全氟辛烷磺酸对蚯蚓体内4种酶活性的影响

采用人工土壤法,研究了不同暴露浓度的全氟辛烷磺酸(PFOS)对赤子爱胜蚓(Eisenia fetida)体内过氧化氢酶(CAT)、超氧化物歧化酶(SOD)及谷胱甘肽过氧化物酶(GSH-PX)活性及蚯蚓细胞色素P450(CYP450)含量的影响。研究结果表明,各指标敏感性总体为CYP450>CAT>GSH-PX>SOD。人工土壤试验中PFOS诱导CYP450含量增加,同时又抑制CAT活性。试验第4天时,50mg/kg处理组CAT活性是对照组的2.83倍,SOD活性达到190.769 U/mg,是对照组的2.19倍;12.5 mg/kg处理组GSH-PX活性最高,CYP450含量是对照组的3.85倍。PFOS暴露浓度与蚯蚓CAT、SOD和CYP450活性存在剂量-效应关系,在PFOS环境污染诊断时,可将第4天时的CAT、GSH-PX活性和CYP450含量作为生物标志物。为赤子爱胜蚓体内抗氧化酶和CYP450作为PFOS污染的早期诊断和生态风险监测生物标志物的可行性提供科学依据。     

不同污染区巨菌草生物炭内源污染物分布及其生物毒性

由于生物质原料来源广泛,缺乏生物炭内源污染物及其用量限制标准,极有可能将含有高内源污染物的生物炭用于环境修复,产生潜在的环境风险.采用清洁区、中度和重度污染区的巨菌草为原料制备生物炭,考察其内源铜（Cu）和镉（Cd）全量及其酸溶态含量和持久性自由基（PFRs）分布,并研究生物炭浸出液对小麦根伸长抑制率和抗氧化酶活性的影响.结果表明,重度污染区九牛生物炭Cu和中度污染区水泉生物炭中Cd含量分别是清洁区红壤生物炭Cu和Cd的3.73倍和4.43倍,九牛生物炭中酸溶态Cu含量分别是水泉和红壤生物炭的3.32倍和2.84倍,水泉和九牛生物炭中酸溶态Cd含量分别是红壤生物炭的7.95倍和5.11倍.3种生物炭中均含有相邻氧原子以碳为中心的PFRs,表现为：红壤>九牛>水泉.3种生物炭浸出液对小麦根伸长均表现为抑制作用,但均不同程度地提高了小麦幼苗超氧化物歧化酶（SOD）、过氧化物酶（POD）和过氧化氢酶（CAT）活性,其中九牛生物炭浸出液对小麦根伸长抑制率最高,达到27.7%.本研究表明,生物炭中内源重金属及PFRs等污染物的共同作用对小麦幼苗产生了显著的生物毒性,后期的研究需关注生物炭内源污染物的潜在环境风险,避免产生二次污染等环境问题.     

H2S信号在拟南芥响应SO2胁迫过程中的作用

以拟南芥为实验材料,研究植物对H₂S和SO₂处理的转录响应及其关系,并利用外源喷施H₂S及其清除剂的方法,检测SO₂熏气后植株体内H₂S的产生及其生理效应,探讨气体信号分子H₂S在植物响应SO₂胁迫过程中的作用.高通量测序结果发现,H₂S和SO₂处理诱导拟南芥植株多个基因转录水平改变,并有1220个基因在两种处理条件下均差异表达,其中包括多个硫代谢和谷胱甘肽代谢相关基因,表明H₂S和SO₂在调控硫代谢途径中具有交互作用.SO₂熏气诱导拟南芥植株体内H₂S合成酶基因LCD和DES1转录水平提高,胞内H₂S含量增多.同时,超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活性升高,含硫抗氧化物谷胱甘肽(GSH)含量及其相关酶谷胱甘肽硫转移酶(GST)和谷胱甘肽过氧化物酶(GPX)活性提高,活性氧H₂O₂含量增加,膜脂过氧化产物丙二醛(MDA)含量与对照相比无显著差异.外源喷施H₂S可进一步提高SO₂熏气下拟南芥植株GSH含量及其相关防御酶的活性,H₂O₂含量降低.但喷施亚牛磺酸(HT)清除H₂S后,SO₂熏气拟南芥植株GSH含量、抗氧化酶SOD、CAT和GST活性降低,MDA含量大幅增加.结果表明,SO₂熏气诱导产生的H₂S可作为信号分子,提高机体抗氧化防御能力,增强植物对SO₂胁迫的抗性.     

Long-term impacts of graphene oxide and Ag nanoparticles on anammox process: Performance, microbial community and toxic mechanism

The increasing application of engineered nanoparticles (NPs) has posed an emerging challenge to constructed wetland wastewater treatment. The performance, microbial community and toxic mechanism of anammox-based unplanted subsurface-flow constructed wetlands (USFCWs) were investigated under the long-term exposure of different graphene oxides (GOs) and Ag NP concentrations. Results showed that the addition of GO could promote TN removal, manifesting as function anammox bacteria C. Anammoxoglobus having a relative high abundance, for GO did not cause significant damage to the cell integrity though there was an increase in ROS concentrations. TN removal would not be obviously affected under exposure of 1?mg/L Ag NPs, for the function gene related to cell biogenesis and repair was up-regulated; while the addition of 10?mg/L Ag NPs would have an inhibiting effect on TN removal in the USFCWs, for the disappearance of some species having anammox ability. Key enzymes of anammox process (NIR and HDH) decreased to some extent under GO and Ag NP exposure, and function gene of defense mechanisms had an increase trend in samples.     

Nitrogen-cycling microbial community functional potential and enzyme activities in cultured biofilms with response to inorganic nitrogen availability

Biofilms mediate crucial biochemical processes in aquatic ecosystems. It was hypothesized that eutrophication may promote the growth of biofilms, resulting in larger numbers of functional genes. However, the metabolic activity and the roles of biofilms in N cycling will be affected by ambient inorganic nitrogen availability, not by the abundance of functional genes. Biofilms were cultured either with replete inorganic nitrogen(N-rep) or without exogenous inorganic nitrogen supply(N-def) in a flow incubator, and the N-cycling gene abundances(nifH, N_2 fixation; amoA, ammonia oxidation, archaea and bacteria; nirS and nirK, denitrification) and enzyme activities(nitrogenase and nitrate reductase) were analyzed. The results showed that, comparing the N-def and N-rep biofilms, the former contained lower nifH gene abundance, but higher nitrogenase activity(NA), while the latter contained higher nifH gene abundance, but lower NA. Different patterns of NA diel variations corresponded to the dynamic microbial community composition and different stages of biofilm colonization. Ammonia oxidizing bacteria(AOB), detected only in N-def biofilms, were responsible for nitrification in biofilms. N-rep biofilms contained high nirS and nirK gene abundance and high denitrification enzyme activity, but N-def biofilms contained significantly lower denitrification gene abundance and activity. In general,the strong N_2 fixation in N-def biofilms and strong denitrification in N-rep biofilms assured the balance of aquatic ecosystems. The results suggested that evaluation of the functional processes of N cycling should not only focus on genetic potential, but also on the physiological activity of biofilms.     

磺胺类兽药对土壤酶活性的影响

采用室内培养的方法,研究磺胺类兽药（磺胺二甲基嘧啶、磺胺甲唑）污染对土壤蔗糖酶、硝酸还原酶、过氧化氢酶、磷酸酶、脲酶和多酚氧化酶活性的影响。结果表明,磺胺类兽药可显著抑制土壤蔗糖酶的活性,其抑制率可达50%以上。兽药对土壤硝酸还原酶活性的影响表现为先抑制后激活的趋势,最大抑制率和激活率可达98.6%、580%。兽药对土壤过氧化氢酶活性的影响主要以激活作用为主,对土壤磷酸酶活性的影响则呈现＂激活-抑制＂的循环趋势。兽药对土壤脲酶活性的影响表现为,培养前期低浓度时激活,高浓度时抑制;培养后期低、高浓度时均抑制。兽药对土壤多酚氧化酶活性的影响表现为,培养前期激活,培养后期抑制。     

Interactive effect of dissolved organic matter and phenanthrene on soil enzymatic activities

The investigation of dissolved organic matter (DOM) on urease, catalase and polyphenol oxidase activity in a phenanthrene (Phe)-contaminated soil was conducted under laboratory incubation conditions. Values of soil enzymatic activity depended mainly on incubation time. In the initial 16 days, urease activity increased, and was followed by a decrease. In the initial 8 days, catalase activity decreased and then increased. Variation of polyphenol oxidase activity was just the reverse of catalase activity. After 30 days of incubation, no pronounced difference among treatments with Phe, Phe and DOM, and control were detected in urease, catalase and polyphenol oxidase activity. Phe might inhibit urease and catalase, and stimulate polyphenol oxidase. DOM could improve inhibition of Phe in soil urease and catalase activity during the initial period of applying DOM. Nevertheless, DOM had no significant effect on polyphenol oxidase activity in the Phe contaminated soil. There was a negative correlation between catalase and polyphenol oxidase (r = -0.761~(***)), and catalase and urease (r = -0.554~(**)). Additionally, a positive correlation between polyphenol oxidase and urease was also detected (r = 0.701~(***)). It is implied that the formed DOM after application of organic wastes into soils may counteract the inhibition of polycyclic aromatic hydrocarbons in soil enzyme activities.     

Effect of nitrification inhibitor DMPP on nitrogen leaching, nitrifying organisms, and enzyme activities in a rice-oilseed rape cropping system

DMPP （3,4-dimethylpyrazole phosphate） has been used to reduce nitrogen （N） loss from leaching or denitrification and to improve N supply in agricultural land. However, its impact on soil nitrifying organisms and enzyme activities involved in N cycling is largely unknown. Therefore, an on-farm experiment, for two years, has been conducted, to elucidate the effects of DMPP on mineral N （NH4^＋- N and NO3^--N） leaching, nitrifying organisms, and denitrifying enzymes in a rice-oilseed rape cropping system. Three treatments including urea alone （UA）, urea ＋ 1% DMPP （DP）, and no fertilizer （CK）, have been carded out. The results showed that DP enhanced the mean NH4^＋-N concentrations by 19.1%-24.3%, but reduced the mean NO3^--N concentrations by 44.9%-56.6% in the leachate, under a two-year rice-rape rotation, compared to the UA treatment. The population of ammonia oxidizing bacteria, the activity of nitrate reductase, and nitrite reductase in the DP treatment decreased about 24.5%-30.9%, 14.9%-43.5%, and 14.7%-31.6%, respectively, as compared to the UA treatment. However, nitrite oxidizing bacteria and hydroxylamine reductase remained almost unaffected by DMPP. It is proposed that DMPP has the potential to either reduce NO3^--N leaching by inhibiting ammonia oxidization or N losses from denitrification, which is in favor of the N conversations in the rice-oilseed rape cropping system.     

苜蓿根瘤菌对多氯联苯降解转化特性研究

采用溶液摇瓶实验研究了苜蓿根瘤菌(Rhizobium meliloti)对三氯代联苯(2,4,4′-trichlorobiphenyl)单体以及18种多氯联苯(polychlorinated biphenyls,PCBs)混合物的降解转化能力.结果表明,接入苜蓿根瘤菌转化7d后,随着溶液中底物2,4,4′-TCB浓度的增加,该菌株对其的降解能力也逐渐提高,在1.0、5.0、10.0、25.0、50.0 mg.L-1浓度条件下该菌对2,4,4′-TCB的降解率分别为34.0%、48.3%、69.7%、96.0%、98.5%,并且通过气相质谱分析,发现溶液中出现了一些新的代谢产物.同时,苜蓿根瘤菌对不同浓度下18种PCBs同系物混合物的降解能力,随着底物浓度的升高呈现出从低到高,然后降低,并趋于平衡的趋势,其最高降解率可达54.7%,并存在高氯代PCBs向低氯代PCBs的转化过程.     

Effects of insoluble Zn, Cd, and EDTA on the growth, activities of antioxidant enzymes and uptake of Zn and Cd in Vetiveria zizanioides

A root-bag experiment was conducted to study the effects of insoluble Zn, Cd and ethylenediaminetetraacetic acid (EDTA) on the plant growth, activities of antioxidant enzymes, proline, glutathione (GSH), water-soluble proteins and malondialdehyde (MDA) of Vetiveria zizanioides, and its uptake capacity of Zn and Cd.The results showed that plant growth of V.zizanioides was inhibited by Zn and Cd.The shoot dry weight (SDW) and root dry weight (RDW) decrease by 0.3%, 8.0%, 9.4% and 10.4%, 15.1%, 24.2% compared to the control without EDTA addition, respectively.After adding EDTA, shoot and root dry weight decreased over 10% and 15% compared to results in the absence of EDTA, respectively.The toxicity from insoluble Zn and Cd in soil on SDW and RDW of V.zizanioides was in order: Zn+Cd > Cd > Zn.The activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT), and contents of MDA and proline significantly increased, while the contents of GSH and water-soluble proteins markedly decreased with increasing Zn and Cd toxicity.With EDTA, shoot and root Zn concentrations increased in the Zn treatment by 7.3% and 37.4% compared to the plants grown in absence of EDTA.Shoot and root Cd concentrations in the combined Zn and Cd treatment with EDTA increased by 18.6% and 391.9% compared to the treatment without EDTA.However, Zn and Cd concentrations in shoot and roots decreased in the Cd treatment compared to the plants grown in absence of EDTA, with exception of root Cd concentration in the presence of EDTA).