Assessing herbicide concentrations in the saturated and unsaturated zone of a Chalk aquifer in southern England

The behavior of the herbicides isoproturon (IPU) and chlortoluron (CTU) in ground water and shallow unsaturated zone sediments were evaluated at a site situated on the Chalk in southern England. Concentrations of IPU in ground water samples varied from < 0.05 to 0.23 microgram/L over a five-year period of monitoring, and were found to correlate with application of the pesticide. Concentrations of pesticides in ground water samples collected during periods of rising water table were significantly higher than pumped samples and suggest that rapidly infiltrating recharge water contains higher herbicide concentrations than the native ground water. Significant variations in herbicide concentrations were observed over a three-month period in ground water samples collected by an automated system, with concentrations of IPU ranging from 0.1 to 0.5 microgram/L, and concentrations of a recent application of CTU ranging from 0.2 to 0.8 microgram/L. Different extraction methods were used to assess pore water concentrations of herbicides in the unsaturated zone, and samples were analyzed by standard HPLC analysis and immunoassay (ELISA) methods. These data indicated highly variable concentrations of herbicide ranging from 4 to 200 g/ha for HPLC and 0.01 to 0.04 g/ha for ELISA, but indicate a general pattern of decreasing concentrations with depth. The results of this study indicate that transport of IPU and CTU through the unsaturated zone to shallow ground water occurs and that this transport increases immediately following herbicide application. Measured concentrations of herbicides are generally lower than specified by the European Union Drinking Water Directive, but are observed to spike above this limit. These results imply that, while delivery of pesticides to ground water can occur as a result of normal agricultural practices, the impact on potable supplies is likely to be negligible due to the potential for degradation during the relatively long travel time through the unsaturated zone and high degree of dilution that occurs within the aquifer. As a result of the wide variation in concentrations detected by different techniques, it is suggested that for future site investigations more than one sampling strategy be employed to characterize the occurrence of pesticide residues and elucidate the transport mechanisms.     

The Spectroscopic Orbit of the Planetary Companion Transiting HD 209458

Three new silicon-bearing radicals of astrophysical interest, SiCCH and the two nearly isoenergetic isomers SiCN and SiNC, were detected in a laboratory discharge in their X2Pi ground states by Fourier transform microwave and millimeter-wave absorption spectroscopy. Hyperfine structure was observed in the low rotational transitions of the (2)Pi(1/2) ladder, and well-resolved Lambda-doubling was observed in both fine-structure ladders. With the spectroscopic constants derived from the laboratory measurements, the spectra of all three can be calculated to an uncertainty of less than 0.1 km s(-1) in equivalent radial velocity over the entire range of interest to radio astronomers. SiCN, with a dipole moment of 2.9 D, is probably the most promising of the three for astronomical discovery.     

6Li from Solar Flares

By introducing a hitherto ignored 6Li producing process, due to accelerated 3He reactions with 4He, we show that accelerated particle interactions in solar flares produce much more 6Li than 7Li. By normalizing our calculations to gamma-ray data, we demonstrate that the 6Li produced in solar flares, combined with photospheric 7Li, can account for the recently determined solar wind lithium isotopic ratio, obtained from measurements in lunar soil, provided that the bulk of the flare-produced lithium is evacuated by the solar wind. Further research in this area could provide unique information on a variety of problems, including solar atmospheric transport and mixing, solar convection and the lithium depletion issue, and solar wind and solar particle acceleration.     

临汾市地裂缝灾害模拟与灾情预报的GIS研究

山西临汾市地裂缝灾害受控于多种因子．在详尽分析了诸如地质构造、地下水渗流场、地层条件和地貌环境等各个致灾因子的基础上,分别建立了它们各自的专题层;然后利用先进的ＡＨＰ方法确定出它们之间的相互关系,通过应用ＧＩＳ强大的空间分析和处理操作功能,构建出地裂缝灾害模拟评价的多元地学信息复合叠加模型．在此基础上,对地裂缝灾害的灾情发展趋势进行了预测．     

贵州独山锑矿田地质地球化学特征和构造动力热液成矿

独山锑矿田位于独山箱状背斜核部近倾伏端,矿床、矿体的产出严格受断裂控制,其半坡半锑矿呈脉状产于下泥盆统、志留系碎屑岩的陡倾斜断裂中;其巴年式的锑矿呈层状产于泥盆统碎屑岩与碳酸盐岩之间的层间滑动带中。成矿温度低,矿石组分和围岩蚀变简单,锑主要还原于下伏地层,硫主要来源于赋矿地层,成矿流体主要为大气降水,构造动力成矿作用导致锑矿床的形成,矿床类型为一典型的构造动力热液矿床。     

中国东部边缘海潮波系统形成机制的模拟研究

以三维高精度潮波数值模拟为基础,动用系统分析方法和地理信息系统技术,对影响中国东部边缘海潮波系统的因素,包括入射潮波、科氏力、海区地形、岸线形状及底摩擦等,进行了模拟试验。结果表明,它们对潮波系统的模式有不同程度的作用,其中科氏力的有无、岸线形态的变化和水下地形的巨变化对潮波系统有重要影响。研究认为,中国东部边缘海潮波系统是一个海－潮相互作用的整体;在一定的入射潮波条件下,该区的海区条件、特别是岸     

太古宙一元古界线研究现状

根据大量资料,分析了近年来对太古宙－元古宙界线（A／P）及其附近的研究成果,并着重论述了有关构造－岩浆事件的研究及其意义,结合我国华北A／P界线的相关问题的研究概况,认为在五台山和太行山乖地的变质岩区选择典型剖面,对太古宙基底的变基性岩体进行构造背景、精确同位素年代学以及盖层的沉积特征等多科综合研究,是今后深入探讨这一领域的关键,其研究成果对明确我国A／P界线标志将提供重要依据。     

东昆仑卡而却卡铜矿区花岗闪长岩及其暗色微粒包体成因:锆石U-Pb年龄、岩石地球化学及Sr-Nd-Hf同位素证据

卡而却卡铜多金属矿区花岗闪长岩体中广泛分布具有似斑状结构的闪长质包体,包体主要为椭圆形,定向排列,具有与寄主岩石相似的矿物组合,但角闪石含量明显比寄主岩石高,具有明显的不平衡反应结构,发育针状磷灰石。LA-MC-ICP-MS锆石U-Pb测试表明,暗色微粒包体形成于(234.1±0.6)Ma,寄主花岗闪长岩形成于(234.4±0.6)Ma,为岩浆混合作用的存在提供了有力证据。地球化学特征显示,暗色包体Si O2、Mg O含量较寄主岩石高,更偏基性;均富集大离子亲石元素和轻稀土元素,亏损高场强元素,但寄主花岗闪长岩LaN/YbN值(11.6~19.0)明显高于暗色包体(5.0~9.7),Nb/Ta值(10.6~11.7)低于暗色包体(11.6~14.8)。二者具有相近的Sr-Nd-Hf同位素组成,花岗闪长岩的εNd(t)值为-5.3~-4.2,(87Sr/86Sr)i值为0.71110~0.71125,εHf(t)为-5.8~-3.4,tDM(Hf)为1012~1102 Ma;暗色包体的εNd(t)值为-5.2~-5.0,(87Sr/86Sr)i值为0.71114~0.71171,εHf(t)为-6.3~-1.6,tDM(Hf)为937~1129 Ma。综上推测,在中三叠世俯冲—碰撞转换阶段,EMⅡ型富集岩石圈地幔在上涌软流圈物质的作用下发生部分熔融产生基性岩浆,并底侵下地壳物质局部熔融形成长英质岩浆房,进而由基性岩浆注入长英质岩浆房后,经过演化形成微粒包体,演化了的基性岩浆与长英质岩浆混合,最终形成含微粒包体的均一岩浆,这种岩浆结晶后形成含暗色包体花岗闪长岩。     

三氯化铁絮凝小球藻的采收工艺

【目的】研究三氯化铁对小球藻絮凝采收效果的影响,并优化采收工艺条件。【方法】分析FeCl₃浓度、小球藻初始浓度和絮凝时间对小球藻采收效率影响,利用响应面法优化利用FeCl₃采收小球藻的工艺参数。【结果】单因素实验表明,FeCl₃质量浓度为0.6 g/L、小球藻初始质量浓度为0.42 g/L和絮凝时间为30 min时,小球藻的采收效率最高。响应面法分析表明,小球藻初始浓度对小球藻采收率有显著影响(P<0.05);影响采收效率的主次因素顺序为小球藻初始浓度>FeCl₃浓度>絮凝时间;FeCl₃浓度和小球藻初始浓度的交互作用对小球藻的采收效率有显著影响(P<0.05);FeCl₃浓度二次项对小球藻的采收效率有极显著影响(P<0.01)。【结论】利用FeCl₃采收小球藻的最佳工艺条件:小球藻初始质量浓度为0.55 g/L,FeCl₃质量浓度为0.6 g/L,絮凝时间为38 min,此时的采收效率为(98.6±1.9)%。     

Lamb波相控阵结构健康监测成像技术

在分析相控阵波束指向的控制过程与介绍相控阵结构健康监测原理的基础上,利用相控阵原理控制Lamb波的时间延迟使其在结构损伤处聚焦.通过比较结构健康状态与损伤状态的传感器响应信号,获取Lamb波损伤散射信号;采用相控阵技术控制损伤散射信号时间延迟得到不同方向的信号,进而实现对结构的多方位扫描,根据扫描信号特点,将各方向的监测结果信号采用灰度图像显示.该方法在铝板结构中实现损伤的定位成像,其不仅能够精确定位损伤位置,而且能够直观清晰显示结构损伤.