锆英石基An4+放射性核素固化体性能研究

为研究锆英石基An4+(四价锕系核素)放射性核素固化体的性能,利用Ce4+作为An4+的模拟替代物质,以ZrO2、SiO2和CeO2粉体为原料,采用高温固相法制备出包容20%(物质的量,下同)Ce4+的锆英石基固化体,利用60Co源γ射线辐照装置对其进行572.1kGy的γ射线辐照.利用粉末X射线衍射仪、扫描电子显微镜和电感耦合等离子体质谱仪对γ射线辐照前后固化体的物相、结构、微观形貌及模拟核素的浸出行为进行了研究.结果表明,固化体中虽包容有20%的Ce4+,但其主物相仍以锆英石物相为主,与标准样品相比晶胞参数发生10-4nm量级的变化,经γ射线辐照后样品晶胞参数仅发生了10-5~10-4nm量级的微弱变化,在pH6.5的HCI浸出液中Ce4+的平衡浓度低于0.30μg/L.     

RESIDENCE TIME OF WATER DISCHARGING FROM THE HANGING GARDENS OF ZION PARK1

ABSTRACT: The Hanging Gardens are a unique feature of Zion National Park. Knowledge of the source and residence time of water discharging from the Hanging Gardens is necessary to help preserve these features. Ground-water chemical and isotopic data distinguish the discharge from seeps and springs into two groups, one of low and one of high conductivity. Water with low conductivity likely originates as recharge near the seeps and springs, and it only interacts with the Navajo Sandstone. High conductivity water, on the other hand, originates as recharge on the tops of plateaus to the east, where it interacts with marine rocks of the Carmel Formation. Carbon dating of these ground waters indicates that the low conductivity water is essentially modern recharge, while the high conductivity water was recharged 1,000 to 4,000 years ago.     

Historical Weathering Based on Chemical Analyses of Two Spodosols in Southern Sweden

Chemical weathering losses were calculated for two conifer stands in relation to ongoing studies on liming effects and ash amendments on chemical status, soil solution chemistry and soil genesis. Weathering losses were based on elemental depletion trends in soil profiles since deglaciation and exposure to the weathering environment. Gradients in total geochemical composition were assumed to reflect alteration over time. Study sites were Horröd and Hasslöv in southern Sweden. Both Horröd and Hasslöv sites are located on sandy loamy Weichselian till at an altitude of 85 and 190 m a.s.l., respectively. Aliquots from volume determined samples from a number of soil levels were fused with lithium metaborate, dissolved in HNO₃, and analysed by ICP – AES. Results indicated highest cumulative weathering losses at Hasslöv. The weathering losses for the elements are in the following order:Si > Al > K > Na > Ca > MgTotal annual losses for Ca+Mg+K+Na, expressed in mmol_c m^-2 yr^-1, amounted to c. 28 and 58 at Horröd and Hasslöv, respectively. Variations between study sites could not be explained by differences in bulk density, geochemistry or mineralogy. The accumulated weathering losses since deglaciation were larger in the uppermost 15 cm than in deeper B horizons for most elements studied.     

进口锆英砂的放射性及其对人体的危害

通过对进口锆英砂实施放射性的监测与计算，论述了对于样品的放射性监测结果接近豁免限值标准的锆英砂会对人体产生较大危害，提出了对放射性货物监测管理的改进措施。     

Pesticide and Transformation Product Detections and Age‐Dating Relations from Till and Sand Deposits1

Abstract:  Pesticide and transformation product concentrations and frequencies in ground water from areas of similar crop and pesticide applications may vary substantially with differing lithologies. Pesticide analysis data for atrazine, metolachlor, alachlor, acetochlor, and cyanazine and their pesticide transformation products were collected at 69 monitoring wells in Illinois and northern Indiana to document occurrence of pesticides and their transformation products in two agricultural areas of differing lithologies, till, and sand. The till is primarily tile drained and has preferential fractured flow, whereas the sand primarily has surface water drainage and primary porosity flow. Transformation products represent most of the agricultural pesticides in ground water regardless of aquifer material – till or sand. Transformation products were detected more frequently than parent pesticides in both the till and sand, with metolachlor ethane sulfonic acid being most frequently detected. Estimated ground‐water recharge dates for the sand were based on chlorofluorocarbon analyses. These age‐dating data indicate that ground water recharged prior to 1990 is more likely to have a detection of a pesticide or pesticide transformation product. Detections were twice as frequent in ground water recharged prior to 1990 (82%) than in ground water recharged on or after 1990 (33%). The highest concentrations of atrazine, alachlor, metolachlor, and their transformation products, also were detected in samples from ground water recharged prior to 1990. These age/pesticide detection relations are opposite of what would normally be expected, and may be the result of preferential flow and/or ground‐water mixing between aquifers and aquitards as evident by the detection of acetochlor transformation products in samples with estimated ground‐water ages predating initial pesticide application.     

湘北华容地区小墨山花岗岩体SHRIMPU—Pb年龄及地球化学特征

小墨山岩体侵位于中元古代冷家溪群中,由两期侵入体组成,早期为粗中粒—中粒斑状黑云母二长花岗岩;末期为细粒黑(二)云母二长花岗岩。通过锆石SHRIMP U-Pb法测得岩体侵位年龄为122.5±2.1 Ma(2σ),MSWD=1.9,成岩时代为早白垩世。主元素中,SiO2变化于67.20%~75.16%,K2O含量高,且K2O>Na2O,K2O/Na2O为1.16~1.72;ASI值变化于0.96~1.10之间,平均1.02,属准铝质-微过铝质、高钾钙碱性系列。岩石明显富集大离子亲石元素,亏损高场强元素,Rb/Sr=0.27~15.13;Nb/Ta=15.9~17.1,为锶和铌亏损型。ΣREE总体较高,重稀土含量相对较高,轻重稀土分馏稍弱,ΣCe/ΣY为0.49~6.18,(La/Yb)N为0.66~15.54。有较高的εNd(t),为-6.8~-8.7;T2DM相对较小(1.47~1.62 Ga)。综合研究表明,小墨山花岗岩石为壳源型富黑云母过铝花岗岩类(CPG),其成因应为下地壳物质和上地壳物质混合而成,与花岗岩底侵作用或注入地壳中的幔源岩浆有关,形成的构造背景为陆内挤压造山向非造山转换的后造山拉张环境,是在...     

浙江青田石平川钾长花岗岩特征及其成因探讨

青田县石平川钼矿床是浙江省现已发现的规模最大的钼矿床,多数人认为石平川钼矿床的形成与钾长花岗岩有密切关系.本文主要从岩相学、岩石地球化学、LA-ICPMS锆石U-Pb年代学等方面研究石平川钾长花岗岩,并探讨其成岩环境及成因.研究表明,石平川岩体属于高钾钙碱性、弱过铝质S型花岗岩,其形成于早白垩世晚期挤压环境,源岩物质主要是壳源,并有少部分幔源物质成分参与.     

狮子洞铀系测年与百色盆地第Ⅲ级阶地的年代

布兵盆地是广西百色盆地东南缘一小型附属盆地,狮子洞位于其南侧喀斯特峰林中,其内堆积由上部砂质粘土与下部砾石层构成,类似河流相二元结构。狮子洞与其周围分布广泛的河流第III阶地海拔高度相当,表明洞穴与阶地堆积时代的一致性。本文报道狮子洞内夹生于砂质粘土层次生碳酸盐岩样的铀系测年结果。位于砂质粘土与砾石层界面处的钙板,高精度质谱铀系年代为366±19ka。其左上1.4m贴附于洞壁突岩的石幔,质谱年代为517±42ka。鉴于具明确层位意义、纯净致密次生碳酸盐岩质谱铀系年代高度可信,并基于狮子洞堆积与布兵盆地第Ⅲ级阶地同时、附属盆地与主盆地同步发育的认识,这二个盆地第Ⅲ级阶地应在366～517ka间形成。本文结果对系统研究百色盆地地貌和旧石器文化演化具重要性。     

洞穴上覆土壤层~(210)Pb放射性活度变化特征及其环境意义

土壤210Pb放射性活度变化可以用来指示土壤侵蚀速率变化、计算水土流失速率,但是在其他方面的应用,特别是岩溶环境的应用相对较少。在进行洞穴年轻沉积石笋年代测试过程中,发现目前应用的CIC(恒定初始放射性活度模式)初始活度恒定的假设需要进行验证。通过对广西桂林茅茅头大岩上覆土壤层进行季节采样和210Pb放射性活度、土壤有机质、粒径等分析,发现土壤剖面表层20~30cm内的210Pb放射性活度季节变化明显,可能响应了大气环境、土壤生态环境的变化。但是土壤剖面基底210Pb放射性活度基本保持恒定,说明土壤层厚度大于20~30cm时,土壤层中210 Pb变化对洞穴年轻沉积物表层210Pb活度变化影响不大,洞穴上覆层对洞穴沉积物210Pb放射性活度的影响主要在于土壤有机质和粘粒向下迁移。因此,影响洞穴石笋210Pb放射性活度的关键因素在土壤厚度、土壤中随有机质和粘粒迁移的210 Pb量的变化,进而推广到洞穴年轻沉积物210Pb定年,在土壤层厚度大于20~30cm时,洞穴相对封闭环境下,可以应用CIC模式对洞穴沉积物进行年龄计算。     

西沙赵述岛和北岛海鸟遗迹14C年代模型及意义

对采自西沙赵述岛和北岛的沉积剖面ZS2、BD1进行分析,两个剖面具有十分相似的物源组成和岩性变化。通过测定剖面中海鸟残体的~(14)C年龄,运用传统方法以及Clam和Bacon程序建立了ZS2和BD1沉积剖面的年龄-深度模型。对比年龄-深度模型发现,Bacon程序运用MCMC作为迭代算法,排除异常数据影响,拟合得到的曲线单调相比较于Clam年龄模型显得更为合理。所建立的年代学模型为后期的气候环境演变研究提供了基础。根据Bacon程序所构建的年龄-深度模型结果,我们发现近千年来ZS2和BD1剖面处的平均沉积速率分别为0.86 mm?a~(-1)和1.26 mm?a~(-1)。采样点的沉积速率在一定程度上代表了岛屿的垂向生长速率,均低于当前海平面的平均上升速率。同时,鸟骨的~(14)C年龄也揭示了赵述岛海鸟活动时间应不晚于AD 1172—1290,而海鸟开始在北岛活动的时间则不晚于AD 984—1140。