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161.
分析2001年干旱对岚县谷子产量的影响 总被引:1,自引:0,他引:1
谷子是岚县的主要粮食作物之一,属耐旱晚熟品种,平均生育期141d,播种面积每年均在4000hm2以上,占粮食作物种植面积的12%。由于岚县自然条件差,十年九旱,因此谷子平均产量仅为130kg至180kg左右。2001年岚县谷子在整个生育期主要气候特点是干旱。从播种到成熟的总积温为2824.8℃,日照1113.5h,总降水量为227.0mm,与谷子在生育期所需的气候条件相比,气温偏高,光照充足,降水偏少,且分布不均,因此2001年岚县的谷子平均产量低,是正常年的3成左右。1苗期出苗到拔节期是谷子的苗期。在拔… 相似文献
162.
The effect of biodegradation on polycyclic aromatic hydrocarbons in reservoired oils from the Liaohe basin, NE China 总被引:3,自引:0,他引:3
Haiping Huang Bernard F.J. Bowler Thomas B.P. Oldenburg Steve R. Larter 《Organic Geochemistry》2004,35(11-12):1619
The occurrence and distribution of polycyclic aromatic hydrocarbons (PAHs) has been studied in oil columns from the Liaohe basin, NE China, characterized by varied degrees of biodegradation. The Es3 oil column has undergone light to moderate biodegradation – ranging from levels 2 to 5 on the [Peters, K.E., Moldowan, J.M., 1993. The Biomarker Guide: Interpreting Molecular Fossils in Petroleum and Ancient Sediments. Prentice Hall, Englewood Cliffs, NJ, p. 363] scale (abbreviated as ‘PM level’) – while the shallower Es1 column has undergone more severe biodegradation, ranging from PM level 5 to 8. Both columns show excellent vertical biodegradation gradients, with degree of biodegradation increasing with increasing depth toward the oil–water contact (OWC). The compositional gradients in the oil columns imply mass transport control on degradation rates, with degradation occurring primarily at the OWC. The diffusion of hydrocarbons to the OWC zone will be the ultimate control on the maximum degradation rate. The chemical composition and physical properties of the reservoired oils, and the ‘degradation sequence’ of chemical components are determined by mixing of fresh oil with biodegraded oil.The PAH concentrations and molecular distributions in the reservoired oils from these biodegraded columns show systematic changes with increasing degree of biodegradation. The C3+-alkylbenzenes are the first compounds to be depleted in the aromatic fraction. Concentrations of the C0–5-alkylnaphthalenes and the C0–3-alkylphenanthrenes decrease markedly during PM levels 3–5, while significant isomer variations occur at more advanced stages of biodegradation (>PM level 4).The degree of alkylation is a critical factor controlling the rate of biodegradation; in most cases the rate decreases with increasing number of alkyl substituents. However, we have observed that C3-naphthalenes concentrations decrease faster than those of C2-naphthalenes, and methylphenanthrenes concentrations decrease faster than that of phenanthrene. Demethylation of a substituted compound is inferred as a possible reaction in the biodegradation process.Differential degradation of specific alkylated isomers was observed in our sample set. The relative susceptibility of the individual dimethylnaphthalene, trimethylnaphthalene, tetramethylnaphthalene, pentamethylnaphthalene, methylphenanthrene, dimethylphenanthrene and trimethylphenanthrene isomers to biodegradation was determined. The C20 and C21 short side-chained triaromatic steroid hydrocarbons are degraded more readily than their C26–28 long side-chained counterparts. The C21–22-monoaromatic steroid hydrocarbons (MAS) appear to be more resistant to biodegradation than the C27–29-MAS.Interestingly, the most thermally stable PAH isomers are more susceptible to biodegradation than less thermally stable isomers, suggesting that selectivity during biodegradation is not solely controlled by thermodynamic stability and that susceptibility to biodegradation may be related to stereochemical structure. Many commonly used aromatic hydrocarbon maturity parameters are no longer valid after biodegradation to PM level 4 although some ratios change later than others. The distribution of PAHs coupled with knowledge of their biodegradation characteristics constitutes a useful probe for the study of biodegradation processes and can provide insight into the mechanisms of biodegradation of reservoired oil. 相似文献
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分析了当前运城市水资源面临的严峻形势.由于地下水的严重开采,导致环境水文地质条件的变化;由于乡镇企业的突猛发展,使地面水体污染严重.针对上述一系列问题,提出了综合治理的措施. 相似文献
165.
以实例介绍了三维地震勘探测量中各项作业限差的关系、复测校差的关系以及测点坐标系转换关系.依照规范及限差控制标准,讨论了控制点布设、导线布设的精度计算以及作业方法.通过对极坐标法误差的计算论证了放样点误差主要是由测角误差引起. 相似文献
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168.
Jiachun Shi Haizhen Wang Jianming Xu Jianjun Wu Xingmei Liu Haiping Zhu Chunlan Yu 《Environmental Geology》2007,52(1):1-10
Six hundred and sixty-five soil samples were taken from Changxing County in Zhejiang Province, China, to characterize the
spatial variability of Hg Cd, Pb, Cu, As and Cr. The geostatistics and geographic information system (GIS) techniques were
applied, and the ordinary kriging and lognormal kriging were used to map the spatial patterns of the six heavy metals. Hg,
Pb, Cu and As were fitted to the spherical model with a range of 85.75, 82.32, 86.10, and 23.17 km, respectively. Cr was fitted
to the exponential model with a range of 6.27 km, and Cd was fitted to the linear model with a range of 37.66 km. Both Pb
and Cu had strong spatial dependence due to the effects of natural factors including parent material, topography and soil
type. Hg, Cd, Cr and As had, however, moderate spatial dependence, indicating an involvement of human factors. Meanwhile,
based on the comparison between the original data and the guide values of the six metals, the disjunctive kriging technique
was used to quantify their pollution risks. The results showed that only Cd and Hg exhibited pollution risks in the study
area. The pollution source evaluated was closely corresponded with the real discharge of industrial production and the application
of organomercury pesticides. The results of this study provide insight into risk assessment of environmental pollution and
decision making for agricultural production and industrial adjustment of building materials. 相似文献
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170.
通过对西天山二牧场一带1∶5万水系沉积物测量工作测试分析的16种元素地球化学分布特征、异常组合进行总结,发现二牧场一带的Au、As、Pb、Zn、Y、Mo、W、Sn等元素与西天山背景相比较富集,而Au、Ni、Co、Cr、Cu相对亏损;R型聚类分析以0.4为界,全区元素可分为四组;在对重要异常进行查证时发现铜矿点2处,铅锌矿点1处,铁矿点1处;对该地区的矿床类型及找矿方向进行了探讨,并圈定2处找矿远景区,提出3种矿床类型:火山热液改造型铜矿、中基性岩类磁铁矿、构造(热液)蚀变型铅锌矿。 相似文献