Stable Isotopic Evidence for a Pedogenic Origin of Carbonates in Trench 14 near Yucca Mountain, Nevada

Layered carbonate and silica encrust fault fractures exposed in Trench 14 near Yucca Mountain, site of the proposed high-level nuclear waste repository in southern Nevada. Comparison of the stable carbon and oxygen isotopic compositions of the fracture carbonates with those of modern soil carbonates in the area shows that the fracture carbonates are pedogenic in origin and that they likely formed in the presence of vegetation and rainfall typical of a glacial climate. Their isotopic composition differs markedly from that of carbonate associated with nearby springs. The regional water table therefore remained below the level of Trench 14 during the time that the carbonates and silica precipitated, a period probably covering parts of at least the last 300,000 years.     

40Ar/39Ar Age of the Lathrop Wells Volcanic Center, Yucca Mountain, Nevada

Paleomagnetic and (40)Ar/(39)Ar analyses from the Lathrop Wells volcanic center, Nevada, indicate that two eruptive events have occurred there. The ages (136 +/- 8 and 141 +/- 9 thousand years ago) for these two events are analytically indistinguishable. The small angular difference (4.7 degrees ) between the paleomagnetic directions from these two events suggests they differ in age by only about 100 years. These ages are consistent with the chronology of the surficial geological units in the Yucca Mountain area. These results contradict earlier interpretations of the cinder-cone geomorphology and soil-profile data that suggest that at least five temporally discrete eruptive events occurred at Lathrop Wells approximately 20,000 years ago.     

Streamflow and water well responses to earthquakes

Earthquake-induced crustal deformation and ground shaking can alter stream flow and water levels in wells through consolidation of surficial deposits, fracturing of solid rocks, aquifer deformation, and the clearing of fracture-filling material. Although local conditions affect the type and amplitude of response, a compilation of reported observations of hydrological response to earthquakes indicates that the maximum distance to which changes in stream flow and water levels in wells have been reported is related to earthquake magnitude. Detectable streamflow changes occur in areas within tens to hundreds of kilometers of the epicenter, whereas changes in groundwater levels in wells can occur hundreds to thousands of kilometers from earthquake epicenters.     

地膜厚度对马铃薯生长及农田水热条件和残膜污染的影响

为寻求阴山北麓农牧交错带马铃薯种植适宜的农用地膜厚度,揭示地膜厚度对马铃薯生长发育、土壤水热状况及地膜残留的影响规律,并评价其经济效益,选择当地主栽作物马铃薯为研究对象,在膜下滴灌栽培方式下通过设置4种地膜厚度（0.006、0.008、0.011 mm和0.012 mm）的田间试验,研究地膜厚度对马铃薯生长发育及地膜残留的影响。结果表明,增加地膜厚度对株高有促进作用,出苗率在0.008 mm处理最高。生育期土壤水热状况：增厚地膜可提升4周内0~20 cm土壤贮水量,随后作用相反,播后4周是土壤贮水量响应的拐点,并且在5周内可促进地表以下5 cm处的土壤积温。0.008 mm处理的产量、商品薯率和经济效益均最高。土壤残膜量随地膜厚度增加而增大,但回收难度随之降低,且加深翻耕深度加重了20~30 cm土层的残膜污染,需要通过加强残膜回收机具的研发利用来削减残膜系数,降低农田白色污染,提高土壤环境承载力。推荐阴山北麓农牧交错带马铃薯种植采用0.008 mm地膜配套适宜残膜回收机具以获得优良的经济效益与生态效益。     

Isotopic composition of old ground water from lake agassiz: implications for late pleistocene climate

A uniform oxygen isotope value of -25 per mil was obtained from old ground water at depths of 20 to 30 meters in a thick deposit of clay in the southern part of the glacial Lake Agassiz basin. The lake occupied parts of North Dakota and southern Manitoba at the end of the last glacial maximum and received water from the ice margin and the interior plains region of Canada. Ground water from thick late Pleistocene-age clay deposits elsewhere, a till in southern Saskatchewan, and a glaciolacustrine deposit in northern Ontario show the same value at similar depths. These sites are at about 50 degrees N latitude, span a distance of 2000 kilometers, and like the Lake Agassiz sites, have a ground-water velocity of less than a few millimeters per year. The value of -25 per mil is characteristic of meltwater impounded in the southern basin of Lake Agassiz. This value corresponds to an estimated air temperature of -16 degrees C, compared with the modern temperature of 0 degrees C for this area.     

Meteoric water in magmas

Oxygen isotope analyses of sanidine phenocrysts from rhyolitic sequences in Nevada, Colorado, and the Yellowstone Plateau volcanic field show that delta(18)O decreased in these magmas as a function of time. This decrease in delta(18)O may have been caused by isotopic exchange between the magma and groundwater low in (18)O. For the Yellowstone Plateau rhyolites, 7000 cubic kilometers of magma could decrease in delta(18)O by 2 per mil in 600,000 years by reacting with water equivalent to 3 millimeters of precipitation per year, which is only 0.3 percent of the present annual precipitation in this region. The possibility of reaction between large magmatic bodies and meteoric water at liquidus temperatures has major implications in the possible differentiation history of the magma and in the generation of ore deposits.     

Coupled ferric oxides and sulfates on the Martian surface

The Mars Exploration Rover (MER), Opportunity, showed that layered sulfate deposits in Meridiani Planum formed during a period of rising acidic ground water. Crystalline hematite spherules formed in the deposits as a consequence of aqueous alteration and were concentrated on the surface as a lag deposit as wind eroded the softer sulfate rocks. On the basis of Mars Express Observatoire pour la Minéralogie, l'Eau, les Glaces et l'Activité (OMEGA) orbital data, we demonstrate that crystalline hematite deposits are associated with layered sulfates in other areas on Mars, implying that Meridiani-like ground water systems were indeed widespread and representative of an extensive acid sulfate aqueous system.     

生境条件对沙漠植物约书亚树（Yucca brevifolia）光合生理特性的影响

[目的]研究生境条件对沙漠植物约书亚树（Yucca brevifolia）光合生理特性的影响.[方法]于2011年8月初采用Li-6400便携式光合仪研究了移栽裸沙地、五角枫林地、银中杨林地以及樟子松林地的约书亚树幼苗光合生理特性的日变化规律,并采用通径分析法分析各环境因子对约书亚树净光合速率的直接和间接影响.[结果]裸沙地和银中杨林地的约书亚树Pn日变化呈典型的“双峰”型,在11：00的光合“午休”现象,为非气孔限制因素所致.裸沙地约书亚树日均Pn最大为9.67 μmolCO2/（m2·s）,是五角枫林地的6.89倍,樟子松林地的3.87倍,银中杨林地的1.95倍.通过通径分析可以看出,不同生境条件下约书亚树Pn的主导环境因子是PAR.[结论]该研究提示了约书亚树对不同生境的响应机制,可为在我国大面积种植和推广该树种提供依据.     

Exposed water ice deposits on the surface of comet 9P/Tempel 1

We report the direct detection of solid water ice deposits exposed on the surface of comet 9P/Tempel 1, as observed by the Deep Impact mission. Three anomalously colored areas are shown to include water ice on the basis of their near-infrared spectra, which include diagnostic water ice absorptions at wavelengths of 1.5 and 2.0 micrometers. These absorptions are well modeled as a mixture of nearby non-ice regions and 3 to 6% water ice particles 10 to 50 micrometers in diameter. These particle sizes are larger than those ejected during the impact experiment, which suggests that the surface deposits are loose aggregates. The total area of exposed water ice is substantially less than that required to support the observed ambient outgassing from the comet, which likely has additional source regions below the surface.     

Oregon subduction zone: venting, fauna, and carbonates

Transects of the submersible Alvin across rock outcrops in the Oregon subduction zone have furnished information on the structural and stratigraphic framework of this accretionary complex. Communities of clams and tube worms, and authigenic carbonate mineral precipitates, are associated with venting sites of cool fluids located on a fault-bend anticline at a water depth of 2036 meters. The distribution of animals and carbonates suggests up-dip migration of fluids from both shallow and deep sources along permeable strata or fault zones within these clastic deposits. Methane is enriched in the water column over one vent site, and carbonate minerals and animal tissues are highly enriched in carbon-12. The animals use methane as an energy and food source in symbiosis with microorganisms. Oxidized methane is also the carbon source for the authigenic carbonates that cement the sediments of the accretionary complex. The animal communities and carbonates observed in the Oregon subduction zone occur in strata as old as 2.0 million years and provide criteria for identifying other localities where modern and ancient accreted deposits have vented methane, hydrocarbons, and other nutrient-bearing fluids.     

不同灌水处理下土壤水分动态及玉米水分利用效率研究

试验以"郑单958"和"浚单20"为试材,研究了田间不同灌水处理对土壤贮水量动态变化和玉米水分利用效率的影响。结果表明:表层土壤贮水量受降水影响较大,30～60 cm土壤水分含量在整个生育时期内变化最为剧烈,80～100 cm土壤整个生育时期水分含量稳定,无灌溉处理的耗水深度主要集中在60～100 cm土层。抗旱品种"郑单958"产量受灌水量的影响较小。"浚单20"灌水比不灌水处理平均增产8.02%。玉米2品种处理水分利用效率一般以不灌水处理较高,灌水处理水分利用效率均值比不灌水处理降低51.18%。因此,在水资源紧张的太行山山前平原区,选用抗旱玉米品种并灌水1次,即可减少农田耗水,又能保证较好的作物产量。     

宁夏灵武水田和旱田浅层地下水水位及氮磷特征研究

[目的]研究宁夏灵武水田和旱田浅层地下水的水位及氮磷的变化特征。[方法]于2009～2010年对灵武示范区地下水水位、总氯、总磷等指标进行连续2年监测。[结果]监测结果表明,监测区的旱田和水田的地下水位走势是一致的,地下水位的最高值为每年的6、7月份,为30cm左右,水位最低在每年的2、3月份,为180em左右;灌溉季节,水田地下水总氮含量高于旱田,非灌溉季节,水田地下水总氮含量低于旱田;水田和旱田地下水总磷含量年变化趋势是相同的,灌溉期间总磷含量相对较低,非灌溉期间相对较高。[结论]该研究可为进一步探究灌溉与氯磷水平之间的关系提供依据。     

Analysis on water requirement and water-saving amount of wheat and corn in typical regions of the North China Plain

This paper studied the variation characters on wheat and corn water consumption and irrigation watersaving amount under different water conditions (ample irrigation level, farmers conventional irrigation level and optimizing irrigation level). The water use efficiency and water saving potential of optimizing treatment and farmers’ conventional irrigation treatment were analyzed respectively. The objective of this study was to provide theoretical supporting for popularization and application of optimizing irrigation measures. Crop water requirement under sufficient water supply was calculated by Penman equation. We obtained crop water consumption under conventional treatment and optimizing treatment by field experiment. The main results showed that the irrigation amount of wheat and corn was too much under farmers’ conventional irrigation level and basically satisfied their water requirement, therefore, the water-saving amount was smaller while water-saving potential was bigger compared with the optimizing irrigation treatment. The grain yield under optimizing irrigation treatment was improved or appreciably reduced compared with that under conventional irrigation treatment, while the water consumption and irrigation amount of optimizing irrigation treatment was lower, with a higher water use efficiency. Therefore, the optimizing irrigation treatment could achieve a stable yield and high water efficiency at the same time. Moreover, when the optimizing irrigation measure was adopted, the grain yield reached 5940 kg/hm², water-saving amount reached 91mm for winter wheat, and the grain yield reached 7743 kg/hm², with water-saving amount of 49mm for summer corn in the piedmont region of Taihang Mount. The grain yield got 7710 kg/hm², with water-saving amount of 20mm for winter wheat in Heilonggang Plain. Therefore, the water-saving amount in the piedmont region of Taihang Mountain was obviously higher than that in Heilonggang Plain. Thus, the piedmont region of Taihang Mountain in the North China Plain is viewed as the key district for water-saving.     

Precursory chemical changes in ground water: kobe earthquake, Japan

Chloride (Cl(-)) and sulfate (SO(4)(2-)) ion concentrations of ground water issuing from two wells located near the epicenter of the Kobe earthquake in Japan fluctuated before the disastrous magnitude 7.2 event on 17 January 1995. The samples measured were pumped ground water packed in bottles and distributed in the domestic market as drinking water from 1993 to April 1995. Analytical results demonstrate that Cl(-)and SO(4)(2-) concentrations increased steadily from August 1994 to just before the earthquake. Water sampled after the earthquake showed much higher Cl(-) and SO(4)(2-) concentrations. The precursory changes in chemical composition may reflect the preparation stage of a large earthquake.     

长白山区主要冷水鱼资源现状调查研究

通过对长白山区主要冷水水域调查,得知的冷水鱼为5目7科11种,主要分布于鸭绿江上游及支流中，栖息的最适温度为12～18℃，繁殖期水温一般不超过13℃，食性多属于肉食性，水质要求清澈无污染。调查研究发现长白山区冷水鱼的种类有趋于减少的趋势,种群数量也是越来越少,甚至有的种类已成为珍稀或濒危物种。     

自然因素对祁连山水源涵养能力影响研究

[目的]分析不同自然因素对祁连山区水源涵养能力的影响。[方法]利用祁连山区2003年水源涵养量、高程数据(DEM)和SPOT-VEGETATION遥感数据,采用统计学方法定量分析研究区内差异较大的高程、坡度、坡向及植被条件与水源涵养量的关系,并提出水源涵养强度的概念,研究祁连山区自然因素对水源涵养量的影响。[结果]在祁连山山地水源涵养区内,高程为3 600～4 200 m或坡度为15～40°的区域水源涵养量较大;水源涵养能力最强的区域主要集中在阳坡(90～180°)或植被覆盖程度较高的区域。[结论]该研究为祁连山区的水资源管理和植被保护提供了科学依据。     

基于信息增益法选取柔鱼中心渔场的关键水温因子

西北太平洋海域是我国鱿钓渔船重要的作业渔场之一。影响渔场的环境因子是渔业海洋学的重要研究内容,它有助于理解渔场形成机理和指导渔业生产。根据1998-2008年的8-10月在北太平洋海域（150°E~170°E）不同水层的温度和我国鱿钓船的生产资料,对柔鱼作业渔场分布及其与不同水层(海表面、55 m、105 m) 的温度、水温垂直结构(0~55 m和55~105 m)进行分析,并利用信息增益技术计算作业次数对应的各分类属性的信息增益值。结果表明,8-10月中心渔场的最适海表面温度呈现季节性变化,55 m水层和105 m水层最适温度在9月份相对较低,而对应的0~55 m的温度梯度较大。信息增益值结果表明,影响中心渔场的关键水温因子依次是0~55 m水层温度梯度、55 m水层温度、海表面温度、105 m水层温度和55~105 m水层温度梯度。     

Carbonate compensation depth: relation to carbonate solubility in ocean waters

In situ calcium carbonate saturometry measurements suggest that the intermediate water masses of the central Pacific Ocean are close to saturation with resppect to both calcite and local carbonate sediment. The carbonate compensation depth, located at about 3700 meters in this area, appears to represent a depth above which waters are essentially saturated with respect to calcite and below which waters deviate toward undersaturation with respect to calcite.     

Ground water as a silica source for diatom production in a precipitation-dominated lake

The short-term, seasonal input of ground water to a small, precipitation-dominated oligotrophic lake in northern Wisconsin amounts to less than 10 percent of the annual water budget of the lake but accounts for nearly all the external silica loading. Silica is a necessary nutrient for diatoms. A large spring diatom bloom occurs coincident with high silica inputs from ground water when other possible silica sources are low. The mass budgets of ground water and silica in the lake system demonstrate the importance of ground-water solute inputs to the lake.     

河北省水资源变化及可持续性评估

为探究河北省水资源的变化趋势及可持续性,通过梳理2004-2018年河北省水资源动态变化,根据水资源供需现状,引入水资源生态足迹及承载力模型,分析多年水资源盈亏状况.结果 表明,相较2004-2011年,虽然2012-2018年水资源总量平均值变化不大,但年际间的波动增强,变异系数增加;在用水结构方面,用水总量稳中有降...