Epikarst hydrology and implications for stalagmite capture of climate changes at Grotta di Ernesto (NE Italy): results from long‐term monitoring

Grotta di Ernesto is a cave site well suited for palaeoclimate studies because it contains annually laminated stalagmites and was monitored from 1995 to the end of 2008 for microclimate, hydrology and hydrochemistry. Long‐term monitoring highlighted that cave drips show three different hydrological responses to rainfall and infiltration: (1) fast seasonal drips in the upper part of the cave, which are mostly fed by fractures, (2) slow seasonal drips, located at mid‐depth in the cave characterized by mixed feeding and (3) slow drips, mostly located in the deeper gallery, which are fed by seepage flow from bulk porosity with a minor fracture‐fed component. The slow drips display daily cycles during spring thaw. Monitoring also indicated that drip waters are only slightly modified by degassing within the soil zone and aquifer and by prior calcite precipitation. Hydrochemical studies show a clear seasonality in calcite saturation index, which results in most cave calcite precipitation occurring during late autumn and winter with similar amounts of precipitated calcite on most stalagmites, regardless of drip rate (discharge) differences. Drip rate, and drip rate variability, therefore, has a minor role in modulating the amount of annual calcite formation. In contrast, drip rate, when associated with moderate reduction in calcite saturation index, clearly influences stalagmite morphology. Increasing drip rate yields a passage from candle‐, to cone‐ to dome‐shaped stalagmites. Very high drip rates feed speleothems with flowstone morphology. In summary, monitoring provides information about the karst aquifer and how hydrology influences those physical and chemical characteristics of speleothems which are commonly used as climate proxies. Copyright © 2010 John Wiley & Sons, Ltd.     

贵州七星洞滴水的水文水化学特征及其意义

本文对贵州都匀七星洞9个滴水点进行厂为期1年的动态临测，结果显示滴水的物质组成直接源自于洞穴环境，即土壤和岩石。而大气降雨携带的物质成分较少。洞穴滴水的化学组成中元素含量变化主要由水运移过程中水-土、水-岩作用导致的岩石溶解-方解石沉淀过程所控制。QXD-1#、QXD-2#、QXD-6#、QXD-7#、QXD-8#由于水运移过程中经过的土壤较薄。水-岩作用对滴水化学特性的贡献略大。稀释作用发生在干旱条件下的QXD-2#滴水点，活塞作用在雨季对QXD-7#、QXD-9#滴水产生影响，在不同的季节，QXD-1#、QXD-3#、QXD-8#滴水点的滴率产生跳跃式变化。这些作用均受控于水的来源差异。所有这些过程对滴水点水化学产生影响但其效果较弱。滴水的Mg／Ca指示了大气降雨的变化，其值受控于洞穴顶板内水运移过程中水-土、水-岩作用下的水文地球化学过程即岩石的溶解、方解石沉淀过程及土壤物理、化学、生物学过程等。     

不同灌溉对阜康地区冬小麦产量及土壤水分动态变化的影响

根据阜康生态试验站试验小区1999－2000年冬小麦不同灌溉量控制试验，验证了冬小麦水分敏感期为拔节－灌浆期，探讨了该区冬小麦产量与灌水量之间的关系。提出了阜康地区冬小麦返青水应采用“小水”灌溉的方式。同时通过对小区冬小麦成熟期灌水过程不同深度土壤水分含量的动态观测分析，提出冬小麦在成熟期对灌溉水分的消耗利用集中在0－30cm土壤层内的观点。     

北京市再生水灌溉对地下水的重金属污染风险

通过野外取样分析再生水灌溉、长期污水灌溉条件下土壤剖面和地下水中重金属含量, 预测再生水灌溉对地下水的重金属污染风险。结果表明:污染严重的Cr、Cu和Zn等3种元 素主要在土壤表层0～20cm累积, 0～180cm土层呈先降低后升高, 之后再降低的变化趋势。 污染较轻的As、Ni和Pb在0～60cm土层含量差异不大, 0～180cm土层大致呈先升高后降 低的变化趋势。所有重金属在土壤剖面90cm左右的土层中均存在高值区, 该层含量高于上、 下土层, 高值区的分布位置与北京剖面土壤发生层的分布特征一致, 与成土母质自然发育有 关, 并非表层土壤重金属向下淋溶沉积而成。综合土壤剖面重金属分布特征和调查区地下水 重金属浓度情况, 重金属向下层土壤迁移的趋势很小, 即使凉水河灌区污染严重的Cr、Cu、 Zn,主要在土壤表层累积, 并未导致地下水重金属污染。在当前的水质条件下, 农田再生水 灌溉输入的重金属量低于大气沉降和有机肥施用, 再生水灌溉导致地下水的污染风险小于大 气沉降和有机肥施用。因此相对于大气沉降、有机肥施用等输入途径, 再生水灌溉导致地下 水重金属污染的可能性不大。     

卸荷状态下岩爆岩石变形破裂机制的实验岩石力学研究

岩爆是高地应力区地下工程中常见的一种卸荷破坏地质灾害现象。本文按照地下洞室开挖过程中围岩的实际受力状态,采用卸荷三轴试验方法,探讨了岩爆岩石的变形破坏特征和岩爆形成力学机制问题。     

沙漠腹地乔木状沙拐枣对灌水量的生理生态响应

对不同灌水量条件下塔克拉玛干沙漠腹地乔木状沙拐枣（Calligonum arborescens Litv）的水分生理、生长和土壤水分进行了动态测定与分析。结果表明:①在35、24.5 kg·株-1·次-1和14 kg·株-1·次-1的灌水量下,土壤水分活跃层分别为:0～200、0～160 cm和0～100 cm。根系区土壤水分为3%～4%条件下,沙拐枣能正常生长,低于2.5%就会受到水分胁迫。②早晨和午后,沙拐枣的水势随着灌溉后时间的增加而降低,前期降幅较大。随着灌水量的减小,其水势降低较快,在14 kg·株-1·次-1处理下,灌溉3 d后早晨水势和午后水势分别达到-1.3 MPa和-2.19 MPa。③随着灌水量的减少沙拐枣的日耗水量急剧减小,液流速率也快速降低,灌溉后第15天,在24.5 kg·株-1·次-1和14 kg·株-1·次-1的灌水量下沙拐枣液流速率都为双峰型曲线,第25天3个处理都呈双峰型曲线。④不同灌水量下,沙拐枣的基径、新枝长度以及新枝直径的年增长量都随着灌水量的减少而减小,方差分析表明灌水量对新枝长度的影响非常显著(P=0.05)。     

基于分形理论的灌溉水有效利用系数空间尺度变异

基于2010 年度广东省75 处样点灌区的实测资料和遥感图像, 应用分形理论, 采用网格盒维数法计算了各样点灌区盒维数, 结果表明:广东省灌区具有明显的分形特征, 盒维数介于1.0004~1.675 之间, 分维数均值为1.308, 形状指数均值为0.335, 都随灌区规模呈同步减小趋势。不同规模灌区盒维数大型灌区(1.442) > 中型灌区(1.287) > 小型灌区(1.195)。灌溉水有效利用系数与空间分形特征诸因子中以非空网格对数值最高, 相关性达到0.941。基于此, 建立了不同网格尺度下的灌区面积与灌溉水有效利用系数和盒维数空间尺度变异函数。同时, 从影响灌溉水有效利用系数的众多因素中, 选取了工程评价值、盒子维数、灌区形状指数、参考作物蒸发蒸腾量ET0 和当年降水量5 项指标进行了空间格局影响因素分析, 结合灰关联计算结果表明:空间各影响因素中以工程评价因子的关联度最高, 达到0.8478, 其次为形态特征因子, 自然气象因子影响最小。尝试利用分形理论为不同面积尺度灌区灌溉水有效利用系数的空间变异规律分析和尺度转换提供一种新的思路, 该结果对于指导灌区投资改造和规划建设, 具有较强的理论和应用价值。     

澜沧江流域农业灌溉需水的时空变化(英文)

Based on the data of eight meteorological stations from the 1950s to 2007, current cropping patterns, field water moisture management, we use the Mann-Kendall and the Re-scaled Range Analysis methods to research the changes of humidity and crop irrigation water requirements in the Lancang River Basin. The results show that the annual and dry season average temperatures significantly increased, and the dry season rainfall increased while wet season rainfall decreased. Evaportranspiration (ET0) increased during both dry and wet seasons at all stations except Dali, Jianchuan and Gengma, and the aridity-humidity index decreased at most of the stations. The turning points of weather factors, ET0, the arid-ity-humidity index, paddy irrigation requirements and total agricultural water requirements occurred from the 1960s to the 1990s. The spatial changing tendency of paddy irrigation quota increased with the increase of altitude and latitude, and the correlation coefficients are 0.513 and 0.610, respectively. The maximum value is observed in Weixi, while the minimum in Mengla.     

喷灌条件下土壤水分空间分布特性研究

分别在火山灰土和砂壤土两种土壤上进行了不同喷灌均匀系数和灌水量的土壤水分空间分布试验。对土壤干容重空间分布规律的研究表明,干容重在空间的随机分布可用正态分布来表示。为了确定喷灌洒水量和土壤含水率的空间结构,分别计算了它们的半方差和自相关函数。结果指出,喷灌洒水量的相关距离为h～6m,该距离随风速呈增大趋势;灌水停止4h后的土壤含水率的相关距离为5～6m,喷灌均匀系数对该距离无明显影响。田间试验还表明,喷灌洒水在土壤中的分布要比其在地表的分布均匀得多,土壤水分空间分布的均匀性主要取决于土壤初始含水率的均匀程度和灌水量。     

Long-range underwater photography in the deep ocean

Although the optical properties of seawater at extreme depths are more suitable for underwater photography than those at the surface or on continental shelves, they still impose severe limitations on long-range wide area bottom photography. Additionally, deep ocean operations impose technical limitations on control, power and bandwidth. This chapter reviews the approaches contemplated or made towards improving the camerato-target range in underwater photography in the deep ocean. Further significant improvements await advances in control, power/light sources and bandwidth reduction. With the developments now contemplated, TV and video systems will eventually present a strong challenge to emulsion film techniques.