• 快讯 Agarwal在非理想条件下解释恢复测试的方法

    编译服务:水体修复
    编译者:王阳
    发布时间:2018-08-20
    Pumping tests are performed during aquifer characterization to gain conceptual understanding about the system through diagnostic plots and to estimate hydraulic properties. Recovery tests consist of measuring head response in observation and/or pumping wells after pumping termination. They are especially useful when the pumping rate cannot be accurately controlled. They have been traditionally interpreted using Theis' recovery method, which yields robust estimates of effective transmissivity, but does not provide information about the conceptual model. Agarwal proposed a method, which has become standard in the oil industry, to obtain both early and late time reservoir responses to pumping from recovery data. However, the validity of the method has only been tested to a limited extent. In this work, we analyze Agarwal's method in terms of both drawdowns and log‐derivatives for non‐ideal conditions: leaky aquifer, presence of boundaries and one dimensional flow. Our results show that Agarwal's method provides excellent recovery plots (i.e., the drawdown curve that would be obtained during pumping) and parameter estimates for nearly all aquifer conditions, provided that a constant pumping rate is used and the log‐derivative at the end of pumping is constant, which is too limiting for groundwater hydrology practice, where observation wells are usually monitored. We generalize Agarwal's method by (1) deriving an improved equivalent time for time‐dependent pumping rate, and (2) proposing to recover drawdown curves by extrapolating the pumping phase drawdowns. These yield excellent diagnostic plots, thus facilitating the conceptual model analysis, for a broad range of conditions.
  • 快讯 北落基山森林河道中河道和漫滩大型林木的空间分布

    编译服务:水体修复
    编译者:王阳
    发布时间:2018-08-20
    Planform geometry, spatial heterogeneity, and large wood abundance and distribution were characterized using combined remote imagery and field surveys along lengths of 20‐28 km in four river corridors (channels and floodplains) in northwestern Montana. Study sites included four planform geometries: meandering, straight, braided, and multichannel. Planform spatial heterogeneity of channels and floodplains, such as proportion of the active channel in bars, sinuosity, braiding index, and the number of active channels, differs in relation to channel planform type. Braided and multichannel rivers have significantly greater spatial heterogeneity of channels and floodplains and store significantly greater volumes of wood in the channel. Wood is preferentially stored in jams and jams are preferentially stored in shallow areas of the active channel (midchannel bars, inner bends, secondary channels) and in abandoned channels on the floodplain. We interpret these results using a conceptual model in which boundary conditions create sufficient valley‐bottom width for the development of planform spatial heterogeneity, which then promotes storage of large wood. The results of this study can inform management that protects or restores spatial heterogeneity.
  • 快讯 美国日本共同研发新型脱盐膜 可用于海水淡化

    编译服务:水体修复
    编译者:王阳
    发布时间:2017-09-14
    美国宾夕法尼亚州立大学原子中心主任与日本信州大学的研究人员合作,开发出一种基于石墨烯的脱盐膜,比目前的各种过滤膜更坚固耐用、效率更高。这一技术未来可用于海水淡化、蛋白质分离、废水处理,以及制药和食品工业等。 “我们的梦想是研制一种智能膜,具有高通量、高效率、长寿命、自修复等特点,可为缺水地区消除水体中的生物污染和无机污染、获取清洁水提供解决方案”,宾夕法尼亚州立大学物理化学与材料科学工程教授毛里西奥·特罗内斯(MauricioTerrones)介绍说,“这项研究工作正朝着这个方向前进”。 本研究开发的杂化膜采用简单的喷涂技术将溶液中的氧化石墨烯和少量层状石墨烯包覆在聚乙烯醇改性聚砜的骨架支撑膜上。支撑膜增强了杂化膜的牢固性,使其能够承受强烈的横流、高压和氯接触。尽管目前该技术还处于开发的早期阶段,膜样品已可过滤掉85%的盐,制取的水虽还不能直接饮用,但已可用于农业灌溉。研制的膜还能够过滤掉96%的染料分子,因此可以用于纺织工业的废水处理,防止废水直接排放到河流中污染环境。 氯通常用于降解废水中的生物活性成分,但它也会使目前的各种聚合物膜的性能迅速降低。而这种基于石墨烯的新型膜具有很强的抗氯能力。 众所周知,石墨烯具有很高的机械强度,多孔石墨烯具有很强的过滤能力,几乎可以100%过滤掉水中的盐分,是一种潜在的理想的脱盐膜材料。然而,将石墨烯扩展到工业量方面还有许多挑战,包括控制缺陷和处理二维材料需要复杂转移技术等。研究团队正在试图克服可伸缩性问题,并在生产规模上提供廉价、高质量的膜。 这项成果发表在8月28日出版的《自然·纳米技术》杂志上。论文第一作者亚伦·莫雷洛斯·戈麦斯(AaronMorelosGomez)说:“我们研制的过滤膜克服了氧化石墨烯的水溶性问题,用聚乙烯醇作为粘合剂,使它能抵抗强烈的水流和高压冲击。通过将氧化石墨烯与石墨烯混合,我们还可以显著提高其耐腐蚀性化学制剂(如氯)的腐蚀。”
  • 快讯 西半球最大海水淡化项目Carlsbad因产能未达预期被罚350万美元

    编译服务:水体修复
    编译者:王阳
    发布时间:2017-09-11
    据悉,到今年6月30日为止的过去一年中,美国Carlsbad海水淡化厂因为运营出现的各种问题导致46天都未能供水给圣地亚哥水务局,总体供水量相比承诺产能约少了五分之一。 Carlsbad项目过去一年提供淡水的产能是40400英亩-英尺(约合5000万m³),但按照合同应给圣地亚哥水务局供应的淡水量为49600英亩-英尺(约6130万m³),项目开发商Poseidon Water公司也因此被罚350万美元。 据悉,仅在2017年Carlsbad就已经停产两次。2月份,淡化厂因水箱维修停产10天;4月份又因海岸赤潮关闭15天。 今年8月份,圣地亚哥水务局相关负责人和Poseidon公司主管Carlos Riva专程会面,探讨了Carlsbad海淡厂目前的运行状况,圣地亚哥水务局方面表示依然支持该厂的各方面运作。 据了解,Carlsbad项目与圣地亚哥当地水务公司按照“照付不议”的模式签订了长达一份30年的淡水收购合同,该项目每天应通过海水淡化为当地提供5600万加仑(约合21万m³)饮用水,应可满足该地区10%的供水需求。
  • 监测快报 水体修复动态快报

    编译服务:水体修复
    编译类型:快报,简报类产品
    发布时间:2020-09-15
    《水体修复动态快报》主要报道水体污染治理领域的国际科技战略与规划、科研计划与项目资助、科研进展与动态、科技前沿与热点、重要科技政策与管理等方面内容。