Quantification of the effect of fumigation on short- and long-term nitrogen mineralization and nitrification in different soils

The effect of soil fumigation on N mineralization and nitrification needs to be better quantified to optimize N fertilizer advice and predict NO(-)(3) concentrations in crops and NO(-)(3) leaching risks. Seven soils representing a range in soil texture and organic matter contents were fumigated with Cyanamid DD 95 (a mixture of 1,3-dichloropropane and 1,3-dichloropropene). After removal of the fumigant, the fumigated soils and unfumigated controls were incubated for 20 wk and N mineralization and nitrification were monitored by destructive sampling. The average short-term N mineralization rates (k(s)) were significantly larger in the fumigated than in the unfumigated soils (P = 0.025), but the differences in k(s) between fumigated and unfumigated soils could not be related to soil properties. The average long-term N mineralization rates (k(l)) were slightly larger in the fumigated soils but the difference with the unfumigated soils was not significant. Again, the differences in k(l) values could not be related to soil properties. Nitrification was inhibited completely for at least 3 wk in all soils, and an effect on nitrification could be observed up to 17 wk in one soil. An S-shaped function was fitted to the nitrification data corrected for N mineralization, and both the rate constant (gamma) and the time at which maximum nitrification was reached (t(max)) were strongly correlated to soil pH. However, since no correlations were found between the effect of fumigation on N mineralization and soil properties, taking into account the effects of fumigation in fertilizer advice and in the prediction of NO(-)(3) leaching risks will need further research.     

城市及其遗产：保存的根源和条件

城市遗产的保存和利用将都市管理的负责人置于艰难选择的境地 .下面的文字对城市的构成进行了简短的历史回顾,得出了在场所利用及其保存之间保持平衡发展条件 .     

Improving the health and safety of 911 emergency call centre agents: an evaluability assessment of a knowledge transfer strategy

A knowledge transfer (KT) strategy was implemented by the IRSST, an occupational health and safety research institute established in Québec (Canada), to improve the prevention of psychological and musculoskeletal problems among 911 emergency call centre agents. An evaluability assessment was conducted in which each aspect of the KT approach was documented systematically to determine whether the strategy had the potential to be evaluated in terms of its impact on the targeted population. A review of the literature on KT in occupational health and safety and on the evaluation of such KT programmes, along with the development of a logic model based on documentary analysis and semi-structured interviews with key stakeholders, indicated that the KT strategy was likely to have had a positive impact in the 911 emergency call centre sector. Implications for future research are discussed.     

Habitat use of a multispecific seagrass meadow by green turtles Chelonia mydas at Mayotte Island

We investigated the habitat use in green turtles exploiting a 13-ha multispecific seagrass meadow at Mayotte Island, south-western Indian Ocean. A phyto-ecological survey shows the occurrence of eight seagrass species, dominated by Halodule uninervis and Syringodium isoetifolium, distributed according to four distinct seagrass communities along the depth gradient. Direct underwater censuses show that green turtles occurred all over the meadow. Yet when community relative surface area was taken into account green turtles preferentially frequented the most seaward, biomass-richer S. isoetifolium-dominated community, suggesting that green turtles compensate for their intrinsically nutrient-poor herbivorous diet. Additionally, smaller (<80 cm standard curved carapace length, SCCL) individuals also preferentially occurred in the most shoreward H. univervis-dominated community where no larger (>80 cm SCCL) individuals were sighted, suggesting habitat use is indicative of diet selection and may reflect size-specific food requirements and physiology.     

An Evaluation of Air Pollution Health Impacts and Costs in São Paulo, Brazil

The need to determine cost estimates of the hazardous effects of diseases is important in order to establish the priorities of actions for prevention and health management. The evaluation of air pollution impacts on health, based on expenditures, has been carried out, but there are obvious comparison difficulties among countries, as the health-per-capita investment varies enormously. In order to achieve a standard indicator, we applied the Disability-Adjusted Life Years (DALY) method to estimate the health burden and cost estimate due to air pollution in São Paulo, Brazil. The basic methodology was the utilization of dose–response curves of epidemiological studies conducted in São Paulo to assess air pollution and its health effects. DALY attributable to air pollution in São Paulo added up to 28,212 years annually. An indirect health cost attributable to air pollution resulted in US$ 3,222,676. This estimate refers to the children and the elderly population. These results give a preliminary and underestimated value of the burden of diseases promoted by air pollution.     

Quantifying chlorinated ethene degradation during reductive dechlorination at Kelly AFB using stable carbon isotopes

Stable isotope analysis of chlorinated ethene contaminants was carried out during a bioaugmentation pilot test at Kelly Air Force Base (AFB) in San Antonio Texas. In this pilot test, cis-1,2-dichloroethene (cDCE) was the primary volatile organic compound. A mixed microbial enrichment culture, KB-1, shown in laboratory experiments to reduce chlorinated ethenes to non-toxic ethene, was added to the pilot test area. Following bioaugmentation with KB-1, perchloroethene (PCE), trichloroethene (TCE) and cDCE concentrations declined, while vinyl chloride (VC) concentrations increased and subsequently decreased as ethene became the dominant transformation product. Shifts in carbon isotopic values up to 2.7 per thousand, 6.4 per thousand, 10.9 per thousand and 10.6 per thousand were observed for PCE, TCE, cDCE and VC, respectively, after bioaugmentation, consistent with the effects of biodegradation. While a rising trend of VC concentrations and the first appearance of ethene were indicative of biodegradation by 72 days post-bioaugmentation, the most compelling evidence of biodegradation was the substantial carbon isotope enrichment (2.0 per thousand to 5.0 per thousand) in ?13C(cDCE). Fractionation factors obtained in previous laboratory studies were used with isotope field measurements to estimate first-order cDCE degradation rate constants of 0.12 h(-1) and 0.17 h(-1) at 115 days post-bioaugmentation. These isotope-derived rate constants were clearly lower than, but within a factor of 2-4 of the previously published rate constant calculated in a parallel study at Kelly AFB using chlorinated ethene concentrations. Stable carbon isotopes can provide not only a sensitive means for early identification of the effects of biodegradation, but an additional means to quantify the rates of biodegradation in the field.     

Fetal fibrochondrogenesis at 26 weeks' gestation

An Erratum has been published for this article in Prenatal Diagnosis 22(13) 2002, 1241. Fibrochondrogenesis is a rare and lethal osteochondrodysplasia with an autosomal recessive mode of inheritance. We report a male fetus in which the diagnosis of lethal osteochondrodysplasia was suspected on prenatal ultrasound and radiological examinations during the second trimester of pregnancy. After termination of pregnancy, fibrochondrogenesis was diagnosed by radiological examination and histological study of fetal bones. Interwoven fibrous septa and fibroblastic degeneration of chondrocytes are pathognomonic. The recurrence rate is 25% and accurate diagnosis is necessary to enable genetic counselling. Copyright © 2002 John Wiley & Sons, Ltd.