Effect of salt solution treatment on impurity removal: A case study on phosphogypsum

This study gives a brief demonstration of impurity removal efficiency upon salt solution treatment of phosphogypsum (PG). The experimental set up has been designed according to a multi-variable Box–Behnken Design (BBD) with stirring time, solid: liquid (PG:salt solution) ratio and temperature as the conducted in various salt solutions. PG sample has been treated with sea water, 5% NaCl and 10% NaCl solutions according to the BBD matrix. Fluoride (F), copper (Cu), manganese (Mn), and nickel (Ni) amounts in the PG sample have been measured upon pre- and post-treatment with salt solutions. Among other operating conditions, temperature has been the dominant factor on fluoride removal efficiency, and responses for the factors determined in the experiment runs indicated that a significant correlation could be established between temperature and fluoride removal, sea water being the most efficient salt solution. Higher copper, manganese, and nickel removal efficiencies have been observed in single salt NaCl solution systems however no significant correlation could be established between factors. Results indicate that pre-treatment of PG located near coastal regions with sea water can be a cost-effective approach and applicable on industrial scale when fluoride removal is of importance.     

The impacts of anthropogenic factors on the environment in Nigeria

Generally speaking, there has been a consensus on the primary drivers of anthropogenic induced environmental degradation. However, little progress has been made in determining the magnitude of the impacts, particularly in developing countries. This creates a lacuna that needs to be filled up. The purpose of this study therefore is to ascertain the degree of anthropogenic induced environmental impacts in Nigeria. To achieve the aim, fossil fuel consumption was used as a surrogate for carbon dioxide emissions while the magnitude of the impacts was determined by regression statistics and the STIRPAT model. The results show that only three variables, namely population, affluence and urbanization, were statistically significant and that the regression model accounts for 60% of the variation in the environmental impacts. However, population and affluence, which have ecological elasticities of 1.699 and 2.709, respectively, are the most important anthropogenic drivers of environmental impacts in Nigeria while urbanization, with an elasticity of -0.570, reduces the effect of the impacts. This implies that modernization brings about a reduction in environmental impacts. The paper therefore makes a significant contribution to knowledge by successfully testing the STIRPAT model in this part of the world and by being the first application of the model at political units below the regional or nation states.     

Recreation impacts in some riparian forests of the Eastern United States

Ecological impacts on camp and picnic sites were examined in three National Park Service units along the Delaware and New rivers, in the eastern United States. All sites experienced pronounced impact to trees, groundcover vegetation, and soils. The nature and magnitude of impacts in these riparian forests were quite similar to those reported in wilderness areas in the mountainous western states and northern Minnesota, despite more favorable growing conditions. The relationship between amount of use and amount of impact and the importance of differences in type of use and environment were also roughly comparable. High-use sites were more heavily impacted than low-use sites, but differences were small when compared with differences in amount of use. The areal extent of impact was the major difference between sites in different environments and sites used by different clienteles. This suggests that the effectiveness of basic strategies for managing impact should not differ greatly between regions. Here, as elsewhere, actions taken to control the areal extent of impact appear to be particularly important.     

为发展21世纪的生态工业必须大力实施清洁生产工艺战略

本世纪末，许多工业企业在对付环境问题的广度牙，逐步放弃传统的对工业废弃物进行处理的作法，转而致力于各种废料的产生。工业界应大力实施清洁生产工艺战略，它即可降低生产成本，又可达到环境效果。该战略要求企业在设计和生产产品时谅充分考虑事前如何控制废料产生和环境污染的问题。     

Canadian manufacturing: The impacts of natural resource price increases on input demands and costs

The separate effects of 50% increases in the prices of energy, renewable and nonrenewable natural resource inputs on factor demands and production costs are simulated for Canadian total manufacturing and six two-digit industries. Both renewable and nonrenewable natural resource price increases have a substantially greater effect upon the demands for other factors and upon production costs than a parallel energy price increase. These results are important from a policy perspective and justify the further disaggregation of inputs in this and in other models of input demand.     

Environmental impact and management of phosphogypsum

The production of phosphoric acid from natural phosphate rock by the wet process gives rise to an industrial by-product called phosphogypsum (PG). About 5 tons of PG are generated per ton of phosphoric acid production, and worldwide PG generation is estimated to be around 100–280 Mt per year. This by-product is mostly disposed of without any treatment, usually by dumping in large stockpiles. These are generally located in coastal areas close to phosphoric acid plants, where they occupy large land areas and cause serious environmental damage. PG is mainly composed of gypsum but also contains a high level of impurities such as phosphates, fluorides and sulphates, naturally occurring radionuclides, heavy metals, and other trace elements. All of this adds up to a negative environmental impact and many restrictions on PG applications. Up to 15% of world PG production is used to make building materials, as a soil amendment and as a set controller in the manufacture of Portland cement; uses that have been banned in most countries. The USEPA has classified PG as a “Technologically Enhanced Naturally Occurring Radioactive Material” (TENORM).     

Populations of domesticated cattle and buffalo in the Western Forest Complex of Thailand and their possible impacts on the wildlife community

The Western Forest Complex (WEFCOM) of Thailand is comprised of many protected areas and has one of the highest wildlife populations in the country. Populations of wildlife in the WEFCOM have decreased dramatically over recent years. Rapid economic development has resulted in the conversion of forest into agricultural and pastoral land, which has directly and indirectly impacted the wildlife community. This research aimed to evaluate populations of domesticated cattle (Bos indicus) and buffalo (Bubalus bubalis) in the WEFCOM and their possible impacts on the wildlife community. Domesticated cattle and buffalo keepers from 1561 (or 3.3%) of houses in and near WEFCOM were interviewed. The average number of animals per household was 15.6 cattle and 8.5 buffalo. Most villagers released domesticated cattle and buffalo to forage in the protected areas. This tended to have a high impact on the wildlife community in Huai Kha Khaeng Wildlife Sanctuary and Tungyai Naresuan Wildlife Sanctuary. The least impacted areas were Luam Khlong Ngu National Park, Thong Pha Phum National Park and Chaleam Ratanakosin National Park. With a high risk to the wildlife community, law enforcement should be used in combination with a certain level of co-management with local communities.     

A review of textile industry: Wet processing,environmental impacts,and effluent treatment methods

The word “textile” means to weave and was taken from the Latin word “texere.” Nowadays, textiles not only fulfill humankind's basic necessity for clothing, they also allow individuals to make fashion statements. As one of the oldest industries, the textile industry occupies a unique place in India. It is responsible for 14% of the total industrial manufacture in India. However, the textile industry is also considered to be one of the biggest threats to the environment. Pretreatment, dyeing, printing, and finishing operations are among the various stages of the industrial textile manufacturing process. These fabrication operations not only utilize huge quantities of power and water, they also generate considerable amounts of waste. The textile industry utilizes a number of dyes, chemicals, and other materials to impart the required qualities to the fabrics. These operations produce a significant amount of effluents. The quality of effluents is such that they cannot be put to other uses, and they can create environmental problems if they are disposed of without appropriate treatment. This review discusses different textile processing stages, pollution problems associated with these stages, and their eco‐friendly alternatives. Textile wet processing is described in detail, as it is the key process in the industry and it also generates the greatest amount of pollutants in textile processing. The environmental impact of textile effluents is discussed, as textile effluents not only impose negative effects on the quality of water and soil, they also imperil plant and animal health. In this paper, various methods for treating textile effluents are described. Discussion of physical, chemical, biological, and advanced treatment technologies of effluent treatment are included in this paper.     

山区生态产业及其环境保育的作用研究

山区生态产业是依赖于山区丰富的自然资源按照生态学原理组织形成的生态与经济有机统一的产业发展形式。本文阐述了山区生态产业七个方面的特征：即山区生态产业对自然资源的特殊依赖性、受高度景观带的制约性、结构多样性与复杂性、建设长期性、经济收益级差性、开发水平落后性和开发任务艰巨性。在此基础上,文章从要素调控设计、垂直带幅生态调控设计、产业模式系统生态设计出发探讨了生态产业与垂直地带性的构建关系,并举例说明了山区生态产业开发建设对环境保护的积极作用。得出了山区生态产业的开发就是努力避免产业活动对生态环境干扰的逆向作用,积极引导与实现产业活动对生态环境干扰的正向作用的结论。     

Recreational impacts on backcountry campsites in Grand Canyon National Park,Arizona, USA

Backcountry campsites were studied in three desert vegetation types (pinyon-juniper, catclaw, and desert scrub) in Grand Canyon National Park, Arizona. Relationships between amount of use and amount of impact were examined within each vegetation type. The area disturbed was small, but impacts were generally severe. Important impacts were increased soil compaction and associated decreases in infiltration rates and soil moisture content; these were substantially more pronounced on high than low use sites. The only impact parameter that differed significantly between vegetation types was core area. The types of impact identified are similar to those found in the coniferous forests studied elsewhere, as is the logarithmic relationship between amount of use and amount of impact. However, Grand Canyon sites can support more visitor use before reaching near-maximum levels of impact for important impact parameters.     

Issues and impacts of Redwood National Park expansion

In 1968, Redwood National Park was created in an atmosphere of controversy and compromise to preserve remnants of the coastal redwood (Sequoia sempervirens) ecosystems and the streams and seashores with which they are associated. The 1968 boundary included the lower portions of several watersheds in the park, which meant that potential impacts from upstream, privately owned lands might occur. Between 1968 and 1978, controversy continued between preservation and forest industry interests over the impacts of harvesting old growth timber upslope and upstream from the park. In 1978, the southern portion of the park around Redwood Creek was expanded by 48,000 acres, moving the boundary from a narrow, one-half mile riparian corridor to ridgelines, but still leaving two-thirds of the total watershed outside of the park. The park expansion has generated biological and social impacts and opportunities. Meeting the objectives of the 1978 legislation will require close coordination between federal and state government and local communities.     

生态城市的数学模型建立

本文首先论述了生态城市的概念和内涵；其次对于目前的生态城市的系统模型和指标体系进行了综述；然后建构了新的生态城市数学模型，重点讨论了建构该模型的理论基础及其指标体系的相关运算；最后指出该生态系统数学模型的理论和实践意义并对今后相关研究进行展望。     

Environmental monitoring at Hanford,Washington, USA: A brief site history and summary of recent results

Nuclear and nonnuclear industrial and research activities have been conducted on the Hanford reservation since 1943. Materials originating from these activities may enter the surrounding environment through releases of airborne and liquid effluents and solid wastes. Concern about the environmental effects of these releases has evolved over the past four decades into a comprehensive onsite and offsite monitoring program. Today, environmental monitoring to assess potential impacts of released materials includes field sampling and chemical and physical analyses of air, ground and surface water, fish and wildlife, soil, vegetation, and foodstuffs. This paper reviews the history of Hanford operations and summarizes the current environmental monitoring program and its major findings. Mathematical models based on monitoring data show that radiation doses to people living near the Hanford site are well below existing regulatory standards. Only trace amounts of radionuclides from Hanford have been detected in the offsite environment.     

生态城区建设中的生态第三产业发展对策--以长沙市芙蓉区为例

发展生态第三产业是生态城区建设的必然要求.本文以长沙市芙蓉区为例,在分析了芙蓉区第三产业现状的基础上,提出了建设生态第三产业的发展对策.     

沿海滩涂生态型围垦指标体系研究

随着近几年滩涂围垦工程的进行,为了协调围垦开发与生态环境保护之间的矛盾,生态型围垦的理念应运而生。本文对"生态型围垦"的内涵进行了深入辨析,提出了沿海滩涂生态型围垦概念模型,针对围垦工程规划前期、工程实施和运行管理3个阶段的特点,从管理、环境和生态3个方面提出相应指标,初步构架了生态型围垦指标体系,为沿海滩涂围垦的可持续及匡围区域生态环境管理提供技术支撑。     

中国长城沿线生态脆弱性分析及生态保护对策

中国长城沿线是半湿润—半干旱和半干旱—干旱气候的过渡地带,也是农牧业的交错地带,生态极其脆弱,生态压力又大,容易发生生态破坏,而且很难恢复。为了保护中国长城沿线的生态环境,必须调整产业结构,合理布局,采用先进技术,加大投入,提高生态意识,加强法制建设。     

我国城市生态评价研究进展

城市建设带来了越来越多的生态环境问题,生态城市建设是解决这些问题的良好途径。生态城市的建设要有一定的评价体系作为支撑,本文综述了国内基于AHP方法建立的应用较为广泛的城市生态评价体系和方法,并对国内城市生态评价的现状做了分析。     

Assessing the impact of leather industries on the quality of water discharged into the East China Sea from Wenzhou Watersheds

Ammonium nitrogen and total germanium are among the main pollutants in the wastewater discharged from the leather industry. The intake of high concentrations of ammonium nitrogen and/or total germanium harms human health and biological species, as is well documented in literature. This paper focuses on assessing the trends of ammonium nitrogen and total germanium concentrations through time in two watersheds (Aojiang and Oujiang) in the Wenzhou metropolitan area of Zhejiang Province and their relationships with the released wastewater using regression and correlation statistics. The paper also utilizes the integrated pollution index to evaluate water quality in the two watersheds. Preliminary results show that, from 1992 to 1998 in the Aojing watershed, the concentrations of ammonium nitrogen and total germanium increased 13 and 14 times, respectively, decreasing somewhat after 1998, while between 1992 and 1997 in the Oujiang watershed, the concentrations increased, then decreased after 1997. The concentrations of ammonium nitrogen and total germanium are positively related to the amount of released wastewater. The concentrations of ammonium nitrogen and total germanium exceeded water standards 12 and 3 times, respectively, in Pingyang county of the Aojiang watershed, 14 and 3.3 times in Lucheng District of the Oujiang watershed, and 14 and 3.8 times in the Ouhai Oujiang watershed, respectively. In Pingyang county of the Aojiang watershed, the water quality degraded from Type III in 1992 to over Type V in 2003, and in the Oujiang watershed, the water quality degraded from Type II to over Type IV in 1999, when they were compared with the water quality standards. The water quality slightly improved in 2003 for the Oujiang watershed. It appears that pollution did have a direct positive correlation with leather industry production in the Pingyang Aojing watershed, while there was a negative correlation between the two in the Oujiang watershed. In these two watersheds, the integrated pollution index did not appear to relate to population dynamics and agricultural production. This paper also discusses the current new methodologies and approaches adopted nationally and internationally to reduce the contaminants and purify the environment for maintaining a sustainable and healthier environment in Wenzhou.     

Investigations of Contaminated Fluvial Sediment Deposits: Merging of Statistical and Geomorphic Approaches

Concentrations of contaminants in sediment deposits can have large spatial variability resulting from geomorphic processes acting over long time periods. Thus, systematic (e.g., regularly spaced sample locations) or random sampling approaches might be inefficient and/or lead to highly biased results. We demonstrate the bias associated with systematic sampling and compare these results to those achieved by methods that merge a geomorphic approach to evaluating the physical system and stratified random sampling concepts. By combining these approaches, we achieve a more efficient and less biased characterization of sediment contamination in fluvial systems. These methods are applied using a phased sampling approach to characterize radiological contamination in sediment deposits in two semiarid canyons that have received historical releases from the Los Alamos National Laboratory. Uncertainty in contaminant inventory was used as a metric to evaluate the adequacy of sampling during these phased investigations. Simple, one-dimensional Monte Carlo simulations were used to estimate uncertainty in contaminant inventory. We also show how one can use stratified random sampling theory to help estimate uncertainty in mean contaminant concentrations.     

Recovery of phosphate from calcinated bone by dissolution in hydrochloric acid solutions

In this study, the optimum conditions of dissolution of calcinated bone in HCl solutions with different concentrations are investigated. Recovery of phosphate from calcinated bone by dissolution with hydrochloric acid solutions was investigated in a batch reactor, it was observed that a 32% hydrochloric acid solution can dissolve the calcinated bone effectively. Using the Taguchi fractional design method, it was found that the optimum process conditions, at which 67.2% P₂O₅ dissolution was reached, were as follows: Reaction temperature: 318 K, solid-to-liquid ratio: 1/5 (g ml⁻¹), acid concentrations:32 (% w/v), stirring speed:400 min⁻¹ and reaction time: 60 min.