1998年珊瑚死亡事件对肯尼亚珊瑚礁和渔业的影响

为了评价1998年珊瑚脱色和死亡事件的影响,在南肯尼亚收集了有关珊瑚礁生态系统和渔业的数据.我们比较了1998年前3年和后3年在未经捕捞的海洋公园和经受捕捞的珊瑚礁区中的海底覆盖物、海胆和鱼类丰度及与珊瑚礁有关的渔业.     

Evaluation of an integrative masters program in occupational health at the Tel Aviv University Medical School

Tel Aviv University conducts the Master's program in occupational health in Israel. The program is composed from three different disciplines: occupational physicians, industrial hygienists and psychosocial workers. The aim of the program was to train graduate academic professionals for the developing occupational health system in Israel. The program is a two year study, opens every second year and accommodates about thirty students per class. After the second class, comprehensive assessment was conducted by the Unit of Medical Education. The evaluation was done by means of personal interview of class leaders, teachers and students, using structured questionnaires. A similar evaluation was again conducted after graduation of the fourth class in 1993. Three aims of the assessment were defined: to learn about the students' and teachers' expectations of the course, the level of integration achieved between the occupational health professionals in the three disciplines; and to evaluate the employment status of the graduates upon completion of the course. Following the first evaluation, changes were implemented in the methods of student selection for the program. A new entering examination was constructed to ensure a common basic knowledge of the potential students in the three disciplines. Changes were also made in the curriculum regarding teaching hours and subjects. A major problem at that time was that most of the graduates could not find positions in the field, because of low awareness for occupational health in Israel. In the second evaluation done in 1993 a higher level of satisfaction of students and teachers from the program was noted. The average level of the accepted students was higher compared with those accepted earlier. Better and deeper integration between the three disciplines of studies was appreciated. More graduates of the program found jobs in the area of occupational health and there is a higher level of awareness of employers and high regards to the course.     

Sorption of apolar aromatic compounds to soil humic acid particles affected by aluminum(III) ion Cross-Linking

Sorption of hydrophobic compounds in soils often shows nonlinearity, competition, and hysteresis. Since such behaviors have been associated with organic polymers in glassy state, it has been postulated that some forms of soil humic substances are glassy. The glassy state is favored by properties that decrease the flexibility of macromolecules, such as cross-linking, presence of unsaturated bonds, and high molecular weight. Polyvalent metal ions, which are abundant in soils, may cross-link humic substances by coordinating to multiple functional groups on different strands. Accordingly, we prepared an Al(3+)-cross-linked humic acid (Al-HA) from the H(+) form (H-HA) of a soil humic acid by a flocculation technique that leaves Al ions bound to organic groups. Sorption of naphthalene and 1,2,4-trichlorobenzene (TCB) on H-HA was nonlinear, competitive, and slightly hysteretic, in agreement with previous studies showing glass transition temperatures of humic acids that lie above room temperature. Nonlinearity, competition, and hysteresis were all enhanced in Al-HA, validating the hypothesis that metal ion cross-linking enhances nonideal sorption. Application of a glassy polymer sorption model reveals that cross-linking increases the affinity of solutes for the hole domain relative to the dissolution domain. The results (i) indicate that isolated, purified soil humic acid behaves like a glassy solid, (ii) indicate that metal-ion cross-linking creates a more rigid-chain structure and supports a link between nonideal sorption and the glassy character of soil organic matter, and (iii) underscore the importance of metal ions on humic structure in relation to sorption of hydrophobic organic compounds.     

Facilities for diesel exhaust studies

It is the major intent of this report to examine the animal inhalation facilities at the EPA Health Effects Research Laboratory in Cincinnati, Ohio, associated with the exposure to the exhaust of diesel-powered equipment. The facility serves as a center for toxicologic evaluation, in relevant animal models, of potentially hazardous environmental pollutants from diesel engine exhaust. Briefly, the entire engine exhaust is mixed with filtered and conditioned air in a dilution tube. That diluted exhaust enters a large volume mixing chamber and a portion passes through dynamic flow irradiation chambers (to simulate sunlight) and is then conducted to animal exposure chambers. The system provides nonirradiated exhaust in the same concentration (directly from the mixing chamber) and also filtered, conditioned ambient air for control animal exposure. The major physical components of the diesel emission system include: air purifiers, animal exposure chambers, engine-dynamometers, irradiation chambers, monitoring instrumentation and data acquisition systems.     

Minimum Wet‐Season Flows and Levels in Southwest Florida Rivers1

Abstract: Regulation of river flows can result in decreased stage fluctuations and alteration of inundation patterns of floodplain wetlands. However, floodplain inundation has historically not been addressed in most minimum flow determinations. Florida law requires the water management districts of the state to establish minimum flows and levels to protect water bodies from significant harm associated with water withdrawals. The Southwest Florida Water Management District utilizes a 15% reduction in habitat criterion as a threshold for defining significant harm to freshwater segments of rivers. Utilizing a multi‐parameter approach and different habitat measures for seasonal flow periods, the District has recommended minimum flow compliance standards for the Alafia, Myakka and middle Peace rivers. For the high‐flow period, the District utilized a 15% reduction in the number of days of floodplain inundation (a temporal loss) as a significant harm threshold. This approach yielded allowable flow reductions of 8% for the Alafia and Peace rivers during the high‐flow season and a 7% allowable reduction of natural flows on the Myakka River. Comparison of changes in flows associated with temporal and spatial loss thresholds indicated that flow reductions required to effect a 15% spatial loss of habitat on the Alafia, Myakka and middle Peace rivers are higher than those that would yield a 15% temporal loss. This indicates that with respect to natural flow protection, the District’s consideration of temporal reductions in habitat for establishing minimum river flows for seasonal high‐flow periods is more conservative than the use of a spatial loss criterion.     

Visible-near infrared reflectance spectroscopy for rapid, nondestructive assessment of wetland soil quality

Recent evidence supports using visible-near infrared reflectance spectroscopy (VNIRS) for sensing soil quality; advantages include low-cost, nondestructive, rapid analysis that retains high analytical accuracy for numerous soil performance measures. Research has primarily targeted agricultural applications (precision agriculture, performance diagnostics), but implications for assessing ecological systems are equally significant. Our objective was to extend chemometrics for sensing soil quality to wetlands. Hydric soils posed two challenges. First, wetland soils exhibit a wider range of organic matter concentrations, particularly in riparian areas where levels range from <1% in sedimentation zones to >90% in backwater floodplains; this may mute spectral responses from other soil fractions. Second, spectral inference of cation concentrations in terrestrial soils is for oxidized species; under reducing conditions in wetlands, oxidation state variability is observed, which strongly affects chroma. Riparian soils (n = 273) from western Florida exhibiting substantial target parameter variability were compiled. After minimal pre-processing, soils were scanned under artificial illumination using a laboratory spectrometer. A multivariate data mining technique (regression trees) was used to relate post-processed reflectance spectra to laboratory observations (pH, organic content, cation concentrations, total N, C, and P, extracellular enzyme activity). High validation accuracy was generally observed (r2(validation) > 0.8, RPD > 2.0, where RPD is the ratio of the standard deviation of an attribute to the observed standard error of validation); where accuracy was lower, categorical models (classification trees) successfully screened samples based on diagnostic functional thresholds (validation odds ratio > 10). Graphical models verified significant association between predictions and observations for all parameters, conditioning on biogeochemical covariates. Visible-near infrared reflectance spectroscopy offers both cost and statistical power advantages; hydric conditions do not appear to constrain application.