闽西南古田-小陶花岗质杂岩体的形成时代和成因

古田-小陶花岗质杂岩体是由小陶、古田、华家、蛟洋和姑田等单元组成。小陶、古田和华家单元为含黑云母二长花岗岩,蛟洋和姑田单元是含角闪石黑云母石英二长岩。小陶和古田花岗岩以高 SiO_2(>71.77%)、K_2O(>4.67%)和低 CaO(<1.71%)为特征,属于弱过铝-强过铝花岗岩;它们含高的 Rb、Nh、Ta、Th、U 和低的 Sr、Ba 含量;稀土(REE)含量和轻重稀土分异((La/Yb)_N)变化大,分别变化于143×10~(-6)～548×10~(-6),和3.3～26.5,Eu 亏损中等到强。姑田和蛟洋单元都以低SiO_2(62.88%～66.38%)和高 Al_2O_3(15.44%～16.51%)为特征。姑田单元的 REE 总量低而蛟洋单元的 REE 总量高,但两者的 Eu 负异常都不明显。华家单元花岗岩的地球化学特征介于上述两组花岗岩之间。LA-ICPMS 锆石 U-Pb 定年显示小陶花岗岩形成于222±3Ma,而古田花岗岩形成于161±1Ma。小陶、古田和姑田花岗岩具有相似的~(87)Sr/~(86)Sr 初始比值(0.7089～0.7099)和ε_(Nd)(t)值(-11.1～-11.5),而且古田和小陶花岗岩的锆石 Hf 同位素组成也相似,表明它们起源于相同的源区。地球化学和 Sr-Nd-Hf 同位素指示它们的源区物质是具有1.73～1.5Ga 平均地壳存留年龄的变质沉积岩。而位于杂岩体南部的华家花岗岩显示明显高的~(87)Sr/~(86)Sr 初始比值(0.7310)和更低的ε_(Nd)(t)值(-16.4),指示它的母岩浆起源于古元古代壳源物质,暗示杂岩体南北基底组成可能不同。古田花岗岩形成于燕山早期的板内伸展构造背景,而小陶花岗岩形成于印支晚期,地球化学特征以及同时代岩石组合以及构造应力场分析表明其最可能形成于后造山构造背景。     

A comparison of estimated and calculated effective porosity

 Effective porosity in solute-transport analyses is usually estimated rather than calculated from tracer tests in the field or laboratory. Calculated values of effective porosity in the laboratory on three different textured samples were compared to estimates derived from particle-size distributions and soil–water characteristic curves. The agreement was poor and it seems that no clear relationships exist between effective porosity calculated from laboratory tracer tests and effective porosity estimated from particle-size distributions and soil–water characteristic curves. A field tracer test in a sand-and-gravel aquifer produced a calculated effective porosity of approximately 0.17. By comparison, estimates of effective porosity from textural data, moisture retention, and published values were approximately 50–90% greater than the field calibrated value. Thus, estimation of effective porosity for chemical transport is highly dependent on the chosen transport model and is best obtained by laboratory or field tracer tests. Received, March 1997 · Revised, August 1997 · Accepted, August 1997     

A discrete particle representation of hillslope hydrology: hypothesis testing in reproducing a tracer experiment at Gårdsjön,Sweden

Despite the long history of the continuum equation approach in hydrology, it is not a necessary approach to the formulation of a physically based representation of hillslope hydrology. The Multiple Interacting Pathways (MIPs) model is a discrete realization that allows hillslope response and transport to be simultaneously explored in a way that reflects the potential occurrence of preferential flows and lengths of pathways. The MIPs model uses random particle tracking methods to represent the flow of water within the subsurface alongside velocity distributions that acknowledge preferential flows and transition probability matrices, which control flow pathways. An initial realization of this model is presented here in application to a tracer experiment carried out in Gårdsjön, Sweden. The model is used as an exploratory tool, testing several hypotheses in relation to this experiment. Copyright © 2011 John Wiley & Sons, Ltd.     

南京市降水化学特征及其来源研究

为了解南京江北地区降水化学特征,分析了2011年3—6月共25个降水日的109个降水样品中的主要水溶性离子,并利用后向轨迹模式探讨了降水气团来源.结果表明:1)南京地区3—6月降水主要受南、北2种气团影响,北方气团降水的主要离子浓度高于南方气团降水.2)海盐示踪法和相关性分析显示,降水中NO₃^-和SO₄^2-主要来自燃煤、工业排放和汽车尾气;Ca²⁺主要来自地壳源;Cl^-主要来自海洋;海洋源和陆源对Mg²⁺和K⁺都有贡献,Mg²⁺的陆源贡献大于海洋源贡献,K⁺受海洋源的影响程度要低于Mg²⁺.3)南、北气团初期降水的各离子浓度高于总降水的各离子浓度,且初期降水的主要离子的富集系数高于总降水.这说明在降水初始阶段,雨水对南京大气中污染物(气态污染物和颗粒物)的云下冲刷去除作用较强,降水的离子浓度最高,局地源对降水离子的贡献较明显.     

Quantitative assessment of dissolved radiotracers in the English Channel: Sources, average impact of la Hague reprocessing plant and conservative behaviour (1983, 1986, 1988, 1994)

Knowledge of long-term movements of water-masses in the English Channel has been substantially improved using hydrodynamic modelling coupled with radio-tracers studies; nevertheless, the precision of results so obtained is still largely dependent on measurement precision. New tools are now available to make more accurate determinations of radio-tracer distribution: (1) Repositioning of station locations at the same tide reference-time, giving a homogeneous spatial data set, coupled with the possibility of interpolating and quantifying the amounts of dissolved radioactivity flowing through the English Channel; (2) the first measurements of tritium (³H) in seawater on a large scale in the English Channel demonstrate that this fully conservative radionuclide is a clearly identifiable marker of industrial releases; (3) recent campaigns carried out during the FLUXMANCHE II CCE (1994) programme show the general distribution of dissolved radionuclides ¹³⁷Cs, ¹³⁴Cs, ⁶⁰Co, ¹²⁵Sb, ¹⁰⁶Ru and ³H in the English Channel and the Irish Sea; and (4) the re-utilisation of data from previous campaigns (1983, 1986, 1988) provides indications, at any given location in the English Channel, about the average dilution and distribution of releases derived from the La Hague reprocessing plant. Excesses and losses of radionuclides are now quantified with respect to known source terms; estimates of losses are provided for non-conservative radionuclides, while an excess of ¹³⁷Cs was observed in the English Channel during the period 1983–1994. This excess, which has the same order of magnitude as the quantities released from La Hague plant in the English Channel, could be explained by about 1% of the Sellafield reprocessing plant releases entering the Channel. These results confirm and give a more detailed picture of the previously known distribution of water masses in the English Channel. They lead to clear information about transit times and dilution at this scale, and provide directly comparable data for the validation of hydrodynamic models.     

大陆深部地壳物质成分识别方法综述

本文系统总结了大陆深部地壳物质成分识别研究方法和元素丰度合理性检验的方法,以期为大陆深部地壳物质成分探测提供技术方法体系。深部地壳物质成分识别的主要方法有:①因构造运动抬升出露到地表的中下地壳剖面;②地表出露的高级变质地体;③产于火山岩中的深部地壳捕掳体,如麻粒岩捕掳体;④地球物理测深资料与深部岩石物理性质的高温高压实验测定结果之间的拟合和⑤壳源岩浆岩源区地球化学示踪。元素丰度合理性检验的方法主要有地表热流和元素比值法。     

时间矩在地下水相关参数确定中的应用

应用矩分析方法定量分析示踪剂数据需要一系列严格的步骤,包括数据标准化,浓度衰减的校正,去卷积,外推和积分。正确的分析,可以得出示踪剂扫描孔隙体积、流体几何和流体速度等场地的特殊信息,有助于了解库区边界的特征。通过实例分析,结果表明：采用时间矩方法确定地下水有关参数时,效果良好。     

人工示踪方法评价地下水入渗补给及其优先流程度——以河北栾城和衡水为例

利用传统人工示踪剂峰值方法评价地下水入渗补给存在精度低和适用性差等缺点。为此,本文提出了多区模型方法,采用保守型示踪剂溴和氚对河北栾城和衡水地区进行了不同土地利用方式和不同深度下地下水入渗补给评价。结果表明,栾城和衡水地区地下水入渗补给量分别为124.3 mm/a和13.7 mm/a,与传统方法(103.3 mm/a和0.0 mm/a)相比,多区模型方法的评价结果更符合实际。同时对由优先流引起的地下水入渗补给量进行了分析,栾城和衡水地区优先流程度分别为28.7%和2.3%。秸秆覆盖抑制降雨或灌溉水入渗补给地下水,降低优先流程度,而植被覆盖有利于土壤水优先流的形成。地下水入渗补给量及其优先流程度与示踪深度均无明显相关性,且受土壤结构控制。     

Groundwater dating with 3H and SF6 in relation to mixing patterns,transport modelling and hydrochemistry

A comprehensive study of a sandy aquifer of deltaic origin in southern Poland included water chemistry, isotopes, dissolved trace gases and transport modelling. Tritium, sulphur hexafluoride (SF₆) and freons (F‐11, F‐12 and F‐113) showed the presence of modern waters in the recharge areas and shallow confined parts of the aquifer. The presence of older Holocene waters farther from the recharge areas was indicated by lack of ³H, SF₆ contents ≤0·02 fmol l⁻¹ and relatively low ¹⁴C values. The discharge from the system is by upward seepage in the valley of a major river. Pre‐Holocene waters of a cooler climate, identified on the basis of δ¹⁸O, δ²H, ¹⁴C, Ne and Ar data, were found in some distant wells. Concentrations of N₂, Ne and Ar determined by gas chromatography were used for calculating the noble gas temperatures, air excess needed for correction of SF₆, and nitrogen content released by denitrification process. The time series of ³H content available for some wells supplied quantitative information on age distributions and the total mean ages of flow through the unsaturated and saturated zones. The derived ³H age distributions turned out to be very wide, with mean values in the range of about 30 to 160 years. For each well with determined ³H age, the SF₆ data showed either a lower age range or the possibility of a lower age as expected due to shorter travel times of SF₆ through the unsaturated zone, which most probably also resulted in different types of age distributions of these tracers. Freons appeared to be of little use for individual age determinations. A quantitative estimation of two‐component mixing from SF₆ ³H relations is not possible unless the travel time of ³H through the unsaturated zone is comparable to that of SF₆. The ratio of integrals of the response function over the age range with tracer and the whole response function yields the ratio of water with tracer to total flow of water. That ratio is a tracer‐dependent function of time. Transport modelling of SF₆ tracer done with MT3D code yielded initially large discrepancies between calculated and measured tracer concentrations. Some discrepancies remained even after calibration of the transport model with SF₆. Simulation of tritium contents with a calibrated transport model yielded reasonable agreement with measured contents in some wells and indicated a need for further investigations, particularly in the eastern part of the aquifer. The existence of distinct hydrochemical zones is consistent with the tracer data; young waters with measurable ³H and SF₆ contents are aerobic and of HCO₃ Ca or HCO₃ SO₄ Ca types. Slightly elevated Na and Cl contents, as well as the highest concentrations of SO₄ and NO₃ within this zone are due to anthropogenic influences. Anaerobic conditions prevail in the far field, under the confining cover, where pre‐bomb era Holocene waters dominate. In that zone, dissolved oxygen, NO₃ and U contents are reduced, and Fe, Mn and NH₄ contents increase. In the third zone, early Holocene and glacial waters occur. They are of HCO₃ Ca Na or HCO₃ Na types, with TDS values higher than 1 g l⁻¹ and Na content higher than 200 mg l⁻¹, due to either small admixtures of ascending or diffusing older water or freshening of marine sediments, a process that is probably occurring till the present time. Copyright © 2005 John Wiley & Sons, Ltd.     

城市小型河流水动力弥散和潜流交换过程

为研究城市小型河流中污染物的物理迁移过程规律,分析基流条件下流动水体与暂态存储区之间的滞留交互作用,采用溴化锂(LiBr)作为保守性示踪剂进行野外现场示踪试验,结合一维溶质运移存储模型(One-dimensional Transport with Inflow and Storage model, OTIS)定量解析潜流交换特性,估算纵向弥散系数(D)、潜流交换面积(A_s)、主河道断面面积(A)和潜流交换系数(α).模型度量指标D_aI值和均方根误差值结果表征参数模拟结果可靠性高,拟合效果理想.由泵入点O至下游1 300 m设置的A、B、C、D 4处监测点的模拟结果表明,水文参数D、A_s、A和α均随水文条件而变,OB河段(0~600 m)潜流交换能力较弱,主要以对流弥散过程为主;BD河段(600~1 300 m)具有较强的暂态存储能力,对溶质的滞留时间长;BC(600~1 000 m)和CD(1 000~1 300 m)河段交换系数分别为(3.42×10-6±0.65×10-6)s-1和(2.87×10-6±0.81×10-6 )s-1;河段BC存在2.2×10-5m3/(s·m)的侧向补给流量.4个河段对比发现,城市河流渠道化、河床沉积物贫瘠等特征导致潜流交换能力弱化.