超细化学纤维填料用于净化含油循环冷却水研究

研究了一种高比表面积化学纤维填料对泄漏于工业循环冷却水中机油的循环吸附效果.讨论了填料静态饱和吸附量和循环饱和吸附量的差别;考察了水中分散(或乳化)油的初始浓度、运行温度及pH值变化的条件下填料对循环吸附量和循环吸附能力的影响;比较了吸附前后填料的表面水接触角变化.实验结果表明,填料的循环饱和吸附量约是静态饱和吸附量的...     

Use of amendments to reduce leaching loss of phosphorus and other nutrients from a sandy soil in Florida

Goal, Scope and Background Transport of P from agricultural land contributes to the eutrophication of surface waters. Soil amendment is considered one of the best management practices (BMPs) to reduce P loss from sandy soils. Laboratory column leaching experiments were conducted to evaluate the effectiveness of different soil amendments in reducing P leaching from a typical sandy soil in Florida. Methods The tested amendments were CaCl₂, CaCO₃, Al(OH)₃, cellulose, and mill mud, and applied at the rate of 15 g/kg for a single amendment and each 7.5 g/kg if two amendments were combined. Leaching was conducted every four days for 32 days, 250 mL of deionized water being leached for each column per leaching event. Leachates were collected from each leaching event and analyzed for reactive P, PO₄-P, and macro and micro-elements. Results and Discussion Except for the soils amended with CaCl₂, or CaCl₂+CaCO₃, reactive P and PO₄-P leaching losses mainly occurred in the first three leaching events. Phosphorus leaching from the soils amended with CaCl₂ or CaCl₂+CaCO₃ was less but more persistent than that of other amendments. Reactive Pleaching loss was reduced by 36.0% and 40.4% for the amendments of CaCl₂, and CaCl₂+CaCO₃, respectively, as compared with chemical fertilizer alone, and the corresponding values for PO₄-P were 70.8% and 71.9%. The concentrations of K, Mg, Cu, and Fe in leachate were also decreased by CaCl₂ or CaCl₂+CaCO₃ amendment. Among the seven amendments, CaCl₂, CaCO₃, or their combination were most effective in reducing P leaching from the sandy soil, followed by cellulose and Al(OH)₃, the effects of mill mud and mill mud + Al(OH)₃ were marginal. Conclusions These results indicate that the use of CaCl₂, CaCO₃, or their combination can significantly reduce P leaching from sandy soil, and should be considered in the development of BMPs for the sandy soil regions. Recommendations and Outlook Most agricultural soils in south Florida are very sandy with minimal holding capacities for moisture and nutrients. Repeated application of fertilizer is necessary to sustain desired yield of crops on these soils. However, eutrophication of fresh water systems in this area has been increasingly concerned by the public. Losses of P from agricultural fields by means of leaching and surface runoff are suspected as one of the important non-point contamination sources. The benefits and effectiveness of soil amendment in reducing P losses from cropping production systems while sustaining desired crop yield need to be demonstrated. Calcium chloride, CaCO₃, or their combination significantly reduce Pleaching from sandy soil, and should be considered in the development of BMPs for the sandy soil regions.     

滨海风砂地种植后土壤生物化学特性的分析

对福建省长乐市大鹤林场滨海风砂地果园套种前后土壤生物化学特性变化进行研究,结果表明,滨海风砂地果园种植后土壤养分水平提高;土壤微生物数量增加,而且出现了新的种类;土壤酶活性增强;土层含水量提高;沙层和地表的温度下降;小生境得到了一定程度的改善。     

填埋场渗滤液灌溉对粘壤土N2O释放的影响

以生活垃圾填埋场渗滤液和粘壤土为实验材料,研究了不同的渗滤液灌溉量、灌溉后土壤中矿物氮含量和反硝化酶活性对粘壤土N2O释放的影响.结果表明:渗滤液灌溉可促进土壤中N2O的释放,投加渗滤液的土壤样品N2O的释放通量是投加(NH4)2SO4溶液的2-3倍.粘壤土含水率为25%并且保持氧含量的条件下,渗滤液灌溉土壤后,土壤中N2O主要在硝化过程中产生.相关性统计分析表明:N2O释放通量与NO-2和渗滤液灌溉量呈显著正相关(分别为r=0.928,p＜0.001;r=0.425,P<0.05),而与土壤中NO-3和反硝化酶活性无显著相关性.     

陕北长城沿线沙质荒漠化遥感研究

采用1975年MSS卫星图像、2000年ETM卫星图像为遥感信息源,通过建立科学的沙质荒漠化土地分类体系,并结合地理信息系统方法,对位于农牧交错带生态环境脆弱的陕北长城沿线沙质荒漠化进行了现状及动态变化分析,结果表明,经过20多年来沙质荒漠化防治,现代沙质荒漠化过程得到了明显的逆转,25年间,沙质荒漠化土地面积减少了195.18km²,逆转区的面积比发展区的面积大1280.48km²,为该区能源化工基地的建设提供了良好的生态环境,但是目前该区的沙质荒漠化土地强度依然较大,危害较大的极重度和重度沙质荒漠化土地占到总沙质荒漠化土地面积的35.64%,同时煤炭、油气资源的开发对沙质荒漠化的负面影响具有潜在性和长期性,因此,建立合理的资源开发和环境保护体系具有重要的生态和社会意义。     

条形基础砂土地基的破坏模型试验

为了研究条形基础砂土地基的剪切破坏形式和承载机理,在相似理论的指导下,进行了一组条形基础砂土地基的模型试验,模拟了砂土地基受荷后产生变形、扩展直到破坏的全过程;测量并分析了地基中不同点处的土压力大小及其分布规律,观测了剪切带的形成和发展过程。结果表明,模型试验能够很好地体现砂土地基变形、破坏的整个过程及其沉降变形特性、地基中各点的真实应力状态及其变化规律,对于研究深基坑变形过程和破坏形态具有应用价值。     

饱和砂土最大动剪切模量的不同试验对比研究

对233个饱和砂土土样室内试验确定的最大动剪切模量和同一位置现场原位试验确定的最大动剪切模量进行了对比研究。结果表明:两者相差很大,室内试验结果基本上小于现场试验结果,埋藏深的土样相差更大;室内试验的最大动剪切模量与深度符合幂函数规律,且与砂土的密实度有关,与砂土的颗粒成分关系不大。通过工程实例,比较了2种试验最大动剪切模量对地震反应分析的影响,得到了室内试验最大动剪切模量与现场剪切波速的统计经验关系式。该经验关系式对工程场地地震反应分析具有一定的参考应用价值。     

无汞污染的水柱型大气压强计

提出一种小尺寸（１．２ｍ）的水柱型大气压强计,解决了生产和使用水银柱大气压强计时产生的汞污染环境问题,讨论水柱大气压强计的工作原理和使用方法,分析测量误差,简述应用中的若干问题,文中给出的压强计在海拔的０－３ｋｍ,环境温度为６－４０℃范围使,测量结果的标准误差小于±０．９ｍｍＨｇ,能分辨±０．１ｍｍＨｇ的大气压强变化,适用于环境温度变化不大的室内大气压强测定。由于水的饱和蒸气压随环境温度的较大变化     

酚在饱水亚砂土层中迁移转化的研究

通过静态吸附实验,静态降解实验和动态土柱实验,研究了苯酚在饱和亚砂土层中的吸附性能,在好氧和厌氧条件下的降解性能以及其他有机物和氮,磷等营养元素对苯酚降解过程的影响;实验结果用计算机进行线性拟合和参数估值,求解出分配系数Ｋｄ＝０．１１２ｃｍ＾３／ｇ和降解系数Ｋ＝０．５５ｄ＾－１。研究表明,苯酚在亚砂土层中的吸附性能较差,在好氧条件下具有很好的降解性能,而在厌氧条件下,其降解性能极差,营养元素氮,磷     

抽尘热风管内壁尘垢治理探讨

在工业生产中,加热工序中产生的含尘热气由抽尘系统抽走,确保生产场所空气达标.这种含尘气流的温度高于常温,在风管中流动时,在管外常温空气冷却下,水汽会部分凝结成露粘附在管内表面.露水又粘结尘灰,形成一层粘结强度很好的尘垢层,影响抽尘热风流正常流动,也影响风管的使用寿命.分析了抽尘热风管内壁尘垢生成机理并提出了防治措施.