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。     

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.     

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。     

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。     

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%。     

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.     

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.     

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.     

Provincial development plans in Zimbabwe: an analysis of their content,structure and methodology

Zimbabwean provincial plans were instituted to help in the achievement of the national goal of the creation of an egalitarian, socialist and integrated society. The national goal itself was adopted as an antithesis to the dualist society characterised by spatial, economic, social, politican and technological inequalities that Zimbabwe inherited from colonialism. This meant that provincial plans had to play both a functional (or growth allocating/distribution) and a territorial (or redistribution) role.

This paper reviews their role in achieving the national goal by examining their functions, content, structure and methodology. The paper concludes that because of their nature, provincial plans are not suitable tools for the achievement of the national goal.     

Effect of Light on Biodegradation of Estrone, 17β‐Estradiol,and 17α‐Ethinylestradiol in Stream Sediment

Biodegradation of [A‐ring ¹⁴C] Estrone (E1), 17β‐estradiol (E2), and 17α‐ethinylestradiol (EE2) to ¹⁴CO₂ was investigated under light and dark conditions in microcosms containing epilithon or sediment collected from Boulder Creek, Colorado. Mineralization of the estrogen A‐ring was observed in all sediment treatments, but not epilithon treatments. No difference in net mineralization between light and dark treatments was observed for ¹⁴C‐E2. Net mineralization of ¹⁴C‐E1 and ¹⁴C‐EE2 was enhanced in light treatments. Extents of ¹⁴CO₂ accumulation and rates of mineralization were significantly greater for E2 than E1 under dark conditions, but were comparable under light conditions. These results indicate substantial differences in the uptake and metabolism of E1 and E2 in the environment and suggest biorecalcitrance of E1 relative to E2 in light‐limited environments. The extent of ¹⁴CO₂ accumulation and rate of mineralization for EE2 in dark treatments were less than half of that observed for E2 and generally lower than for E1, consistent with previous reports of EE2 biorecalcitrance. However, ¹⁴CO₂ accumulation and rates of mineralization were comparable for EE2, E2, and E1 under light conditions. These results indicate photoactivation and/or phototransformation/photodegradation processes can substantially enhance heterotrophic biodegradation of estrogens in sunlit environments and may play an important role in estrogen transport and attenuation.     

Bioremediation of Soils by Plant–Microbe Systems

Abstract

Sustainable ecosystems can be designed to eliminate environmental toxins and reduce pathogen loads through the direct and indirect consequences of plant and microbial activities. We present an approach to the bioremediation of disturbed environments, focusing on petroleum hydrocarbon (PHC) contaminants. Treatment consists of incorporating a plant-based amendment to enhance ecosystem productivity and physiochemical degradation followed by the establishment of plants to serve as oxidizers and foundations for microbial communities. Promising amendments for widespread use are entire plants of the water fern Azolla and seed meal of Brassica napus (rapeseed). An inexpensive byproduct from the manufacture of biodiesel and lubricants, rapeseed meal is high in nitrogen (6% wt/wt), stimulates >100-fold increases in populations of resident Streptomyces species, and suppresses fungal infection of roots subsequently cultivated in the amended soil. Synergistic enzymatic and chemical activities of plant and microbial metabolism in root zones transform and degrade soil contaminants. Emphasis is given to mechanisms that enable PHC functionalization via reactive molecular species.     

National minerals policies and stakeholder participation for broad-based development in the southern African development community (SADC)

This paper explains how the well-accepted concept of improved stakeholder participation during mineral policy development leads to a national mineral policy that accommodates the diverging views and interests that allows wide acceptance of decisions, enhancing the success of implementation and, ultimately, national benefits. This process is based on lessons learnt during the South African experience and has been successfully applied in the development of the Namibian and Malawian national minerals policies. An effective policy in the SADC will engineer the delicate balance between poverty reduction and an internationally competitive minerals sector. This balance enhances the possibility of long-term economic growth and development in the SADC region. The overriding advantage of this strategy is that it generates ‘home-grown’ policy instruments and implementation of mineral law with which stakeholders can identify. This process presents a new challenge to traditional policy formulation strategies in emerging economies and the bottom-up approach, linked to wide political support, allows the potential realisation of national objectives.     

Energetics and environmental costs of agriculture in a dry tropical region of India

The present article, based on a study of five village ecosystems, assesses the energy efficiency of rain-fed agriculture in a dry tropical environment and the impact of agricultural activity on the surrounding natural ecosystems. Agronomic yield is insufficient to meet the food requirement of the human population, hence 11.5%–49.7% of the required amount of food grains are imported from the market. Energy requirements of five studied agroecosystems are subsidized considerably by the surrounding forest in the form of fodder and firewood. Natural ecosystems supply about 80%–95% of fodder needs and 81%–100% of fuelwood needs. The output-input ratio of agriculture indicated that, on average, 4.1 units of energy are expended to obtain one unit of agronomic energy. Of this, 3.9 units are supplied by the natural ecosystem. In addition, 38% of the extracted firewood is marketed. The illegal felling and lopping of trees result in ever-increasing concentric circles of forest destruction around the villages and together with excessive grazing results in savannization. The forests can be conserved by encouraging fuelwood plantations (0.7 ha/ha cultivated land) and developing village pastures (1.6 ha/ha cultivated land) and reducing the livestock numbers. Agricultural production in the region can be stabilized by introducing improved dry farming techniques such as intercropping, planned rainwater management, and adequate use of fertilizers.     

WHAT DO WE MEAN BY “METROPOLITAN WATER MANAGEMENT INSTITUTIONS?”1

ABSTRACT The term “institution” and several variants are used frequently in the literature on metropolitan water management. The state-of-the art investigation on which this paper is based revealed that 1) many uses of the term do not include careful definitions; 2) many users of the term seemed unaware of the general, theoretical literature on the subject of institutions; 3) there was little consistency among uses, either in the practical literature dealing with water or in the conceptual literature dealing with theories of institutions or institutionalization; 4) some usages were without significant meaning; 5) in many cases the term was used as a kind of “black box” to account for behavioral, societal, or managerial factors; 6) the term was often used as a synonym for “organization”. This latter use is frequently found in federal reports, including National Water Commission studies, and is most unfortunate because it tends to slight significant social-psychological factors. A suggested definition is: “An institution is the structured result or outcome of a process by which values are articulated, arranged, and communicated, having continuity over time, and influencing behavior of persons who did not necessarily participate in formulating those values (norms).”     

Waste minimisation in practice

One of the major hindrances to waste minimisation on a construction site is the difficulty in establishing a methodology and using this methodology to benchmark future construction projects. This paper introduces SMARTWaste, a software tool that has been used to audit, reduce and target waste arisings on a construction site. This tool tries to link the construction process and the waste hierarchy. That is reducing waste on a construction site rather than landfilling it. Three applications of the SMARTWaste software will be discussed using case studies from three different types of construction. An evaluation of these case studies shows that, by implementing a waste minimisation scheme on-site, you can improve material recovery for reuse. Also, by using the waste arisings as a benchmark you can reduce your waste arisings on future sites. Application of SMARTWaste or a similar waste minimisation tool on a wider basis could reduce waste arisings and could result in a built environment that consumed less natural resources and energy, and also produced less pollution and waste. Such a built environment would be environmentally and socially more responsive and responsible.