attempt to ground our moral concern for biodiversity are reviewed and critiqued, not only for their consistency but also for their power to move us to action. The final section of the paper shows how conflicts in the values of personal and environmental health can impair ethical action and especially policy formation.An earlier version of this paper was read at the conference on Agriculture, Food, and Human Values: Tradition and Change, Orlando, Florida, October 7–9, 1987.     

Journalists' views of advertiser pressures on agricultural news

All major journalism ethical codes explicitly state that journalists should protect editorial copy from undue influence by outside sources. However, much of the previous research on agricultural information has concentrated on what information various media communicate (gatekeeping studies) or communication's role in increasing innovation adoption (diffusion studies). Few studies have concentrated specifically on organizational and structural constraints that might adversely affect agricultural journalists' ethical standards; those that have, focus largely on farm magazines. A study of newspaper reporters who cover agricultural news found that the most pressing ethical concern is the effect of advertiser (agri-business) pressure on editorial copy, and that their concerns in general parallel those of farm magazine writers and editors. The majority reported being in situations in which they might be exposed to advertiser pressure, including pressures to change or withhold editorial copy. Large minorities suggested that advertising pressures affect the overall environment in which agricultural journalists work, and more than one in ten said they allow advertiser pressures to influence editorial decisions. The newspaper reporters who cover agricultural beats showed slightly more resistance to advertiser pressure than did farm magazine editors in a parallel study.     

Definition Procedures Have Little Effect on Performance of Environmental Classifications of Streams and Rivers

Mapped environmental classifications are defined using various procedures, but there has been little evaluation of the differences in their ability to discriminate variation in independent ecological characteristics. We tested the performance of environmental classifications of the streams and rivers of France that had been defined from the same environmental data using geographic regionalization and numerical classification of individual river valley segments. Test data comprised invertebrate assemblages, water chemistry, and hydrological indexes obtained from sites throughout France. Classification performance was measured by analysis of similarity (ANOSIM). Geometric regions defined by a regular grid and without regard to environmental variables and a posteriori classifications based on clustering the test datasets defined lower and upper bounds of performance for a given number of classes. Differences in classification performances were generally small. The ANOSIM statistics for the a posteriori classifications were around twice that of all environmental classifications, including geometrically defined regions. The hydro-ecoregions performed slightly better for the invertebrate data and the network classification performed slightly better for the chemistry and hydrological data. Our results indicate that environmental classifications that are defined using different procedures can be comparable in terms of their ability to discriminate variation of ecological characteristics and that alleged differences in performance arising from different classification procedures can be small relative to unexplained variation. We conclude that definition procedures might have little effect on the performance of large-scale environmental classifications and decisions over which procedures to use should be based primarily on pragmatic considerations.