用BaCl2滴定法快速测定硫酸盐的研究

用铬酸钡光度法、EDTA滴定法、间接原予吸收法、离子色谱法等方法测定SO4^2-检测上限都很低（12—200mg／L），且只适用于清洁水，若水样混浊则会引起较大的误差。有的地下水，SO4^2-浓度高迭44000mg／L，用BaCl2滴定法测定SO4^2-：测试水样，以溴酚蓝做酸碱指示剂，加1：50盐酸，调为pH=3．5，加入30ml异丙醇，以钍试荆做终点指示荆，滴加0．01mol／L BaCl2，砖红色为终点，根据BaCl2用量计算SO4^2-浓度。本方法快捷、准确、测定范围大，上限可迭2000mg／L，克服了光度法测定浑浊水样引起误差大的缺点。     

用BaCl2滴定法快速测定硫酸盐的研究

用铬酸钡光度法、EDTA滴定法、间接原子吸收法、离子色谱法等方法测定SO42-检测上限都很低(12-200mg/L),且只适用于清洁水,若水样混浊则全引起较大的误差.有的地下水,SO42-浓度高达44000mg/L,用BaCl2滴定法测定SO42-:测试水样,以溴酚蓝做酸碱指示剂,加1∶50盐酸,调为pH=3.5,加入30ml异丙醇,以钍试剂做终点指示剂,滴加0.01mol/L BaCl2,砖红色为终点,根据BaCl2用量计算SO42-浓度.本方法快捷、准确、测定范围大,上限可达2000mg/L,克服了光度法测定浑浊水样引起误差大的缺点.     

Landscape change: Perceptions and physical measures

This paper addresses questions of affective responses of residents of rural Arizona to changes in proximate community and riparian landscapes and the congruence of their perceptions of change with physical measures of change in those landscapes. Based on findings and concepts from previous studies, perceptions of change were assessed using a mail survey. Physical measures of land use and vegetation change were obtained from aerial photography for two points in time spanning approximately 13 years and were analyzed using a geographic information system. Significant differences were found in perceptions of change in the community and riparian landscapes. In contrast with previous findings, a majority of respondents found the changes as either improving or having no effect on landscape quality. Those who were more frequent users of the riparian landscape tended to be more aware of changes in it. The findings also suggest challenges for planners and resource managers working in rural areas adjacent to riparian landscapes.     

LEAD AND CADMIUM ASSOCIATED WITH SALTWATER INTRUSION IN A NEW JERSEY AQUIFER SYSTEM1

ABSTRACT: The U.S. Geological Survey collected ground-water samples from the upper and middle aquifers of the Potomac-Raritan-Magothy aquifer system in a 400-square-mile area of New Jersey from 1984 through 1986. Concentrations of lead were greater than the U.S. Environmental Protection Agency maximum contaminant level (MCL) of 50 micrograms per liter in water from 16 of 239 wells. The cencentrations of cadmium were greater than the MCL of 10 micrograms per liter in water from 10 to 241 wells. One-half of the wells that exceeded the lead MCL were in known areas of saltwater intrusion, as were all 10 wells that exceeded the cadmium MCL. The association of elevated concentrations of these metals with elevated concentrations of chloride indicates a mochanism related to saltwater intrusion.     

Intrauterine left chamber myocardial infarction of the heart and hydrops fetalis in the recipient fetus due to twin-to-twin transfusion syndrome

A rare complication of twin-to-twin transfusion syndrome (TTTS) is described: myocardial infarction of the recipient fetus. Myocardial infarction and hydrops are considered to be consequences of hypertension in the recipient. No other organs were affected. Pathological signs of intrauterine hypertension were estimated by the thickness of vessel walls and signs of hypertrophied myocardial cells. In the heart of the recipient fetus there was a chronic myocardial infarction near the apex cordis on the anterior wall with an aneurysm 4×5 mm in diameter. Diagnosis was based on light microscopic examination. The poor myocardial systolic function resulted in hydrops. Since the mother was administered β sympathomimetics in therapeutic doses the contribution of the drug to the myocardial infarction is uncertain, but we would like to suggest this as a possible adverse effect in TTTS. The present case is the first reported myocardial infarction in connection with the syndrome. Copyright © 2002 John Wiley & Sons, Ltd.     

Pulmonary stenosis and reactive right ventricular hypertrophy in the recipient fetus as a consequence of twin-to-twin transfusion

The present study describes an association between adverse outcome in the twin-to-twin transfusion syndrome (TTTS) and pulmonary stenosis or reactive right ventricular hypertrophy. Six discordant monozygotic twin pregnancies with TTTS are described. Ventricular hypertrophy and atrioventricular valvular regurgitation occurred in all the recipient twins with pulmonary valvular stenosis in three cases and infundibular stenosis in one case. The recipient twin in one pair and both twins in another pregnancy died as a consequence of immaturity but the remaining twins all survived. Surgical intervention was required in one baby for valvular pulmonary stenosis. Our observations suggest that elevated blood pressure in the transfusion recipient may play an important role in pathogenesis. We hypothesise that both pulmonary stenosis and right chamber hypertrophy are secondary to hemodynamic changes. Although we have found valvular pulmonary stenosis in three recipients and infundibular stenosis in only one, this (obstruction to outflow) could be due to right chamber hypertrophy. Copyright © 2001 John Wiley & Sons, Ltd.     

Native ecotypic variation and the role of host identity in the spread of an invasive herbivore, Cactoblastis cactorum

Environmental niche models (ENMs) have gained enormous popularity as tools to investigate potential changes in species distributions resulting from climate change and species introductions. Despite recognition that species interactions can influence the dynamics of invasion spread, most implementations of ENMs focus on abiotic factors as the sole predictors of potential range limits. Implicit in this approach is the assumption that biotic interactions are relatively unimportant, either because of scaling issues, or because fundamental and realized niches are equivalent in a species' native range. When species are introduced into exotic landscapes, changes in biotic interactions relative to the native range can lead to occupation of different regions of niche space and apparent shifts in physiological tolerances. We use an escaped biological control organism, Cactoblastis cactorum (Berg.), to assess the role of the environmental envelope as compared with patterns of host-herbivore associations based on collections made in the native range. Because all nonnative populations are derived from a single C. cactorum ecotype, we hypothesize that biotic interactions associated with this ecotype are driving the species' invasion dynamics. Environmental niche models constructed from known native populations perform poorly in predicting nonnative distributions of this species, except where there is an overlap in niche space. In contrast, genetic isolation in the native range is concordant with the observed pattern of host use, and strong host association has been noted in nonnative landscapes. Our results support the hypothesis that the apparent shift in niche space from the native to the exotic ranges results from a shift in biotic interactions, and demonstrate the importance of considering biotic interactions in assessing the risk of future spread for species whose native range is highly constrained by biotic interactions.     

Designing Systematic Conservation Assessments that Promote Effective Implementation: Best Practice from South Africa

Abstract:  Systematic conservation assessment and conservation planning are two distinct fields of conservation science often confused as one and the same. Systematic conservation assessment is the technical, often computer-based, identification of priority areas for conservation. Conservation planning is composed of a systematic conservation assessment coupled with processes for development of an implementation strategy and stakeholder collaboration. The peer-reviewed conservation biology literature abounds with studies analyzing the performance of assessments (e.g., area-selection techniques). This information alone, however, can never deliver effective conservation action; it informs conservation planning. Examples of how to translate systematic assessment outputs into knowledge and then use them for "doing" conservation are rare. South Africa has received generous international and domestic funding for regional conservation planning since the mid-1990s. We reviewed eight South African conservation planning processes and identified key ingredients of best practice for undertaking systematic conservation assessments in a way that facilitates implementing conservation action. These key ingredients include the design of conservation planning processes, skills for conservation assessment teams, collaboration with stakeholders, and interpretation and mainstreaming of products (e.g., maps) for stakeholders. Social learning institutions are critical to the successful operationalization of assessments within broader conservation planning processes and should include not only conservation planners but also diverse interest groups, including rural landowners, politicians, and government employees.     

Adverse health effects of outdoor air pollutants

Much research on the health effects of outdoor air pollution has been published in the last decade. The goal of this review is to concisely summarize a wide range of the recent research on health effects of many types of outdoor air pollution. A review of the health effects of major outdoor air pollutants including particulates, carbon monoxide, sulfur and nitrogen oxides, acid gases, metals, volatile organics, solvents, pesticides, radiation and bioaerosols is presented. Numerous studies have linked atmospheric pollutants to many types of health problems of many body systems including the respiratory, cardiovascular, immunological, hematological, neurological and reproductive/ developmental systems. Some studies have found increases in respiratory and cardiovascular problems at outdoor pollutant levels well below standards set by such agencies as the US EPA and WHO. Air pollution is associated with large increases in medical expenses, morbidity and is estimated to cause about 800,000 annual premature deaths worldwide [Cohen, A.J., Ross Alexander, H., Ostro, B., Pandey, K.D., Kryzanowski, M., Kunzail, N., et al., 2005. The global burden of disease due to outdoor air pollution. J Toxicol Environ Health A. 68: 1-7.]. Further research on the health effects of air pollution and air pollutant abatement methods should be very helpful to physicians, public health officials, industrialists, politicians and the general public.     

From synthesis to analysis and back again

This is a retrospective view of experiences and events centered around participation in the geography Ph.D program at Clark University in the early 1970s. It traces my career from that of a landscape architect practitioner-teacher to involvement as a graduate student with the Clark resources management group and to current research interests and activities. Two themes are highlighted, the effects of the Clark experience and the continuity of my interest in values, issues and problems related to landscapes.