Inactivation of bacteria by sun light in a solar reactor with Immobilised TiO2

The photocatalytical inactivation of bacteria (Escherichia coli, Staphylococcus epidermidis,...) in the flow‐through plate solar reactor by sunlight was investigated. The low stability of bacteria in the reactor was attributed to bacteria sensitivity to mixing and/or gas bubbling. Sunlight inactivation proceeds with sufficient rate even under cloudy conditions.     

TiO2 photocatalyzed degradation of diazinon in an aqueous medium

The photocatalytic degradation of diazinon was studied over TiO₂ catalysts. The kinetics obtained demonstrated that powder titania (t_1/2 = 9.7 min) was more efficient compared to pure titania thin film catalysts (t_1/2 = 29.4 min). Mineralization of organic carbon to CO₂ after 360 min of irradiation was found to be 75% while heteroatoms (P, S, N) were mineralized into phosphate, sulfate and nitrate ions, respectively. A microtox test was performed to evaluate the toxicity of solutions treated by catalysts. Illumination of diazinon in the presence of TiO₂ gave rise to several intermediates that have been identified by means of solid phase extraction and gas chromatography-mass spectrometry, while a simple degradation pathway is proposed.     

Photocatalytic formation of hydrogen peroxide over highly porous illuminated ZnO and TiO2thin film

The photocatalytic formation of hydrogen peroxide over ZnO and TiO₂thin films has been investigated in aqueous phase in the presence of molecular oxygen as an electron acceptor. These films are highly porous and showed enhanced catalytic activity in the photochemical formation of hydrogen peroxide. The amount of H₂O₂formed during 2 hour light illumination is 4–6 μM and the rates of formation of hydrogen peroxide of both the films are almost comparable. The yield of hydrogen peroxide increases with the increase in irradiation time and a trend of steady state concentration of H₂O₂is observed in the case of TiO₂thin film. Photodissolution of ZnO particles is observed in some extent during the process of prolonged UV light illumination.     

Toxicity of nano-anatase TiO2 to mice: Liver injury,oxidative stress

There are concerns regarding the toxicity of nano-TiO₂, but data are limited on the mechanism underlying oxidative damage to liver of mice. In order to further study these mechanisms of nano-TiO₂ particles, nano-anatase TiO₂ (5 nm) were injected into the abdominal cavity of ICR mice daily for 14 days and biochemical parameters in liver were investigated. The increase of hepatic lipids peroxide produced by nano-anatase TiO₂ suggested an oxidative attack that was activated by a reduction of antioxidative defense mechanisms as measured by analyzing the activities of superoxide dismutase, catalase, ascorbate peroxidase, and glutathione peroxidase, as well as antioxidant levels such as glutathione and ascorbic acid. The antioxidative responses of liver were reduced in mice by nano-anatase TiO₂. The oxidative stress of nano-anatase TiO₂ on liver was greater than that seen with bulk-TiO₂.     

Kinetics study of photocatalytic process for treatment of phenolic wastewater by TiO2 nano powder immobilized on concrete surfaces

In this study, kinetics of photocatalytic degradation of phenolic wastewater in immobilized photocatalytic reactor was investigated. Immobilization of titanium dioxide (TiO₂) nano powders on concrete surfaces were accomplished with epoxy concrete sealer. Kinetics of photocatalytic reactions has been proposed to follow the Langmuir–Hinshelwood model in different initial phenol concentration, pH, and UV lamp intensity. First-order reaction kinetics with respect to the pollutant concentration was obtained for the reaction. Effect of UV lamp intensity showed that kinetic constants were proportional to the power of 0.73–1 of the photonic flow. In all cases kinetic constant increases as pH of the system reached up to 12 units. Several reaction intermediates were identified using the GC/Mass analysis. Products at the initial stage of the reaction were aromatic compounds, contained hydroquinone, benzoquinone, and catechol. These intermediates underwent further photocatalytic oxidation to aliphatic compounds and finally into CO₂ and H₂O after 4?h. Kinetic constants of intermediate compounds were determined using mathematical–chemical equations and nonlinear regression. Data showed that the differences between the mathematical model and Langmuir–Hinshelwood model for the kinetic constant was less than 5%.     

Photodegradation of fungicide triadimefon and pesticide pirimicarb in aqueous TIO2 suspension

Two agrochemicals composed of nitrogen‐containing heterocyclic ring, triadimefon and pirimicarb, were degraded photocatalytically. The disappearance and TOC elimination rates of triadimefon were close to those of pirimicarb, whereas the photolysis of triadimefon was 4 times slower than that of pirimicarb. For triadimefon its aromatic moiety degraded quickly and Cl^‐ was released immediately, while triazole moiety degraded slowly. The formation rates of NH⁺ ₄ and NO₃ ^‐ by the degradation of triazole moiety were influenced by the rest of the molecule. The difference between disappearance and TOC elimination rates of both triadimefon and pirimicarb were far larger than those of aromatic compounds.     

纳米TiO2与重金属Cd对铜绿微囊藻生物效应的影响

为了更全面地评价纳米TiO2的生物效应,尤其是纳米TiO2与其他环境污染物的联合作用,以铜绿微囊藻为受试生物,探讨了不同浓度的纳米TiO2,以及纳米TiO2与Cd联合作用对藻生长的影响。根据叶绿素a及藻胆蛋白的含量变化,低浓度的纳米TiO2溶液(0～50mg.L-1)可以促进藻的生长,当纳米TiO2的浓度大于50mg·L-1时,藻细胞的生长有所抑制,生长减慢,并呈剂量-效应关系;当纳米TiO2与Cd离子同时存在时,由于纳米TiO2对Cd离子的吸附作用,水中游离态Cd离子浓度降低,Cd离子对藻的毒性明显降低。因此,纳米TiO2的生态毒性和环境效应不容忽视,同时,应重视纳米材料及与其他环境污染物质共同作用后的生物效应。     

Interaction between cadmium,lead and potassium fertilizer (K<Subscript>2</Subscript>SO<Subscript>4</Subscript>) in a soil-plant system

A pot experiment was conducted to examine the influence of potassium (K) fertilizer (K₂SO₄) application on the phytoavailability and speciation distribution of cadmium (Cd) and lead (Pb) in soil. Spring wheat (Triticum aestivum L.) was selected as the test plant. There were seven treatments including single and combined contamination of Cd and Pb. CdCl₂·2.5 H₂O and Pb(NO₃)₂ were added to the soil at the following dosages: Cd + Pb = 0.00 + 0.00, 5.00 + 0.00, 25.0 + 0.00, 0.00 + 500, 0.00 + 1000, 5.00 + 500 and 25.0 + 1000 mg kg⁻¹, denoted by CK, T1, T2, T3, T4, T5 and T6, respectively. The K fertilizer had five levels: 0.00, 50.0, 100, 200 and 400 mg K₂O kg⁻¹ soil, denoted by K0, K1, K2, K3 and K4, respectively. The results showed that the K fertilizer promoted the dry weight (DW) of wheat in all treatments and alleviated the contamination by Cd and Pb. The application of K₂SO₄ reduced the uptake of Cd in different parts including roots, haulms and grains of wheat; the optimum dosage was the K2 level. K supply resulted in a significant (P < 0.05) decrease in the soluble plus exchangeable (SE) fraction of Cd and there was a negative correlation (not significant, P > 0.05) between the levels of K and the SE fraction of Cd in soil. The application of the K fertilizer could obviously restrain the uptake of Pb by wheat and there were significant (P < 0.05) negative correlations between the concentrations of Pb in grains and the levels of K in soil. K supply resulted in a decrease in the SE fraction of Pb (except the K1 level) from the K0 to K4 levels. At the same time, the application of the K fertilizer induced a significant (P < 0.05) decrease in the weakly specifically adsorbed (WSA) fraction of Pb and a significant (P < 0.05) increase in the bound to Fe–Mn oxides (OX) fraction of Pb. At different K levels, the concentration of Pb in the roots, haulms and grains had a positive correlation with the SE (not significant, P > 0.05) and WSA (significant, P < 0.05) fractions of Pb in the soil. All the K application levels in this experiment reduced the phytoavailability of Cd and Pb. Thus, it is feasible to apply K fertilizer (K₂SO₄) to alleviate contamination by Cd and/or Pb in soil. Moreover, the level of K application should be considered to obtain an optimal effect with the minimum dosage.     

过氧化氢和一氧化氮在小球藻抗阿特拉津胁迫中的作用

过氧化氢(H_2O_2)和一氧化氮(NO)作为信号分子,可调节植物生长、发育以及应对外源性胁迫。利用过氧化氢酶(CAT)以及NO清除剂(PTIO),研究了除草剂阿特拉津(atrazine,100μg·L~(-1))影响小球藻生长的机理,并分析内源性H_2O_2和NO在小球藻抗除草剂胁迫中的作用。研究结果表明,阿特拉津在诱发小球藻细胞死亡的过程中,不同程度促发了H_2O_2和NO生成;外源CAT可通过清除H_2O_2和诱导NO来缓解阿特拉津对小球藻的生长抑制;PTIO与阿特拉津的联合实验进一步证实,小球藻体内的NO诱导与H_2O_2的爆发无关,它们之间的合成没有相关性。因此,除草剂阿特拉津主要通过诱导小球藻体内的H_2O_2爆发来破坏藻细胞,抑制其生长,与NO的信号传递无关。     

Histopathological effects of copper oxide nanoparticles on the gill and intestine of common carp (Cyprinus carpio) in the presence of titanium dioxide nanoparticles

In current research, the combined effects of copper oxide nanoparticles (CuO NPs) and titanium dioxide nanoparticles (TiO₂ NPs) on the histopathological anomalies of gill and intestine tissues in common carp (Cyprinus carpio) were studied. Common carp were exposed to TiO₂ NPs (10.0?mg L^?1), CuO NPs (2.5 and 5.0?mg L^?1), and mixture of TiO₂ NPs (10.0?mg L^?1)?+?CuO NPs (2.5 and 5.0 mg?L^?1) for two periods of exposure (10 and 20 days) and recovery (30 and 40 days). The most common histopathological anomalies in the gill of common carp such as hyperplasia, oedema, curvature, fusion, aneurism, and necrosis were observed. The synergistic effect of co-existing TiO₂ NPs and CuO NPs reduced the length of secondary lamella and increased the diameters of the gill filaments and secondary lamellae. Moreover, the presence of TiO₂ NPs increased the CuO NPs effects on the histopathological anomalies of intestine tissue and the synergistic effect of TiO₂ NPs and CuO mixture leads to an increase in the severity of histopathological lesions such as degeneration, swelling of goblet cells, and necrosis - erosion in the intestine tissue. In conclusion, the presence of TiO₂ NPs increased the toxicity of CuO NPs.     

Effects of ethyl 2-methyl acetoacetate (EMA) on the growth of Phaeodactylum tricornutum and Skeletonema costatum

We investigated the effects of ethyl 2-methyl acetoacetate (EMA) on growth of the marine diatom algae Phaeodactylum tricornutum (P. tricornutum) and Skeletonema costatum (S. costatum). Growth of P. tricornutum was significantly inhibited by the minimum concentration (3.5 mmol·L ^?1) of EMA at lower initial algal densities (IADs) (3.6×10⁴ and 3.3×10⁵ cells·mL ^?1). However, at the highest IAD, significant growth inhibition was found at above 7 mmol·L ^?1 of EMA exposure. In S. costatum, EMA concentrations of 10.5 mmol·L ^?1 or more significantly inhibited growth at lower IAD (3×10⁴ and 1.8×10⁵ cells·mL ^?1); at the highest IAD, only EMA concentrations above 14 mmol·L ^?1 obviously inhibited the growth of S. costatum. Changes in specific growth rates and pigment were consistent with algal growth, but only at higher EMA concentrations or lower IAD values was the ratio of chlorophyll a (Chla) to carotenoid significantly lower than the control. Medium effective concentration (EC ₅₀) values were in the order 4.07, 8.03 and 12.27 mmol·L ^?1 for P. tricornutum and 7.48, 11.92 and 17.22 mmol·L ^?1 for S. costatum. All these results show that the effect of EMA on the growth of algae was species specific and mainly depended on IAD, which might be an important factor to influence algal growth.     

Histopathology of cerebro neuronal cells in freshwater snail Bellamya bengalensis: impact on respiratory physiology,by acute poisoning of mercuric and zinc chloride

Mercuric (Hg) and zinc (Zn) chloride toxicity was investigated in cerebroneuronal cells and gills of Bellamya bengalensis using sublethal concentrations under lab conditions. Freshwater snail B. bengalensis was exposed to mean LC₅₀ concentration (1.56 ppm and 12.7 ppm) of Hg and Zn chloride, respectively. Bioaccumulation of Hg and Zn was observed in nervous and gill tissue in proportion to the time of exposure. Respiratory mechanisms and rate of oxygen consumption was depleted by both metals. Histopathological alterations in cerebro neuronal cells (giant, large, medium, and small) and gill filamental epithelia were apparent in Hg and Zn-exposed snails. Histopathology demonstrated increased cytoplasmic basophilia, extreme indentation of plasma membrane, karyolitic and eccentric nuclei, nuclear envelope with irregular size, and shrunken appearance of cerebroneuronal cells. Histologically, gill filamental epithelia showed hypertrophy, enlarged ciliated margins reduced length of cilia, nuclear dilations, thickening of basal lamina, and hemocytic accumulations in induced cells and severe loss of goblet mucus cells at the tip. Histopathology was accompanied by dysfunctioning cilia with decreased rate of respiration. Overall, neuronal impairment with damaged gill filament produced improper gaseous exchange leading to sluggish movement.     

H_2O_2致大鼠RTE细胞系氧化应激作用及GSH保护作用的体外研究

许多具有氧化作用的空气污染物,均能使细胞产生氧化损伤,使胸腺基质淋巴生成素(thymic stromal lymphopoietin,TSLP)含量上升。而TSLP是一种启动过敏性炎症的重要因子,会导致哮喘等疾病发生率的上升。在本研究中用过氧化氢(H_2O_2)模拟具有氧化作用的空气污染物进行染毒,研究细胞氧化应激水平的变化,并讨论还原型谷胱甘肽(GSH)对细胞受氧化损伤的保护作用。将大鼠支气管上皮细胞(RTE)分组培养,每组设置6个平行实验,分别用低、中、高剂量H_2O_2染毒3 h;高剂量设置1个重复,作为保护组,在染毒前用GSH保护2 h。结果显示,高剂量组H_2O_2(3.2 mmol·L~(~(-1)))染毒的细胞,其细胞活力下降(P0.01),丙二醛(MDA)水平上升(P0.01),TSLP水平上升(P0.05),与之相比,用GSH保护后的同剂量染毒组,上述指标得到全面缓解(P0.01)。这表明高浓度的H_2O_2会损伤细胞活力,并使MDA及TSLP水平上升,而GSH对TSLP及MDA的升高有极显著的抑制作用,即对细胞有一定的保护作用。     

纳米Al_2O_3和Cd联合暴露对铜锈环棱螺体内Cd的生物积累和抗氧化酶活性的影响

金属氧化物纳米颗粒的广泛应用导致它们大量地释放到水环境中,其独特的理化性质有可能改变水环境中其他共存污染物(如重金属)的生态毒性。为评价沉积物中纳米氧化铝(Al2O3-NPs)对重金属Cd生态毒性的影响,采用底栖生物慢性暴露研究了Al2O3-NPs存在条件下Cd在底栖动物铜锈环棱螺体内生物积累的变化和Cd对肝胰脏抗氧化防御系统关键成分超氧化物歧化酶(SOD)与脂质过氧化指标丙二醛(MDA)以及Ⅱ相反应的关键酶谷胱甘肽-S-转移酶(GST)的影响。结果表明,低Cd浓度(5μg·g-1)时,Al2O3-NPs对Cd生物积累没有影响;中、高Cd浓度(25、100μg·g-1)时,Al2O3-NPs显著促进Cd的生物积累,Al2O3-NPs对Cd的生物转运具有明显的携带效应。低Cd浓度时,无Al2O3-NPs处理组和Al2O3-NPs处理组的SOD活性与对照组相比均没有显著差异;中Cd浓度时,SOD活性显著升高,而高Cd浓度时,SOD活性显著下降,而且Al2O3-NPs处理组的SOD活性显著低于无Al2O3-NPs处理组,Al2O3-NPs的存在加重了Cd对肝胰脏细胞的氧化胁迫或损伤。高Cd浓度时,无Al2O3-NPs处理组和Al2O3-NPs处理组的MDA水平均显著升高,但Al2O3-NPs处理组的MDA水平显著低于无Al2O3-NPs处理组,进一步证明Al2O3-NPs对Cd氧化损伤的增强作用。中、高Cd浓度时,无Al2O3-NPs处理组和Al2O3-NPs处理组的GST活性均显著下降,但Al2O3-NPs处理组的GST活性均显著低于无Al2O3-NPs处理组,同样说明了Al2O3-NPs对Cd毒性的增强作用。本研究提供了在沉积物-底栖动物体系中Al2O3-NPs促进重金属生物积累的证据,而且Cd毒性的变化与肝胰脏中Cd的生物积累水平的变化基本一致,在中、高Cd浓度下,由于Al2O3-NPs的存在显著促进了Cd的生物积累,因而增强了Cd对铜锈环棱螺的生态毒性。     

Effect of nitrification inhibitor on plant biomass and N2O emission rates in alpine meadows on the Tibetan Plateau

ABSTRACT

Treatment with nitrification inhibitors, such as dicyandiamide (DCD) and 3,4-dimethylpyrazole phosphate (DMPP) have been strongly indicated to increase grassland biomass and mitigate soil N₂O emission rates. However, the responses of both alpine meadow aboveground biomass and N₂O emission rates to nitrification inhibitors remains unclear. We separately applied three doses of DCD and DMPP to alpine grassland soils with three duplicates. The biomass and N₂O emission rates were subsequently measured by a clear-cut method and in-situ static chamber gas chromatography during the growing season. Our findings indicated that aboveground biomass increased significantly, and N₂O emission rate decreased significantly at 6.8?kg?ha^?1 DCD and DMPP. Furthermore, the biomass increase effect was more significant than the N₂O emission rate mitigation effect (p?<?0.05). The highest ratios of DCD treatments on meadow production increase and N₂O emission rate decrease were 27.2% and 36.3%, respectively. Our findings provide insight into the enhanced grassland primary production and decreased N₂O flux by nitrification inhibitor treatment in alpine meadows, which may be beneficial to help mitigate global warming.     

山西工矿区土壤二氧化硫与多环芳烃复合污染对小麦种子萌发和幼苗生长的影响

以小麦为供试植物,山西工矿区生黄土为供试土壤,进行了土壤中二氧化硫(SO2)与多环芳烃(PAHs)单一及复合污染对小麦种子萌发率及小麦幼苗株高、根伸长和地下生物量影响的研究,以期考察复合污染的生态毒性效应。结果表明,小麦种子萌发对SO2与PAHs单一及复合污染均不敏感;SO2和PAHs单一污染时,小麦幼苗的株高与根伸长均受到一定程度的影响,低浓度SO2或PAHs处理对小麦生长起促进作用,高浓度则为抑制作用;小麦幼苗株高与SO2浓度呈显著负相关(r=-0.954,P<0.05),但与PAHs浓度的相关性不显著;SO2与PAHs复合污染条件下,对小麦幼苗株高或根伸长的联合作用多体现为协同作用,在低浓度情况下(SO2<500mg·kg-1)表现为协同促进;当SO2达到500～1000mg·kg-1时,对小麦幼苗株高或根伸长的联合作用均体现为协同抑制。SO2和PAHs单一污染时,小麦幼苗地下生物量与SO2、PAHs浓度均为显著负相关(rPAHs=-0.953,rSO2=-0.916,P<0.05);复合污染条件下,在SO2浓度为10mg·kg-1时,对地下生物量的联合作用多体现协同促进作用;而在SO2浓度为1000mg·kg-1,PAHs为50～100mg·kg-1时,对地下生物量的联合作用均体现为协同抑制作用。多元逐步回归分析进一步表明,SO2与PAHs复合污染条件下,小麦幼苗株高、根伸长都受到了SO2及PAHs的共同影响,而SO2是影响小麦幼苗地下生物量的主要因素。