湖南大义山花岗岩南体黑云母40Ar-39Ar定年及地质意义

大义山岩体是一个多时代形成的复式岩体,习惯有大义山南体和北体之分.岩体内外接触带产有较多的W、Sn、Cu、Pb、Zn等多金属矿产.长期以来对南体主体形成的时代归属存在较大的差异,一部分人认为是印支期的产物,另一部人认为是燕山期的产物,这种结果对该区成矿作用的研究和指导找矿都带来很大的不利.本次研究通过对岩体的解体以及精确的黑云母氩氩法定年,确切地将大义山南体归属于两个不同的时代,即南体的北部为中侏罗世,南部为晚三叠世.这一成果对该岩体和成矿作用的研究都具有重要的现实意义.     

低压离子色谱与化学发光联用检测镍

利用离子色谱与鲁米诺化学发光联用技术,在一定的条件下,尝试分离检测过渡金属离子,进行无机流动相低压离子色谱分离-化学发光法检测痕量镍的研究。     

末次冰期以来青州黄土光释光测年及其对古气候的指示

黄河下游湿润-半湿润地区的鲁中黄土-古土壤沉积,是记录东亚季风气候变化的良好载体。山东青州邵庄黄土剖面粗颗粒石英（63—90 µm）光释光年代和磁化率、粒度、色度以及主量元素测试结果表明：（1）邵庄黄土末次冰期以来（(51.3±2.5)— (8.1±1.1) ka）沉积连续;（2）与粒度、磁化率和色度指标相比,化学蚀变指数能够更灵敏地反映冰期-间冰期沉积旋回;（3）粒度结果表明“古土壤”层中值粒径（16.9—24.6 μm）明显高于下伏黄土层中值粒径（11.8—22.7 μm）,主要是因为近源沉积在总的沉积通量中所占比例在冰期-间冰期尺度上的变化;（4）灰黑色“古土壤”层底界年龄为(19.1±1.6) ka,明显老于黄土高原全新世古土壤层底界年代（约10—11 ka）,其既包含全新世沉积的加积型土壤,也包含下伏末次冰期黄土层基础上受风化、淋溶形成的非加积型土壤。虽然研究区的“古土壤”包含非加积型土壤,记录了间冰期风化成壤过程,但依然能够反映冰期-间冰期气候旋回,是东亚乃至全球气候变化的产物。     

他念他翁山中段仁措湖地区花岗岩风化晕生长侵蚀模型研究及原地生成宇宙成因核素测年思考

通过建立他念他翁山流域仁措湖地区的花岗岩风化晕生长模型与侵蚀模型,并利用此模型定量了仁措湖地区花岗岩暴露年代。研究结果显示：该地区花岗岩风化晕平均生长速率为4.88 mm? (10 ka) ^?1;平均侵蚀速率为2.15 mm?ka^?1。通过此模型对仁措湖地区的年代进行计算,得出该地区花岗岩风化时间约为(236±88)— (19834±1560) a。结合原地生成宇宙成因核素（terrestrial in situ cosmogenic nuclide,TCN）测年原理,推算出青藏高原花岗岩冰川沉积物至少侵蚀速率分别为：青藏高原东北部为(2.61±0.05) mm?ka^?1、青藏高原东南部为(3.43±0.70) mm?ka^?1、青藏高原中部为(3.42±0.34) mm?ka^?1、喜马拉雅中部为(3.71±0.72) mm?ka^?1、高原西部为(3.14±0.52) mm?ka^?1、喜马拉雅山脉西部为(3.36±0.67) mm?ka^?1、帕米尔高原东部为(3.45±0.59) mm?ka^?1、帕米尔高原西部为(3.11±0.41) mm?ka^?1、天山为(3.63±0.53) mm?ka^?1,恢复后整个青藏高原的TCN测年精度提高了10%左右。     

大渡河石广东古滑坡堰塞湖沉积物光释光年代研究

堰塞是重要的极端地表过程之一,往往会造成灾难性的后果,对古堰塞湖的研究有助于对区域堰塞风险的认识。本文以青藏高原东缘大渡河上游石广东古滑坡堰塞湖为研究对象,地质证据显示该古堰塞湖的堵江高坝高约23 m,堵江滑坡的体积约1.6×10~7 m~3,堰塞湖的最小蓄水量为2.0×10~7 m~3。并选取两个湖相沉积剖面,采用单片再生法(single aliquot regeneration,SAR)与标准生长曲线法(standard growth curve,SGC)相结合的方法,测定了7个样品的光释光(optically stimulated luminescence,OSL)年龄,测年结果表明堰塞湖形成于距今约3.0 ka,结束于1.6 ka,即全新世晚期。初步推测堵江的古滑坡体可能由于地震诱发。     

Compromise ultrasound dating policy in maternal serum screening for Down syndrome

Routine ultrasound biometry is the method of choice for gestational dating when screening for Down syndrome. However, it is costly and an alternative policy is to restrict ultrasound to women most likely to have menstrual dating errors. This was evaluated by statistical modelling with parameters from 14 274 women screened between January 1997 and July 2001 using free beta-human chorionic gonadotrophin (free β-hCG), α-fetoprotein (AFP) and unconjugated estriol (uE₃). A total of 12 711 (89%) women had both ultrasound and menstrual gestations, but in 4101 (29%) women either the last menstrual period (LMP) was uncertain or a pill-withdrawal period, or there were irregular or abnormal length cycles. The LMP was not entered in the test request form for a further 1404 (9.8%) women. Routine ultrasound dating yielded a predicted detection rate higher than for menstrual dating by 3.9–7.1%, depending on the marker combination and cut-off. The false-positive rate was reduced by 0.2–1.1%. Selectively scanning the 39% with unreliable dates increased detection by 2.6–4.6%, and reduced the false-positive rate by 0.04–0.6%. Some centres only use the ultrasound estimate of gestation when it differs from the menstrual estimate by more than 7 days. Such a rule reduces the gain in detection rate to 2.5–4.6% for routine ultrasound and 1.7–3.1% with the compromise policy; the false-positive rate reductions are 0.06–0.6% and 0.0–0.3%, respectively. We conclude that if routine ultrasound is not financially and practically feasible, the compromise policy yields a clinically important improvement in screening performance compared to menstrual dating. Copyright © 2002 John Wiley & Sons, Ltd.     

Comprehensive evaluation of heavy metal contamination of sediment in Lake Dianchi by using modified AHP method and 137Cs dating

Through the use of general sampling and measurement by ¹³⁷ Cs dating, problems regarding the absence of monitoring data can easily be resolved. Further, weighted values need to be determined while Environment Quality Comprehensive Index (EQCI) is commonly used as applied in environmental quality comprehensive evaluation. In order to overcome the subjectivity in determining weights, the modified Analytical Hierarchy Process (AHP) method was designed. The modified AHP method involved the following key procedures: First, the parameters y _i1 and y _i2 were calculated based on the monitoring data; second, the factors were put in order according to the symbol and value of y _i1 and y _i2; third, the continuous odd integers, which represented the importance of factors, were given to factors according to their seating order; and, fourth, the factor weights were determined from the pair-wise comparison matrix calculated by the ratio of the given odd integers. Therefore, the weights were completely based on the monitoring data. In the present study, the comprehensive quality of sediments in five sections of Lake Dianchi were evaluated and the results indicated that the current contamination of sediments in each lake section is much more serious than at any other time in history. __________ Translated from Environmental Science, 2006, 27(8): 1531–1536 [译自: 环境科学]     

Life in extreme environments: survival strategy of the endolithic desert lichen Verrucaria rubrocincta

Verrucaria rubrocincta Breuss is an endolithic lichen that inhabits caliche plates exposed on the surface of the Sonoran Desert. Caliche surface temperatures are regularly in excess of 60 degrees C during the summer and approach 0 degrees C in the winter. Incident light intensities are high, with photosynthetically active radiation levels typically to 2,600 micromol/m(2) s(-1) during the summer. A cross-section of rock inhabited by V. rubrocincta shows an anatomical zonation comprising an upper micrite layer, a photobiont layer containing clusters of algal cells, and a pseudomedulla embedded in the caliche. Hyphae of the pseudomedulla become less numerous with depth below the rock surface. Stable carbon and oxygen isotopic data for the caliche and micrite fall into two sloping, well-separated arrays on a delta(13)C-delta(18)O plot. The delta(13)C(PDB) of the micrite ranges from 2.1 to 8.1 and delta(18)O(SMOW) from 25.4 to 28.9, whereas delta(13)C(PDB) of the caliche ranges from -4.7 to 0.7 and delta(18)O(SMOW) from 23.7 to 29.2. The isotopic data of the micrite can be explained by preferential fixing of (12)C into the alga, leaving local (13)C enrichment and evaporative enrichment of (18)O in the water. The (14)C dates of the micrite range from recent to 884 years b.p., indicating that "dead" carbon from the caliche is not a significant source for the lichen-precipitated micrite. The endolithic growth is an adaptation to the environmental extremes of exposed rock surfaces in the hot desert. The micrite layer is highly reflective and reduces light intensity to the algae below and acts as an efficient sunscreen that blocks harmful UV radiation. The micrite also acts as a cap to the lichen and helps trap moisture. The lichen survives by the combined effects of biodeterioration and biomineralization. Biodeterioration of the caliche concomitant with biomineralization of a protective surface coating of micrite results in the distinctive anatomy of V. rubrocincta.     

基于生物光学模型的二类水体光学活性物质估算：以晋江下游河段为例

水体中各组分对光谱的吸收和散射构成了水体的固有光学特性,是生物光学模型的重要参数,是建立水质遥感半分析模型的基础.目前该方法多应用于湖泊水质监测,很少用于河流.因此, 本研究以福建晋江下游河段为例, 探讨水面下反射率R(0^-)与光学活性物质之间的关系,并建立了光学活性物质的估算模型.结果表明,利用R(0^-)₇₅₃与总悬浮物浓度、R(0^-)₇₀₂/R(0^-)₆₈₀与浮游植物色素浓度、R(0^-)₆₇₀/R(0^-)₄₂₃与CDOM吸收系数分别建立的估算模型能取得理想的效果,其决定系数分别是0.953、 0.820 5和0.621 3,对应的相对误差分别是6.1%、 21.87%和22.18%.三者中以悬浮物浓度的反演精度最高,然后依次为浮游植物色素浓度和CDOM.主要原因在于浮游植物色素的浓度相对较低,光谱信号较弱;CDOM的特征光谱波段很窄,而且该波段内的R(0^-)受到其它２种物质存在的影响.     

曝气条件下微电解-Fenton工艺联合处理模拟染料废水的研究

曝气条件下采用微电解-Fenton工艺处理模拟染料废水。在最佳微电解工艺即铁炭比为45 g∶45 g,pH=3,反应时间为60 min;在Fenton工艺pH值为3,H2O2投加量0.7 mL,反应时间为120 min时,染料废水总脱色率达92%,其色度去除率高于单独微电解工艺时的63%和单独Fenton工艺时的67%。模拟染料废水经微电解及Fenton工艺处理后,废水pH值、Fe2+浓度和色度均发生变化。