Denitrification and phosphorus uptake by DPAOs using nitrite as an electron acceptor by step-feed strategies

Denitrifying phosphorus accumulating organisms (DPAOs) using nitrite as an electron acceptor can reduce more energy. However, nitrite has been reported to have an inhibition on denitrifying phosphorus removal. In this study, the step-feed strategy was proposed to achieve low nitrite concentration, which can avoid or relieve nitrite inhibition. The results showed that denitrification rate, phosphorus uptake rate and the ratio of the phosphorus uptaken to nitrite denitrified (anoxic P/N ratio) increased when the nitrite concentration was 15 mg·L^-1 after step-feeding nitrite. The maximum denitrification rate and phosphorus uptake rate was 12.73 mg NO2-–N·g MLSS-1?h-1 and 18.75 mg PO43-–P·g MLSS-1?h-1, respectively. These rates were higher than that using nitrate (15 mg·L^-1) as an electron acceptor. The maximum anoxic P/N ratio was 1.55 mg PO43--P?mg NO2--N-1. When the nitrite concentration increased from 15 to 20 mg NO2--N?L-1 after addition of nitrite, the anoxic phosphorus uptake was inhibited by 64.85%, and the denitrification by DPAOs was inhibited by 61.25%. Denitrification rate by DPAOs decreased gradually when nitrite (about 20 mg·L^-1) was added in the step-feed SBR. These results indicated that the step-feed strategy can be used to achieve denitrifying phosphorus removal using nitrite as an electron acceptor, and nitrite concentration should be maintained at low level (<15 mg·L^-1 in this study).     

Heavy Metal Concentrations in Water, Sediment, Fish and Some Benthic Organisms from Tigris River, Turkey

In this study concentrations of heavy metals, such as Cd, Co, Cu, Fe, Mn, Ni, Pb and Zn were determined in water, sediment, muscle, liver and gill of fish (Silurus triostegus, Mastacembelus simack, Mystus halepensis, Orthrias euphraticus) the muscle and liver of crab (Potamon fluviatilis), the internal organs of fresh water snail (Physa acuta), and mussel (Unio elongatulus), and in whole biomass of green algae (Spirogyra sp.) examples collected seasonally from three selected sites (I, II, and III) of Tigris River and from a reference site on Resan Creek. In general, the average Cd, Cu, Mn, Ni, Zn, and Fe values in Sites I, II, and III were found to be high in spring and summer. The concentrations of heavy metals in the Tigris River are compared with previous studies in the same sites. The results showed that Cu levels have gradually decreased during recent years. In Tigris River, among the living organisms, i.e., those which are living in benthic region and showing biomonitor characteristic, crab, snail, green algae, mussel and fish are seen to be formed in sequence. Cu, Fe, Mn and Zn values obtained from the muscle of fish and from the mass of internal organs of mussel and snail were found to be under the acceptable values suggested.     

转基因生物风险评估和管理的国家能力建设的探讨

转基因生物风险评估和管理的国家能力建设的内容,包括机构、机制、专家知识、环境监测以及信息收集和交流等。风险评估和管理的能力建设必须根据本国生物技术研究和应用水平、资金、信息以及人员数量和素质来确定其优先领域、行动和项目。目前,中国转基因生物风险评估和管理的国家能力建设工作亟待开展的有:成立国家生物安全委员会;建立转基因生物风险评估和管理的制度以及公众参与的机制;提高技术人员和管理者在生态学、遗传学和风险评估方法学等方面的专家技能;制定转基因生物的环境监测规划;建立有关转基因生物的环境监测网络和基地;新建一批生物安全数据库和信息库     

Trace elements and stable isotopes (delta13C and delta15N) in shallow and deep-water organisms from the East China Sea

Trace elements (22) and stable isotope ratios (δ¹⁵N and δ¹³C) were analyzed in marine organisms from shallow (SW) and deep-water (DW) of the East China Sea to understand biomagnification and prey source of trace elements. In the benthic marine organisms from DW, δ¹⁵N values were negatively correlated with Ba, Cu, Ag, Mo, Sr, As, and Co concentrations. This may be due to the specific accumulation in lower trophic animals and/or the biodilution through the food web in DW. Relationships between δ¹⁵N and concentrations of Co, Cr, Bi, and Tl in fish and Ag, Bi, V, Hg, and Tl in crustaceans showed positive correlations, suggesting that trophic position was affecting the concentrations of those elements in phyla, with higher trophic animals retaining higher concentrations than the lower trophic animals. Positive correlations between δ¹³C and Rb were observed in marine organisms. Therefore, Rb may be a possible substitute of δ¹³C as tracer of prey source in the East China Sea although further investigation is required.     

微塑料污染现状及对海洋生物影响的研究进展

综述了微塑料的主要来源、空间分布及我国水体和沉积物中微塑料的污染现状,以及微塑料与有机污染物的复合污染影响,并从海洋生物摄食微塑料、微塑料与污染物的复合生态风险、微塑料对水生生物的承载作用、微塑料在食物链中的传递及对人类健康的风险4个方面探讨了微塑料对海洋生物的影响。指出,采样方法和分析技术的标准化、微塑料-污染物复合体的毒性效应机制、微塑料对人类健康风险的评估是未来的重点研究方向。     

多溴联苯醚、六溴环十二烷和四溴双酚A在环境中污染现状的研究进展

作为最主要的三大传统溴系阻燃剂(BFRs),多溴联苯醚(PBDEs)、六溴环十二烷(HBCD)、四溴双酚A(TBBPA)具有半挥发性、环境持久性和远距离传输性,目前在全球各种环境介质、生物体内广泛存在.毒理学研究表明,PBDEs、HBCD、TBBPA均具有明显的生物毒性和致癌性,对生态环境和人体健康存在潜在危害.本文简...     

3株反硝化聚磷菌的分离与鉴定

通过烛缸法培养富集、分离,结合除磷试验、硝酸盐还原产气试验及异染颗粒和PHB颗粒染色辅助检验相结合的方法筛选,得到3株具有较高脱氮除磷效率的反硝化聚磷菌DNPA8, DNPA9和DNPA10。在富氮富磷培养基中培养48 h,各菌株的脱氮率均大于75%,除磷率均大于78%。采用多相分类的方法确定了3株反硝化聚磷菌的分类地位,DNPA8为嗜麦芽寡养单胞菌,DNPA9为水生丛毛单胞菌属首次发现的反硝化聚磷菌;DNPA10为约翰逊氏不动杆菌。该研究结果为富营养化水体的治理提供了有效的菌种资源。     

基于生物导向的水生态健康监测及评估概述

环境监测是水生态健康监测与评估的重要环节,基于物理、化学监测的传统水质监测通常仅能提供独立的数据信息,不能全面、直观地反映水环境状况。基于生物等生命体导向的水生态监测通过生物对环境的响应,能够直接反应复杂水体状况,在水环境健康监测与评估中占据重要地位。基于病原微生物、指示生物介绍了生物监测中的常规生物指标,总结了包括藻类、无脊椎动物和鱼类在内的常见指示生物在不同类型污染水体中的环境指示作用。从生物毒性效应出发介绍了常用的毒性效应测试方法、分析了污染物在不同生物学水平的响应,从而指明生物毒性效应在水环境健康评估中的发展优势。再从生态完整性角度阐述了生态完整性评价的一般方法和新兴分子生物学技术在水生态健康评估中的应用。重点指出环境毒理学和分子生物学在水环境监测的优势,以期为更加科学精确地进行水生态健康监测预警提供支撑。     

影响聚磷菌与聚糖菌竞争的关键因素研究进展

增强生物除磷（EBPR）是一种高效、经济的除磷工艺,然而在某些条件下聚糖菌的过量繁殖导致除磷效果恶化。文章阐述了影响聚磷菌和聚糖菌生长的关键因素,从而可以选择性的培养聚磷菌并使其处于竞争优势,这对于提高EBPR的除磷效果、增强工艺的稳定性具有重要的意义。     

除磷颗粒污泥系统中不同粒径颗粒的理化特性分析

采用SBR反应器培养具有同步脱氮除磷特性的颗粒污泥.使用目数分别为100、60、40的标准检验筛将污泥颗粒按粒径大小筛分为3个等级,即150～280μm、280～450μm、>450μm进行研究,分析了不同粒径颗粒的理化特性.结果表明,颗粒化初期(第7～18 d),密实的颗粒提供良好的厌氧环境有利于加速GAOs和PAOs在颗粒内部的对底物的竞争;密实颗粒有利于PAOs的富集和加速生长,使得不同粒径颗粒含磷量存在差异:280～450μm的颗粒(以SS计)有机磷含量最高,达113.25 mg.g-1,无机磷含量最低,达15.55 mg.g-1.颗粒化后期,反应器运行第34 d,3种粒径颗粒中有机磷含量趋于一致,约为50 mg.g-1,第52 d,无机磷含量也趋于一致,约70 mg.g-1.成熟颗粒中总磷含量占11%,其中无机磷占4.24%.同时,反应器中污泥的磷含量比排水中污泥高,分析表明污泥活性和污泥龄对磷的去除效果有影响.另外,就反硝化而言,大、小粒径颗粒都有较好的厌氧反硝化能力,颗粒内部与外部溶液环境中的NO3--N浓度梯度是影响反硝化速率的重要因素.