不同结构芳香酸对厌氧颗粒污泥特性与微生物群落的影响

以苯甲酸（BA）、邻苯二甲酸（PA）、连苯三甲酸（HA）、1-萘甲酸（1NA）为研究对象,探究了不同结构芳香酸对厌氧颗粒污泥理化特性与微生物群落的影响.结果表明,在40 d的接触实验中,1NA实验组对溶解性化学需氧量（SCOD）的去除率为86.09%,与空白对照组相比降低了7%.4个实验组污泥疏松胞外聚合物（LB-EPS）和紧密胞外聚合物（TB-EPS）中多糖含量分别比对照组高0.30~1.28、0.19~1.03 mg·g^-1,蛋白含量分别提高了0.025~0.326、0.007~0.171 mg·g^-1.在LB-EPS三维荧光（EEM）光谱中,HA和1NA实验组中出现了类腐殖酸物质荧光峰,且辅酶F₄₂₀峰强度有所降低.对于酶活性而言,HA、1NA实验组乙酸激酶相对活性比对照组减少了65.26%、6.93%.通过高通量测序发现,对照组与实验组中的优势菌群均为Proteobacteria、Chloroflexi和Firmicutes.HA与1NA的加入降低了Actinobacteria的相对丰度,提高了Bacteroidetes和Synergistetes的相对丰度.对于古细菌而言,Methanothrix在对照组与实验组中为优势种属,其相对丰度达到49.95%~80.40%;但实验组Methanothrix的相对丰度减少了10.69%~30.45%,且1NA实验组尤为明显;而1NA的加入提高了Methanospirillum的相对丰度,达到34.08%.同时,细菌和古细菌代谢通路预测表明,其主要功能组为代谢、遗传信息处理、环境信息处理和细胞过程,芳香酸使得厌氧颗粒污泥中氨基酸的代谢功能有所增强.     

植物修复土壤重金属污染中外源物质的影响机制和应用研究进展

重金属进入土壤后难以被降解,并通过食物链在生物体内富集,长此以往会导致中毒、癌症、畸形、突变,严重影响了人类生产活动及地球生态系统的稳定。植物修复技术是一种经济有效的重金属污染修复技术,其依靠超富集植物强大的自身抗性机制,从土壤中提取或稳定重金属,达到污染治理的目的。然而修复土壤重金属污染的超富集植物通常生长缓慢、生物量低,其抗性机制也会受到植物本身对重金属胁迫的阈值限制,当胁迫超过这个阈值,植物修复的效率就会大大降低甚至失去修复功能。文章在解析植物重金属相互作用机制的基础上,综述了添加外源物质对重金属毒害植物的缓解效应以及其在强化植物修复土壤重金属污染中的应用研究进展;介绍了应用外源物质调控植物吸收转运重金属的3种途径,分别为提高土壤重金属生物利用度、促进植物生长以及增强植物耐性。提出了应用外源物质作为强化植物修复措施的潜力及今后的研究方向,其未来的研究应着重于以下方面:明确外源物质的应用浓度、时期、方式与植物吸收转运重金属之间的关系;从植物内源激素及信号分子间的互作、抗逆基因表达、内生及根际微生物等不同层面上揭示外源物质对植物积累重金属的调控机理;开展外源物质与其他植物修复强化技术的联合应用研究。这些研究可为土壤重金属污染的植物修复技术及其强化措施研究提供科学依据,同时也对植物修复工程技术的发展实践具有一定的指导意义。     

饮水型砷暴露对小鼠多系统脏器的毒性作用

为揭示饮水型砷暴露对机体的毒性,系统研究了砷摄入对实验动物基础生理和多系统脏器的毒性损伤作用.选雄性ICR小鼠为受试动物,以自由饮用含砷10 mg·L^-1的水溶液进行染毒,连续染毒60 d后检测发现,饮水砷暴露对小鼠一般体征和体重无显著影响,肝脏脏器系数显著降低,心脏、肺脏、肾脏和睾丸脏器系数降低,但无统计学意义.砷染毒组血清谷丙转氨酶（ALT）和谷草转氨酶（AST）活性显著升高,总胆固醇（TC）和甘油三酯（TG）含量显著升高,高密度脂蛋白胆固醇（HDL-C）含量显著降低,低密度脂蛋白胆固醇（LDL-C）含量显著升高;肝脏、小肠、心脏、肺脏、肾脏和睾丸组织中还原型谷胱甘肽（GSH）含量和超氧化物歧化酶（T-SOD）活性显著降低,过氧化氢（H₂O₂）和丙二醛（MDA）含量显著升高,并出现程度不同的组织形态结构损伤.研究结果表明,饮水砷暴露可诱发实验小鼠肝脏功能异常、生理代谢紊乱,导致消化系统、循环系统、呼吸系统、泌尿系统与生殖系统等多系统脏器组织的氧化损伤和结构病变,砷暴露对机体的毒性作用存在组织器官差异性,对肝脏的损伤较严重.     

四环素对微囊藻生长及光合作用的毒性效应机制

光合作用是蓝藻生长繁殖的生理基础,研究四环素胁迫下蓝藻的生长和光合作用的变化和响应,有助于揭示其作用机制。为探究四环素对微囊藻的毒性效应,对培养在0、0.1、0.2、0.5、1.0、2.0和5.0 mg·L~(-1)共7个浓度下的微囊藻的细胞数、叶绿素a含量、微囊藻光合系统Ⅱ(PSⅡ)快速光响应曲线(RLCs)及快速叶绿素荧光诱导动力学曲线(OJIP)进行了测定。结果表明,四环素处理7 d后,微囊藻的半致死浓度(LC_(50))为(0.571±0.036) mg·L~(-1)。随着四环素浓度的增加,微囊藻生长受到抑制,叶绿素含量减少,PSⅡ中单位反应中心失活。当四环素浓度高于0.5 mg·L~(-1)时,微囊藻Q_A~-到Q_B的电子传递被抑制,造成Q_A~-大量积累,影响PSⅡ的电子受体侧。然而,在低浓度四环素处理中,以吸收光能为基础的性能指数(PI_(ABS))、用于电子传递的量子产额(φ_(Eo))和最大光化学效率(φ_(Po))显著升高,用于热耗散的量子比率(φ_(Do))显著降低。这些结果表明,低浓度四环素处理时,微囊藻能通过自身调节改变PSⅡ中能量配置,改变电子传递速率,提高光合效率,从而应对低浓度四环素胁迫,而当四环素浓度较高时,微囊藻的光合作用显著降低,生长受到抑制。     

Rapid control of black and odorous substances from heavily-polluted sediment by oxidation: Efficiency and effects

Oxidants were proposed to rapidly control black and odorous substances in sediments. NaClO and KMnO₄ had excellent efficiency to remove black and odorous substances. NaClO dramatically accelerated the release of organics, NH₄⁺-N, P, and heavy-metals. Moderate oxidation had a limited effect on microbial communities. NaClO of 0.2 mmol/g was viewed to be the optimum option. The control of black and odorous substances in sediments is of crucial importance to improve the urban ecological landscape and to restore water environments accordingly. In this study, chemical oxidation by the oxidants NaClO, H₂O₂, and KMnO₄ was proposed to achieve rapid control of black and odorous substances in heavily-polluted sediments. Results indicate that NaClO and KMnO₄ are effective at removing Fe(II) and acid volatile sulfides. The removal efficiencies of Fe(II) and AVS were determined to be 45.2%, 94.1%, and 93.7%, 89.5% after 24-h exposure to NaClO and KMnO₄ at 0.2 mmol/g, respectively. Additionally, rapid oxidation might accelerate the release of pollutants from sediment. The release of organic matters and phosphorus with the maximum ratios of 22.1% and 51.2% was observed upon NaClO oxidation at 0.4 mmol/g. Moreover, the introduction of oxidants contributed to changes in the microbial community composition in sediment. After oxidation by NaClO and KMnO₄ at 0.4 mmol/g, the Shannon index decreased from 6.72 to 5.19 and 4.95, whereas the OTU numbers decreased from 2904 to 1677 and 1553, respectively. Comparatively, H₂O₂ showed a lower effect on the removal of black and odorous substances, pollutant release, and changes in sediment microorganisms. This study illustrates the effects of oxidant addition on the characteristics of heavily polluted sediments and shows that chemical oxidants may be an option to achieve rapid control of black and odorous substances prior to remediation of water environments.     

Specific association of 36Cl with low molecular weight humic substances in soils

Soils initially contaminated with ³⁶Cl in the chloride form were subjected to solid–liquid extractions using a variety of reagents including deionised water and 1 M sodium hydroxide (NaOH). 1 M NaOH was found to result in the greatest recovery of ³⁶Cl from the soils, a result which provided initial evidence that radioactive chlorine became attached to humic substances present naturally within the soils. Deionised water and 1 M NaOH extracts were subjected to analysis involving separation by gel filtration chromatography (GFC). It was found that ³⁶Cl in 1 M NaOH extracts associated preferentially with low molecular weight (LMW) fractions of humic substances whereas, in deionised water extracts, ³⁶Cl appeared to be present exclusively in the chloride form. Previous literature evidence, mainly from highly organic forest soils, suggests that conversion of stable chlorine from chloride to organic forms can occur as a result of biological action. The present paper also presents good evidence for the specific attachment of stable chlorine (³⁷Cl) to a LMW humic fraction, again demonstrated using GFC separation. Current risk assessments of the deep geological disposal of solid radioactive wastes containing ³⁶Cl typically assume a very low degree of sorption based on the notion that the predominant environmental species of radiochlorine is chloride. This paper concludes with a brief discussion on the implications of organochlorine formation in the biosphere for assessment of the radiological impact of deep geological disposal of solid radioactive wastes.     

Concentrations of natural radionuclides in imported mineral substances

Levels of natural radionuclides, such as thorium-232 (232Th), radium-226 (226Ra) and potassium-40 (40K), were determined in about 2,000 samples of imported mineral substances using gamma spectrometry. The maximum concentration levels of 232Th, 226Ra and 40K were 1,260 +/- 54, 13,400 +/- 94 and 1,256 +/- 260 Bq kg(-1), respectively, in zirconium compounds. Due to relatively high concentrations of the above-mentioned radionuclides in some imported mineral substances, the National Radiation Protection Department (NRPD), as the competent authority, has established national limits (900 Bq kg(-1) for 232Th, 1800 Bq kg(-1) for 226Ra and 11,000 Bq kg(-1) for 40K), based on the external exposures, for general importation permits of these materials.     

CONFLICTS IN ATTAINING NATIONAL GOALS FOR BOTH WATER QUALITY AND ENERGY PRODUCTION1

ABSTRACT: The “policy environment” is defined herein as the institutional setting in which planning is conducted and policy decisions are made with regard to meeting two of the Nation's high priority goals: water quality protection and energy independence. The simultaneous pursuit of these goals has resulted in numerous conflicts among the energy industry, environmentalists, and government. An analysis of selected energy development-water quality conflicts shows that these conflicts can be described in terms of one or more of the following policy environment characteristics: resource scarcity, sense of urgency, lack of experience, administrative complexity, uncertainty about future policies and regulations, technological complexity, and uncertainty about impacts. These characterics provide a useful framework for formulating potential strategies for the resolution of energy development-water quality conflicts.     

澜沧铅矿井下有毒有害气体测评与控制

通过对井下作业点空气中CO、SO2、H2S、NO2和CO2等有毒有害气体的测定,将测定结果与进行比较,发现澜沧铅矿井下部分作业地点空气中CO、NO2和CO2浓度超过规定标准.根据分析、评价的结果,结合该矿实际情况,提出了控制井下有毒有害气体、改善井下空气质量的通风排毒等技术措施,以及防止井下有毒有害气体中毒的管理和个体防护措施.通过实施这些措施,使澜沧铅矿井下有毒有害气体得到了有效控制,其浓度达到了规定的要求.