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61.
62.
Cui B Zhao S Zhang K Li S Dong S Bai J 《Environmental monitoring and assessment》2009,158(1-4):545-559
The disturbance of highway construction upon surrounding vulnerable ecosystems is a common threat in the Longitudinal Range Gorge Region of southwestern China. We evaluated the disturbance of highway on plant species richness and diversity and soil nutrients from adjacent to the highway to 300 m upslope and 100 m downslope in forests and grasslands by setting 12 belt transects in forests and grasslands (six belt transects and six control belt transects, respectively). The results showed that there were some significant variances in belt transects with respective control belt transects for species richness and diversity in both forests and grasslands. Species richness and diversity of trees were lower within a 50-m distance from the highway and more noticeable on the downslope portion. Species richness and diversity of shrubs and herbs appeared higher near highway edge. Both species richness and diversity of herbs were similar in forests. In addition, exotic species, such as Eupatorium adenophorum, were further from the road and more widely dispersed in grasslands. Soil nutrients except total potassium (TK) were lower in the downslope area adjacent to highway edge and showed a significant increase with increasing distance from the highway in both forests and grasslands. This indicates that grasslands acted as microhabitats for exotic species and are more easily to be invaded than forests, especially if disturbed. Once destroyed, plant species and soil nutrients will require a significant amount of time to be restored to control levels. This work illustrates that the effects extend considerably to distances upslope and downslope from the construction site. Given that these changes occurred relatively quickly, the study suggests that the environmental "footprint" grows far beyond the road and adjacent zone of disruption. 相似文献
63.
Heavy metal pollution is an increasing environmental problem in Chinese regions undergoing rapid economic and industrial development, such as the Pearl River Delta (PRD), southern China. We determined heavy metal concentrations in surface soils from the PRD. The soils were polluted with heavy metals, as defined by the Chinese soil quality standard grade II criteria. The degree of pollution decreased in the order Cd?>?Cu?>?Ni?>?Zn?>?As?>?Cr?>?Hg?>?Pb. The degree of heavy metal pollution by land use decreased in the order waste treatment plants (WP)?>?urban land (UL)?>?manufacturing industries (MI)?>?agricultural land (AL)?>?woodland (WL)?>?water sources (WS). Pollution with some of the metals, including Cd, Cu, Ni, and Zn, was attributed to the recent rapid development of the electronics and electroplating industries. Cd, Hg, and Pb (especially Cd) pose high potential ecological risks in all of the zones studied. The soils posing significantly high and high potential ecological risks from Cd covered 73.3 % of UL, 50 % of MI and WP land, and 48.5 % of AL. The potential ecological risks from heavy metals by land use decreased in the order UL?>?MI?>?AL?>?WP?>?WL?>?WS. The control of Cd, Hg, and Pb should be prioritized in the PRD, and emissions in wastewater, residue, and gas discharges from the electronics and electroplating industry should be decreased urgently. The use of chemical fertilizers and pesticides should also be decreased. 相似文献
64.
Yanying Bai Weiping Chen Andrew C. Chang Albert L. Page 《Journal of environmental science and health. Part. B》2013,48(6):531-539
Potentially hazardous trace elements such as Cd, Cu, Cr, Ni and Zn are expected to accumulate in biosolids–amended soil and remain in the soil for a long period of time. In this research, uptake of metals by food plants including cabbage, carrot, lettuce and tomato grown on soils 10 years after biosolids application was studied. All the five metals were significantly accumulated in the biosolids-amended soils. The accumulation of metal in soil did not result in significant increase in concentrations of Cu, Cr and Ni in the edible plant tissues. However, the Cd and Zn concentrations of the edible tissues of plants harvested from the biosolids receiving soils were significantly enhanced in comparison with those of the unaffected soils. The plant uptake under Greenfield sandy loam soil was generally higher than those under the Domino clayey loam soil. The metal concentration of edible plant tissue exhibited increasing trends with respect to the concentrations of the ambulated metals. The extents of the increases were plant species dependent. The indigenous soil metals were absorbed by the plants in much higher rates than those of the biosolids–receiving soils. It appeared that the plant uptake of the indigenous soil-borne metal and the added biosolids-borne metals are independent of one another and mathematically are additive. 相似文献
65.
按照校验费和损失费最小以及有效度最大的原则分别给出了安全监测系统校验的等周期模型。当安全监测系统的无故障工作时间服从威布尔分布时,给出了模型的解法。 相似文献
66.
Boqiang Cui Yin Liu Jinwen Bai Xianjie Du Changxiang Wang 《International Journal of Green Energy》2020,17(12):730-741
ABSTRACT In order to study the effect of fly ash content in cemented paste backfill (CPB) on its anti-sulfate erosion, the apparent phenomenon, strength development, and hydration products change the law of CPB with different fly ash content under long-term soaking of 5% sodium sulfate solution were studied by the macrotest and microanalysis, in addition, the mechanism of CPB anti-sulfate attack was analyzed by combining with a scanning electron microscope (SEM). The results indicated that the effect of sulfate environment on the strength of fly ash cemented paste backfill (FCPB) was mainly determined by the hydration products in the FCPB at different soaking times. In the early soaking stage, the formation of ettringite (AFt) in FCPB could improve its compactness, which was conducive to improving the strength of FCPB. In the late soaking stage, there were ettringite-type erosion damage and gypsum erosion-type damage internal of the FCPB with low content fly ash, resulting in microfracture, cracking of the FCPB, and reducing the strength. CPB with an appropriate content of fly ash could improve the internal structure of the FCPB to achieve the purpose of anti-sulfate erosion. 相似文献
67.
介绍了液化气的危险特性,结合实际对洛阳石化液化气低温储存装置存在的管道泄漏风险进行了原因分析,提出了相应的措施,保证了装置安全运行. 相似文献
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70.
The association between the rhizospheric microbial community and Cd accumulation in rice is poorly understood. A field trial was conducted to investigate the different rhizobacterial communities of two rice cultivars with high Cd accumulation (HA) and low Cd accumulation (LA) at four growth stages. Results showed that the Cd content in the roots of the HA cultivar was 1.23 - 27.53 higher than that of the LA cultivar (0.08 - 10.5 µg/plant) at four stages. The LA cultivar had a significantly lower Cd availability in rhizosphere and a higher quantity of iron plaque (IP) on the root surface than the HA cultivar at four stages. This resulted in the reduction of Cd concentration in IPs and Cd translocation from IP-to-root. Microbial analysis indicated that the LA cultivar formed a distinct rhizobacterial community from the HA cultivar and had less α-diversity. The rhizosphere of the LA cultivar was enriched in specific bacterial taxa (e.g., Massilia and Bacillus) involved in Cd immobilization by phosphate precipitation and IP formation by iron oxidization. However, the rhizosphere in the HA cultivar assembled abundant sulfur-oxidizing bacteria (e.g., Sulfuricurvum) and iron reduction bacteria (Geobacter). They promoted Cd mobilization and reduced IP formation via the metal redox process. This study reveals a potential approach in which specific rhizobacteria decrease or increase Cd accumulation in rice on contaminated soil and provides a new perspective for secure rice production. 相似文献