The potential of cost-effective coconut husk for the removal of toxic metal ions for environmental protection

Coconut (Cocos nucifera) husk, an agricultural waste, has been thoroughly investigated for the removal of toxic Cd(II), Cr(III) and Hg(II) ions from aqueous media. The parameters like nature and composition of electrolyte, concentration of toxic ions, dosage of coconut husk, and equilibration time between the two phases were optimized for their maximum accumulation onto the solid surface. The effect of common ions on the uptake of metal ions has been monitored under optimal conditions. The variation of retention of each metal ion with temperature was used to compute the thermodynamic quantities DeltaH, DeltaS and DeltaG. The values 18.1+/-0.6 kJmol(-1), 74+/-2 Jmol(-1)K(-1), and -3.8+/-0.04 kJmol(-1) at 298 K; 10.8+/-0.8 kJmol(-1), 48.8+/-2.7 Jmol(-1)K(-1), and -4.6+/-0.3 kJmol(-1) at 298 K; and -37.4+/-2k Jmol(-1), 105+/-7 Jmol(-1)K(-1) and -2.58+/-0.5 kJmol(-1) at 298 K were obtained for Cd(II), Cr(III) and Hg(II) ions, respectively. The sorption data were analysed by applying different sorption isotherms. The sorption capacity and energy were evaluated for each metal ion. The values of the Freundlich constants 1/n and C(m) were 0.92+/-0.04 and 52.6+/-22.2 mmolg(-1); 0.85+/-0.05 and 56.0+/-0.03 mmolg(-1); and 0.88+/-0.03 and 6.84+/-0.45 mmolg(-1) for Cd(II) Cr(III) and Hg(II) ions, respectively. Similarly, the Dubinin-Radushkevich (D-R) constants beta, X(m,) and E were evaluated for the three metal ions. To check the selectivity of the sorbent, sorption of a number of elements was measured under similar conditions. Separation of Zn(II) from Cd(II); Cr(III) from I(I), Zr(IV), Se(IV), and Hg(II) from Se(IV) and Zn(II) can be achieved using this sorbent. This cheap material has potential applications in analytical chemistry, water decontamination, industrial effluent treatment and in pollution abatement.     

Fish mercury increase in Lago Manso, a new hydroelectric reservoir in tropical Brazil

It has been frequently demonstrated that mercury (Hg) concentrations in fish rise in newly constructed hydroelectric reservoirs in the Northern Hemisphere. In the present work, we studied whether similar effects take place also in a tropical upland reservoir during impoundment and discuss possible causes and implications. Total Hg concentrations in fish and several soil and water parameters were determined before and after flooding at Rio Manso hydroelectric power plant in western Brazil. The Hg concentrations in soil and sediment were within the background levels in the region (22-35 ng g(-1) dry weight). There was a strong positive correlation between Hg and carbon and sulphur in sediment. Predatory fish had total Hg concentrations ranging between 70 and 210 ng g(-1) f.w. 7 years before flooding and between 72 and 755 ng g(-1) f.w. during flooding, but increased to between 216 and 938 ng g(-1) f.w. in the piscivorous and carnivorous species Pseudoplatystoma fasciatum, cachara, and Salminus brasiliensis, dourado, 3 years after flooding. At the same time, concentrations of organic carbon in the water increased and oxygen concentrations decreased, indicating increased decomposition and anoxia as contributing to the increased Hg concentrations in fish. The present fish Hg concentrations in commonly consumed piscivorous species are a threat to the health of the population dependent on fishing in the dam and downstream river for sustenance. Mercury exposure can be reduced by following fish consumption recommendations until fish Hg concentrations decrease to a safe level.     

Assessment of Environmental Water Demands (EWD) of Forests for Two Distinct Indian Ecosystems

Sustainable use of water and land resources requires that these scarce resources be appropriately allocated among various competing human activities. Worldwide, there is a realization now that sustainable river basin management should be accorded the highest priority, because it deals not only with technical, but also with ecological and socioeconomic aspects, and thus calls for a multidisciplinary and integrated approach. However, most of the policy and planning documents have either remained silent, or have made only implicit reference to the importance of environmental water demand (EWD) and its quantification. Therefore, in the light of its importance, a methodology has been evolved in this article for quantifying EWD for various forested areas in two distinctly different Indian river basins: Brahmani (humid zone) and Sabarmati (dry zone). The article analyzes and discusses EWD estimates at three different spatial levels: river basins, states, and districts within them, and finally presents a comparative analysis of all these results. Findings of the present study will be immensely useful in understanding various ecological issues connected with water resource projects and proposals in these river basins.     

Definition of Homogeneous Environmental Management Units for the Catalan Coast

Geographical areas constitute the basic implementation locus for integrated coastal zone management strategies and activities. Because the definition of territorial planning objectives may be affected by socioeconomic and environmental characteristics, one of the main steps in the process involves dividing the coast into homogeneous environmental management units (HEMUs). This article presents a general and simple method for regionalizing the landside of a coastal zone into HEMUs and illustrates it through application to the Catalan coast. Socioeconomic and natural (biophysical) subsystems were selected as the most appropriate dimensions of the regionalization process. Dimensions were described using 11 spatial themes, which were managed in a geographic information system environment that proved to be an adequate tool for the purpose. A final coastal zone map of four classes of HEMUs connected to local administrative units was obtained, and because it reflects the current natural and socioeconomic dynamics, it can be considered as an initial step in the planning process for the Catalan coast. Although the proposed method was developed based on the characteristics of the Catalan coast, it is general enough to be adapted and applied to most developed or developing coastal areas.     

峨眉山景区旅游商品的开发与营销模式

通过对旅游商品定义的综述,界定了旅游商品的定义、范围和功能,同时对峨眉山景区旅游商品的开发、需求、购买力等抽取420份问卷作为样本,分析了峨眉山旅游商品的需求现状,并以旅游者需求现状为依据,对峨眉山旅游商品的开发和营销提出了“4P＋4C＋4R”营销策略,以期对其它景区的旅游商品开发和营销具有一定的借鉴意义。     

Communicative Aspects of Environmental Management by Objectives: Examples from the Swedish Context

Management by objectives (MBO) is a technique for integrating ecological concerns into national political and administrative structures. Politicians determine environmental objectives and interim targets to be implemented and assessed by civil servants in national, regional, and local contexts. Well-developed organizational communication is a prerequisite for MBO. However, communication-related obstacles can arise when using MBO in public environmental management. We examine communicative aspects of environmental MBO, looking specifically at the implementation, administration, and assessment of Swedish environmental quality objectives. Our argument is illustrated by quotations from individual and focus group interviews. We conclude that communicative problems may arise, because different actors interpret messages from different perspectives, depending on their agendas, prior knowledge and experience, and positions in the administrative system. It is crucial to recognize the dialogical aspects of communication, by involving the receiver of a message in a process of response. In addition, the different timeframes underlying different arguments could contribute to misunderstandings between actors involved in handling environmental issues. In assessing the achievement of environmental objectives, indicators are used as communicative tools. It is important to investigate whether and how these indicators contribute to the de- and recontextualization of environmental objectives.     

河口近岸水体中颗粒态重金属的潮周期变化

对长江口崇明东滩近岸水体中颗粒态重金属的潮周期变化特征及其影响机制进行了研究.结果表明,受粒度影响,底层水体中颗粒态Cu、Pb、Fe、Mn、Zn、Cr、Al的总量分别高出表层沉积物的184%、99%、56%、62%、147%、50%和45%,其中Cu、Pb、Fe、Mn、Zn、Al可还原态部分在底层水体悬浮颗粒物中的含量也明显高出表层沉积物的2～3倍,但与重金属总量相比,上述元素的可还原态部分所占比例与表层沉积物相差不大.在5次潮汐循环过程中,颗粒态重金属均在涨潮初期、高平潮前后及落潮末期出现较高含量.这种变化主要与水动力条件有关,当水体流速增大时,从底部沉积物再悬浮起来的颗粒态重金属对水体中的永久性悬浮颗粒起了很大的稀释效应.水体中的盐度、DO及pH等环境因子对潮周期内颗粒态重金属的变化影响不大.     

清洁生产与企业结构调整

清洁生产是工业生产追求的最高境界,而结构调整阶段给企业提供了一个很好的实施清洁生产的契机,使企业可以借助结构调整机会,将清洁生产渗透至企业的所有方面,最大限度地取得清洁生产的效果。     

我国电子废弃物的管理及发展道路研究

我国电子废弃物的处理处置正向产业化方向稳步推进。本文概括了电子废弃物的特点,以及我国目前处理电子废弃物的现状。遵照循环经济理念,并基于我国国情,提出了我国在电子废弃物处理处置过程中应遵循的主要原则和今后的发展方向。     

厌氧-好氧生物滤池处理城市污水试验

研究了生物滤池处理城市污水的性能特点,结果表明:厌氧-好氧生物滤池去除城市污水中的CODCr、SS和NH4+-N等具有较好的效果,当进水CODCr、SS和NH4+-N分别为23、112mg/L和56mg/L时,水力停留时间8h,曝气强度在0·5~0·6L/(m2·s)时,CODCr、SS和NH4+-N的去除率分别在90%、80%和75%以上。