Usage of polystyrene disposable food dishes in the lightweight concrete making

The increasing use and subsequent accumulation of polystyrene containers has triggered a substantial environmental problem. This study investigated using varied percentages of solid waste polystyrene disposable food dishes in the production of lightweight concrete samples with 350 kilograms per cubic meter (kg/m³) of cement and a density of 1,300 kg/m³. The polystyrene disposable dishes were ground into beads of 0–3 millimeters (mm) and 3–6 mm in size. First, the characteristics of Type II Portland cement, polystyrene, and aggregates were examined. The following characteristics of concrete using ASTM International and British Standards Institution standards were tested: slump, compressive strength, ability to resist chloride ion penetration, and resistance of concrete to rapid freezing and thawing cycles. Scanning electron microscopy (SEM) and energy dispersive X‐ray spectroscopy analytical techniques were also used. The slump of samples varied between 40 and 70 mm and was not dependent on either the polystyrene percentage or the size of the polystyrene beads in the concrete samples (p‐value > .05). The compressive strength of the concrete samples after 90 days of curing, and using different percentages of polystyrene, varied between 96 and 113 kilograms per square centimeter (kg/cm²). The resistance of the samples to the freezing and thawing cycle and chloride ion penetration were affected unfavorably by the presence of the polystyrene. The SEM technique indicated that concrete samples containing 15% and 25% polystyrene had denser crystals and less void than concrete samples with 40% and 55% polystyrene.     

深部煤层钻屑粒度随钻进深度分布规律

为了研究煤层钻屑粒度随钻进深度分布规律，选取具有冲击危险性的平煤八矿己15煤作为研究对象，采取钻屑量测试和孔口瓦斯浓度监测，通过筛分实验煤样并应用Rosin Rammler分布模型，探究了钻屑粒度和钻屑量大小随孔深变化关系，分析不同点钻屑粒度分布特征。结果表明:小于0.075 mm钻屑粒度分布随孔深变化与钻屑量变化规律相吻合；不同钻孔随深度变化分别对应不同Rosin Rammler分布函数，随着应力过渡越平缓，粒径分布宽度系数n值越小，煤体应力越大粒径相关系数D越大；不同范围钻屑粒度占比大小也会影响钻屑量大小；在钻屑量较大时，孔口瓦斯体积分数会出现增高现象。通过对钻屑粒度分布规律分析，更好地了解深部煤体应力分布，有助于冲击危险的预警。     

铁磁流体对煤粒瓦斯解吸性能影响实验研究*

为探究铁磁流体对煤体瓦斯解吸性能的影响，采用水浴恒温吸附解吸系统，开展0.44，0.65，1.14 MPa 3组不同平衡压力下加铁磁流体前后的瓦斯解吸对比实验，根据Langmuir方程经验公式计算瓦斯极限解吸量和初始扩散系数，分析铁磁流体对煤体瓦斯解吸影响的机理。结果表明:在3组不同平衡压力下加入铁磁流体后瓦斯极限解吸量由2.5，10，20 mL/g降低为2.22，3.33，10 mL/g，降低11.2%，66.7%，50%；初始扩散系数由0.997 1，1.629 9，3.888 3 μm2·s降低为0.685 5，0.997 1，2.933 5 μm2·s，降低31.25%，38.82%，24.56%。在铁磁流体的作用下，煤体瓦斯解吸性能得到大幅降低。     

高应力巷道底臌变形机理及控制技术分析

为了分析高应力巷道底臌变形机理，以铜川玉华煤矿2407工作面巷道为研究背景，采用理论分析和现场观测相结合的研究方法。根据巷道底臌主要由原岩应力、支承应力、围岩遇水膨胀、流变作用而引起进行分析，推导出计算底臌量的表达式。针对玉华煤矿高应力巷道底臌变形，提出在巷道顶板采用锚网梁索支护，帮部采用锚网支护的原支护条件下，底板采用锚杆注浆和切槽联合支护方式控制底臌。现场观测结果表明:这种联合支护方式能够有效控制巷道底臌变形，底臌量降低了61.5%。将底臌量理论解与现场监测的结果进行比较，误差小于8.93%，验证了理论的合理性，为巷道底臌量分析提供了参考。     

北京市“十三五”大气污染物排放总量控制基本思路探讨

随着各项环保措施的深入实施,北京市大气环境质量进一步改善的难度逐渐加大。对北京市"十二五"时期的大气污染物排放总量控制工作进行了经验总结,并分析了"十三五"时期大气污染物的排放形势和减排压力。在此基础上,从6个方面提出了北京市"十三五"期间大气污染物排放总量控制的基本思路。     

梯级稻田主要营养元素的平衡特点

通过研究梯级稻田主要营养元素的输入、输出途径，发现了丘陵梯田所存在的生态环境问题及其营养丰缺状况，为合理施肥、发挥资源潜力提出了一系列的意见和建议。     

Morphologic development, relative sea level rise and sustainable management of water and sediment in the Ebre Delta, Spain

The Ebre (Ebro) Delta is one of the most important wetland areas in the western Mediterranean. Ca. 40 % of the delta plain is less than 0.5 m above mean sea level and part of the southern margin of the delta is at mean sea level in an area protected by dikes. Both mean rates of secular subsidence in the Ebre Delta and eustatic sea level rise are ca. 1 – 2 mm/yr. Thus, the present annual relative sea level rise (RSLR) rate in the Ebre Delta may be at least 3 mm/yr. Measured accretion rates in the delta range from 4 mm/yr in the wetlands surrounding the river mouth to <0.1 mm/yr in impounded salt marshes and rice fields. The annual sediment deficit in the delta plain to offset RSLR is close to 1 million m³/yr. Accretion rates in the rice fields prior to the construction of large dams in the Ebre watershed were higher than RSLR rates, from 3 – 15 mm/yr. At present, >99 % of the riverine sediments are retained in the reservoirs and rice fields are losing ca. 0.2 mm/yr. Future management plans should take RSLR into account and include control of freshwater and sediment flows from the river in order to offset negative effects from waterlogging and salt intrusion, and maintain land elevation. This will include the partial removal of sediments trapped behind the Ribarroja and Mequinença dams. Stocks and inputs of sediments in the corresponding reservoirs are large enough for land elevation of ca. 50 cm in the whole delta plain. Advantages of this solution include (1) new sediments to the delta to offset subsidence (via rice fields) and coastal retreat, (2) enhanced functioning of the delta (productivity and nutrient processing), (3) avoidance of accumulation of sediments in the reservoirs. Hence, it is important to manage river discharges at the dams from an integrated viewpoint, whereas currently only hydropower and agricultural requirements are considered. It is also crucial to maintain periods of high discharge, to have enough river energy to transport as much sediments as possible.     

蔬菜对硒的吸收及适宜补硒食用量

以小白菜、番茄和萝卜为研究对象，通过施用外源硒，研究了不同蔬菜对硒的吸收特性。结果表明，施硒均明显提高了蔬菜可食部分的含硒量，且含硒量随施硒量的增加而增加；随生长时间的增加，小白菜的含硒量逐渐增加，而萝卜的含硒量逐渐降低。随着采收时间延后，番茄的含硒量逐渐降低；为保证合理补硒，确定了本试验所生产富硒蔬菜的适宜食用量。     

砖红壤上花生作物铅临界含量的研究

利用盆栽试验，研究在砖红壤上添加不同浓度的铅对花生作物的生长和残留的影响，从农产品卫生质量和作物效应两方面出发，提出花生作物的铅参考临界含量．     

Managing erosion and water quality in agricultural watersheds by small detention ponds

Terrace-contouring systems with on-site water detention cannot be installed in areas of complex topography, small parceling and multi-blade moldboard plow use. However, field borders at the downslope end may be raised at the deepest part where runoff overtops to create detention ponds, which can be drained by subsurface tile outlets and act similar to terrace-contouring systems. Four of such detention ponds were monitored over 8 years. Monitored effects included the prevention of linear erosion down slope, the sediment trapping from upslope, the enrichment of major nutrients in the trapped and delivered sediments, the amount of runoff retained temporarily, the amount of runoff reduced by infiltration, the decrease in peak runoff rate and the decrease in peak concentrations of agrochemicals due to the mixing of different volumes of water within the detention ponds. The detention ponds had a volume of 30–260 m³ ha⁻¹ and trapped 54–85% of the incoming sediment, which was insignificantly to slightly depleted (5–25%) in organic carbon, phosphorus, nitrogen and clay as compared to the eroding topsoil, while the delivered sediment was strongly enriched (+70–270%) but part of this enrichment already resulted from the enrichment of soil loss. The detention ponds temporarily stored 200–500 m³ of runoff. A failure was never experienced. Due to the siltation of the pond bottom, the short filled time (1–5 days) and the small water covered area, infiltration and evaporation reduced runoff by less than 10% for large events. Peak runoff during heavy rains was lowered by a factor of three. Peak concentrations of agrochemicals (Terbutylazin) were lowered by a factor of two. The detention ponds created by raising the downslope field borders at the pour point efficiently reduced adverse erosion effects downslope the eroding site. They are cheap and can easily be created with on-farm machinery. Their efficiency is improved where they are combined with an on-site erosion control like mulch tillage because sediment and runoff input are reduced. Ponds had to be dredged only after the first year when on-site erosion control was not fully effective.