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201.
Finn Stener Jørgensen MD Jens Bang Anne-Marie Lind Britta Christensen Claes Lundsteen John Philip 《黑龙江环境通报》1992,12(4):277-283
Genetic amniocentesis performed at 7–14 weeks of gestation was studied in a series of 138 patients of whom 50 wanted termination of pregnancy (⩽ 12 weeks). The material for analysis consisted of 132 samples due to two sampling failures and four samples being handled incorrectly. Forty-eight samples (36 per cent) were taken at 7–12 weeks of gestation, mainly transvaginally (36/48:75 per cent). The success rate of culture and karyotyping increased with the duration of pregnancy, but was only satisfactory from week 11 onwards. The time until harvest was then 14–15 days. The transvaginal approach is easy to perform and was accepted by the women, but we experienced bacterial or fungal overgrowth in 17 per cent of these samples, whereas no infection occurred in the samples taken transabdominally (n = 96). We conclude that genetic amniocentesis is feasible from week 11, but further studies concerning side effects, especially focusing on the procedure-related abortion risk, should be carried out before early amniocentesis is routinely applied. 相似文献
202.
Louis V. Verchot Meine Van Noordwijk Serigne Kandji Tom Tomich Chin Ong Alain Albrecht Jens Mackensen Cynthia Bantilan K. V. Anupama Cheryl Palm 《Mitigation and Adaptation Strategies for Global Change》2007,12(5):901-918
Agriculture is the human enterprise that is most vulnerable to climate change. Tropical agriculture, particularly subsistence
agriculture is particularly vulnerable, as smallholder farmers do not have adequate resources to adapt to climate change.
While agroforestry may play a significant role in mitigating the atmospheric accumulation of greenhouse gases (GHG), it also
has a role to play in helping smallholder farmers adapt to climate change. In this paper, we examine data on the mitigation
potential of agroforestry in the humid and sub-humid tropics. We then present the scientific evidence that leads to the expectation
that agroforestry also has an important role in climate change adaptation, particularly for small holder farmers. We conclude
with priority research questions that need to be answered concerning the role of agroforestry in both mitigation and adaptation
to climate change. 相似文献
203.
Volatile iodinated organic compounds play an important role in the tropospheric photochemical system, but the current knowledge of the known sources and sinks of these alkyl iodides is still incomplete. This paper describes a new source of alkyl iodides from the pedosphere. Different organic-rich soils and humic acid were investigated for their release of volatile organoiodides. Six volatile organoiodides, iodomethane, iodoethane, 1-iodopropane, 2-iodopropane, 1-iodobutane and 2-iodobutane were identified and their release rates were determined. We assume an abiotic reaction mechanism induced by the oxidation of organic matter by iron(III). The influence of iron(III), iodide and pH on the formation of alkyl iodides was investigated. Additionally, different organic substances regarded as monomeric constituents of humus were examined for the production of alkyl iodides. Two possible reaction pathways for the chemical formation of alkyl iodides are discussed. As humic acids and iron(III) are widespread in the terrestrial environment, and the concentration of iodide in soil is strongly enriched (compared to seawater), this soil source of naturally occurring organoiodides is suggested to contribute significantly to the input of iodine into the troposphere. 相似文献
204.
The mechanisms and functions of mixed-species shoaling were investigated in two sympatric species of cyprinids, the chub and the European minnow, from the river Wharfe where they comprised approximately 70% of all year 0+ fish over a 20-year survey. Chub preferred conspecific shoals over heterospecific ones with olfactory cues being more important than visual ones for shoal choice. This preference was consistent with measurements of length:flank area ratios and length:weight ratios which suggest that both species are similar in appearance. When presented with mixed-species shoals, chub increased the percentage time spent with stimulus shoals with increasing proportions of conspecifics. Feeding experiments suggest that the preference for conspecific shoals is driven by interspecific competition (with minnows out-competing similar-sized chub) and the oddity effect. The importance of this work in the context of species assortment in free-ranging shoals is discussed. 相似文献
205.
This paper analyses some of the higher education and research capacity building experiences gained from 1998-2006 by Danish and Malaysian universities. The focus is on waste management, directly relating to both the environmental and socio-economic dimensions of sustainable development. Primary benefits, available as an educational legacy to universities, were obtained in terms of new and enhanced study curricula established on Problem-oriented Project-based Learning (POPBL) pedagogy, which strengthened academic environmental programmes at Malaysian and Danish universities. It involved more direct and mutually beneficial cooperation between academia and businesses in both countries. This kind of university reach-out is considered vital to development in all countries actively striving for global and sustainable development. Supplementary benefits were accrued for those involved directly in activities such as the 4 months of field studies, workshops, field courses and joint research projects. For students and academics, the gains have been new international dimensions in university curricula, enhanced career development and research collaboration based on realworld cases. It is suggested that the area of solid waste management offers opportunities for much needed capacity building in higher education and research, contributing to sustainable waste management on a global scale. Universities should be more actively involved in such educational, research and innovation programmes to make the necessary progress. ISWA can support capacity building activities by utilizing its resources--providing a lively platform for debate, securing dissemination of new knowledge, and furthering international networking beyond that which universities already do by themselves. A special challenge to ISWA may be to improve national and international professional networks between academia and business, thereby making education, research and innovation the key driving mechanisms in sustainable development in solid waste management. 相似文献
206.
Availability of radium isotopes and heavy metals from scales and tailings of Polish hard coal mining
Radium and heavy metal contaminated tailings and scales resulting from Polish hard coal mining were investigated for their mobilisation potential by using leaching methods. The main focus is set on a three-step extraction procedure proposed by BCR (Bureau Communautaire de Référence, now Standards Measurements and Testing Programme) of the European Union, which was used for investigating the availability of radium isotopes. In addition, the results of a Polish extraction procedure for the heavy metals' water solubility are presented for rough comparison. After a special treatment, the BCR-reagents were measured by gamma-spectrometry to define their radium activity concentrations; the heavy metal content in the water soluble fractions was determined by ICP-AES. The samples were collected at two different sites influenced by the discharge of pit water from hard coal mining. The tailings were taken from a former tailing pond, which now is no longer in use, but the settled material is still present. At another abandoned and meanwhile flooded tailing pond, the scales were scraped from the inside of a discharge tube. The results obtained show that there is different leaching behaviour between the radium isotopes. The tailings being characterised by surface adsorbed radium provide up to 25% of the initial (226)Ra content, (228)Ra is altogether leached up to 15%. The scales comprise stable radiobaryte (Ba[Ra]SO(4)) and can be considered as being unable to provide radium isotopes, since no trace of radium dissolution was observed. The leaching behaviour of heavy metals is similar to that of radium. Mn, Ni and Zn are dissolved by water from the tailings; the scales do not provide any. 相似文献
207.
Kruse J Negassa W Appathurai N Zuin L Leinweber P 《Journal of environmental quality》2010,39(6):2179-2184
The phosphorus (P) in agro-industrial by-products--a potential source of freshwater eutrophication but also a valuable fertilizer--needs to be speciated to evaluate its fate in the environment. We investigated to what extent X-ray absorption near edge structure (XANES) spectroscopy at the P K- and L2.3-edges reflected differences in sequentially extracted filter cakes from sugarcane (Saccharum officinarum L.) (FIC) and niger seed (Guizotia abyssinica Cass.; NIC) processing industry in Ethiopia. The P fractionation removed more labile (54%) and H2SO4-P (28%) from FIC than from NIC (18% labile, 12% H2SO4-P). For the FIC residues after each extraction step, linear combination (LC) fitting of P K-edge spectra provided evidence for the enrichment of Ca-P after the NaOH-extraction and its almost complete removal after the H2SO4-treatment. The LC-fitting was unsuccessful for the NIC samples, likely because of the predominance of organic P compounds. The different proportions of Ca-P compounds between FIC (large) and NIC (small) were more distinctive in L2-than in the K-edge XANES spectra. In conclusion, the added value of complementary P K- and L2.3-edge XANES was clearly demonstrated, and the P fractionation and speciation results together justify using FIC and NIC as soil amendments in the tropics. 相似文献
208.
Organic Farming and Soil Carbon Sequestration: What Do We Really Know About the Benefits? 总被引:1,自引:0,他引:1
Organic farming is believed to improve soil fertility by enhancing soil organic matter (SOM) contents. An important co-benefit
would be the sequestration of carbon from atmospheric CO2. Such a positive effect has been suggested based on data from field experiments though many studies were not designed to
address the issue of carbon sequestration. The aim of our study was to examine published data in order to identify possible
flaws such as missing a proper baseline, carbon mass measurements, or lack of a clear distinction between conventional and
organic farming practices, thereby attributing effects of specific practices to organic farming, which are not uniquely organic.
A total of 68 data sets were analyzed from 32 peer-reviewed publications aiming to compare conventional with organic farming.
The analysis revealed that after conversion, soil C content (SOC) in organic systems increased annually by 2.2% on average,
whereas in conventional systems SOC did not change significantly. The majority of publications reported SOC concentrations
rather than amounts thus neglecting possible changes in soil bulk density. 34 out of 68 data sets missed a true control with
well-defined starting conditions. In 37 out of 50 cases, the amount of organic fertilizer in the organic system exceeded that
applied in the compared conventional system, and in half of the cases crop rotations differed between systems. In the few
studies where crop rotation and organic fertilization were comparable in both systems no consistent difference in SOC was
found. From this data analysis, we conclude that the claim for beneficial effects of organic farming on SOC is premature and
that reported advantages of organic farming for SOC are largely determined by higher and often disproportionate application
of organic fertilizer compared to conventional farming. 相似文献
209.
Ove C. Mφrck Jens O. Hansen 《生态毒理学报》2001,23(3):16-17
MEDUCA(教育性建筑模式)项目包括7个国家的8个示范项目.这些项目分布在挪威的格龙(65°);瑞典的哥德堡(58°N);瑞典的Falkenberg(57°N);丹麦的巴勒鲁普(56°N);德国的新明斯特(54°N);西班牙的阿尔梅里亚(36°50'N);意大利的Bagheria(38°N);和希腊的Legraina(38°N). 相似文献
210.
Zoobenthos as indicators of ecological status in coastal brackish waters: a comparative study from the Baltic Sea 总被引:2,自引:0,他引:2
A new method for classifying soft-bottom zoobenthic assemblages along the Finnish coasts (northern Baltic Sea) is presented and tested against traditional physicochemical monitoring data in the complex Archipelago Sea. Although multivariate methods for assessing the state of the marine environment have become widely used, few numerical indices can operate over a wide salinity range. We compare indices currently in use and propose a new index, BBI (brackish water benthic index), for the low-saline and species-poor Baltic coastal waters. BBI offers a salinity-corrected tool for classification of the soft-bottom zoobenthos under the demands of the European Union Water Framework Directive. 相似文献