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111.
R Burt M.A WilsonT.J Keck B.D Dougherty D.E StromJ.A Lindahl 《Advances in Environmental Research》2003,8(1):51-67
Long-term copper smelting in the Anaconda and Deer Lodge Valley area of Montana has resulted in an extensive area of trace element contamination. Aerial extent of contamination is generally established, but total analysis of soils does not correlate to relative degree of impact on vegetation growth. Three pedons (Beaverell, Cetrack and Judco) were analyzed by routine soil characterization methods, aqua regia microwave digestion, sequential chemical extraction, and X-ray diffraction analysis with the objective of providing a better understanding of chemical forms and potential reactivity of selected trace elements (Cd, Co, Cr, Cu, Hg, Mn, Ni, P, Pb). Surface horizons of soils are more acidic than subsoils, with pH for all horizons ranging from 4.0 to 8.7. Beaverell is the most contaminated in the upper 20 cm with the sum of total extractable (SUMTE) trace elements by microwave digestion ranging from 1836 to 3605 mg kg−1, largest H2O-soluble (WS) and exchangeable (EX) fractions (e.g. 1.6 and 9.3%, respectively), and smallest residual (RES) fraction (e.g. 14.3%). Cetrack has greater SUMTE elements than Judco, though a lower WS+EX fraction due to the effects of alkaline pH, carbonates and high P. Oxide (OX), organic matter/sulfide (OM/S), and RES fractions predominate over WS, EX, and specially-sorbed/carbonate-bound fractions (SS/CAR) for all horizons. Copper, Zn, Pb and Cd are elevated in surface over subsurface horizons in these latter fractions, indicating these elements were anthropogenic additions. X-ray data indicate that Pb, Cu, Cr and Cd partially exists as both OX and sulfide mineral forms. 相似文献
112.
Gamergates (i.e. mated reproductive workers) are mostly known from ant species within the Ponerinae. We report here the discovery of gamergates in two species of the subfamily Myrmicinae. Until now, mated reproductive females in colonies of myrmicine species have been considered morphologically distinct from the worker caste. However, in two species of the myrmicine Metapone (Metapone madagascarica and a newly discovered, not yet described Metapone species) all workers have six ovarioles and a spermatheca; and some of them are mated. There are no morphological differences between mated and non-mated workers. Field observations and laboratory studies indicate that colonies of the Metapone species can reproduce with gamergates only. 相似文献
113.
Urban Flood Damage and Greenhouse Scenarios - The Implications for Policy: An Example from Australia
Urban flooding is often used as an illustration of the potentially adverse effects of greenhouse-induced climate change on extreme events. There is however, a paucity of studies that convert climate scenarios into changes in flood damage. This account summarises the use of modelling techniques, for three flood prone urban catchments in south eastern Australia, to assess changes to urban flood losses for the 'most wet' and 'most dry' scenarios for the year 2070. The most wet scenario indicates that annual average flood damage could increase within the range of 2.5 to 10 times, under the most dry scenario flood regimes would be similar to those experienced at present. The socio-economic scenarios based on the changes to flood losses are used to consider policy responses. It is unlikely that many local government authorities will respond because of lack of interest and because of major changes to the climate scenarios proposed over the last decade. Any response is likely to be incremental and accord with the 'no regrets' and the precautionary principle'. 相似文献
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Intergeneric transmission of a marine plant DNA virus 总被引:1,自引:0,他引:1
D. G. Müller 《Die Naturwissenschaften》1992,79(1):37-39
117.
David Jeffrey Gray D.O. Haynes B. Robinson James Malone Richard B. Thomson Jr 《黑龙江环境通报》1992,12(2):111-117
Infections in pregnancy with Ureaplasma urealyticum have been associated with a wide range of adverse outcomes, such as early abortion, stillbirth, prematurity, and neonatal morbidity and mortality. Causality has been difficult to demonstrate secondary to the high prevalence of asymptomatic lower genital tract (LGT) colonization and culture data from inaccessible or potentially contaminated sites. Between 1985 and 1989, 2461 second-trimester genetic amniocenteses were evaluated at the cytogenetics section of the Children's Hospital Medical Center of Akron. All were cultured for the genital mycoplasmas: Mycoplasma hominis and Ureaplasma urealyticum. A total of nine patients were positive, all for Ureaplasma urealyticum, with one patient excluded because of subsequent therapeutic abortion. In addition, complete follow-up data, such as indication for amniocentesis, serum alpha-fetoprotein levels, gestational age at parturition, and out- come of pregnancy, were available on 86 Ureaplasma-negative (U –) patients during an approximate 2-year span within the time-frame of the study. This was in part due to physician response to a questionnaire sent after amniocentesis. Of the eight positive cultures, 100 per cent were associated with an adverse outcome, defined as fetal loss or premature delivery. This was significant compared with the U–group (p<0.001) with a more than eight times greater risk of adverse outcome. Six (75 per cent) resulted in spontaneous miscarriage within 4 weeks of amniocentesis and at less than 21 weeks' gestation. Two (25 per cent) delivered prematurely, with one (12.5 per cent) neonatal death at 24+ weeks. Histological examination of all eight placentae and the seven fetuses revealed a 100 per cent incidence of chorioamnionitis and pneumonia, respectively. In addition, in four of the five cases (80 per cent), cultures were positive for Ureaplasma urealyticum in pure culture from either placenta, fetal lung, or both tissues. The remaining case (20 per cent) was negative for aerobes, anaerobes, and mycoplasmas. The study demonstrates a significant association and supports a causal relationship between isolation of Ureaplasma from mid-trimester amniotic fluid with fetal wastage and premature birth. 相似文献
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We describe our experience of prenatal diagnosis of non-ketotic hyperglycinaemia in four at-risk pregnancies using the glycine/serine ratio in amniotic fluid obtained between 18 and 20 weeks of gestation. All glycine levels were in the normal range. Serine levels were normal in two patients and borderline in the others. Glycine/serine ratios were normal in two patients, moderately increased in one patient ( + 3 SD), and highly increased in one patient ( + 8 SD). All the children were perfectly normal at birth. Because of this false-positive prediction and the false-negative prediction recently reported, we suggest that this unreliable method should not be used. 相似文献