Redox potential EH [Se(VI)/Se(IV)] of aqueous extractof soils from Yongshou Kaschin-Beck diseaseregion and the influence by humic acid

The relation between E_H [Se(VI)/Se(IV)] and pH of soil aqueous extract in Kaschin-Beck disease region and the effects of natural redox agents, namely humic substances, MnO₂ and Fe²⁺, on the redox property of the system were studied. The results indicated that both humic acid and Fe²⁺ could enhance the reducibility of Se(VI) and MnO₂, a limited oxidizability for Se(IV). Fe²⁺ showed a weak reducibility only at low pH value. The reducibilities of three sulfur-containing compounds for Se(VI) were in following order:thioglycollic acid > L-cysteine > sulfide     

渤海沉积物中的"活性铁"与其氧化还原环境的关系

应用2001年12月航次所取得的渤海三个典型区域沉积物柱样品，用5％HCl浸取溶解自然粒度下的沉积物，测定了其中的Fe^3 ，Fe^2 ，Fe^3 /Fe^2 值，探讨了其分布特性及其与沉积物氧化还原环境的关系。结果表明Fe^3 在整个研究海域均是从表层向下逐渐递减的，Fe^2 在辽东湾是从表层向下逐渐减小的，而在其他海域是逐渐增加的。沉积物的上层（约50cm厚）Fe^3 含量变化复杂。一些柱状样Fe^2 含量随深度的增加而降低，可能除与沉积物来源有关外，还与“活性铁”的总量有关，“活性铁”含量在垂直方向上随深度而降低。从“活性铁”与Fe^3 /Fe^2 判断，所研究的渤海区沉积环境以弱氧化环境为主，局部地区为还原环境。     

热带西太平洋部分海域海水的化学状况分析

本文对１９９２年１１月棉兰老岛东南海域，伊里安岛北部海域上层水及４０°Ｓ１５６°Ｅ定点长达４个月的ｐＨ，Ｅｈ，ΣＳ调查分析，研究了上述海域的海水化学状况，结果表明，１９９２年１１月，在上层水中，棉兰老岛东南海域海水的碱性较弱，氧化性较强，伊里安岛北部海域海水碱性较强，还原性较强，４°Ｓ１５６°Ｅ的上层水界于二者之间。     

两株产电菌电子介体介导的胞外电子传递机理研究

构建了Klebsiella oxytoca d7和Shewanella sp.F1 2种纯菌燃料电池，探究了产电菌在产电过程中电子介体传递电子机制.结果表明：K.oxytoca d7只有作产电呼吸时，才会产生电子介体，而Shewanella. sp.F1在好氧呼吸、厌氧呼吸、产电呼吸下均能产生介电体，说明电子介体的产生与产电菌种类有关.两种菌介电体氧化还原电位相当（-250，210mV），且介于呼吸链NADH和辅酶Q之间.其介电体在胞内呼吸链上截获的电子均源于NADH，说明电子“逸出”位点只取决于介电体本身.K.oxytoca d7在碳源充足和不足时，电子介体产电量分别占总电量的60%和41%；Shewanella. sp.F1分别是57%和50%，说明在碳源充足时，2种菌的产电呼吸都以电子介体机制为主.介电体传递电子过程直接影响了阳极底物的转化和燃料电池的产电性能.     

石墨烯气凝胶强化氯霉素废水厌氧生物处理效能及机制研究

针对高浓度氯霉素（CAP）废水在实际厌氧生物处理过程中难降解、毒性大及对活性污泥产生的抑制问题,本文采用三维石墨烯气凝胶（GA）作为外源强化介质,通过批次试验探究了不同初始石墨烯气凝胶浓度、电子供体（蔗糖）浓度以及氯霉素浓度对氯霉素废水厌氧降解过程中氯霉素去除速率、有机物去除率以及甲烷产量等影响.结果表明：当初始石墨烯气凝胶浓度为0.5 g·L^-1、初始电子供体浓度为8.8 mmol·L^-1、初始氯霉素浓度为50 mg·L^-1时,强化效果最为显著,当反应进行到18 h时,强化系统中氯霉素的去除率达到94%以上,COD的去除率稳定在26.6%~35.6%之间,强化系统比只加入污泥的生物系统氯霉素去除速率增加了48%~51.6%,COD去除率增加了10%左右.石墨烯气凝胶作为电子转移中间介体和微生物富集的载体,促进微生物种间进行直接电子转移,加速氯霉素的脱氯过程和甲烷的产生,为高浓度抗生素废水的厌氧生物处理提供了新的处理思路和参考.     

硫素对氧化还原条件下水稻土氧化铁和砷形态影响

通过充N2和充O2的氧化还原反应装置,在添加外源砷污染的水稻土中,施用不同形态的无机硫(不施硫S0,单质硫S1和硫酸盐S2),模拟水稻田的氧化还原状况.结果表明,通N2时,土壤溶液氧化还原电位(Eh)在-100~-200 mV之间,溶液pH在7.0~8.0之间,pe+pH为4~7之间;通O2时,溶液Eh在200mV左右,溶液pH在6.5~7.5之间,pe+pH为9~12之间.无论通N2还是通O2,土壤溶出铁的浓度在1.2~1.6 mg·L-1,均有处理S0>S1>S2和AsS0>AsS1>AsS2.在通N2时,各处理HCl提取土壤氧化铁的含量比原土[(21.4±0.3)g·kg-1]低5 g·kg-1,有利于结晶态氧化铁向无定形氧化铁转化和形成Fe2+,无定形氧化铁活化度比原土活化度46.8%有所增加,且处理AsS2(49.4%)AsS2(36.1%).通N2时,土壤溶液中砷浓度变化为AsS0[(1.13±0.04)mg·L-1]>AsS1[(0.89±0.01)mg·L-1]>AsS2[(0.77±0.04)mg·L-1];通O2时,土壤溶液中砷浓度变化AsS1[(0.77±0.01)mg·L-1]>AsS0[(0.20±0.09)mg·L-1]>AsS2[(0.09±0.01)mg·L-1].通N2时,不同处理各形态砷占总砷比例变化为残渣态(34.9%~41.4%)≈专性吸附态(37.4%~39.5%)>晶态铁锰结合态(23.3%~25.6%)>非专性吸附态(2.4%~3.3%)>无定形铁锰结合态(0.5%~0.8%).通O2时,各处理形态砷占总砷比例变化为残渣态(30.8%~39.3%)≈专性吸附态(30.3%~34.7%)>晶态铁锰结合态(26.0%~28.7%)>无定形铁锰结合态(9.3%~10.7%)>非专性吸附态(0.5%~1.6%),其中,无定形铁锰氧化物结合态砷比通N2时提高了约9%,也就是无定形铁锰的老化作用对砷形态转化的影响.这表明还原条件能够使氧化铁的活化度升高,砷的移动性增强,但硫酸盐体系降低氧化铁的活化度,单质硫体系的砷移动性要大于硫酸盐体系的砷移动性.     

渗滤液污染羽中沉积物氧化还原缓冲能力研究

通过土柱模拟实验研究含水层沉积物的氧化还原缓冲能力及其在不同氧化还原带中的变化.结果表明,随着污染的加重,沉积物的氧化容量(OXC)减小,而还原容量(RDC)升高.在未受污染的沉积物中,Fe³⁺是OXC的主要组成,约占OXC的70.5%;TOC是RDC的主要组成,约占RDC的98.7%.在厌氧环境中大部分无定型态和部分晶体态Fe³⁺被还原,还原产物主要以FeCO₃和FeS形式沉淀;在产甲烷带/硫酸盐还原带和铁还原带中,Fe²⁺的沉积使得可离子交换态Fe²⁺含量由原样中的0.5%分别升高至3%和1.84%.因此Fe³⁺是含水层中主要的氧化还原缓冲剂,Fe³⁺还原、Fe²⁺沉淀和Fe2+的离子交换等作用大大减小了厌氧渗滤液污染羽的扩展,对进入含水层的还原性污染物有重要的缓冲作用.     

复合垂直流人工湿地氧化还原特征及不同功能区净化作用研究

研究了复合垂直流人工湿地系统氧化还原电位（Eh）的时空变化规律及不同功能区中污染物的净化效果。结果表明：湿地系统下行流池表层、两池底层、上行流池表层Eh的变化范围分别为402～585、-87～-130、308～432 mV，沿水流方向依次形成了好氧A区/缺氧、厌氧区/好氧B区3个功能区。好氧A区是污染物去除的主要区域，BOD₅、COD_Cr、NH⁺_4- N的去除率分别为430%、484%、541%，特别是NH+4 N去除率占总去除率的79%；缺氧、厌氧区主要是进行反硝化反应和有机物的厌氧分解；好氧B区则主要是去除厌氧分解后的有机物以及进一步脱氮。另外，NH+4 N的去除率与系统各功能区Eh呈显著相关关系（〖WTBX〗p〖WTBZ〗＜001），而BOD₅、COD_Cr、NO^-_3-N的去除率与系统各功能区Eh相关性不显著。     

Variations among rice cultivars on root oxidation and Cd uptake

In order to understand the mechanisms on the variation between rice cultivars in Cd uptake and accumulation, two pot soil experiments were conducted with typical rice cultivars that varied greatly in soil Cd uptake. The experiments with six rice cultivars showed that the root oxidation abilities of rice differed with rice cultivars and also with types of the cultivars, the cultivars with indica consanguinity were significantly higher than the cultivars with japonica consanguinity. Root oxidation abilities of the rice cultivars correlated positively and significantly （P〈0.01） with their Cd concentrations and Cd quantity accumulations in rice plants. The experiments with two rice cultivars showed that significant differences also existed between the two cultivars in pot soil redox potentials, which of Shan you 63 （higher soil Cd accumulator） were significantly higher than that of Wu yun jing 7 （lower soil Cd accumulator） under different soil Cd levels, but the degrees of the differences varied with soil Cd levels. The differences were larger under soil Cd treatments than the control. The results indicate that root oxidation ability, especially in Cd contaminated soil, is one of the main mechanisms which dominate Cd uptake and accumulation by rice plant.     

Utilizing transparent and conductive SnO2 as electron mediator to enhance the photocatalytic performance of Z-scheme Si-SnO2-TiOx

• A novel Z-scheme Si-SnO₂-TiO_x with SnO₂ as electron mediator is first constructed. • Transparent and conductive SnO₂ can pass light through and promote charge transport. • V_O from SnO₂ and TiO_x improve photoelectrochemical performances. • Efficient photocatalytic degradations originate from the Z scheme construction. Z-scheme photocatalysts, with strong redox ability, have a great potential for pollutants degradation. However, it is challenging to construct efficient Z-scheme photocatalysts because of their poor interfacial charge separation. Herein, by employing transparent and conductive SnO₂ as electron mediator to pass light through and promote interfacial charge transportation, a novel Z-scheme photocatalyst Si-SnO₂-TiO_{x (1<x<2)} was constructed. The Z-scheme photocatalyst displayed an order of magnitude higher photocurrent density and a 4-fold increase in open-circuit potential compared to those of Si. Moreover, the onset potential shifted negatively for approximately 2.2 V. Benefiting from these advantages, this Z-scheme Si-SnO₂-TiO_x exhibited efficient photocatalytic performance toward phenol degradation and mineralization. 75% of the phenol was degraded without bias potential and 70% of the TOC was removed during phenol degradation. Other typical pollutants such as bisphenol A and atrazine could also be degraded without bias potential. Introducing a transparent and conductive electron mediator to construct Z-scheme photocatalyst gives a new sight to the improvement of photocatalytic performance in Z scheme.