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651.
The US economy annually needs over 4 billion tons of new mineral supplies. The value of domestically produced energy and processed materials of mineral origin exceeds $175 billion annually, but domestic production of both raw and processed minerals is not keeping pace with demand. 相似文献
652.
A fetal abnormality detected at 15 weeks by ultrasound consisted of cystic appearing masses in the neck and back region. The differential diagnosis included gonadal dysgenesis (Turner's syndrome) with cystic hygroma, neural tube defect, e.g. encephalocele or meningomyelocele, and fetal hydrops. Intrauterine fetal demise occurred at 17 weeks. The fetus had marked edema possibly related to umbilical cord occlusion. 相似文献
653.
Utilization of amniocentesis for prenatal diagnosis because of the indication of advanced maternal age (≥ 35 years at delivery) was examined in the population of B.C. over an 8-year period (1976–1983). As of 1983, approximately one out of three eligible women (≥ 35 years at delivery) is having the test. In the older group (≥ 38 years at delivery) approximately one out of two eligible women is having the test. The data do not indicate that the proportion of eligible women having amniocentesis has reached a plateau; utilization is continuing to increase. It appears that prenatal diagnosis is an ethically acceptable alternative for a large proportion of the population. 相似文献
654.
655.
Neanthes arenaceodentata (Moore) accumulates glycine –C14 from a dilute solution of seawater. After a 30 min exposure, 5 to 102 times as much radioactivity per unit volume is found in the animals (depending on the size and feeding stage of the worm) as is present in the medium. The relation between the log of cpm and log of weight is linear over 4 orders of magnitude variation in size. The rates of uptake were more variable in non-feeding stages of the life cycle. Non-feeding larvae showed rates of glycine accumulation which were significantly higher than those predicted from data on feeding stages.This work was supported in part by PHS Grant GM 12889 to the University of California, Irvine. 相似文献
656.
The variations of aluminium species in mountainous forest soils and its implications to soil acidification 总被引:1,自引:0,他引:1
Monika?BradováEmail author Václav?Tejnecky Lubo??Bor?vka Karel?Něme?ek Christopher?Ash Ond?ej??ebek Miroslav?Svoboda Jitka?Zenáhlíková Ond?ej?Drábek 《Environmental science and pollution research international》2015,22(21):16676-16687
Aluminium (Al) speciation is a characteristic that can be used as a tool for describing the soil acidification process. The question that was answered is how tree species (beech vs spruce) and type of soil horizon affect Al speciation. Our hypotesis is that spruce and beech forest vegetation are able to modify the chemical characteristics of organic horizon, hence the content of Al species. Moreover, these characteristics are seasonally dependent. To answer these questions, a detailed chromatographic speciation of Al in forest soils under contrasting tree species was performed. The Jizera Mountains area (Czech Republic) was chosen as a representative mountainous soil ecosystem. A basic forestry survey was performed on the investigated area. Soil and precipitation samples (throughfall, stemflow) were collected under both beech and spruce stands at monthly intervals from April to November during the years 2008–2011. Total aluminium content and Al speciation, pH, and dissolved organic carbon were determined in aqueous soil extracts and in precipitation samples. We found that the most important factors affecting the chemistry of soils, hence content of the Al species, are soil horizons and vegetation cover. pH strongly affects the amount of Al species under both forests. Fermentation (F) and humified (H) organic horizons contain a higher content of water extractable Al and Al3+ compared to organo-mineral (A) and mineral horizons (B). With increasing soil profile depth, the amount of water extractable Al, Al3+ and moisture decreases. The prevailing water-extractable species of Al in all studied soils and profiles under both spruce and beech forests were organically bound monovalent Al species. Distinct seasonal variations in organic and mineral soil horizons were found under both spruce and beech forests. Maximum concentrations of water-extractable Al and Al3+ were determined in the summer, and the lowest in spring. 相似文献
657.
Ewa Łuszczek-Trojnar Ewa Drąg-Kozak Włodzimierz Popek 《Environmental science and pollution research international》2013,20(5):3122-3132
We studied the bioaccumulation of lead in selected tissues of Prussian carp Carassius gibelio (Bloch, 1782) during 12 and 24 months exposure to different doses of this metal in feed and the elimination of lead from tissues during the following 12-month depuration period. Lead concentration was determined using atomic absorption spectrometry method. The highest lead concentrations were observed at 2.0?±?0.54 to 7.4?±?1.1 mg?kg?1 in the kidney, 3.0?±?0.13 to 5.2?±?0.17 mg?kg?1 in the bone, and 4.5 (±0.4)?mg?kg?1 in the hepatopancreas of fish from groups exposed to lead dietary concentration from 8 to 49 mg?kg?1 for 24 months. The rate of accumulation were generally the highest at the beginning of exposure as evidenced by the highest monthly increments of bioaccumulation observed after 3 months of contamination for muscles, hepatopancreatic gland, intestine, and gills. Also analysis of the monthly increments of lead bioaccumulation in bone tissue and the highly significant coefficients of correlation indicate that the dynamics of accumulation are clearly dependent on dose of exposure. Depuration of accumulated lead from the organs depended mainly on tissue and duration of elimination period. Very rapid depuration was observed in soft tissues such as the intestine or muscles. Very low elimination was observed for scales and bones where until the end of the experiment highly significant lead concentration differences were observed in all groups in relation to the control group. Chronic dietary exposure in the range of 8–49 mg Pb?kg?1 resulted in no significant effects on the growth and survival of Prussian carp females. 相似文献
658.
The Journal of the Air Pollution Control Association presents its third directory of air pollution control consultants. This 8-page guide lists individual consultants and firms who have indicated a capability in this field by responding to a questionnaire published in three consecutive issues of the Journal. The listing gives corporate names, addresses and phone numbers alphabetically within five broad geographic areas which are shown below. 相似文献
659.
Carl M. Shy M.D. Dr. P.H John P. Creason M.S. Martin E. Pearlman M.D. Kathryn E. McClain Ferris B. Benson Marion M. Young M.D. 《Journal of the Air & Waste Management Association (1995)》2013,63(9):582-588
A study of acute respiratory illness was conducted from November 1968 through April 1969 among families residing in an area of relatively high nitrogen dioxide exposure, in an area of elevated suspended particulate exposure, and in two control areas of Greater Chattanooga. Respiratory illness rates were consistently higher in all family segments in the high-nitrogen dioxide exposure area when rates were averaged for the entire 24 weeks of study, the A2/Hong-Kong epidemic period, or post-epidemic interval. A relative excess in respiratory illness of 18.8 percent was found among families exposed to elevated NO2 concentrations and an excess of 10.4 percent was found among families in the elevated-suspended particulate exposure area. 相似文献
660.
Dr Jo Williams 《Journal of Environmental Planning and Management》2008,51(1):107-140
The new housing growth programme planned for England and Wales between now and 2016 could provide the government with an opportunity to build housing to significantly higher environmental performance (EP) standards. Equally, if the government continues with its current strategy a great opportunity could be missed. This paper considers and critically analyses the government's approach to ensuring higher EP standards in new housing. Using Greenwich Millennium Village as a case study it assesses the likely outcomes of the approach. It suggests how regulation, fiscal incentives and educational programmes could help to deliver better EP amongst housing and households in the growth region. 相似文献