Carbon sequestration in the global carbon cycle is almost always attributed to organic carbon storage alone, while soil mineral carbon is generally neglected. However, due to the longer residence time of mineral carbon in soils (102–106 years), if stored in large quantities it represents a potentially more efficient sink. The aim of this study is to estimate the mineral carbon accumulation due to the tropical iroko tree (Milicia excelsa) in Ivory Coast. The iroko tree has the ability to accumulate mineral carbon as calcium carbonate (CaCO3) in ferralitic soils, where CaCO3 is not expected to precipitate. An estimate of this accumulation was made by titrating carbonate from two characteristic soil profiles in the iroko environment and by identifying calcium (Ca) sources. The system is considered as a net carbon sink because carbonate accumulation involves only atmospheric CO2 and Ca from Ca-carbonate-free sources. Around one ton of mineral carbon was found in and around an 80-year-old iroko stump, proving the existence of a mineral carbon sink related to the iroko ecosystem. Conservation of iroko trees and the many other biomineralizing plant species is crucial to the maintenance of this mineral carbon sink. 相似文献
Parental decisions concerning the continuation of pregnancy following prenatal detection of abnormal chromosomes were evaluated for 80 patients whose diagnosis and prenatal counselling were performed in our centre. Twenty-two anomalies were diagnosed by chorionic villus sampling (CVS) and 58 by amniocentesis. The severity of the chromosome anomaly and associated ultrasound findings in the first vs. second trimester were correlated with patients' decisions. No difference was found in the likelihood of parental decisions to interrupt or continue a pregnancy between CVS and amniocentesis for either the‘severe’ or the‘questionable’ group of chromosome anomalies. Ninety-three per cent of patients with severe prognosis and 27 per cent with questionable prognosis opted for pregnancy termination (p <0·0001). The association of ultrasound anomalies and termination was highly significant (p< 0·001). The severity of the chromosome anomaly, and, to a lesser extent, the visualization of anomalies on ultrasound were the major determinants of parental decisions to terminate the pregnancy. The diagnosis of an anomaly in the first trimester was no more likely ito lead to a termination of pregnancy than in the second trimester. 相似文献
Sciurus carolinensis ) have been labor intensive and costly, I demonstrate the use of line transect surveys to estimate gray squirrel density and
determine the costs of conducting surveys to achieve precise estimates. Density estimates are based on four transects that
were surveyed five times from 30 June to 9 July 1994. Using the program DISTANCE, I estimated there were 4.7 (95% CI = 1.86–11.92)
gray squirrels/ha on the Clemson University campus. Eleven additional surveys would have decreased the percent coefficient
of variation from 30% to 20% and would have cost approximately $114. Estimating urban gray squirrel density using line transect
surveys is cost effective and can provide unbiased estimates of density, provided that none of the assumptions of distance
sampling theory are violated. 相似文献
Rapid economic growth in Asia and the increasing transboundary movement of secondary resources will increasingly require both
3R endeavors (reduce, reuse, recycle) in each country and appropriate control of international material cycles. Recently,
managing electrical and electronic waste (E-waste) has become an important target for domestic and international material
cycles from the viewpoints of environmental preservation and resource utilization efficiency. To understand the current status
of E-waste issues in the context of international material cycles and to discuss the future tasks related to achieving 3R
in the region, we organized the National Institute for Environmental Studies (NIES) E-waste Workshop in December 2004. This
article reviews past studies on E-waste and briefly describes the topics presented and discussions held at the workshop. The
topics at the workshop included E-waste generation, recycling systems, international trade, and environmental impacts. In
addition, we discussed various issues such as terminology, current environmental concerns, and possible solutions. Transboundary
shipments of E-waste should be conducted taking into consideration the concept of sustainable development. The direction of
future research and possible collaborations are also discussed. 相似文献
The applications of chlorine have been broadly used in many industrial products, such as bleaching agents, synthetic rubbers, plastics, disinfectants, iron chlorides, fire refractory materials, insecticides, and anti-freezers, etc. According to the Taiwan Environmental Protection Administration (TEPA), more than 30 thousand tons were used in the year 2000. In addition, there were more than 12 reported incidents from 2000 to 2003—mostly on using chlorine as disinfectants (five) and as process agents (four).
This study investigated 15 chlorine operation plants in central Taiwan. These chlorine usages included bleaching agents, disinfectants, iron chloride, synthesizing rubber plastics, and others. Thirteen plants were located in the industrial parks and two were in or near residential zones. The consequence analysis were used three different methods to analyze the worst-case scenarios (WCSs) and alternative release case scenarios (ACSs) in order to compare impact zones for applying various active and passive mitigation systems, such as confined space, scrubber, water-spray, and so no. For two plants in or near residential zones, multi-layers mitigation systems and operation limits should be implemented in order to enforce more stringent protection measures. However, there was no specific regulation for chlorine plants operated at different locations, such as industrial parks or residential zones. In order to reduce chemical accidents and their impacts on public safety, our results suggest that source mitigation/management and warning systems should be adopted simultaneously. 相似文献
Sustainable development goals are achievable through the installation of Material Recovery Facilities (MRFs) in certain solid waste management systems, especially those in rapidly expanding multi-district urban areas. MRFs are a cost-effective alternative when curbside recycling does not demonstrate long-term success. Previous capacity planning uses mixed integer programming optimization for the urban center of the city of San Antonio, Texas to establish that a publicly owned material recovery facility is preferable to a privatized facility. As a companion study, this analysis demonstrates that a MRF alleviates economic, political, and social pressures facing solid waste management under uncertainty. It explores the impact of uncertainty in decision alternatives in an urban environmental system. From this unique angle, waste generation, incidence of recyclables in the waste stream, routing distances, recycling participation, and other planning components are taken as intervals to expand upon previous deterministic integer-programming models. The information incorporated into the optimization objectives includes economic impacts for recycling income and cost components in waste management. The constraint set consists of mass balance, capacity limitation, recycling limitation, scale economy, conditionality, and relevant screening restrictions. Due to the fragmented data set, a grey integer programming modeling approach quantifies the consequences of inexact information as it propagates through the final solutions in the optimization process. The grey algorithm screens optimal shipping patterns and an ideal MRF location and capacity. Two case settings compare MRF selection policies where optimal solutions exemplify the value of grey programming in the context of integrated solid waste management. 相似文献