咸阳地区某典型地热井的地热水地球化学特征分析

地球化学方法是了解地热系统特点、变化及起源的重要手段,合理开发利用地热资源的前提。基于咸阳地热田XY1地热井1999年与2017年两期水质资料、多年水温变化资料,参考其他学者在研究区取得的研究成果,综合分析了该热水井及区域地热流体地球化学因子的变化特征。根据地热水δD、δ¹⁸O、¹⁴C同位素分析,探讨了该地区地热水的起源及其同位素水文特征。结果表明：该热水井水温变化不大,水-岩平衡状态未改变,大部分离子组分浓度呈上升趋势,水质变差。水化学类型未改变,为Cl-Na型,其中多种水化学组分浓度达到一定标准,可作为医疗热矿水开发利用。研究区热储层以消耗静态储量为主,无现代降水补给。该井地下热水属于第四纪末次冰期北山山区海拔1200 m大气降水入渗成因,为混入古溶滤水的残存沉积水。建议生产过程中应采取地热水回灌措施,使地热资源开发具有可持续性。     

Trace elements and stable sulfur isotopes in plants of acid mine drainage area: Implications for revegetation of degraded land

The abundances of trace elements, a low pH of water and soil in areas impacted by the acid mine drainage (AMD) may cause an excessive uptake of potentially toxic elements and nutritional imbalances in plants. Metal-tolerant, native plants are used for revegetation of degraded mining areas. We established levels of selected trace elements and stable sulfur isotopes in the above-ground plant biomass collected in a mining area in south-central Poland. In 2016, 20 samples of the most common species were collected from sites with a different influence of acid mine drainage and analyzed for trace elements by the inductively coupled plasma mass spectrometry technique. On the basis of the results obtained in 2016, the most contaminated site was selected for a more detailed study, in which sulfur contents and stable sulfur isotope ratios were determined together with trace elements in 17 samples. The results confirmed that the plants native to the AMD area efficiently accumulated trace elements, especially As and rare earth elements. Mosses showed the highest content of trace elements, but exhibited the lowest concentrations of sulfur accompanied by the highest δ³⁴S values. It has been shown for the first time that stable sulfur isotope composition of AMD plants in south-central Poland is significantly depleted in the ³⁴S isotope showing an average δ³⁴S value of –10.5‰ in comparison with positive δ³⁴S values in local vegetation growing outside the AMD area and in local precipitation.     

雷州半岛岭北地区地下水水文地球化学特征

地下水是雷州半岛重要的供水水源.本研究在雷州半岛岭北地区开展了水化学和氢氧稳定同位素调查,报道了区域地下水水化学特征;基于水化学及同位素地球化学理论和方法揭示了控制水质的主要水文地球化学过程.结果表明,地下水pH、总硬度、TDS以及K⁺、Cl^-、SO₄^-质量浓度较低;H₂SiO₃和NO₃^-质量浓度较高.孔洞裂隙水水化学类型以Mg-Ca-HCO₃和Mg-Ca-HCO₃-Cl型为主,Cl^-沿径流方向增加明显;浅层孔隙水以Ca-Cl、Na-Ca-HCO₃-Cl和Na-Ca-Mg-HCO₃-Cl型为主;中深层孔隙水以Mg-Ca-HCO₃、Na-Ca-Mg-HCO₃和K-Na-HCO₃-SO₄型为主,K⁺、Na⁺、Cl^-和SO₄^-沿径流方向有所增加.地下水受大气降水补给,Cl^-和Na⁺起源于海洋性大气降水,Mg⁺、Ca²⁺和HCO₃^-源自硅酸盐矿物水解,NO₃^-主要来自化学肥料;浅层孔隙水、裂隙孔洞水受蒸发浓缩作用影响,中深层孔隙水受阳离子交换作用影响.计入硝酸盐后,50.85%的NO₃型水指示着地下水具有污染趋势.本研究结果为可持续开发利用区域地下水提供了依据.     

Sources,Fate and Distribution of Organic Matter on the Western Adriatic Continental Shelf,Italy

In the framework of the EUROSTRATAFORM projects, a multidisciplinary research was focused on processes that involve transport and deposition of riverine material in the Adriatic Sea. The aim of our contribution was to increase a more complete understanding of organic matter deposition on the Adriatic shelf, also taking into account the role of Apennine rivers beyond the Po influence. In order to characterize origin, fate and variability of sedimentary organic carbon we utilized elemental and stable carbon isotope data in surficial sediments along shallow cross-shelf transects on the western Adriatic shelf.     

碳酸盐岩Sr同位素比值的选择性溶解及测定技术

传统的碳酸盐岩的Sr同位素比值测定由于采用盐酸溶样 ,虽然具有溶解迅速的优点 ,但同时也使非碳酸盐组分被溶解而往往导致测定值偏高 ,同时也增加了Sr分离与纯化的难度。因此 ,我们考虑用弱酸来溶解碳酸盐岩矿样 ,以改进传统方法的不足。实验中采用醋酸作为溶解介质 ,对比了不同浓度的醋酸的溶解效果 ,对较难溶解的白云岩样品作了弱酸溶解实验 ,同时比较了 2 .5mol/L盐酸和 4mol/L醋酸溶样后的测定结果和测定精度。实验结果表明碳酸盐岩Sr同位素的选择性测定技术可以使溶解对象局限于样品中的目标组分———碳酸盐岩 ,防止样品中的非碳酸盐岩组分的溶解 ,避免过多的杂质进入溶解液 ,使碳酸盐岩中的微量元素———Sr(通常含量在 10 4 — 10 5范围内 )的同位素比值测定趋于准确和可靠 ,同时也减少了杂质元素的干扰 ,便于Sr的分离与纯化。     

高放废物处置库北山预选区及其邻区深部地下水氢、氧同位素特征

为了解高放废物处置库北山预选区深部地下水是否会通过断裂流入河西走廊地区,危害当地的生态环境和人民安全,本文以北山预选区及其邻区为研究对象,利用同位素地球化学方法,建立了研究区当地大气降水线方程和同位素高程效应方程,通过对比两个系统地下水δD、δ~(18)O值和氘盈余特征的差异,确定北山地区与走廊地区的深部地下水具有不同的起源,即北山预选区深部地下水起源于地质历史时期受到过强烈蒸发的大气降水,祁连山北麓-河西走廊地区地下水呈现出典型的现代大气降水补给特征,没有表现出明显的蒸发特征,氢、氧稳定同位素特征表明北山预选区深部地下水并未进入走廊地区,为高放废物处置库的选址工作提供一定的理论依据。     

黄土丘陵区枣农复合系统土壤水分利用与竞争

探明黄土丘陵区农林复合系统植物土壤水分利用策略对评价其配置合理性与可持续性具有重要意义。论文以黄土丘陵区枣农（枣树+农作物）复合系统为对象,测定不同生育期植物木质部水和土壤水氧稳定同位素比率（δ¹⁸O）,利用IsoSource模型分析了复合系统中枣树与间作农作物（黄花菜和饲料油菜）土壤水分利用策略,判断两种复合系统作物间是否发生水分竞争。结果表明：枣树各时期对表层（0~20 cm）土壤水利用较少,在旱季主要使用中层（20~60 cm）和深层（60~200 cm）土壤水,雨季有显著降雨后主要利用中层土壤水。黄花菜、饲料油菜在旱季对低雨量有效降雨反应灵敏,但其仍主要利用中层土壤水,雨季显著降雨后两者对表层土壤水利用比例显著增加。总之枣树与黄花菜和饲料油菜土壤水分利用策略存在明显区别,但在较为干旱的5月和7月对中层和深层土壤水存在明显竞争。因此可在枣树株间修建深度为40 cm肥水坑,增加中层和深层土壤含水量,促进枣树根系向下生长,缓解水分竞争对枣树生长和产量造成的不利影响。     

汉江上游金水河流域河水的化学特征

本文以汉江上游金水河流域为研究区域,通过对大气降水、河水的水化学及氢氧稳定同位素分析,揭示河水水化学特征及其补给来源.结果表明,(1)流域内大气降水和河水的水化学类型为Ca2+-HCO3-型,主要占优势的阴阳离子分别为HCO3-和Ca2+;(2)河水水质总体表征良好,其离子、金属及微量元素和营养盐的含量较低;(3)河水的δD和δ18O关系表明,河流的主要补给来源为大气降水.     

Influence of hydrodynamic conditions on the production and fate of Posidonia oceanica in a semi-enclosed shallow basin (Stagnone di Marsala,Western Sicily)

An integrated approach using hydrodynamic and transport numerical models, lepidochronology and stable isotope analysis was used to investigate how local hydrodynamic conditions influence the primary production and fate of the seagrass Posidonia oceanica in a Mediterranean semi-enclosed marine system (Stagnone di Marsala). The water mass exchange aptitude of different sectors of the basin was analysed, and data collected were used to select two sectors (colonized by Posidonia oceanica showing the lowest and highest water exchange values) for biological analyses. According to the mean dispersal coefficient differences simulated by the hydrodynamic model, growth rate and primary production of P. oceanica differed between sectors, with average values lower in the central sector where water exchange is lower than in the southern sector. Although P. oceanica coverage and primary production were higher in the southern sector, carbon and nitrogen stable isotope analysis suggests that the transfer of seagrass organic matter to higher trophic levels of the food web was higher in the central sector. The possibility of a link between hydrodynamism, production and fate of organic matter is proposed to explain the observed patterns.