Competition of bloom-forming marine phytoplankton at low nutrient concentrations

Competition of three bloom-forming marine phytoplankton (diatom Skeletonema costatum, and dinoflagellates Prorocentrum minimum and Alexandrium tamarense) was studied through a series of multispecies cultures with di erent nitrate (NaNO3) and phosphate (NaH2PO4) levels and excess silicate to interpret red tide algae succession. S. costatum outgrew the other two dinoflagellates in nitrate and phosphate replete cultures with 10 mol/L Na2SiO3. Under nitrate limited (8.82 mol/L NaNO3) conditions, the growth of S. costatum was also dominant when phosphate concentrations were from 3.6 to 108 mol/L. Cell density of the two dinoflagellates only increased slightly, to less than 400 and 600 cells/mL, respectively. Cell density of S. costatum decreased with time before day 12, and then increased to 4000 cells/mL (1.5 mg/L dry biomass) at NaNO3 concentrations between 88.2 and 882 mol/L with limited phosphate (0.36 mol/L NaH2PO4) levels. In addition, P. minimum grew well with a maximal cell density of 1690–2100 cells/mL (0.5–0.6 mg/L dry biomass). Although S. costatum initially grew fast, its cell density decreased quickly with time later in the growth phase and the two dinoflagellates were dominant under the nitrate-limited and high nitrate conditions with limited phosphate. These results indicated that the diatom was a poor competitor compared to the two dinoflagellates under limited phosphate; however, it grew well under limited nitrate when growth of the dinoflagellates was near detection limits.     

Removal of heavy metal ions from aqueous solution using red loess as an adsorbent

The adsorption behaviors of heavy metals onto novel low-cost adsorbent, red loess, were investigated. Red loess was characterized by X-ray diffraction, scanning electron microscopy and Fourier transform infrared spectra. The results indicated that red loess mainly consisted of silicate, ferric and aluminum oxides. Solution pH, adsorbent dosage, initial metal concentration, contact time and temperature significantly influenced the efficiency of heavy metals removal. The adsorption reached equilibrium at 4 hr, and the experimental equilibrium data were fitted to Langmuir monolayer adsorption model. The adsorption of Cu(II) and Zn(II) onto red loess was endothermic, while the adsorption of Pb(II) was exothermic. The maximum adsorption capacities of red loess for Pb(II), Cu(II) and Zn(II) were estimated to be 113.6, 34.2 and 17.5 mg/g, respectively at 25°C and pH 6. The maximum removal efficiencies were 100% for Pb(II) at pH 7, 100% for Cu(II) at pH 8, and 80% for Zn(II) at pH 8. The used adsorbents were readily regenerated using dilute HC1 solution, indicating that red loess has a high reusability. All the above results demonstrated that red loess could be used as a possible alternative low-cost adsorbent for the removal of heavy metals from aqueous solution.     

不同进水条件对SBR工艺脱氮除磷效能的影响

采用人工配水,研究进水在不同pH值,碳源类型,碳氮比条件下,厌氧/好氧/缺氧(A/O/A)sBR工艺对生物法脱氮除磷效能的影响.结果表明:不同的进水条件对反应器的影响较大,当pH值为7.5,乙酸钠为碳源,碳氮比为1.4时,反应器运行效果最佳,系统对PO43--P,NH4+-N的去除率分别达到97.28%,99.5%.N...     

羟基磷灰石-四氧化三铁-沸石复合材料制备及去除水中刚果红研究

采用可溶性磷酸盐、钙离子、二价铁离子、三价铁离子和天然沸石等材料制备了羟基磷灰石-四氧化三铁-沸石(HAPFe3O4-沸石)复合材料,对该复合材料进行了表征,并考察了该复合材料对水中刚果红的吸附作用.结果表明,HAP-Fe3O4-沸石复合材料对水中的刚果红具备良好的吸附能力.当pH由3增加到4或由7增加到11时,HAP-Fe3O4-沸石复合材料对水中刚果红的去除能力下降;当pH由4增加到7时,对刚果红的吸附能力基本保持不变.HAP-Fe3O4-沸石复合材料对水中刚果红的去除率随吸附剂投加量的增加而增加,而对水中刚果红的单位吸附量则随吸附剂投加量的增加而降低.HAP-Fe3O4-沸石复合材料对水中刚果红的吸附动力学过程可以较好地采用准二级动力学模型加以描述,对刚果红的吸附平衡数据可以采用Langmuir和Freundlich等温吸附模型加以描述.根据Langmuir模型确定的最大吸附容量为117 mg·g-1.(pH 7和303 K).HAP-Fe3O4-沸石复合材料对水中刚果红的吸附是自发吸热并伴随熵增加的过程.当pH为7时,HAP-Fe3O4-沸石复合材料吸附水中刚果红的主要机制包括表面配位作用、氢键作用以及路易斯酸碱反应.采用热再生的方法可以使吸附刚果红后的HAP-Fe3O4-沸石复合材料得到再生,热再生后的复合材料可以循环使用并且对水中刚果红的吸附性能良好.X射线衍射分析结果表明HAP-Fe3O4-沸石复合材料含Fe3O4,磁滞回线结果表明HAP-Fe3O4-沸石复合材料具备较高的磁饱和强度,复合材料吸附刚果红后可以很容易地通过外加磁场的作用快速地与水溶液分离.结果表明,HAP-Fe3O4-沸石复合材料适合作为一种吸附剂去除废水中的刚果红.     

高效聚磷菌Alcaligenes sp. ED-12菌株的分离鉴定及其除磷特性

利用经典的微生物筛选方法,从福州市闽侯县上街镇高岐村某排污口淤泥中分离出1株高效聚磷菌,并结合16S rRNA基因序列分析进行了菌株鉴定.结果表明,该菌株为产碱杆菌,将其命名为Alcaligenes sp.ZGED-12.理化因素实验显示,在以乙酸钠为碳源、NH4Cl为氮源,当C/N为3∶1,pH为8.0,温度和摇床转速分别为35℃和100 r·min-1时,该菌株的生长状态最好,对磷的去除能力也最强,最高除磷率可达80%.此外,该菌株能够耐受较高浓度的磷,当磷浓度超过45 mg·L-1时会产生抑制效应.同时,以聚乙烯醇(PVA)和海藻酸盐(SA)制备了聚磷微生物固定化小球,并考察了菌球对氮磷废水的净化效果.结果表明,氮磷的去除包括固定化材料的吸附作用及微生物的生长利用和/或贮存,显示出了良好的应用前景.     

黄孢原毛平革菌处理染料废水过程中细胞结构损伤效应研究

利用透射电子显微镜观察分析白腐真菌(黄孢原毛平革菌)在处理染料废水活性艳红X-3B过程中,染料和盐度对黄孢原毛平革菌的细胞结构产生的毒性作用.结果表明:活性艳红X-3B染料对黄孢原毛平革菌产生生物毒性作用,且随着染料浓度的增加,细胞受损伤程度不断加深.加入100 mg/L的染料活性艳红X-3B后,黄孢原毛平革菌菌丝细胞形态发生变化,出现质壁分离现象;染料浓度进一步加大,菌丝细胞超微结构受到损伤逐渐严重.染料废水中的盐度对黄孢原毛平革菌细胞也会造成损伤,且损伤程度随盐度增大而增大.NaCl浓度为3 g/L时,菌丝细胞发生质壁分离;而当NaCl加入量高于8 g/L时,细胞膜受损,线粒体、细胞核呈现空泡化,表现为受到不可逆的损伤.染料和盐双因子对黄孢原毛平革菌细胞的损伤效应表现为其损伤程度与单因子作用一致,且染料的影响作用占主导.     

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.     

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     

赤泥制备含钛聚硅酸铝铁及亚甲基蓝溶液的混凝脱色

以拜耳法赤泥为原料、Na Cl为助溶剂,采用酸浸法溶出赤泥中的铁、铝元素,再与硅酸钠、硫酸氧钛反应制备出高效混凝剂含钛聚硅酸铝铁(T-PSAF),并将其用于模拟亚甲基蓝印染废水的脱色。实验结果表明:在硫酸浓度为8 mol/L、液固比(硫酸体积与干赤泥质量之比)为14 m L/g、酸浸温度为80℃、酸浸时间为80 min、Na Cl加入量为0.10 g/g(以干赤泥计)的优化酸浸条件下,铁、铝的浸出率分别为88.25%和73.21%;在n(Fe+Al)∶n(Ti)∶n(Si)=0.3∶0.3∶1、熟化p H为4~5、熟化时间为2 h、混凝剂加入量为25 m L/L的优化混凝条件下,初始亚甲基蓝质量浓度为10 mg/L的废水的脱色率可达87.1%,而当初始亚甲基蓝质量浓度增至150~200 mg/L时废水脱色率可达99%以上。