Model evaluation of the phytoextraction potential of heavy metal hyperaccumulators and non-hyperaccumulators

Evaluation of the remediation ability of zinc/cadmium in hyper- and non-hyperaccumulator plant species through greenhouse studies is limited. To bridge the gap between greenhouse studies and field applications for phytoextraction, we used published data to examine the partitioning of heavy metals between plants and soil (defined as the bioconcentration factor). We compared the remediation ability of the Zn/Cd hyperaccumulators Thlaspi caerulescens and Arabidopsis halleri and the non-hyperaccumulators Nicotiana tabacum and Brassica juncea using a hierarchical linear model (HLM). A recursive algorithm was then used to evaluate how many harvest cycles were required to clean a contaminated site to meet Taiwan Environmental Protection Agency regulations. Despite the high bioconcentration factor of both hyperaccumulators, metal removal was still limited because of the plants' small biomass. Simulation with N. tabacum and the Cadmium model suggests further study and development of plants with high biomass and improved phytoextraction potential for use in environmental cleanup.     

湖岸缓冲带反硝化作用的研究进展

反硝化作用是湖岸缓冲带去除硝酸盐的重要途径。湖岸缓冲带是联系陆地与湖泊生态系的纽带,不仅为许多动植物提供适宜生境,而且通过反硝化作用能去除地下水中的硝酸盐,提高湖泊水质。概述不同检测反硝化速率的方法,并对比各种方法的优点与缺点。阐述反硝化作用的影响因素：厌氧环境、有机碳、湖岸坡度、缓冲带坡度、pH与温度、硝酸盐浓度。介绍反硝化速率模型的研究开发状况。最后,提出了目前国内外反硝化研究中存在的不足及发展方向。     

新型转式垃圾焚烧过程中脱氯脱硫机理的研究

为了探讨有机垃圾焚烧过程钙基添加剂对HCl,SO_x生成特性的影响,分别在自行设计的中空水冷转式垃圾焚烧炉和固定床加热炉中进行了一系列的实验,研究结果表明新型转式焚烧炉具有强化传热传质特性,能提高HCl、SO_x的脱除率,可抑制有害气体的生成;同时也研究了 HCl,SO₂气体同时存在时,钙基添加剂对脱氯脱硫效率的影响规律。     

Population dynamics and the economics of invasive species management: the greenhouse whitefly in California-grown strawberries

In agriculture, relatively few efficacious control measures may be available for an invasive pest. In the case of a new insect pest, insecticide use decisions are affected by regulations associated with its registration, insect population dynamics, and seasonal market price cycles. We assess the costs and benefits of environmental regulations designed to regulate insecticide applications on an invasive species. We construct a bioeconomic model, based on detailed scientific data, of management decisions for a specific invasion: greenhouse whiteflies in California-grown strawberries. The empirical model integrates whitefly population dynamics, the effect of whitefly feeding on strawberry yields, and weekly strawberry price. We use the model to assess the optimality of alternative treatment programs on a simulated greenhouse whitefly population. Our results show that regulations may lead growers to "under-spray" when placed in an economic context, and provide some general lessons about the design of optimal invasive species control policies.     

Teachers' conceptions of nature and environment in 16 countries

By using an original framework involving complementary statistical approaches, we investigated the environmental attitudes of 6379 pre-service and in-service teachers in 16 countries of Europe and its neighbourhood. To test hypotheses about the nature of environmental attitudes, we examined the variation across groups of individuals (between-class analysis), investigated the independent effects of several candidate explanatory factors (orthogonal analysis), and finally inspected potential relationships between conceptions on a variety of topics (co-inertia analysis).     

Batch sorption dynamics and equilibrium for the removal of lead ions from aqueous phase using activated carbon developed from coffee residue activated with zinc chloride

Lignocellulosic materials are good precursors for the production of activated carbon. In this work, coffee residue has been used as raw material in the preparation of powder activated carbon by the method of chemical activation with zinc chloride for the sorption of Pb(II) from dilute aqueous solutions.The influence of impregnation ratio (ZnCl₂/coffee residue) on the physical and chemical properties of the prepared carbons was studied in order to optimize this parameter. The optimum experimental condition for preparing predominantly microporous activated carbons with high pore surface area (890 m²/g) and micropore volume (0.772 cm³/g) is an impregnation ratio of 100%. The developed activated carbon shows substantial capability to sorb lead(II) ions from aqueous solutions and for relative impregnation ratios of 75 and 100%, the maximum uptake is practically the same. Thus, 75% represents the optimal impregnation ratio.Batch experiments were conducted to study the effects of the main parameters such as contact time, initial concentration of Pb(II), solution pH, ionic strength and temperature. The maximum uptake of lead(II) at 25 °C was about 63 mg/g of adsorbent at pH 5.8, initial Pb(II) concentration of 10 mg/L, agitation speed of 200 rpm and ionic strength of 0.005 M. The kinetic data were fitted to the models of pseudo-first order and pseudo-second order, and follow closely the pseudo-second order model. Equilibrium sorption isotherms of Pb(II) were analyzed by the Langmuir, Freundlich and Temkin isotherm models. The Freundlich model gives a better fit than the others.Results from this study suggest that activated carbon produced from coffee residue is an effective adsorbent for the removal of lead from aqueous solutions and that ZnCl₂ is a suitable activating agent for the preparation of high-porosity carbons.     

Removal of Pb(II) ions from aqueous solution using activated tea waste: Adsorption on a fixed-bed column

An inexpensive and effective adsorbent was developed from waste tea leaves for the dynamic uptake of Pb(II). Characterization of the adsorbents showed a clear change between physico-chemical properties of activated tea waste and simply tea waste. The purpose of this work was to evaluate the potential of activated tea waste in continuous flow removal of Pb(II) ions from synthetic aqueous effluents. The performance of the system was evaluated to assess the effect of various process variables, viz., of bed height, hydraulic loading rate and initial feed concentration on breakthrough time and adsorption capacity. The shape of the breakthrough curves was determined for the adsorption of Pb(II) by varying different operating parameters like hydraulic loading rate (2.3–9.17 m³/h m²), bed height (0.3–0.5 m) and feed concentration (2–10 mg/l). An attempt has also been made to model the data generated from column studies using the empirical relationship based on the Bohart–Adams model. There was an acceptable degree of agreement between the data for breakthrough time calculated from the Bohart–Adams model and the present experimental study with average absolute deviation of less than 5.0%. The activated tea waste in this study showed very good promise as compared with the other adsorbents available in the literature. The adsorbent could be suitable for repeated use (for more than four cycles) without noticeable loss of capacity.     

The whole relationship between environmental variables and firm performance: Competitive advantage and firm resources as mediator variables

The examination of the possible direct link between environmental protection and firm performance in the literature has generally produced mixed results. The present paper contributes to the literature by using the resource-based view as a mediating process in this relationship. The study specifically tests whether or not the resource-based view of the firm mediates the positive relationships of proactive environmental management and improved environmental performance with competitive advantage, which also has consequences for financial performance. We also check the possible link between the adoption of a pioneering approach and good environmental management practices. Our findings support that early investment timing and intensity in environmental issues impact on the adoption of a proactive environmental management, which in turn helps to improve environmental performance. The findings also show that a firm's resources and competitive advantage act as mediator variables for a positive relationship between environmental protection and financial performance. This contribution is original because the present paper develops a comprehensive whole picture of this path process, which has previously only been partially discussed in the literature. In addition, this study clarifies a relevant point in the literature, namely that the effect of environmental protection on firm performance is not direct and can vary depending on the sector considered. Whereas competitive advantage in relation to costs influences financial performance in the IPPC law sector, the relevant influence in the hotel sector comes from competitive advantage through differentiation.     

基于“反规划”视角的乡村旅游规划新途径探析

引入"反规划"思想,针对传统规划方法给乡村旅游带来的不利影响,强调"反规划"在乡村旅游规划中应用的必要性与可行性。通过与传统规划方法进行对比分析发现,当前乡村旅游规划中存在不少亟待解决的问题。同时,探析了"反规划"思想在乡村旅游规划中的运用,建立乡村旅游"反规划"发展模式为保障乡村旅游可持续性发展提供了理论依据。     

应用CALINE4模式估算机动车排放污染物的浓度——以济南市主干道为例

随着经济的快速发展,机动车排气污染已成为我国城市空气污染的重要来源,而且在一定时段,机动车排气污染已成为空气污染最主要的污染源之一。以济南市经十路为例,采用实地调查的方法,得出各时段的车流量,选用大气环评助手EIAA中的CALINE4模式对机动车尾气中的主要污染物CO、NOx、THC的排放浓度进行估算,得出3种污染物CO、NOx、THC最大值均出现在7:00—8:00之间,最小值均出现在12:00-13:00之间,排放强度由大到小为:CO、THC、NOx。