Preparation and performance of arsenate (V) adsorbents derived from concrete wastes

Solid adsorbent materials, prepared from waste cement powder and concrete sludge were assessed for removal of arsenic in the form of arsenic (As(V)) from water. All the materials exhibited arsenic removal capacity when added to distilled water containing 10–700 mg/L arsenic. The arsenic removal isotherms were expressed by the Langmuir type equations, and the highest removal capacity was observed for the adsorbent prepared from concrete sludge with heat treatment at 105 °C, the maximum removal capacity being 175 mg-As(V)/g. Based on changes in arsenic and calcium ion concentrations, and solution pH, the removal mechanism for arsenic was considered to involve the precipitation of calcium arsenate, Ca₃(AsO₄)₂. The enhanced removal of arsenic for the adsorbent prepared from concrete sludge with heat treatment was thought to reflect ion exchange by ettringite. The prepared adsorbents, derived from waste cement and concrete using simple procedures, may offer a cost effective approach for arsenic removal and clean-up of contaminated waters, especially in developing countries.     

The Coastal Environmental Characteristics of Taiwan

Abstract

There are three major factors affecting the coastal environment in Taiwan: tidal current, long-shore current and land subsidence. in Taiwan, most industrial areas are located on the southwestern coast. Most of the pollutants from the factories are discharged directly to the ocean, harbours or rivers. the pollutants in harbours or rivers will eventually be delivered to coastal waters. There, the tidal current is the major force dispersing the pollutants nearshore. the polluted water extends to an area about 5 km on both sides from the discharge source, and within about 3–4 km off-shore. in this study, Hsien-Da Harbour in southwestern Taiwan is cited to explain the effects of tidal current on the coastal environment. the long-shore current induced by breaking waves is the major force shaping the coastal morphology. Along the western coast of Taiwan, the long-shore current mainly flows northward along the southern section, and southward along the northern section. in the last one hundred years, in general, the coast has been eroded along the northern and southern sections of western coast, and some reclaimed lands were formed in the middle section. Recently, erosion in some coastal zones is quite serious because of excess groundwater extraction, especially along the southwestern coast. Groundwater extraction might also induce land subsidence. There are some areas near the coast which suffer serious land subsidence problems.     

Poaching Risks in Community‐Based Natural Resource Management

Poaching can disrupt wildlife‐management efforts in community‐based natural resource management systems. Monitoring, estimating, and acquiring data on poaching is difficult. We used local‐stakeholder knowledge and poaching records to rank and map the risk of poaching incidents in 2 areas where natural resources are managed by community members in Caprivi, Namibia. We mapped local stakeholder perceptions of the risk of poaching, risk of wildlife damage to livelihoods, and wildlife distribution and compared these maps with spatially explicit records of poaching events. Recorded poaching events and stakeholder perceptions of where poaching occurred were not spatially correlated. However, the locations of documented poaching events were spatially correlated with areas that stakeholders perceived wildlife as a threat to their livelihoods. This result suggests poaching occurred in response to wildlife damage occurred. Local stakeholders thought that wildlife populations were at high risk of being poached and that poaching occurred where there was abundant wildlife. These findings suggest stakeholders were concerned about wildlife resources in their community and indicate a need for integrated and continued monitoring of poaching activities and further interventions at the wildlife‐agricultural interface. Involving stakeholders in the assessment of poaching risks promotes their participation in local conservation efforts, a central tenet of community‐based management. We considered stakeholders poaching informants, rather than suspects, and our technique was spatially explicit. Different strategies to reduce poaching are likely needed in different areas. For example, interventions that reduce human‐wildlife conflict may be required in residential areas, and increased and targeted patrolling may be required in more remote areas. Stakeholder‐generated maps of human‐wildlife interactions may be a valuable enforcement and intervention support tool. Riesgos de Cacería Furtiva en el Manejo de Recursos Naturales Basado en Comunidades     

The Declining Influence of Science On Marine Environmental Policy

Abstract

Differences between the scientific and environmental policy communities regarding marine environmental protection strategies are discussed in the context of the nature and extent of scientific influence on marine environmental policy. Public perceptions of the nature and severity of marine pollution frequently differ from scientific assessments. the thesis of this paper is that the increasing influence of public perception on marine environmental protection policy is leading to the adoption of simplistic and unnecessarily extreme approaches to marine pollution prevention and to a reduced reliance on science. This trend is illustrated by some recent international developments and some suggestions are made towards enhancing the influence of science on marine protection policy.     

Management Decentralization and Montane Forest Conditions in Tanzania

Abstract: We examined how differences in local forest‐management institutions relate to disparate anthropogenic forest disturbance and forest conditions among three neighboring montane forests in Tanzania under centralized, comanaged, or communal management. Institutional differences have been shaped by decentralization reforms. We conducted semistructured interviews with members of forest management committees, local government, and village households and measured anthropogenic disturbance, tree structure, and species composition in forest plots. We assessed differences in governance system components of local institutions, including land tenure, decision‐making autonomy by forest users, and official and de facto processes of rule formation, monitoring, and enforcement among the three management strategies. We also assessed differences in frequencies of prohibited logging and subsistence pole cutting, and measures of forest condition. An adjacent research forest served as an ecological reference for comparison of forest conditions. Governance was similar for comanaged and centralized management, whereas communal managers had greater tenure security and decision‐making autonomy over the use and management of their forest. There was significantly less illegal logging in the communal forest, but subsistence pole cutting was common across all management strategies. The comanaged forest was most disturbed by recent logging and pole cutting, as were peripheral areas of the larger centralized forest. This manifested in more degraded indicators of forest conditions (lower mean tree size, basal area, density of trees ≥ 90 cm dbh, and aboveground biomass and higher overall stem density). Greater tenure security and institutional autonomy of the communal strategy contributed to more effective management, less illegal logging, and maintenance of good forest conditions, but generating livelihood benefits was a challenge for both decentralized strategies. Our results underscore the importance of well‐designed institutional arrangements in forest management and illustrate mechanisms for improved forest governance and conservation in the context of Tanzanian decentralization reforms.     

四川省环境污染经济损失与污染治理投资比例探讨

环境保护同经济建设和社会发展相协调,是我国环境保护的基本原则。本文从环境保护与经济发展的相互关系出发,比较实际地估计了我省各种污染排放物及造成的经济损失,探讨了环保治理资金社会投入的比例问题。     

ECONOMIC POLICIES FOR REGULATING AGRICULTURAL DRAINAGE WATER1

ABSTRACT: Agricultural drainage water is a major source of environmental pollution in many areas. This paper reviews the literature on the economics of nonpoint-source pollution and applies it to the regulation of agricultural drainage water. Four types of regulatory policies are considered. The empirical analysis is carried out for cotton production in the San Joaquin Valley of California. Variable inputs are the quantity of water applied and the type of irrigation system. All four policies can achieve economic efficiency under the conditions assumed here, but the policies differ in terms of the distributional impacts and administrative requirements.     

ITERATIVE EVALUATION OF A LAKE WATER QUALITY MANAGEMENT PROGRAM1

ABSTRACT: Local governments often face environmental problems that cross political boundaries. The onus for solution usually falls on the moat severely affected jurisdiction, others do nothing until impacted. Resolution of these problems requires cooperation across political boundaries which means that local governments must be persuaded first that there is a problem, and second that action is required to solve it. This paper presents a method to supply low cost, credible information that can be used to achieve consensus on problem solution. A case study of a lake water quality management problem is described. Formative evaluation techniques was adapted to provide a minimum of evidence which was then used to persuade less impacted local jurisdictions to cooperate in the problem solution.     

ESTIMATING THE WATER QUALITY BENEFITS FROM SOIL EROSION CONTROL1

ABSTRACT: A framework for estimating the water quality benefits from soil erosion was developed. The framework is based on the linkages between soil erosion and offsite damages. The linkages are: erosion on the field, movement of eroded materials to waterways, impact of discharged material on water quality parameters, impact of water quality changes on ability of water to provide economic services, and the economic value of the changes in water use. These linkages need to be modeled in order to estimate the water quality benefits from reductions in soil erosion. Methods for modeling each link on a geographic level, which enables the analyses of national soil conservation, were examined. Areas where data or models were found to be lacking include transport of sediment and nutrients to water systems, impact of discharged materials on water quality parameters, and impact of water quality on ability of water to provide economic services. An economic evaluation of 1983 soil conservation programs was presented as an example of how the framework could be used. A number of simplifying assumptions were made to represent links that could not be modeled with available data.     

环境电磁污染和防治

本文对环境电磁污染的现状,危害及产生作了部份介绍;同时阐述了污染的防治技术和目前该项工作尚存在问题。