贵州南明河水环境综合整治与水质模拟

以贵州南明河为例,对城市河道水环境综合治理全流程进行了系统的定量综合分析.污染识别结果表明,外源污染是造成南明河污染的关键原因,其对南明河COD、氨氮和TP等污染物的贡献分别达68%、95%和77%;COD和氨氮是南明河的主要入河污染物(80%和60%的入河外源来水中COD和氨氮水平劣于地表V类水).采取截污纳管、污水处理及河底清淤等针对性的治理措施,可共削减南明河COD、氨氮和TP污染负荷41414.6、874.2和218.0 t·a~(-1);通过生态建设恢复河道自净能力并运行半年后,南明河整治段劣V类河道长度占比从整治前的51.0%下降至17.4%,达到地表水V类的水质段由原来的10.1%提高至24.3%.建立MIKE模型预测综合整治措施3期工程全部完工时南明河水质运营情况发现,南明河下游水质断面能稳定达到IV类水体,但在枯水期仍可能存在部分河段TP和氨氮超标的情况.通过从上游水库(红枫湖,II类水)进行生态补水以保障南明河干流城区段稳定达标IV类水体,在考虑模拟误差且保证率高于90%的情况下,枯水期最高补水量应达到3.47m~3·s~(-1).     

水分管理和外源硒对水稻吸收累积铅的影响

通过盆栽试验,研究了不同水分管理和外源亚硒酸盐的添加对水稻根际铅的动态变化和水稻吸收累积铅的影响.结果表明,淹水显著增加了根表铁膜对铅的吸附和根系对铅的吸收,淹水下苗期和成熟期水稻根系铅含量分别是非淹水处理时的4.2~8.5和1.4~1.5倍;淹水降低了地上部的铅分配,在苗期和成熟期分别降低85.9%~86.7%和51.8%~74.0%.加硒降低了土壤溶液、苗期水稻根系和地上部的铅含量以及成熟期水稻根表铁膜、根系和茎中的铅含量.与对照相比,淹水和非淹水下加硒处理使苗期水稻根系铅含量分别降低了5.4%~24.3%和2.7%~61.7%,使成熟期水稻根系铅含量分别降低了56.1%~64.1%和53.8%~63.2%.水稻籽粒中的铅含量在不同处理间无显著差异.因此,水分管理和外源硒的添加显著影响了水稻根系对铅的吸收,而对水稻籽粒对铅的累积无显著影响.     

苯为前驱物形成二噁英的反应机理

苯作为垃圾中普遍存在的成分是形成多氯二苯并对二噁英/呋喃（PCDD/Fs）的重要前驱物之一.应用密度泛函理论（DFT）在B3LYP/6-311+G （d,p）水平上研究了苯生成PCDD/Fs的两阶段气相反应机理,获得相关基元反应的势垒与反应热.采用隧道效应校正的变分过渡态理论（VTST）对300~1300K的各基元反应进行速率常数计算.结果表明：苯的氯化过程在合成PCDD/Fs各基元反应中势垒最高,是整个过程的控速步骤;氯酚更有可能被HO·进攻氯苯发生亲核反应后经分子内脱氢形成;邻位Cl能提高芳香烃H的抽取势垒,降低分子反应活性;苯氧自由基经碳碳或碳氧耦合二聚化过程形成不同PCDD/Fs存在竞争机制.相关计算结果可以用于在总二噁英产量基础上评估由苯产生的PCDD/Fs贡献率.     

Formation of water disinfection byproduct 2,6-dichloro-1,4-benzoquinone from chlorination of green algae

We report that green algae in lakes and rivers can serve as precursors of halobenzoquinone(HBQ) disinfection byproducts(DBPs) produced during chlorination. Chlorination of a common green alga, Chlorella vulgaris, produced 2,6-dichloro-1,4-benzoquinone(2,6-DCBQ), the most prevalent HBQ DBP in disinfected water. Under varying p H conditions(p H 6.0–9.0), 2,6-DCBQ formation ranged from 0.3 to 2.1 μg/mg C with maximum formation at p H 8.0. To evaluate the contribution of organic components of C. vulgaris to 2,6-DCBQ formation, we separated the organics into two fractions, the protein-rich fraction of intracellular organic matter(IOM) and the polysaccharide-laden fraction of extracellular organic matter(EOM). Chlorination of IOM and EOM produced 1.4 μg/mg C and 0.7 μg/mg C of 2,6-DCBQ, respectively. The IOM generated a two-fold higher 2,6-DCBQ formation potential than the EOM fraction, suggesting that proteins are potent 2,6-DCBQ precursors. This was confirmed by the chlorination of proteins extracted from C. vulgaris: the amount of 2,6-DCBQ produced is linearly correlated with the concentration of total algal protein(R2= 0.98). These results support that proteins are the primary precursors of 2,6-DCBQ in algae, and control of green algal bloom outbreaks in source waters is important for management of HBQ DBPs.     

Effects of tourmaline on nitrogen removal performance and biofilm structures in the sequencing batch biofilm reactor

The effects of tourmaline on nitrogen removal performance and biofilm structures were comparatively investigated in two identical laboratory-scale sequencing batch biofilm reactors(SBBRs)(denoted SBBR1 and SBBR2) at different nitrogen loading rates(NLRs) varying from(0.24 ± 0.01) to(1.26 ± 0.02) g N/(L·day). SBBR1 was operated in parallel with SBBR2, but SBBR1 was filled with polyurethane foam loaded tourmaline(TPU) carriers and another(SBBR2) filled with polyurethane foam(PU) carriers. Results obtained from this study showed that the excellent and stable performance of SBBR1 was obtained. Ammonia nitrogen removal and total nitrogen removal were higher in SBBR1 than that in SBBR2 with increase of NLR. At an NLR of(0.24 ± 0.01) g N/(L·day), the majority of the spherical and elliptical bacteria were surrounded by the extracellular polymeric substance(EPS) and bacillus or filamentous bacteria in two SBBRs biofilms. When NLR increased to(1.26 ± 0.02) g N/(L·day), the clusters were more obvious in the SBBR1 biofilm than that in the SBBR2 biofilm. Bacteria in SBBR1 were inclined to synthesis more EPS, and the formed EPS could protect the bacteria from free ammonia(FA) under extreme condition NLR(1.26 ± 0.02) g N/(L·day). The results of polymerase chain reaction-denaturing gradient gel electrophoresis analysis showed that the microbial community similarity in SBBR2 decreased more obviously than that in SBBR1 with the increase of NLR, which the microbial community in SBBR1 was relatively stable.     

Inhibitive effects of chlortetracycline on performance of the nitritation-anaerobic ammonium oxidation (anammox) process and strategies for recovery

The short-and long-term effects of chlortetracycline(CTC) on the nitritation-anaerobic ammonium oxidation(anammox) process were evaluated. The half maximal inhibitory concentration of CTC in the batch tests of the nitritation-anammox process was 278.91 mg/L at an exposure time of 12 hr. The long-term effects of CTC on the process were examined in a continuous-flow nitritation-anammox reactor. Within 14 days, the nitrogen removal rate significantly decreased from 0.61 to 0.25 kg N/m~3/day with 60 mg/L CTC in the influent.The performance suppressed by CTC barely recovered, even after CTC was removed from the influent. Furthermore, the inhibition of CTC also reduced the relative abundance of ammonium oxidizing bacteria(AOB) and anaerobic ammonium oxidizing bacteria(An AOB)in the reactor, resulting in both a decreased amount of and an imbalance between AOB and An AOB. When fresh anammox sludge was reseeded into the nitritation-anammox reactor,the nitrogen removal rate recovered to 0.09 ± 0.03 kg N/m~3/day.     

载溴石油焦脱除烟气痕量Hg0的动力学机理

采用化学-机械溴化法对废弃物石油焦进行改性,制得的载溴石油焦吸附剂用来脱除燃煤烟气中的痕量Hg⁰.通过比表面积及孔径分析（BET）、X射线衍射（XRD）和X-射线光电子能谱（XPS）对石油焦载溴前后进行表征和分析,发现石油焦中的有机硫促进了溴的负载,且负载方式为化学吸附.通过固定床脱汞试验,并应用4种动力学模型对初始汞浓度梯度和反应温度梯度下的实验数据进行拟合分析,结果表明：温度在150℃时,载溴石油焦的汞吸附效果最优;增加烟气中痕量Hg⁰浓度能提高载溴石油焦的汞吸附速率和单位累积汞吸附量;描述化学吸附的Elovich动力学模型的拟合相关系数达到0.9999以上,说明化学吸附在载溴石油焦脱汞过程中起主导作用.     

Particles and porous tablets based on Fe0/ZSM-5 composites prepared by ball-milling for heavy metals removal: Dissolved Fe2 +, pH, and mechanism

Novel, low-cost Fe~0/ZSM-5-based particles and porous tablets were prepared by a ballmilling method and used for the removal of Pb~(2+) in solution. Solid-phase characterization by scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy(SEMEDS) and transmission electron microscopy(TEM) revealed that the Fe0 microparticles were evenly loaded and tightly immobilized on the surface of ZSM-5 because of the extrusion/welding impact during ball-milling. For different Pb~(2+) concentrations, batch experiments indicated that the removal of Pb~(2+) increased with the decline of dissolved Fe2+and p H value in the solution for particles; opposite results were obtained for the tablets. The differences in the contact between both materials and Pb~(2+) were the main factor controlling Pb~(2+) removal in the solution. Investigation into the effect of initial p H value revealed that high p H reduced the number of electrons released from Fe corrosion. Consequently, low levels of removed Pb~(2+) and dissolved Fe~(2+) were synchronously observed. Also, simulated electroplating wastewater was treated using the prepared particles and porous tablets,and the removal order of Pb~(2+) Cr~(6+) Cu~(2+)≈ Cd~(2+) was observed. The Fe~0/ZSM-5 particles and tablets prepared through ball-milling show potential as materials for treatment of Pb~(2+) and other toxic metals.     

反应堆瞬发伽玛活化分析装置屏蔽性能研究

瞬发伽玛活化分析是一种高灵敏、非破坏的核分析技术。反应堆瞬发伽玛中子活化分析装置屏蔽设计是保护实验人员和提高装置分析灵敏度的重要保障。采用蒙特卡罗方法计算了中国先进研究堆瞬发伽玛活化分析装置的屏蔽性能和测量本底。利用公式修正的通过单晶铋过滤器的中子束流参数,使后续辐射水平计算结果更准确;采用分段-衔接的方法节省了计算时间。模拟结果显示,瞬发伽玛活化分析装置屏蔽性能满足辐射防护和低本底的要求,可为后续辐射防护措施的制定,实验人员辐射剂量优化以及同类装置屏蔽设计提供参考。     

黄河流域夏季水质量评价及管理对策

为了有效保护黄河水资源,促进黄河流域绿色发展,本研究在黄河流域上、中、下游贵德、兰州、三门峡和东营地点分别采样,分析p H、溶解氧、固体悬浮物、氨氮、硝态氮、总氮、亚硝态氮、总有机碳、总无机碳、总碳、总磷、化学需氧量、五日生化需氧量、粪大肠菌群、挥发酚含量变化趋势,并进行水质综合评价。结果发现:(1)固体悬浮物变化呈现东营兰州三门峡贵德;(2)氨氮、硝态氮、总氮、总有机碳、总无机碳、总碳、总磷、化学需氧量、五日生化需氧量、粪大肠菌群变化趋势依次为三门峡兰州东营贵德;(3)亚硝态氮和挥发酚含量变化趋势为兰州三门峡东营贵德;(4)综合水质评价结果为贵德水质好于东营,东营水质好于兰州,兰州好于三门峡。研究表明邻近城市和大型支流汇入点下游河段是黄河氮污染的主要来源,流域各省各级政府领导,要认真学习习总书记提出的"绿水青山就是金山银山"的生态思想,要入脑入心,严格科学减排,"一定要把黄河的事情办好"。