基于HHT的三峡水库蓄水后坝下游水情多尺度时频特征

利用基于噪声辅助经验模态分解（EEMD）的改进型希尔伯特-黄变换（HHT）,对三峡蓄水后8 a的三峡日入库、出库流量和坝下各水文站日水情信号进行多尺度时频分析,并与连续小波和离散小波变换进行异同性比较。结果表明,三峡蓄水后2004～2011年三峡日入库、出库流量和宜昌、大通站日径流量均具显著的1 a尺度主周期振荡规律,三峡季节性调蓄对坝下流量1 a尺度的主周期振荡规律无显著影响。三峡蓄水后河口北支江水位的半月主周期振荡特征始终占主导地位,表明三峡调蓄影响下上游来水量变化对河口北支水位波动的影响权重小于河口自身海潮波动的影响权重。与离散小波变换固定频带下的信号分解比较,基于HHT的水文信号多尺度分解有更好的自适应性;与连续小波变换比较,HHT方法在水文信号高频部分周期振荡特征的揭示和频域混叠现象的避免方面更具优势     

颗粒计数法在高锰酸钾强化常规工艺运行优化中的应用

以引黄水库水为实验原水,通过颗粒计数和浊度的联用检测优化评估了高锰酸钾强化常规处理工艺中的各制水环节的处理效果。结果表明,絮凝出水10μm颗粒数和过滤出水2~7μm颗粒数的可作为水厂运行管理的依据,滤后水的颗粒物数量变化比浊度更灵敏准确地反映滤池运行状况;在高锰酸钾强化预处理的最佳投加量为0.8 mg/L时,原常规工艺沉淀对颗粒总数的去除率提高20.55%,滤后颗粒总数减少56.40%,显著降低了"两虫"穿透滤池的风险。     

初始温度对人粪便好氧堆肥过程的影响

温度是好氧堆肥过程中需要控制的一个重要因素。不同的初始温度直接影响了堆肥过程中微生物活性及有机物的降解。为了研究初始温度对粪便好氧堆肥过程的影响,采用序批式好氧堆肥反应器,以新鲜锯末为载体,控制含水率在55%~60%的范围左右并强制通风的好氧条件下,进行了初始温度分别为25、35、45和55℃,20 d为一个周期好氧堆肥实验,研究了不同初始温度条件下堆肥过程有机物降解、氮的迁移转化及种子发芽指数的变化。结果表明,初始的高温度会抑制堆肥反应的进行,但初始温度越高,水解效果越显著;初始的高温有利于COD的去除,最终COD的去除率分别为88.2%、89.3%、92.0%和89.9%。初始高温对种子发芽率有抑制作用,同时延迟了堆肥的腐熟期。     

稻壳生物质炭对水中氨氮的吸附

以稻壳生物质为原材料,在350℃和500℃2种温度条件下制备生物质炭(BC350和BC500),采用扫面电镜(SEM)和红外光谱(FTIR)对稻壳生物质炭进行了表征。通过实验考查了稻壳生物质炭对氨氮的吸附等温线、影响因素和动态吸附。结果表明,稻壳生物质炭的平衡吸附量随着平衡浓度的增大而增大后趋缓,Langmuir方程比Freundlich方程更好地描述稻壳生物质炭吸附氨氮的行为,BC500比BC350具有更大的吸附氨氮的能力,其最大吸附量分别为5.82 mg/g和6.51 mg/g。p H和离子强度影响BC500对氨氮的吸附效果。动态吸附实验表明,BC500对氨氮的平均吸附量为1.78 mg/g。可见,稻壳生物质炭可以用作高效吸附剂去除废水中的氨氮。     

酸性条件下微波改性活性碳纤维对Pb(Ⅱ)的吸附

采用微波辐照的方法,在混酸条件下对活性碳纤维(ACF)进行改性,制备得到一种改性活性碳纤维(M-ACF).通过小试吸附实验考察了微波功率、溶液pH值对M-ACF吸附Pb(Ⅱ)的影响.通过扫描电子显微镜(SEM)、红外光谱(FTIR)、电子能谱(EDX)等技术对ACF和M-ACF进行表征.结果表明,M-ACF表面的羧基等酸性含氧官能团增多,纤维长度变短且表面粗糙化.当M-ACF的投加量为10 mg、含铅溶液初始浓度为50 mg/L、pH为6、吸附时间为24 h、吸附温度为308 K时,M-ACF对Pb(Ⅱ)的吸附量高达248.5 mg/g.吸附过程符合准二级动力学模型和Langmuir等温吸附模型;热力学参数表明吸附为吸热、自发的过程.     

磁性纳米γ-Fe2O3/SiO2去除水中亚甲基蓝

以纳米γ-Fe₂O₃为磁性介质制备了磁性纳米γ-Fe₂O₃/SiO₂,并将其用于水中亚甲基蓝的吸附。表征结果显示：制备的γ-Fe₂O₃/SiO₂呈不规则核壳结构,平均粒径为38 nm,比表面积为74.35 m²/g,比饱和磁化强度为55 A·m²/kg。实验结果表明：γ-Fe₂O₃/SiO₂对亚甲基蓝的吸附适宜在中碱性条件下进行,4 h即可达吸附平衡;在初始亚甲基蓝质量浓度为180 mg/L、γ-Fe₂O₃/SiO₂加入量为2 g/L、初始溶液pH为7.0、吸附温度为298 K的条件下,吸附量最高为25.4 mg/g;共存金属离子会降低吸附效率,而少量的腐殖酸则会促进吸附;吸附过程符合准二级动力学方程,颗粒内扩散不是唯一的控速步骤;等温吸附满足Langmuir模型,该吸附是一个物理吸附过程;用乙醇洗涤的γ-Fe₂O₃/SiO₂重复使用4次时仍能保持约80%的原吸附量。     

两种接触氧化填料处理洗涤剂废水的比较

以某日化企业在生产过程中产生的洗涤剂废水为处理对象,以接触氧化法为核心工艺,比较了悬挂式组合填料和移动床生物膜反应器(MBBR)悬浮填料对洗涤剂废水的处理效果。实验结果表明:悬挂式组合填料和MBBR悬浮填料的挂膜启动时间分别为13,25 d;当悬挂式组合填料反应器的DO为4.0 mg/L时,COD和LAS的去除率分别为84.33%和89.06%;当MBBR悬浮填料反应器的DO为3.0 mg/L时,COD和LAS的去除率分别为82.54%和90.31%;当MBBR悬浮填料反应器的COD容积负荷为0.5~1.3 kg/(m3·d)时,平均COD去除率为83.91%,继续增大COD容积负荷,COD去除率仍能保持在80%以上;MBBR悬浮填料在COD的高效降解及高浓度有机废水的处理方面优于悬挂式组合填料。     

高尔夫球场土壤和水中毒死蜱农药残留的测定

介绍了土壤和水样中毒死蜱农药残留的测定方法 ,并应用该方法调查了某地高尔夫球场使用毒死蜱农药后对周围土壤和地表水的污染影响。测定结果表明 ,在调查区范围内 ,地表水中毒死蜱农药的浓度小于 0 .4μg/L。参照国外有关标准 ,它低于美国健康与福利部 (MHW)制定的高尔夫球场饮用水中允许的残留值 (毒死蜱 :4μg/L )。     

Potential effects of large linear pipeline construction on soil and vegetation in ecologically fragile regions

Long-distance pipeline construction results in marked human disturbance of the regional ecosystem and brings into question the safety of pipeline construction with respect to the environment. Thus, the direct environmental impact and proper handling of such large projects have received much attention. The potential environmental effects, however, have not been fully addressed, particularly for large linear pipeline projects, and the threshold of such effects is unclear. In this study, two typical eco-fragile areas in western China, where large linear construction projects have been conducted, were chosen as the case study areas. Soil quality indices (SQI) and vegetation indices (VI), representing the most important potential effects, were used to analyze the scope of the effect of large pipeline construction on the surrounding environment. These two indices in different buffer zones along the pipeline were compared against the background values. The analysis resulted in three main findings. First, pipeline construction continues to influence the nearby eco-environment even after a 4-year recovery period. During this period, the effect on vegetation due to pipeline construction reaches 300 m beyond the working area, and is much larger in distance than the effect on soil, which is mainly confined to within 30 m either side of the pipeline, indicating that vegetation is more sensitive than soil to this type of human disturbance. However, the effect may not reach beyond 500 m from the pipeline. Second, the scope of the effect in terms of distance on vegetation may also be determined by the frequency of disturbance and the intensity of the pipeline construction. The greater the number of pipelines in an area, the higher the construction intensity and the more frequent the disturbance. Frequent disturbance may expand the effect on vegetation on both sides of the pipeline, but not on soil quality. Third, the construction may eliminate the stable, resident plant community. During the recovery period, the plant community in the work area of the pipeline is replaced by some species that are rare or uncommon in the resident plant community because of human disturbance, thereby increasing the plant diversity in the work area. In terms of plant succession, the duration of the recovery period has a direct effect on the composition and structure of the plant community. The findings provide a theoretical basis and scientific foundation for improving the environmental impact assessment (EIA) of oil and gas pipeline construction as it pertains to the desert steppe ecosystem, and provide a reference point for recovery and management of the eco-environment during the pipeline construction period.