Desorption kinetics of neutral hydrophobic organic compounds from field-contaminated sediment

The chemical release rates from a field-contaminated sediment (Lake Charles, LA) using Tenax desorption were studied. Two dichlorobenzenes (m-, p-), hexachlorobutadiene, and hexachlorobenzene were investigated. Contrary to reports that sorption rates are inversely related to K(OW), the slow desorption rates were found to be similar for the four compounds. The data were modeled by a two-compartment irreversible adsorption and radial diffusion model. Desorption kinetics from the first irreversible compartment can be modeled by radial diffusion and assume an irreversible adsorption constant and soil tortuosity of 4.3. The desorption half-life is approximately 2-7 days. Desorption from the second irreversible compartment is very slow (half-life of approximately 0.32-8.62 years) presumably caused by entrapment in soil organic matter that increases the constrictivity of the solid phase to chemical diffusion. From the kinetic data, it is deduced that the diffusion pore diameter of the second irreversible compartment is approximately equal to the critical molecular diameter. The mass of chemicals in this highly constrictive irreversible compartment is approximately one-fourth of the maximum irreversible, or resistant, compartment. The slow kinetics observed in this study add additional support to the notion that the irreversibly sorbed chemicals are 'benign' to the environment.     

基于集成全相关技术的水环境治理装备设计

针对现有水环境治理装备设计开发技术存在的不足，提出了一种融合全相关技术与CAD、CAE、CAM、CAPP技术的集成一体化装备系统设计开发方案，并给出了这种集成全相关技术的初步实现方法，而且进行了射流曝气器的设计应用。这种方法有望实现水环境治理装备系统完整、可靠的设计，并缩短了设计开发周期。     

偶氮染料直接大红GBE脱色细菌的筛选及研究

从保定市某印染厂曝气池废水中分离到一株对染料直接大红GBE有高效脱色效果的菌株HD 1,经鉴定 ,该菌为沙门氏菌属 (Salmonella) ,在 2 5— 3 7℃都有较高的脱色率 ,最佳脱色温度为 3 7℃ ,在pH 6— 8范围内对染料具有明显的脱色效果 ,最佳脱色 pH值为 7.0 ,氧气对脱色具有一定的抑制作用。染料脱色产物的紫外 -可见光谱分析表明 ,可见光区 488nm处的吸收峰完全消失 ,而在紫外区出现了两个吸收峰     

Zn2+胁迫及恢复下番茄幼苗根系中抗氧化系统的动态变化

通过温室水培试验,研究1.0×10-4mol/LZn2 胁迫及解除胁迫对番茄(Lycopersicom esculentum Mill.)幼苗根系中抗氧化系统的动态变化.结果表明,胁迫条件下,番茄根系丙二醛(MDA)和蛋白质含量增加;超氧化物歧化酶(SOD,EC1.15.1.1),过氧化氢酶(CAT,EC1.11.1.6)和谷胱甘肽过氧化物酶(GPX,EC1.11.1.9)活性上升,而过氧化物酶(POD,EC1.11.1.7)活性下降;AsA-GSH循环代谢受影响;抗坏血酸过氧化酶(APX,EC1.11.1.11)活性在胁迫d1、d3上升,随后下降,而谷胱甘肽还原酶(GR,EC1.6.4.2)活性在胁迫1~5d时下降,随后上升;抗坏血酸(AsA)和谷胱甘肽(GSH)含量上升.解除胁迫后,根系中MDA和蛋白质含量随时间延长逐渐减少,接近对照;POD和APX活性增加,而SOD、CAT和GR活性及GSH含量先升高,随后减少;GPX活性和AsA含量却降低;恢复后根系中抗氧化物水平仍然高于对照.依据实验结果,文中讨论了胁迫及恢复过程中植物AsA-GSH循环代谢的作用.图3参16     

丙酮、异丙醇的分离和顶空气相色谱测定

研究了环境大气及水质中丙酮和异丙醇的分析方法，采用顶空气相色谱法测定，用ＰＥＧ－２０Ｍ３０ｍ＊５３ｕｍ和ＦＦＡＰ３０ｍ＊５３０ｕｍ大口径弹性石英毛细管柱分离，氢火争离子化检测器检测，避免了复杂的基体干扰，得到了良好的分离效果和较高的灵敏度，丙酮和异丙醇检出限最低分别＝可达０．０３ｍｇ／Ｌ、０．０４ｍｇ／Ｌ，０．００２ｍｇ／ｍ＾３、０．００３ｍｇ／ｍ＾３。     

氮肥施用对紫色土-玉米根系系统N2O排放的影响

通过不同施氮水平与不同氮肥品种2个田间试验,结合静态箱-气相色谱法研究了川中丘陵区2005年5～9月石灰性紫色土-玉米根系系统的N2O排放变化.结果表明:1)施用氮肥显著地增加了N2O排放,在3个施氮水平下(0、150和250 kg·hm-2),N2O排放总量分别为0.88、2.19和2.52 kg·hm-2;施氮量越高,N2O排放量也越高.当施氮量超过一定水平后,施肥量高低对N2O排放总量的影响并不显著.由氮肥施用引起的N2O排放量占施氮量的0.87%(150 kg·hm-2)和0.66%(250 kg·hm-2).2)氮肥品种显著影响N2O排放,尿素(酰胺态氮肥)和硫酸铵(铵态氮肥)处理的N2O排放量分别为2.09和1.80 kg·hm-2,显著高于硝酸钾(硝态氮肥)处理(1.27 kg·hm-2),三者排放量分别占施氮量的0·80%、0.60%和0.27%.3)降雨是玉米生长季N2O排放的主要影响因子,而无机氮则是影响N2O排放的主要限制因子.     

生物酶强化厌氧消化去除污泥中的PhACs

为降低污水污泥中药理活性化合物（PhACs）产生的环境风险,利用生物方法强化污泥厌氧消化,提高其去除效果.以CFA（氯贝酸）、TCS（三氯生）、DCF（双氯芬酸）、CBZ（卡马西平）4种典型的PhACs为目标污染物,利用气相色谱-质谱联用仪（GC-MS）定量分析污泥中的目标物,探究外加生物酶联合污泥厌氧消化法强化对PhACs的作用效果.结果表明,随着SRT（污泥停留时间）的增大,目标物的去除率有一定程度的增大,特别是在高温条件下,当SRT由7 d增至20 d时,CFA的去除率增长了45%;木瓜蛋白酶对中高温系统中CBZ的去除效果最佳,分别为63.8%和67.5%,同时对4种目标物总的去除率最高,分别为57.3%和61.8%;添加溶菌酶试验中,4种目标物去除效果差异较大,中温、高温系统中对TCS的去除效果最佳为81.7%和80.9%,去除效果最差的是CBZ,去除率为40.4%和33.5%;纤维素酶处理中,4种目标物的去除率均小于60%.混合生物酶试验中,高温条件下更易去除PhACs.研究显示,生物酶强化污泥厌氧消化能有效去除污水污泥中的PhACs.      

城市污水处理厂出水低浓度污染物的生物降解研究

由于城市污水处理厂出水中含有的低浓度污染物的性能稳定而不易被去除,为探索一种快速、直接的低浓度污染物的深度处理方法,通过采用富二价阳离子斜发沸石作载体的生物沸石曝气滤池对某城市污水厂二级处理出水中的低浓度污染物的去除进行了实验研究,研究结果表明,当污水厂二级处理出水水质年平均指标NH3-N、COD、BOD5、TP及浊度分别为27.4 mg/L、57.2 mg/L、20.4 mg/L、1.7 mg/L和16 NTU时,采用两级生物沸石曝气滤池串联工艺,在第一级生物沸石曝气滤池装填3 m生物沸石,水力停留时间1 h,气水比为2∶1;第二级生物沸石曝气滤池装填2 m生物沸石,水力停留时间为0.5 h,气水比为1∶1,最终出水年平均指标NH3-N 0.13 mg/L、COD 7.55 mg/L(CODMn)、BOD50.78 mg/L、TP0.6 mg/L、浊度为0.13 NTU,出水水质可满足热力发电厂循环冷却补充水的水质要求.此种方法为污水处理厂的出水提供了经济有效的回用途径。     

电混凝处理电镀综合废水

采用电混凝法处理酸性电镀综合废水，首先研究了不同电流密度对总氰化物、重金属和化学需氧量（COD）去除率的影响。实验结果表明，电混凝可有效去除酸性电镀综合废水中的氰化物与重金属。随着电流密度的增大，总氰化物与重金属的去除率逐渐提高。当电流密度为10mA／cm2时，废水中残留的总氰化物、Cu2＋、Ni2＋、Cr6＋和Zn2＋ 的浓度分别为23．0、25．0、4．5、0．2和0．2mg／L。为了进一步提高去除率，在电化学体系中添加H2O2，随着H2O2投量的增大，总氰化物、重金属、COD去除率不断提高。当H2O2投量为3mL／L时，处理过废水中残留总氰化物、Cu2＋、Ni2＋、Cr6＋、Zn2＋和COD的浓度分别为0．2、2．0、3．0、1．5、0．1和220mg／L。     

Source,distribution, and health risk assessment of polycyclic aromatic hydrocarbons in urban street dust from Tianjin,China

To better assess and understand potential health risk of urban residents exposed to urban street dust, the total concentration, sources, and distribution of 16 polycyclic aromatic hydrocarbons (PAHs) in 87 urban street dust samples from Tianjin as a Chinese megacity that has undergone rapid urbanization were investigated. In the meantime, potential sources of PAHs were identified using the principal component analysis (PCA), and the risk of residents’ exposure to PAHs via urban street dust was calculated using the Incremental Lifetime Cancer Risk (ILCR) model. The results showed that the total PAHs (∑PAHs) in urban street dust from Tianjin ranged from 538 μg kg^?1 to 34.3 mg kg^?1, averaging 7.99 mg kg^?1. According to PCA, the two to three- and four to six-ring PAHs contributed 10.3 and 89.7 % of ∑PAHs, respectively. The ratio of the sum of major combustion specific compounds (ΣCOMB)?/?∑PAHs varied from 0.57 to 0.79, averaging 0.64. The ratio of Ant/(Ant?+?Phe) varied from 0.05 to 0.41, averaging 0.10; Fla/(Fla?+?Pyr) from 0.40 to 0.68, averaging 0.60; BaA/(BaA?+?Chry) from 0.29 to 0.51, averaging 0.38; and IcdP/(IcdP?+?BghiP) from 0.07 to 0.37, averaging 0.22. The biomass combustion, coal combustion, and traffic emission were the main sources of PAHs in urban street dust with the similar proportion. According to the ILCR model, the total cancer risk for children and adults was up to 2.55?×?10^?5 and 9.33?×?10^?5, respectively.