颗粒活性炭诱导亚硝化污泥快速颗粒化

采用两组平行SBR反应器,R1反应器投加颗粒活性炭,R2反应器不投加,其他运行参数保持一致.在常规生活污水中投加氨氮作为进水,研究颗粒活性炭对亚硝化颗粒污泥形成的影响.结果表明,在颗粒形成初期,投加的颗粒活性炭作为初始晶核,节约了小颗粒的形成时间,R1反应器仅22d便实现污泥颗粒化,而R2反应器运行38d才形成颗粒;同时,在整个运行阶段,R1反应器中的胞外聚合物(EPS)含量,尤其是其中的蛋白质(protein, PN)含量,明显高于R2反应器的,进一步证实颗粒活性炭的投加有利于亚硝化颗粒污泥的快速形成.除此之外,R1反应器中的氨氧化率和亚硝化率相对较高,且波动幅度小,表明颗粒活性炭的投加有助于维持亚硝化颗粒污泥处理效果的稳定性.     

硝酸铊对浮萍(Lemna gibba L.)的生长抑制及其氧自由基损伤作用

为了探讨硝酸铊(Tl(I)-nitrate)对浮萍(Lemna gibba L.)的生长抑制作用及其可能的氧化损伤机制,设置了Tl(I)-nitrate的8个处理组(0.005、0.01、0.02、0.04、0.08、0.1、0.5和1.0 mg·L-1)和对照组(0.0 mg·L-1),进行96 h急性毒性实验,测定96 h内超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性及丙二醛含量。结果表明:96 h暴露时间下,浮萍生长受抑制程度与Tl(I)浓度之间呈正相关,Tl(I)-nitrate对浮萍的96 h EC50为0.076 mg·L-1,NOEC为0.01 mg·L-1。CAT活性随着Tl(I)-nitrate浓度升高逐渐降低,在0.5和1 mg·L-1时,有极显著差异(p0.01)产生,SOD活性在0.1 mg·L-1时显著升高(46%),POD活性和MDA含量在Tl(I)浓度0.5 mg·L-1时明显上升。当Tl(I)-nitrate胁迫超出浮萍抗氧化酶系统清除活性氧的能力时,活性氧积累导致浮萍受到不可逆转的氧化损伤。Tl(I)-nitrate对浮萍生长产生明显的抑制作用     

Smokeless tobacco extract impairs iron homeostasis in rats and human hepatoma,HepG2 cells

Tobacco exposure may alter homeostasis of iron (Fe), one of the most abundant and essential transition metals in the body. In this study, the effect of aqueous extract of smokeless tobacco was evaluated on Fe homeostasis in rats and human hepatoma, HepG2 cells. Our findings suggested that tobacco consumption even at low doses impairs Fe homeostasis leading to Fe deficiency anemia. Significant alterations were noted with respect to hematological parameters and expression patterns of selected intestinal Fe-transporters, Fe-binding proteins, and Fe-regulatory hormone, hepcidin. Impairment in the hepatic and renal antioxidant defense system was also observed in the treated rats. Histopathological studies revealed cirrhosis of liver and goblet cell hyperplasia of small intestine. Further, analysis of hepcidin promoter and its expression along with ferritin (expression and ELISA) in HepG2 cells demonstrated an enhanced expression of both the genes resulting in sequestration of Fe in treated cells, thus indicating systemic Fe deficiency.     

Sub-lethal effect of chlorpyrifos on protein metabolism of the food fish Clarias batrachus and monitoring of recovery

The effect of sub-lethal concentrations of chlorpyrifos on protein metabolism in physiological important tissues, namely gills, kidney, liver, and muscle of the freshwater fish, Clarias batrachus, was studied. Fish were exposed to 1/20th and 1/10th of 96?h LC₅₀ concentrations for 7, 14, 21, and 28 days. After 28 days of exposure, fish were released into fresh water and kept in the same for 21 days in order to study the recovery. Fish were sacrificed at the stipulated periods and gills, kidney, liver, and muscle tissues were used for the estimation of total protein, amino acids, ammonia, urea, glutamine, protease, transaminases, and phosphatases. Total protein, amino acid, and ammonia contents were decreased in all tissues for 28 days and recovery was observed during the recovery period. Urea and glutamine levels were elevated, except in kidneys, and recovered at the end of the recovery period. The activities of protease, alanine, and aspartate aminotransferases, and acid and alkaline phosphatases were elevated in the tissues for 28 days exposure at both concentrations. Recovery of these enzymes activities was noticed during depuration.     

Effects of copper on lipid peroxidation,glutathione, metallothionein,and antioxidative enzymes in the freshwater mussel Anodonta anatina

Copper is an essential element to all animals. At elevated concentrations, it is toxic and can participate in the formation of reactive oxygen species, leading to cellular damage. In this study, the ecotoxicological relevance of copper was investigated with freshwater mussels, Anodonta anatina. When the mussels were exposed to copper at environmentally realistic concentrations, either via the water (0.3?µmol?L^?1 Cu) or fed with Cu-loaded algae (equivalent to 0.06?µmol?L^?1 Cu), the level of thiobarbituric acid-reactive substances rose and glutathione decreased. This was associated with the induction of metallothionein and, relative to total protein, of glutathione reductase and the antioxidative enzymes superoxide dismutase, catalase, and glutathione peroxidase. But, since the overall protein-synthetic capacity was hampered by the copper insult, the activities of the enzymes relative to tissue weight and copper concentrations were depressed. During depuration, most parameters started to normalize although not returning to control values within 12 days.     

PCB disposition and different biological effects in rats following direct soil exposure vs. PCBs off-gassed from the soil

A comparison of PCB congener profiles and limited biological effects was made between direct exposure to PCB-contaminated soil and vapor phase PCBs from that soil to determine congener patterns useful for identifying exposure sources in humans and wildlife. Weanling female Sprague–Dawley rats were exposed to either control or PCB-contaminated soil (from a landfill in Southern Illinois) for 1 and 2 weeks. The exposures were via direct contact with the soil or via airborne exposure with the rats isolated from the soil by a wire screen. Total PCB of 25% contaminated soil used in the study was 13?500?ppm. No PCBs were detectable in control rats. In direct-exposed rats, total PCB residues in fat pad, ear skin, serum, liver, and inguinal lymph nodes after the 1-week exposure were 6256, 185, 3.2, 149, and 41?ppm, respectively, but decreased to 465, 72, 1.7, 106, and 32.4?ppm after the 2-week exposure. In airborne-exposed rats, total PCB residues were 7.8, 1.6, 0.03, 0.2, and 0.6 in the same manner and slightly increased in fat pad and ear skin to 11.6 and 2.14, respectively. Decreases in both the concentrations and percentages of “episodic” PCBs (those congeners rapidly metabolized) in the fat pad were apparent following the 2-week exposure compared to the 1-week exposure by both routes. Both EROD and BROD activities were significantly increased in the direct-exposed rats, whereas only BROD activity increased in airborne-exposed rats. Serum T ₄ levels were depleted in the direct-exposed rats regardless of time of exposure but were increased insignificantly after 1-week and significantly after 2 weeks in the airborne-exposed rats. No significant changes in serum insulin levels were apparent in any of the treated groups. The results suggested that exposure of animals to PCBs via different routes could result in different PCB profiles, which could cause different biological effects.     

Oxidative stress and changes in locomotor behavior and gill morphology of Gambusia affinis exposed to chromium

Sublethal effects of chromium trioxide on mosquito fish, Gambusia affinis, were carried out for 28 days on day 4, 8, 12, 16, 20, 24, and 28. The sublethal effects of chromium (LC₁₀, 77.62?mg?L^?1) on antioxidant enzymes, thiobarbituric acid reactive substance (TBARS), locomotor behavior, and gill morphology were studied. The antioxidant enzymes like superoxide dismutase (SOD) and catalase were induced throughout the exposure span of 28 days. Percent induction was also increase with the days of exposure. Lipid peroxidation product, malondialdehyde was enhanced in the viscera tissue of chromium-exposed fish. Perturbation of locomotor behavior like decrease in distance travelled (m?min^?1) and in swimming speed (cm?s^?1) was observed in exposed fish. Chromium toxicity caused alterations in gill morphology like hypertrophy and hyperplasia in secondary lamellae followed by detached epithelium with severe necrosis. It can be concluded from the results that Cr intoxication in Gambusia fish, caused induction in antioxidant enzymes and lipid peroxidation, plus changes in gill morphology and locomotor behavior.     

Acute effects of low-dose cypermethrin on male rat cells

Effects of synthetic pyrethroid insecticide α-cypermethrin were investigated following intradermal dose (5–50 mM) of cypermethrin to male albino Wistar rats. Glucose, protein, cholesterol, triglycerides, urea, uric acid, creatinine, hemoglobin, blood RBC, and WBC content were determined 6 h after pesticide administration. Biochemical parameters and blood cell count changed significantly in treated rats at all doses. Low-dose cypermethrin affected early biochemical changes in rats.     

矸石山不同造林模式对土壤养分及酶活性影响的研究

本文以抚顺矸石山立地条件下树龄为10年的刺槐Robinia pseudoacacia L.、火炬Rhus typhina Nutt、白榆Ulmus pumila L.、沙棘Hippophae rhamnoides L.林以及植被自然恢复裸地（CK）5种植被恢复模式为研究对象,按土壤发生学层次进行采样,对土壤有机质、碱解氮、有效磷、速效钾、pH、过氧化氢酶、蔗糖酶和脲酶等指标进行研究,结果表明：与CK相比,4种造林模式显著提高了Ah层的土壤有机质和养分含量,其中,有机质、有效磷改良效果最好的是白榆模式,分别增加了194.8%、442.9%;速效钾改良效果最好的是刺槐模式,增加了262.0%;碱解氮则是火炬模式改良效果最好,增加了509.2%。不同造林模式与CK相比增加了各层次的过氧化氢酶、脲酶、蔗糖酶活性,其中,蔗糖酶和过氧化氢酶活性Ah层最大的是火炬模式,增加了134.5%和880.9%;脲酶酶活性最大的是白榆模式,增加了119.1%。从垂直角度看,有机质、碱解氮、过氧化氢酶、脲酶随土层加深含量降低,在C层达到最小值,而速效钾、有效磷、蔗糖酶的最小值则出现在AC层;不同模式对土壤pH影响不一,垂直规律不明显。     

曝气强度对膜生物反应器运行特性的影响

以膜生物反应器（MBR）处理模拟生活废水为研究体系,考察曝气强度对系统污染物去除效果、脱氢酶活性、胞外聚合物（EPS）组分和含量、Zeta电位、污泥粒径及跨膜压差等的影响.结果表明,随着曝气强度降低,COD去除率变化不大,均大于94.0%,脱氢酶活性明显降低,VSS/SS比值下降;污泥LB-EPS增加,Zeta电位降低,污泥平均体积粒径减小,膜通量下降速率增大.曝气强度为800—400 L.m-.2h-1的条件下,曝气产生的水力剪切力不是影响污泥粒径大小的主导因素,污泥Zeta电位则起着决定作用,但水力剪切力有利于缓解膜污染.