地源热泵土壤热物性测试与分析

运用恒热流测试原理自主研发了岩土热物性测试仪,通过现场测试的方法,调整加热管的加热功率、埋管中循环水流量、埋管进出口水温随时间变化规律,利用线热源理论确定了地下岩土的热物性参数。实验表明,土壤初始温度的测量精度对于提高土壤的导热系数是至关重要的,在未扰动的土壤温度以及给定PE管材的条件下,测试时间为50小时左右时,土壤导热系数逐渐趋于稳定,收敛于3.109 W/(m.℃),整个测试过程平均导热系数为3.489W/(m.℃),该结果为地源热泵系统的准确设计提供了依据。     

HG无机侑机复合土壤固结材料的应用研究

作为一种新型的复合材料,HG无机/有机复合土壤固结材料能提高水泥对地下淤泥质软土的加固作用.经过试验对比,结果表明:HG与水泥复配的最佳质量比例为1.5%;添加HG后水泥土试样的无侧限抗压强度、抗剪强度和抗渗透性与未添加时相比都有明显的提高,同时添加HG能明显降低水泥浆的粘度,增加了水泥浆的输送性能.     

二级水DOM在活性炭及土壤层处理中的迁移转化

为有效控制污水处理厂二级出水在回用水加氯消毒过程中消毒副产物的产生,通过模拟活性炭(GAC)吸附及土壤含水层处理(SAT)实验,研究二级出水经GAC吸附后进行人工地下回灌过程中溶解性有机物(DOM)的迁移及转化规律.利用XAD-8/XAD-4树脂将水样中的溶解性有机物(DOM)分级为疏水性有机酸(HPO-A)、疏水性中性有机物(HPO-N)、过渡亲水性有机酸(TPI-A)、过渡亲水性中性有机物(TPI-N)和亲水性有机物(HPI).HPO-A和HPI为二级水DOM中最主要组分(占到其DOC总含量的75%).GAC能有效吸附二级出水中HPO-A、HPO-N和TPI-A,而对TPI-N和HPI的去除率较低;后续的SAT能有效地去除GAC去除效果不佳的HPI,使DOM的去除率达到70.1%.GAC在有效去除总THMFP的同时(去除率为55.6%),能有效降低HPO-A、TPI-A、TPI-N的三氯甲烷生成活性(STHMFP);后续的SAT处理使系统总THMFP去除率达到67.2%.与单纯的SAT处理相比,GAC+SAT能够有效地降低各组分的STHMFP.     

丛枝菌根真菌-植物对石油污染土壤修复实验研究

为了寻求石油污染土壤的菌根生物修复方法,模拟两种石油污染土壤浓度,以玉米为接种植物,采用Glomus mosseae(G.m)和Glomus versifome(G.v)单接种和双接种,进行菌根真菌-植物对土壤石油烃降解实验研究.结果表明:在石油污染浓度(石油的质量分数)0.2%和2%条件下,石油烃降解率与菌根侵染率、玉米根干重和植株干重均呈现相关性,两组相关系数分别为0.829 6～0.878 5,0.962 0～0.974 5.接种丛枝菌根真菌处理的菌根侵染率、玉米生长量和石油烃降解率均远高于对照处理,丛枝菌根真菌能有效促进石油烃降解;G.v真菌比G.m对高石油污染浓度具有更强的适应性,更适合作为处理高浓度石油污染土壤的接种菌.双接种处理的菌根侵染率和石油烃降解率等均高于单接种处理,两种菌种的协同作用,可有效促进植物生长和石油烃降解.     

确定土壤背景值的Hazen概率法——以铜陵矿区Pb为例

本文选取已知土壤背景含量的铜陵矿区,基于Hazen概率曲线,探讨了土壤污染重金属元素Pb背景含量与污染叠加含量的区分方法.得到Pb元素的背景含量为28.5μg/g,与该区深层土壤样中Pb元素含量的平均值(34μg/g)比较接近.还得到了Pb元素污染叠加含量与背景含量的界线点51μg/g.基于Hazen概率曲线区分铜陵矿区土壤Pb元素背景含量与污染叠加含量的方法是有效的,有必要将该方法推广到土壤中其它重金属污染元素、其它地区作进一步研究.     

Inhibitory effect of Cr（Ⅵ） on activities of soil enzymes

To evaluate the influence of various Cr(VI) concentrations (0.05, 0.25, 0.50, 1.00 and 2.00 g/kg) on the activity of soil enzymes, the activities of catalase, polyphenol oxidase, dehydrogenase, alkaline phosphatase in soils were investigated in the incubation experiment with a period of 35 d. The results indicate that all the tested Cr(VI) concentrations significantly inhibit dehydrogenase activity by over 70% after 35 d. The activity of alkaline phosphatase is slightly inhibited during the whole experiment except for on the day 7. Cr(VI) has no obvious effect on the activity of catalase in soil. On the contrary, Cr(VI) stimulates the activity of polyphenol oxidase. The results suggest that dehydrogenase activity can be used as an indicator for assessing the severity of chromium pollution. Foundation item: Projects(2006AA06Z374, 2007AA021304) supported by the National High-Tech Research and Development Program of China; Project(2008SK2007) supported by the Key Program of Science and Technology of Hunan Province, China     

An improvement to the simulation of phase-change heat-transfer during soil freezing and thawing

A new variable time step method, which is called the backwards calculating time step method, is presented in this paper. It allows numerical simulation of soil freezing and thawing while avoiding "phase change missing and overflowing". A sensitive heat capacity model is introduced through which the calculation errors are analyzed. Then the equation using the self-adjusted time step is presented and solved using finite differences. Through this equation, the time needed for a space cell to reach the phase change point temperature is calculated. Using this time allows the time step to be adjusted so that errors caused by "phase change missing and overflowing" are successfully eliminated. Above all, the obvious features of this method are an accelerated rate for adjusting the time step and simplifing the computations. An actual example proves that this method can accurately calculate the temperature fields during soil freezing and thawing. It is an improvement over traditional methods and can be widely used on com- plicated multi-dimensional phase change problems.     

桂柳高速公路两侧土壤重金属分布特征

选择桂柳高速公路上的4个调查剖面和1个对照剖面测试了公路两侧农田土壤中Pb、Cd、Cr、Hg和As的含量分布。结果表明,公路交通对路两侧土壤重金属含量有一定的影响,运行期较长的对照路段桂黄公路两侧土壤中的Pb、Cd和As的含量明显高于运营期较短的桂柳高速公路段,而Cr、Hg与公路运行期长短的关系不是非常密切;重金属含量在横向上都有随距路肩距离的减小而增大的趋势,Pb、Cd在路肩两侧200m范围内含量的变化较小。以广西水稻土土壤背景值为评级标准,采用单因子指数法评价了路侧土壤的环境质量：所测路段和剖面的Cd、Hg污染均较严重;Cr基本上还处在非污染水平;桂黄公路段Pb的污染指数高于高速公路段。     

开封引黄灌区灌溉条件下稻田土壤盐分阈值研究

结合各生育期水稻耐盐度、各处理实际种前初始土壤含盐量和对应生育期最高的土壤含盐量,分析了各灌溉处理条件下的稻田土壤含盐量在水稻各生育期的动态变化规律和允许初始土壤含盐量阈值.结果表明:控制灌溉及控制灌溉加淋洗条件下,各水稻生育期土壤含盐量均有不同程度降低,随着淋洗水量的增加土壤含盐量逐渐降低,并获得了不同灌溉方式下的允许稻田初始土壤含盐量阈值.此结论对实际应用有指导意义.     

农村简易垃圾焚烧炉周边土壤二恶英分布研究

为了解农村简易生活垃圾焚烧炉排放废气中二恶英对周边地区的环境影响,对焚烧炉周边6个环境土壤及焚烧炉排放的飞灰和灰渣中二恶英的分布规律进行了研究.检测结果显示,焚烧炉周边环境土壤样品中二恶英国际毒性当量在2.29～9.45 ng/kg(干基)之间,高于背景值(0.537 I TEQ ng/kg).而焚烧炉排放的飞灰及灰渣中二恶英国际毒性当量分别为3 454和32.2 ng/kg.利用主成分分析方法,发现环境土壤中的二恶英来源较为复杂,焚烧炉污染物排放不是土壤中二恶英的唯一来源.