不同补水方式下砂壤土渗滤系统对硝态氮去除效果

在水资源短缺的北京地区利用再生水回补城市河湖,一方面对于水资源的可持续利用有着十分重要的作用,另一方面也可能带来地下水环境的潜在污染风险.该文采用100 cm砂壤土柱模拟(河湖岸底)土地渗滤系统,设置定水头淹水、交替淹水落干、定流速补水和侧向补水4种不同再生水回补方式,研究再生水中硝态氮(NO3-N)在土地渗滤系统中的去除效果和迁移转化规律.结果表明,当水力负荷在0.25~2.65 cm/d范围内时,渗滤系统对NO3-N的去除率随着水力负荷的增大而减小;侧向补水方式下渗滤系统对NO3-N的去除效果最优,平均去除率高达96.1%.在定水头淹水和侧向补水方式下,系统对NO3-N的去除主要发生在土柱的上部,而交替淹水落干和定流速补水条件下,土柱中下部对NO3-N也有一定的去除作用.渗滤系统对NO3-N的去除主要取决于系统内部微生物的分布情况,土层中的反硝化细菌数量越大,该土层对NO3-N的去除率就越高.当水温在15~32℃范围内变化时,定水头淹水和交替淹水落干补水方式下,系统对NO3-N的去除率与温度分别呈指数和幂函数关系.该研究表明土地渗滤系统可实现再生水的进一步净化处理,可为再生水安全回补河湖提供参考.     

Optimum Soil Water Content for Chickpea Emergence in Heavy‐Textured Soils of North‐West Bangladesh

Sowing of chickpea in the heavy‐textured soils of north‐west Bangladesh with minimum tillage technology aims to increase the timely planting of large areas during a relatively short sowing window before soil water deficit limits germination and emergence. However, the seedbed conditions into which chickpea is sown need to be better quantified, so that limiting factors which affect germination and emergence can be identified. Two of the soil physical characteristics of importance are soil water and aeration. Growth cabinet studies have identified the fastest germination and emergence of chickpea on representative soils for this area at gravimetric water contents of 17–18 %, whilst soil water contents above and below this delayed germination and emergence. Emergence was recorded at soil water potentials between field capacity (?10 kPa) and wilting point (?1500 kPa). Emergence was possible at lower soil water potentials in the finer textured soil, whilst in coarser textured soil, emergence was still possible at higher soil water potentials.     

Short‐term releases of CO2 from newly mixed biochar and calcareous soil

The work aimed to quantify native organic C mobilized in one calcareous soil in the 21 days after addition of biochar at a range of large to very large applications. The experiment was carried out in unplanted microcosms, and CO₂ flux was used as a measure of net mineralization. A rapid methodological approach, which does not require ¹³C as a tracer, was used to assess any priming effects induced by the biochar. The amount of CO₂‐C mobilized was small relative to the amount of biochar C and proportional to the amount of the biochar added. The additional CO₂‐C was similar to the content of the water‐soluble organic carbon in the biochar added with each application. No interaction with native soil C, that is priming effect, was observed.     

基于叶气温差的生育中期冬小麦水分亏缺诊断研究

为了获取叶片尺度基于叶气温差的冬小麦生育中期水分亏缺诊断阈值,分析了冬小麦叶气温差的典型日变化及其与土壤水分、空气温度及太阳辐射等因子的相互关系,揭示了冬小麦叶气温差对光合气体交换参数的影响,确定了冬小麦叶片水分利用效率较适宜的非气孔限制值及叶气温差范围。结果表明,冬小麦叶气温差在不同的土壤水分条件下表现出不同的日变化规律,随光量子通量增加而升高,随土壤水分、气温增加而降低;4、5和6月冬小麦叶片水分利用效率较适宜的非气孔限制值范围分别为0.7~1.3、1.1~2.0和0.9~1.5,叶气温差控制范围分别为-1.2~0.4、-1.5~-1和-1.25~-0.9℃。     

绿色环保型循环冷却水处理技术

分析了当前绿色环保的循环冷却水的处理工艺、现状、机理和应用情况，指出了绿色环保型循环冷却水的重要性，以期引起业内的重视并提供参考。     

浅论加强我国农村饮用水安全保护——基于法律保障的视角

近年来我国的水环境持续恶化,尤其农村的饮用水安全问题令人堪忧。文章从我国农村饮用水安全的现状以及存在的主要问题出发,着重探析造成现阶段我国农村饮用水安全种种问题的根源,基于法律保障的视角,注重法律制度诸项功能在具体操作层面上的充分发挥,指出我国农村饮用水安全保护的重要意义,提出合理的建议,希望能够对进一步探索和研究有所启示。     

市政工程中给排水施工的管理分析

随着国内城市化的推进，市政工程的给排水工程越发显得重要。传统的给排水施工技术已经无法满足城市发展要求，社会对给排水的施工质量提出了更高地要求。文章结合当前给排水施工管理现状，对给排水施工的施工管理各方面进行简要探析。     

4种种植体系的水肥利用状况和经济效益比较

为了筛选适宜曲周县后老营村农业生产的较优种植体系并设计更好的种植体系,采用随机抽样调查的方法,对该村主要作物的种植体系及其水肥资源利用状况和经济效益进行了详细调查。结果表明:棉花-西瓜套作体系的水肥资源利用率最高,小麦-西瓜-玉米间套作体系的经济效益最好,棉花-西瓜套作体系次之,二者差异不显著。未来可以基于这2种种植体系重新设计新的种植体系,从而在生态、经济、环境等方面取得较好的综合效益。     

白石水库水源富营养化评价及供水可靠性分析

本文在对白石水库水源富营养化进行评价的基础上,对水库供水可靠性进行了分析.从现状水质评价结果看,白石水库的水质满足《地表水环境质量标准》(GB 3838-2002)中的Ⅲ类用水水质要求,可以作为集中式生活饮用水水源地和工业用水水源地.经过水量调节计算,可知白石水库供水水质是可靠的.     

Physiological processes associated with salinity tolerance in an alfalfa half‐sib family

We previously reported an alfalfa half‐sib family, HS‐B, with improved salt tolerance, compared to parental plants, P‐B. In this study, we conducted additional experiments to address potential physiological mechanisms that may contribute to salt tolerance in HS‐B. Vegetatively propagated HS‐B and P‐B plants were treated with a nutrient solution (control) or a nutrient solution containing NaCl (EC = 12 dS/m). Shoots and roots were harvested at various time points after treatment for quantification of proline, soluble sugar, and H₂O₂ using spectrophotometers. Subcellular localization and quantification of Na in roots were conducted using a Na⁺‐specific dye under a confocal microscope. HS‐B produced 86 and 89% greater shoot and root dry biomass, respectively, compared to parental plants, P‐B, under salinity in the greenhouse. Under saline conditions the HS‐B shoots accumulated 115% and roots 55% more soluble sugars than P‐B counterparts. The non‐saline HS‐B shoots, however, showed 72% less soluble sugars than the non‐saline P‐B plants. Under saline conditions HS‐B accumulated 39% less proline in shoots, while roots accumulated 56% more proline, compared to their P‐B parents. HS‐B plants also showed a greater reduction of stomatal conductance under mild saline stress. HS‐B shoots and roots contained 3–4 times less reactive oxygen species (H₂O₂) after salt treatment compared to P‐B plants. Sodium localization and distribution analysis using Na⁺‐specific dye revealed HS‐B plants accumulated 88% and 48% less Na⁺ in stele and xylem vessels compared to P‐B. The study provides insights into the potential mechanisms that may contribute to salt tolerance in HS‐B: maintaining RWC by accumulating soluble sugars while reducing transpiration, maintaining healthy status by reducing oxidative stresses, and preventing salt toxicity by reducing accumulation of Na⁺ inside root cells and xylem.