广东雷州半岛土壤氮、磷、钾元素地球化学特征及其土壤肥力评价          下载免费PDF全文

汪实  朱鑫  黎旭荣  罗思亮 《中国地质》2021,48(4):1177-1187

广东雷州半岛位于中国大陆最南端,是中国菠萝、香蕉、甘蔗等农产品重要产地。土壤氮、磷、钾等养分是作物生长需要最多的营养元素,对农业发展至关重要。文章通过对雷州半岛土壤取样,首次对该地区土壤氮磷钾的背景特征进行了分析,研究了不同成土母质、不同土地利用类型氮磷钾的含量水平,探讨了氮磷钾人为影响因素和时空演化规律,并进行了土壤肥力评价。研究发现,雷州半岛土壤中氮、磷、钾分布受地质背景制约,并受人为活动干扰强烈,氮、磷受人类活动影响显著,钾受人为扰动程度较轻。与20世纪90年代相比,表层土壤磷元素含量增幅较大,钾元素含量与前期相当。土壤肥力评价结果表明,雷州半岛土壤富磷,缺钾,局部缺氮。  相似文献   

安徽五河地区天井湖铅金矿床原生晕地球化学特征     

张建明  肖涛  张家嘉 《江苏地质》2021,45(3):247-253

系统采集安徽五河地区天井湖铅金矿床16个钻孔的岩石、矿石样品,选择钻孔数量较多、矿体连续性较好的90勘探线为研究对象,绘制原生晕地球化学剖面图,建立了5个铅金矿体的原生晕轴向分带序列,结合相关指示元素的分布规律,对铅金矿体的深部延伸进行预测。通过研究,总结出矿床前缘晕元素为As,主成矿元素为Au、Pb,尾晕元素为Bi。根据矿体原生晕特征和相关指示元素的分布规律,推测该矿床为多期成矿的中低温热液矿床,预测Ⅰ号和4号矿体的延伸方向及ZK9004、ZK9006孔深部As异常的延伸方向有盲矿体存在。  相似文献   

泰青威天然气管道临朐段水毁灾害分布特征与风险评价     

张成信  魏龙飞  唐尧  王艳超  代晓光  任永健 《中国地质调查》2021,8(5):108-114

对泰青威天然气管道临朐段地质灾害发育特征进行调查研究发现,临朐段地质灾害类型主要为水毁灾害,具体可分为坡面水毁、河沟道水毁和台田地水毁。野外地质灾害实地调查临朐段管道沿线共发现地质灾害15处,其中坡面水毁点6处,河沟道水毁点4处,台田地水毁点5处。采用定性与半定量相结合的评价方法对其进行地质灾害风险评价,结果表明: 地质灾害风险等级较高的有1处,占6.66%; 风险等级中等的有4处,占26.67%; 风险等级较低的有10处,占66.67%。根据管道沿线地形地貌、地质灾害发育密度、风险等级等因素,划分地质灾害中易发区61 km,低易发区10 km,管道沿线以地质灾害中易发区为主。最后,针对不同类型、不同风险等级地质灾害提出了相应的防治消减措施,为后期管道安全运营和风险整治决策提供了有效的技术依据。  相似文献   

Impact of artificial subsurface drainage on groundwater travel times and baseflow discharge in an agricultural watershed,Iowa (USA)     

Keith E. Schilling  Priyanka Jindal  Nandita B. Basu  Matthew J. Helmers 《水文研究》2012,26(20):3092-3100

Pollutant delivery through artificial subsurface drainage networks to streams is an important transport mechanism, yet the impact of drainage tiles on groundwater hydrology at the watershed scale has not been well documented. In this study, we developed a two‐dimensional, steady‐state groundwater flow model for a representative Iowa agricultural watershed to simulate the impact of tile drainage density and incision depth on groundwater travel times and proportion of baseflow contributed by tile drains. Varying tile drainage density from 0 to 0.0038 m^?1, while maintaining a constant tile incision depth at 1.2 m, resulted in the mean groundwater travel time to decrease exponentially from 40 years to 19 years and increased the tile contribution to baseflow from 0% to an upper bound of 37%. In contrast, varying tile depths from 0.3 to 2.7 m, while maintaining a constant tile drainage density of 0.0038 m^?1, caused mean travel times to decrease linearly from 22 to 18 years and increased the tile contribution to baseflow from 30% to 54% in a near‐linear manner. The decrease in the mean travel time was attributed to decrease in the saturated thickness of the aquifer with increasing drainage density and incision depth. Study results indicate that tile drainage affects fundamental watershed characteristics and should be taken into consideration when evaluating water and nitrate export from agricultural regions. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Simulating the effects of spatial configurations of agricultural ditch drainage networks on surface runoff from agricultural catchments     

F. Levavasseur  J. S. Bailly  P. Lagacherie  F. Colin  M. Rabotin 《水文研究》2012,26(22):3393-3404

The study of runoff is a crucial issue because it is closely related to flooding, water quality and erosion. In cultivated catchments, agricultural ditch drainage networks are known to influence runoff. As anthropogenic elements, agricultural ditch drainage networks can therefore be altered to better manage surface runoff in cultivated catchments. However, the relationship between the spatial configuration, i.e. the density and the topology, of agricultural ditch drainage networks and surface runoff in cultivated catchments is not understood. We studied this relationship by using a random network simulator that was coupled to a distributed hydrological model. The simulations explored a large variety of spatial configurations corresponding to a thousand stochastic agricultural ditch drainage networks on a 6.4 km² Mediterranean cultivated catchment. Next, several distributed hydrological functions were used to compute water flow paths and runoff for each simulation. The results showed that (i) denser networks increased the drained volume and the peak discharge and decreased hillslopes runoff, (ii) greater network density did not affect the surface runoff any further above a given network density, (iii) the correlation between network density and runoff was weaker for small subcatchments (< 2 km²) where the variability in the drained area that resulted from changes in agricultural ditch drainage networks increased the variability of runoff and (iv) the actual agricultural ditch drainage network appeared to be well optimized for managing runoff as compared with the simulated networks. Finally, our results highlighted the role of agricultural ditch drainage networks in intercepting and decreasing overland flow on hillslopes and increasing runoff in drainage networks. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Dynamic evolution of nutrient discharge under stormflow and baseflow conditions in a coastal agricultural watershed in Ishigaki Island,Okinawa, Japan     

Ariel C. Blanco  Kazuo Nadaoka  Takahiro Yamamoto  Koichi Kinjo 《水文研究》2010,24(18):2601-2616

Excessive terrestrial nutrient loadings adversely impact coral reefs by primarily enhancing growth of macroalgae, potentially leading to a phase‐shift phenomenon. Hydrological processes and other spatial and temporal factors affecting nutrient discharge must be examined to be able to formulate effective measures for reducing nutrient export to adjacent reefs. During storm events and baseflow periods, water samples were obtained from the tropical Todoroki River, which drains an intensively agricultural watershed into Shiraho coral reef. In situ nutrient analyzers were deployed for 6 months to hourly measure dissolved nutrient (NO₃⁻‐N and PO₄³⁻‐P) concentrations. Total phosphorus (TP) and suspended solid concentration (TSS) were increased by higher rainfall intensity (r = 0·94, p < 0·01) and river discharge Q (r = 0·88, p < 0·01). In contrast, NO₃⁻‐N concentration tends to decrease drastically (e.g. from 3 to 1 mg l⁻¹) during flood events. When base flow starts to dominate afterwards, NO₃⁻‐N manifested an increasing trend, but decreases when baseflow discharge becomes low. This counter‐clockwise hysteresis for NO₃⁻‐N highlights the significant influence of groundwater discharge. N delivery can therefore be considered a persistent process compared to sediment and P discharge, which are highly episodic in nature. Based on GIS analysis, nutrient concentration along the Todoroki River was largely affected by the percentage of sugarcane/bare areas and bedrock type. The spatial distribution of N concentration in the river reflects the considerable influence of subsurface geology—higher N levels in limestone‐dominated areas. P concentrations were directly related to the total length of artificial drainage, which enhances sediment transport. The use of high‐resolution monitoring data coupled with GIS‐based spatial analysis therefore enabled the clarification of control factors and the difference in the spatio‐temporal discharge characteristics between N and P. Thus, although erosion‐reduction schemes would reduce P discharge, other approaches (e.g. minimize fertilizer) are needed to reduce N discharge. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

Subsoil zoning of Mexico City using qualitative relationships between soil strength and electrical resistivity     

Mario Benhumea Leon 《Geotechnical and Geological Engineering》1989,7(1):59-68

Summary The seismic events occurring on 19 and 20 September 1985, whose epicentre was located in the coastal region of Michoacan, Mexico, produced tremendous damage in Mexico City. As a result of these losses the civil authorities of the city decided to study and evaluate the mechanical characteristics of the subsoil. To achieve this, it was necessary to drill several boreholes to obtain needed geophysical and geotechnical information. The geophysical method of electrical resistivity was the most appropriate to the research. This method enabled us to understand the structure and soil characteristics of the Mexican Valley.  相似文献   

未来地震震级的定量计算   总被引：1，自引：0，他引：1  

蔡静观  刘正荣 《地震研究》1989,(3)

将某一地震带在强震前某一时期内发生的地震,按其面波震级大小自大到小排列,并以N=2、3、4、……来累计频度,采用公式logN=a-bM计算a、b,从而计算出第一个地震的震级M_1,这就是未来可能发生地震的震级。通过对川滇地区和华北地区的九次近期强震进行计算,结果表明,在震级测定误差范围(±0.3级)内,上述的M和logN之间具有很好的线性关系,这就为地震预报和地震区划中定量计算未来地震震级提出了一个新的方法。  相似文献   

A garnet population in Yellowknife schist, Canada   总被引：6，自引：0，他引：6  

R. KRETZ 《Journal of Metamorphic Geology》1993,11(1):101-120

Abstract Data are presented on a garnet population in a specimen of garnet-biotite-plagioclase-quartz schist from the cordierite zone of an Archaean thermal dome in the Southern Slave Province of the Canadian Shield. Garnet crystals are bounded by planar dodecahedral faces and by trapezohedral faces which on the 10-μm scale are corrugated. Crystal distribution, as revealed by dissection of a small cubic volume of rock, is random. The size distribution is normal, with a mean diameter of 0.81 mm and a standard deviation of 0.32 mm. In the largest crystal of the population (mean radius 0.83 mm), [Mn] = 100 Mn/(Fe + Mg + Mn + Ca) decreases from 14.5 at the centre to 7.5 and then increases in the outer margin to 8.5; [Fe] increases continuously from 67 at the centre to 77 at the surface; [Mg] increases from 12.5 to 13.5 and then falls sharply to 11; [Ca] remains unchanged at 4.0 and then drops to 3.3. Progressively smaller crystals have progressively lower [Mn] and higher [Fe] concentrations at their centres, while all crystals have the same margin composition. Growth vectors extending from given concentration contours to crystal surfaces are of equal length regardless of the size of the crystal in which the vector is located. A garnet-forming model is presented in which reaction was initiated by a rise in temperature. Nucleation sites were randomly selected. The nucleation rate increased with time and then declined. Crystal faces advanced at a constant linear rate, which implies an increase in volume proportional to surface area. Initially, the composition of garnet deposited on crystal surfaces was determined by van Laar equations of equilibrium, which demanded the withdrawal of Mn and Fe from within chlorite crystals. This transfer reaction was then accompanied by an ion exchange reaction which moved Mn and Fe to garnet surfaces from biotite, in exchange for Mg. The exchange reaction provides an explanation for the high overall concentration of Mn and Fe in garnet and for the observed Mn and Mg reversals in the margins of crystals. The increase of garnet volume in the garnet population is found to be parabolic, i.e. Vαα⁵.  相似文献   

多源信息方法在殷庄矿开采水文地质预测分区中的应用     

赵林  吴大新  郑世书  徐志斌  孙亚军 《吉林大学学报(地球科学版)》1994,(2)

根据对殷庄矿地质、水文地质、开采条件与矿井涌水之间关系的研究，提出了煤矿开采水文地质条件预测分区的方法——多源信息方法。该方法借助于地理信息系统技术实现了矿井涌水因素间的有机处理。经过将模型与实际情况反复拟合，最终得出了分区预测模型。  相似文献