吉林省1：20万区域化探一些矿致异常的分散模式     

朴清龙 《吉林地质》1993,12(1):16-25

在《吉林省1∶20万水系沉积物地球化学异常筛选研究》工作中,对省内五个典型矿床地球化学异常进行了剖析性研究。本文以其中某已知铜金矿床区域性异常为例,论述了矿致的水系沉积物地球化学异常的基本特征和分散模式,进一步阐述了水系沉积物地球化学找矿模式及找矿远景预测。  相似文献   

Does the integration of the dynamic nitrogen cycle in a terrestrial biosphere model improve the long-term trend of the leaf area index?     

B. Guenet  P. Cadule  S. Zaehle  S. L. Piao  P. Peylin  F. Maignan  P. Ciais  P. Friedlingstein 《Climate Dynamics》2013,40(9-10):2535-2548

The carbon cycle strongly interacts with the nitrogen cycle. Several observations show that the effects of global change on primary production and carbon storage in plant biomass and soils are partially controlled by N availability. Nevertheless, only a small number of terrestrial biosphere models represent explicitly the nitrogen cycle, despite its importance on the carbon cycle and on climate. These models are difficult to evaluate at large spatiotemporal scales because of the scarcity of data at the global scale over a long time period. In this study, we benchmark the capacity of the O–CN global terrestrial biosphere model to reproduce temporal changes in leaf area index (LAI) at the global scale observed by NOAA_AVHRR satellites over the period 1982–2002. Using a satellite LAI product based on the normalized difference vegetation index of global inventory monitoring and modelling studies dataset, we estimate the long-term trend of LAI and we compare it with the results from the terrestrial biosphere models, either with (O–CN) or without (O–C) a dynamic nitrogen cycle coupled to the carbon–water-energy cycles. In boreal and temperate regions, including a dynamic N cycle (O–CN) improved the fit between observed and modeled temporal changes in LAI. In contrast, in the tropics, simulated LAI from the model without the dynamic N cycle (O–C) better matched observed changes in LAI over time. Despite differential regional trends, the satellite estimate suggests an increase in the global average LAI during 1982–2002 by 0.0020 m² m^?2 y^?1. Both versions of the model substantially overestimated the rate of change in LAI over time (0.0065 m² m^?2 y^?1 for O–C and 0.0057 m² m^?2 y^?1 for O–CN), suggesting that some additional limitation mechanisms are missing in the model. We also estimated the relative importance of climate, CO₂ and N deposition as potential drivers of the temporal changes in LAI. We found that recent climate change better explained temporal changes in LAI when the dynamic N cycle was included in the model (higher ranked fit for O–CN vs. O–C). Using the O–C configuration to estimate the direct effect of climate on LAI, we quantified the importance of climate-N cycle feedbacks in explaining the LAI response. We found that the warming-induced release of N from soil organic matter decomposition explains 17.5 % of the global trend in LAI over time, however, reaching up to 40.9 % explained variance in the boreal zone, which is a more important contribution than increasing anthropogenic nitrogen deposition. Our analysis supports a strong connection between warming, N cycling, and vegetation productivity. These findings underscore the importance of including N cycling in global-scale models of vegetation response to environmental change.  相似文献   

下扬子巢湖地区鼓地1井五峰组-高家边组下段页岩地球化学特征及其地质意义     

薛路  陈建文  吴飘  张鹏辉  王拔秀 《海洋地质前沿》2022,38(5):12-22

  相似文献   

Perfectly matched layer for an elastic parabolic equation model in ocean acoustics     

Chuanxiu Xu  Haigang Zhang  Shengchun Piao  Shi’e Yang  Sipeng Sun  Jun Tang 《中国海洋大学学报(英文版)》2017,16(1):57-64

The perfectly matched layer(PML) is an effective technique for truncating unbounded domains with minimal spurious reflections. A fluid parabolic equation(PE) model applying PML technique was previously used to analyze the sound propagation problem in a range-dependent waveguide(Lu and Zhu, 2007). However, Lu and Zhu only considered a standard fluid PE to demonstrate the capability of the PML and did not take improved one-way models into consideration. They applied a [1/1] Padé approximant to the parabolic equation. The higher-order PEs are more accurate than standard ones when a very large angle propagation is considered. As for range-dependent problems, the techniques to handle the vertical interface between adjacent regions are mainly energy conserving and single-scattering. In this paper, the PML technique is generalized to the higher order elastic PE, as is to the higher order fluid PE. The correction of energy conserving is used in range-dependent waveguides. Simulation is made in both acoustic cases and seismo-acoustic cases. Range-independent and range-dependent waveguides are both adopted to test the accuracy and efficiency of this method. The numerical results illustrate that a PML is much more effective than an artificial absorbing layer(ABL) both in acoustic and seismo-acoustic sound propagation modeling.  相似文献   

琼东南盆地深水东区渐新统烃源岩发育模式     

吴飘  侯读杰  甘军  丁文静  梁刚  李兴  冯信荦  王慧 《沉积学报》2019,37(3):633-647

琼东南盆地深水东区勘探程度低,钻井样品受油基泥浆污染严重,目前关于该区浅海相和海陆过渡相烃源岩的有机地球化学研究较为局限。通过对深水东区渐新统受油基泥浆污染的泥岩岩屑进行有效地洗油实验及有机地球化学分析测试,结合东部浅水区渐新统烃源岩样品的有机岩石学、有机地球化学分析测试等地质资料,系统剖析了深水东区渐新统不同沉积相烃源岩的地球化学特征、发育控制因素和发育模式。研究结果认为,琼东南盆地深水东区渐新统烃源岩的发育模式可分为海陆过渡相三角洲前缘模式和浅海相模式。海陆过渡相三角洲前缘烃源岩为中等—高有机质丰度,有机质类型为Ⅲ型,具有Pr/Ph普遍大于3、(nC21+nC22/nC28+nC29)普遍小于1.2、高OL/C30H、高T/C30H、低C23TT/C30H、低C27ST/C29ST和相对较低的Ga/C30H、C35/C3422S的特征,烃源岩的TOC和硫含量相关性极好,沉积水体为氧化性淡水—半咸水环境。三角洲前缘烃源岩的TOC和母源输入参数相关关系较好,而与Ga/C30H、C35/C3422S参数相关关系较差,说明三角洲前缘烃源岩的有机质丰度主要受陆源有机质输入的控制。浅海相烃源岩有机质丰度中等,有机质类型为Ⅱ2~Ⅲ型,具有Pr/Ph普遍小于3、(nC21+nC22/nC28+nC29)普遍大于1.5、低OL/C30H、低T/C30H、高C23TT/C30H、高C27ST/C29ST和相对较高的Ga/C30H、C35/C3422S的特征,且烃源岩的TOC和硫含量相关性较差,沉积水体为弱氧化性半咸水—咸水沉积环境。浅海相烃源岩的TOC和母源输入参数、Ga/C30H、C35/C3422S等相关关系均较好,说明浅海相烃源岩有机质丰度受水生有机质输入和弱氧化性半咸水—咸水沉积环境控制。滨海相烃源岩的有机质丰度为差—中等,有机质类型以Ⅲ型为主,且TOC受母质来源或沉积水体的氧化还原性影响较小,其烃源岩发育模式是一种破坏性模式。  相似文献   

厚层风积黄土覆盖区金矿脉的壤中气汞异常特征及评价     

刘树田  朴寿成  齐清凤  连长云 《吉林大学学报(地球科学版)》1996,(3)

赤峰市莲花山金矿区南部为大片风积黄土覆盖区，壤中气汞测量圈出了许多气汞异常，其中在已开采的４号、５号金矿脉上，气汞异常的形态、规模和强度都较好地反映了矿体的产状和规模。新的工业金矿体的发现，更加证实了壤中气汞测量找金矿脉的有效性。通过壤中气汞异常的评价，认为４号矿脉的北部，５号矿脉的南部，Ｈｇ２号异常的南部及Ｈｇ３号异常的深部有较好的开采远景，而４１号、１５号、２０号石英脉则无工业价值。  相似文献   

含锑地质试样中金的测定   总被引：3，自引：1，他引：3  

李太星  朴哲洙 《岩矿测试》1991,10(1):66-68

本文考查了Sb对氢醌法测Au的影响。实验证明,Sb的存在使Au的结果偏高,酒石酸钾钠只掩蔽2mg的Sb。对于含Sb试样,灼烧除Sb并不完全,即使经活性炭吸附Au处理后的待测样中Sb仍存在。本文采用HBr辅助除Sb取得良好效果。方法简便、准确性好,Au的回收率在95.5—102.75％范围,试样测定结果与其它方法相符。  相似文献   

贵州石灰岩和砂岩地区C₄和C₃植物营养元素的化学计量对N/P比值波动的影响   总被引：12，自引：0，他引：12       下载免费PDF全文

朴河春  刘丛强  朱书法  朱建明 《第四纪研究》2005,25(5):552-560

陆地生态系统植物的生长受到营养元素氮(N)和磷(P)的可利用性的限制。已有的证据表明营养元素的相对丰度将控制生态系统的营养元素循环和能量流动的速度。文章提出如下假设:为了适应环境的变化,植物具有可伸缩性地调整营养元素含量的能力,也就是营养元素化学计量比值变化的能力,植物N/P比值波动的影响不仅来源于N对P的相对可利用性的变化,也来源于其他营养元素化学计量的变化,尤其是与Ca的化学计量的变化。为了验证上述假设,本研究利用3种C₄植物和11种C₃植物,研究了植物N/P化学计量比值的波动随N与Ca和P与Ca化学计量的变化模式:对C₄植物来说,N/P比值的波动主要受生物量P与Ca化学计量变化的影响;而对C₃植物来说,则同时受N与Ca和P与Ca化学计量变化的控制,它们之间的相对控制能力的大小将决定植物N/P比值波动的变化梯度,C₄植物和C₃植物的N/P比值的波动都要受土壤pH值的影响。本研究对了解物种丰度和N对P的相对可利用性、N与Ca,以及P与Ca的化学计量之间关系具有重要意义。  相似文献   

Variations in Vegetation Net Primary Production in the Qinghai-Xizang Plateau, China, from 1982 to 1999   总被引：11，自引：1，他引：11  

Shilong Piao  Jingyun Fang  Jinsheng He 《Climatic change》2006,74(1-3):253-267

Vegetation net primary production (NPP) derived from a carbon model (Carnegie–Ames–Stanford Approach, CASA) and its interannual change in the Qinghai-Xizang (Tibetan) Plateau were investigated in this study using 1982–1999 time series data sets of normalized difference vegetation index (NDVI) and paired ground-based information on vegetation, climate, soil, and solar radiation. The 18-year averaged annual NPP over the plateau was 125 g C m⁻² yr⁻¹, decreasing from the southeast to the northwest, consistent with precipitation and temperature patterns. Total annual NPP was estimated between 0.183 and 0.244 Pg C over the 18 years, with an average of 0.212 Pg C (1 Pg = 10¹⁵ g). Two distinct periods (1982–1990 and 1991–1999) of NPP variation were observed, separated by a sharp reduction during 1990–1991. From 1982 to 1990, annual NPP did not show a significant trend, while from 1991 to 1999 a marked increase of 0.007 Pg C yr⁻² was observed. NPP trends for most vegetation types resembled that of the whole plateau. The largest annual NPP increase during 1991–1999 appeared in alpine meadows, accounting for 32.3% of the increment of the whole region. Changes in solar radiation and temperature significantly influenced NPP variation, suggesting that solar radiation may be one of the major factors associated with changes in NPP.  相似文献   

The partitioning patterns of nutrients between pods and seeds of <Emphasis Type="Italic">Zanthoxylum</Emphasis> fruits impacted by environmental factors     

Hechun Piao  Siliang Li  Zhifeng Yan 《中国地球化学学报》2018,37(5):676-683

The nutritive quality in plant organs is related to the different partitioning patterns of nutrient resources among the organs under various environmental conditions. This study examined the relationship between the nutritive quality of pods and seeds in Zanthoxylum and environmental factors, such as temperature and preciptation by using numerous samples collected from Southwest China to the East China of Shandong peninsula. The increasing accumulations of N, P and C in seeds implied that the nutritive quality in seeds was higher at the regions with relative higher mean annual temperature (MAT) and mean annual precipitation (MAP), while that in pods was on the contrary. By contrast, pod nutritive content was relatively high, but seed nutritive content was relatively low at the regions with relative high MAT and MAP. In addition, C:N ratio in pods was significantly and negatively correlated with MAT and MAP, while that in seed was significantly and positively correlated with MAT and MAP. The partitioning patterns of N-compounds between pods and seeds reflected different nitrogen translocations in the plant organs under various climate condition. The N:P ratios were negatively correlated with MAP, implying a higher proportional allocation of P to seeds than that of N in the areas with a relative high MAP. Therefore, the strategies to assess pod nutritional quality should be taken into account for nutritive translocation under various environmental conditions.  相似文献