基于污染足迹模型的湖州市农业污染评估     

李静  焦雯珺  闵庆文  李文华  赵军凯 《资源与生态学报(英文版)》2022,13(1):93-99

太湖流域的水环境质量呈现严重恶化趋势,农业污染物的排放是太湖流域水体环境恶化的主要原因之一。农业污染物主要来源于种植业、畜禽养殖业和水产养殖业的生产过程,不同于以往分开论述三者对水环境的影响,本文基于全国第一次污染普查数据,运用污染足迹模型定量分析了湖州市农业面源(种植业、畜禽养殖业和水产养殖业)对水环境的影响。研究结果表明:(1)农业生产产生的污染物对水环境的影响排序为:磷>氮>有机物;(2)各农业生产类型对水环境的影响排序为:水产养殖业>种植业>畜禽养殖业;(3)湖州市各区县对水环境的影响也存在着明显的空间差异。通过对湖州市农业污染足迹评估,可以明确地提出哪种污染物类型、农业生产类型和区域是湖州市农业面源污染治理的重点。研究结果可以为太湖流域农业的可持续发展和水资源的可持续利用提供一定的参考价值。  相似文献   

The Unusual Absorption Line Spectrum of Quasar SDSS J2220+0109     

Ji Tuo  Zhou Hong-yan  Wang Ting-gui  Wang Hui-yuan 《Chinese Astronomy and Astrophysics》2013

We report the Balmer broad absorption lines (BALs) in the quasar SDSS J2220 + 0109 discovered from the SDSS data, and present a detailed analysis of the peculiar absorption line spectrum, including the He I* multiplet at λλ3189, 3889 arising from the metastable 2³s-state helium and the Balmer Hα and Hβ lines from the excited hydrogen H I of n = 2 level, which are rarely seen in quasar spectra, as well as many absorption lines arising from the excited Fe II* of the levels 7 955 cm⁻¹, 13 474 cm⁻¹ and 13 673 cm⁻¹ in the wavelength range 3100∼3300 Å. Ca II H, K absorption line doublets also clearly appear in the SDSS spectrum. All absorption lines show a similar blueshifted velocity structure of Δv ≈ − 1500 ∼ 0 km·s⁻¹ relative to the quasar's systematic redshift determined from the emission lines. Detailed analysis suggests that the Balmer absorption lines should arise from the partially ionized region with a column density of N_HI ≈ 10²¹ cm⁻² for an electron density of ne ∼ 10⁶ cm⁻³; and that the hydrogen n = 2 level may be populated via collisional excitation with Lyα pumping.  相似文献   

Local amplification of deep mining induced vibrations Part 1: Experimental evidence for site effects in a coal basin     

L. Driad-Lebeau  N. Lokmane  J.F. Semblat  G. Bonnet 《Soil Dynamics and Earthquake Engineering》2009

The work presented in this paper lies under the scope of a research program aiming to assess the impact of deep coal mining induced vibrations on the surface constructions. The concerned section of the program is dedicated to the study of geological site effects and their influence on the mining induced vibrations for which the experimental investigations have been carried out and developed in this paper (Part 1). The empirical methods based on H/V spectral ratios have been applied on data sets provided from mining induced vibrations recorded within private residences above the deep coalmine as well as complementary measurements of ambient noise. The results evidence an amplified zone in the southern part of the Gardanne basin where drilling data confirmed the presence of particularly fractured and soft stratigraphic units. This joint analysis of induced seismicity and ambient noise enabled to validate the method based on H/V ratios applied to the mining context.  相似文献   

中国地区边界层大气气溶胶辐射吸收特性   总被引：10，自引：4，他引：6  

黄世鸿  李子华  杨军 《高原气象》2000,19(4):487-494

采用粒子采样法对中国２３个地区边界层气溶胶的吸收系数作了测量,研究了其分布特征。结果表明：中国地区边界层气溶胶的吸收系数在１０＾－６－１０＾－３ｍ＾－１之间,明显呈北高南低的趋势,四川盆地和贵州有一相对较高的中心,吸收系数与粒子含量之间的相关系数为０．７４,吸收系数与粒子含量的分布一致性较好。小颗粒的吸收性能好于大颗粒。  相似文献   

Ground vibrations from sheetpile driving in urban environment: measurements, analysis and effects on buildings and occupants     

G. A. Athanasopoulos  P. C. Pelekis 《Soil Dynamics and Earthquake Engineering》2000,19(5)

Following a comprehensive review of the subject of man-made ground vibrations, measurements of ground vibration caused by vibratory sheetpile driving in recent soil deposits are reported in terms of particle velocities vs. distance from the source of vibration. The measurements were conducted on paved surfaces and sidewalks in the inner urban environment. Reconstructed particle displacement paths indicated, predominantly, vertical vibrations of the Rayleigh type. The attenuation rate of vibrations with distance was compared to published results of other studies and satisfactory agreement was found to exist. Values of particle velocity measured in this study, however, were lower than corresponding values of other studies under comparable values of rated vibratory kinetic energy. This is possibly due to different soil conditions. Average and upper bound linear log–log attenuation relationships are proposed, which fit the results of measurements and are representative of the conditions likely to be encountered in the urban environment. Measurement of vibrations on higher floors of multistory reinforced concrete buildings indicated a significant amplification of vertical vibration and an average curve for amplification magnitude vs. floor level was fitted to the results of measurements. A comparison of measured values of vibration with the observed performance of buildings and with damage threshold values suggested by existing codes and standards indicated that the latter do not provide safety against damage caused by vibratory densification of loose sandy soils. On the other hand, the existing criteria for human exposure to vibrations in buildings, according to the results of this study, seem to adequately define the degrees of human discomfort.  相似文献   

振动测井和振动采油在科油的实施及效果评价     

崔德鹏  左万戬 《东北地震研究》2000,16(3):70-74

本文较详细的阐述了应用超低频可控震源在科尔沁油田进行振动测井和振动采油的试验过程,并通过对１９９５年度在该油田包１断块区进行的１３个周期的基础资料的统计,做出了符合实际的效果评价,试验表明在油田开采初期通过振动采油可取得显著增产效果和可观的经济效益。  相似文献   

建筑结构振动中的“鞭梢效应”分析     

张加庆  田刚 《高原地震》2000,12(4):57-59

论述了建筑物的顶端突出剖件在地震引起的振动中“二次共振”的成因及振动的动力学特性,指出要克服“鞭梢效应”现象,就必须合理调整建设刚度与质量,而不能单纯增强刚度。  相似文献   

鲁西枣庄-临沂地区新元古界震碛岩的主要特征   总被引：7，自引：3，他引：4       下载免费PDF全文

张宪依  王炳山  李元仲  杨蕊英 《地质科学》2006,41(3):489-499

鲁西枣庄—临沂地区新元古界碳酸盐岩系中,发育有由地震造成的同沉积构造现象,如微晶方解石脉、层内变形褶曲、层内微断层和内碎屑碳酸盐岩堆积等。野外实地观察、地质剖面测量和室内分析研究认为它们是由地震产生的强震动,使距震中一定范围的未固结沉积物经震动液化,震动变形形成的震积岩组合。根据其发育规律与组合特征,该地区震碛岩的形成应与古郯庐断裂在新元古代的活动密切相关。可初步确定为含有A、B和C3个震积岩单元的震动液化地震序列。  相似文献   

地震波散射研究的新进展——第25届IASPEI大会S13专题报告会“地震波散射与衰减”简介          下载免费PDF全文

吴如山 《地球物理学报》1990,(3)

本文以IASPEI的“地震波的散射与衰减”专题报告会为主,评述了近几年在地震波散射方面的研究进展.述评所涉及的方面有:1.关于地震尾波的起源;2.大震前尾波包络的前兆性变化;3.地震尾波包络衰降的机理;4.区分散射和吸收的新方法;5.新领域的开拓和研究.  相似文献   

Three-dimensional analysis of the screening effectiveness of hollow pile barriers for foundation-induced vertical vibration   总被引：2，自引：0，他引：2  

Pei-hsun Tsai  Zheng-yi Feng  Tin-lon Jen 《Computers and Geotechnics》2008,35(3):489-499

The study applies the three-dimensional boundary element method in frequency domain to investigate the screening effectiveness of circular piles in a row for a massless square foundation subject to harmonic vertical loading. Four types of piles were studied: steel pipe piles, concrete hollow piles, concrete solid piles and timber piles. A parametric study was undertaken to examine the effects of pile dimensions, operational frequency, and source distance on the screening effectiveness. The results showed that screening effectiveness of steel pipe piles is generally better than that of solid piles, and that a concrete hollow pile barrier can be ineffective due to its stiffness. The influence of pile length on screening effectiveness is more significant than that of pile spacing and the distance between the vibrating foundation and the pile barrier.  相似文献