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331.
论述了稀土元素在动物脑部的蓄积性、对脑的毒性以及稀土区人群的脑部毒性效应,分析了稀土农业应用和稀土厂“三废”对生态环境和人群健康的潜在危害。  相似文献   
332.
酸雨对土壤营养元素迁移转化的影响   总被引:7,自引:2,他引:7  
针对近年来北方一些城市大气污染严重并导致部分月份出现酸雨,及酸雨对主要营养元素产生影响的实际情况,通过模拟pH=5.6的酸雨的淋溶实验,对土壤营养元素迁移转化规律作了较深入的研究。结果表明,土壤中硝态氮质量分数随土壤深度的增加而呈下降的趋势;土壤中速效磷、速效钾对酸雨不敏感;拟合出在土壤表层(<5 cm)、10 cm、20 cm、30 cm的不同深度,硝态氮随时间变化的迁移规律方程。  相似文献   
333.
福建丰产荔枝园土壤微量元素含量的研究   总被引:2,自引:0,他引:2  
与我国红壤平均水平相比,福建丰产荔枝园土壤有效态锌、钼及水溶态硼含量较高,而活性锰及有效铜含量较低;土壤全锌、锰、钢量亦较低。在土壤pH4.54—8.76时,pH值与有效态钼含量呈较显著正相关,而与代换态锰、水溶态硼、有效态铁含量呈显著或极显著负相关。本文初步提出福建荔枝园土壤微量元素含量的适宜指标,可供土壤营养诊断及平衡施肥之参考。  相似文献   
334.
1 IntroductionAseveryoneknown ,chelatingresincontainingheteroatomsuchassulfur,nitrogen ,andoxygenpossessexcellentadsorptionandselectivitypropertiesformetalions,especiallyfornoblemetallicions.Therefore ,manyeffortshavebeendonetopreparetheabove mentionedre…  相似文献   
335.
生态环境质量物元可拓评价及实例分析   总被引:15,自引:0,他引:15  
生态环境质量评价属于环境质量评价的重要方面。为了探索建立生态环境质量评价的方法,尝试运用物元可拓的方法来建立生态环境质量评价模型,并且通过用该方法对土壤生态环境质量评价实例验证物元可拓方法的可行性,得到该土壤生态环境质量评价等级值为3.73。从而为尚处在探索发展阶段的生态环境质量评价方法提供一种新思路。  相似文献   
336.
Length of maternal care, i.e. the interval between successfully raised litters, is the most important factor explaining the variation in reproductive rate among brown-bear (Ursus arctos) populations. In this paper, we examine the variation in length of maternal care in radio-marked brown bears and its effect on their offspring in northern Sweden. Young stayed with their mothers for 1.4–1.5 or 2.4–2.5 (in one case 3.5) years and were weaned with body masses varying from 17 to 69 kg. The probability of yearling litters staying with their mother for a 2nd year increased with decreasing yearling body mass, and was higher for litters with two offspring than for litters with one or three to four offspring. Staying with their mothers for a 2nd year had a positive effect on mass gain in yearlings and this effect was more pronounced in litters with two than three to four offspring. Body mass of 2-year-olds was not related to age of weaning, suggesting that keeping offspring for an additional year mainly compensated for low yearling body mass. If large offspring body mass positively affects later offspring survival and reproduction, mothers may be able to optimize the length of maternal care according to the litter size and the size of their yearlings.Communicated by F. Trillmich  相似文献   
337.
The concentrations and distributions of chemical elements (Ag, Al, As, Au, Ba, Bi, Ca, Cd, Co, Cr, Cu, Fe, Ga, Hg, K, La, Mg, Mn, Mo, Na, Ni, P, Pb, S, Sb, Sc, Se, Sr, Te, Th, Ti, Tl, U, V, W and Zn) were studied in till, humus and urban soil in Jakobstad, a small town (20,000 inhabitants) in W. Finland. The analyses were performed with ICP-MS after aqua regia leaching of till (n = 37), urban topsoil (n = 32) and subsoil (n = 32), and HNO3 leaching of humus (n = 37). The till and humus samples, collected at the same sites, were divided into urban and rural samples. The urban till was not significantly enriched in metals. In contrast, a majority of the elements occurred in higher concentrations in the urban than the rural humus samples. Statistical and spatial interpretations of the humus data revealed that traffic (Pb, V and Ni), metal industry (Pb, Zn, Bi, Sb and Cr), an abandoned shooting range (Pb and Sb) and other sources contribute to higher metal levels in the urban humus. The urban soil samples were collected at parks, yards, abandoned industrial sites, roadsides, etc. The topsoil samples were enriched in most elements, also by elements not enriched in the urban humus (e.g. Cd). At several sites, the concentrations far exceeded the limit concentrations for contaminated soils in Finland. A large variety of sources were identified or indicated.  相似文献   
338.
天津市土壤元素背景值的地域差异及成因分析   总被引:3,自引:0,他引:3  
论述了天津土壤中Cu,Pb等13种微量元素背景值在行政区,土壤类型中的差异规律,并分析了引起元素背景值地域差异的原因。  相似文献   
339.
污水土地处理磷污染物迁移转化模拟讨论分析   总被引:6,自引:0,他引:6  
根据磷在土壤中的迁移转化机理,进行了以土柱试验为基础的“污水土地处理条件下磷的迁移转化模拟试验”,总结了污水中的磷在土壤中迁移转化的规律,提出了定量模拟这一规律的迁移转化联合模型。联合模型为研究磷在土壤中的运动提供了定量化依据,避免了已有研究中将迁移和转化割裂研究造成的误差,丰富并完善了不同形态磷的迁移转化模型。  相似文献   
340.
Body mass is a consistent individual trait that characterises the state of adult birds and mammals and is positively related with long-term reproductive success. However, whether and to what extent body mass changes over lifetime in long-lived birds is poorly studied. In this paper, we investigate how individual body mass varies with age. Furthermore, we try to separate possible effects of age and experience on body mass. This study was conducted in a Common Tern colony on the German Wadden Sea coast. Transponders allowed registration of individuals throughout the breeding season and consecutive years with an antenna system combined with electronic balances for recording individual body-mass changes within and between years. Individual body masses of males and females were measured during three stages of the breeding season: at arrival, during incubation and chick rearing when mass was lowest in both sexes. Individual-based longitudinal analyses clearly showed that body mass during arrival, incubation and chick rearing increased up to an age of 5 or 6 years. First-time breeders had lower body mass than experienced breeders. Experience had stronger effects on incubation mass than age. Recruiting age also affected body-mass development of breeders: Three-year-old recruits showed a stronger increase in mass with experience than 4-year-old recruits. We assume that increasing experience enables birds to cope better with the physiological challenge of reproduction. To explain the general phenomenon of higher body mass in older birds, our results support the constraint hypothesis rather than either the selection or restraint hypothesis.  相似文献   
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