零价铁表面积对泥浆反应体系中硝基苯降解行为的影响

硝基苯能够被零价铁还原成为苯胺. 利用气相色谱分析方法,研究了泥浆体系中零价铁表面积对硝基苯污染底质降解行为的影响. 结果表明,在沉积物中初始w(硝基苯)为8.87 μg/g,按照3.27 g/L最佳比例投加还原铁粉,经2 h反应约有97%的硝基苯被降解;其还原机理为表面接触反应,铁粉总表面积是影响硝基苯降解的主要参数;沉积物中硝基苯降解速率常数(K)和残留量(y)与单位体积泥浆中零价铁总表面积(ρ_a)之间表现为线性和负指数相关性,其关系式分别为:K0.006　5+5.165　87×10－4ρ_a和y8.57exp(-ρ_a/7.66)+0.25;零价铁还原硝基苯的降解过程,其降解动力学符合准一级方程,并且通过SEM扫描电镜发现零价铁在反应过程中表面被严重腐蚀,颗粒组成发生明显改变.      

扰动状态下pH值对内源磷生物有效性的影响

为了阐明底泥扰动状态下pH值对内源磷生物有效性的影响机制,以富营养化河流的底泥和上覆水为材料,通过实验室试验模拟了不同初始pH值条件下,底泥扰动对上覆水中溶解性磷酸盐(SRP)和底泥中生物有效磷(BAP)含量的影响。结果表明,底泥扰动显著降低了上覆水中SRP含量,其去除率随着初始pH值升高而降低。去除率从大到小依次排序为,pH5>pH7>pH9.5.SRP的去除与较低初始pH值条件下生成的非晶型铁氧化物有关。基于不同形态磷的迁移活性,采用NH4Cl-P+%BD-P(非闭蓄态Fe-P)+NaOH-nrP估算BAP是合理的.由此计算可知,BAP占总磷(Tot-P)的百分比随着初始pH值升高而降低。不同初始pH值条件下,BAP占Tot-P的百分比为33.36%(3种初始pH值条件下的平均值),该值远小于通过传统方法计算的BAP含量占Tot-P的百分比(平均为85.04%)。但由于2种方法中计算的BAP占Tot-P的百分比的变化趋势恰好相反,其与藻类可利用磷的变化密切相关。     

阳-非离子混合表面活性剂对沉积物吸附硝基苯的影响

研究了非离子表面活性剂Triton X-100、阳离子表面活性剂氯化十六烷基吡啶(CPC)及其混合物在沉积物上的吸附行为,探讨了它们对沉积物吸附硝基苯的影响.结果表明,CPC和Triton X-100在沉积物上的吸附等温线均为非线性,吸附量随着平衡浓度的增加急剧增加,并迅速达到最大吸附量.低浓度CPC能明显增加Triton X-100在沉积物上的吸附,而高浓度的CPC则显著降低Triton X-100在沉积物上的吸附.Triton X-100略微降低CPC在沉积物上的吸附.在表面活性剂浓度较低的实际环境中,无论是阳离子或非离子表面活性剂,将主要被土壤或沉积物吸附并固定.硝基苯在沉积物上的吸附等温线为线性.CPC和Triton X-100促进沉积物对硝基苯的吸附,CPC-Triton X-100混合表面活性剂溶液能进一步增强沉积物对硝基苯的吸附.因此,阳离子和非离子混合表面活性剂可增强土壤或沉积物对有机污染物的吸附固定能力,也可以用来制备有机膨润土以提高其吸附处理废水的性能.     

蓝藻水华及其降解对沉积物-水微界面的影响

模拟研究了不同条件下,蓝藻水华及其降解过程对沉积物-水微界面的影响.采用丙酮法测定水体中叶绿素质量浓度,溶解氧微电极测定界面溶解氧质量浓度,毫米级分层测定沉积物中营养盐与金属元素的垂直分布.结果表明,蓝藻水华及其降解过程改变了界面附近溶解氧环境和表层约3 mm深沉积物中营养盐与金属元素的垂直分布.扰动在蓝藻水华降解过程和C、P营养盐与Fe、Ca、Mg、Al和K等金属元素的早期成岩过程中起着重要作用.遮光加速了蓝藻降解,并且削弱了扰动的影响.无处理对照组沉积物表面出现了一层底栖藻,底栖藻的光合作用产生了氧气,造成表层1 mm沉积物中大部分营养盐与金属元素质量浓度和处理组间的显著性差异.相关分析结果表明,沉积物中P的垂直分布与Mn显著相关,其次是C.高分辨率研究结果可见,蓝藻水华及其降解过程在毫米级厚度内即对沉积物-水界面产生了影响.     

反复扰动下加藻对不同形态磷相互转化的影响

以太湖梅梁湾沉积物和上覆水为材料,研究了反复扰动下加藻与否对沉积物中不同形态磷数量分布的影响.试验结束时,对照试验、单纯反复扰动、加藻反复扰动其上覆水中溶解性总磷(DTP)含量依次增加了75%、62.5%和18.8%,单纯反复扰动和加藻反复扰动试验上覆水中溶解性无机磷(DIP)浓度分别增加了300%和100%.加藻反复扰动和单纯反复扰动下,沉积物中钙磷(Ca-P)的净减少量分别为31mg/kg DW和 9mg/kg DW.表明, DTP和DIP的释放主要取决于沉积物中铁铝结合态磷(Fe/Al-P)和Ca-P的减少量.沉积物中Fe/Al-P和 Ca-P的含量有所降低,主要归因于反复扰动和藻类的同化吸收作用.然而,加藻反复扰动和单纯反复扰动下,藻类可利用磷(AAP)却有所增加.这表明藻类浓度较低时,其对磷的吸附同化量明显低于沉积物中Fe、黏土颗粒以及CaCO3的吸附量.尽管AAP的形成与还原速率很难测定,但其却可以很好地表征沉积物中内源磷的生物有效性.加藻反复扰动下,Ca-P的含量持续降低,这表明藻类吸附同化了部分Ca-P.因此,在一定藻浓度条件下,可用沉积物中NH4Cl-P, AAP, %Ca-P的和来表征生物有效磷(BAP)含量.     

物理改良对湖泊沉积物和间隙水特征的影响

采用物理改良措施覆沙和底质疏松,对南四湖湿地沉积物-水微界面氧化还原状况及间隙水营养盐垂向分布特征的影响进行了研究.结果表明,改良措施能够有效地改善沉积物的物理结构及氧气的垂向分布.在沉积物-水界面附近,覆沙和底质疏松均能显著提高界面处氧化层的厚度,覆沙效果最佳.随着剖面深度的增加,间隙水中NH4+和可溶性PO43-浓度呈指数关系增长,改良措施能有效降低间隙水中PO43-的含量,轻度底质疏松的效果最佳,差异显著(P<0.05).而界面以下NO3-和氧气浓度呈指数关系下降,在沉积物中10cm以下时营养盐接近一个常数,在4mm以下溶解氧接近0.对剖面沉积物不同形态的磷组分进行统计检验表明,改良措施能有效提高表层沉积物中NH4Cl-P 及BD-P(铁磷)的含量.     

Prediction of the environmental fate and aquatic ecological impact of nitrobenzene in the Songhua River using the modified AQUATOX model

An accidental discharge of nitrobenzene happened in November 2005 in the Songhua River,China.The AQUATOX model was modified and adapted to simulate the time-dependent nitrobenzene distribution in this multimedia aquatic system and its potential ecological impacts.Nitrobenzene concentrations in flowing water,sediment,and biota were predicted.Based on the initial concentrations of nitrobenzene observed in the field during the accidental discharge,that is,0.167-1.47 mg/L at different river segments, the pre...     

Growth and photosynthesis responses of Phaeodactylum tricornutum to dissolved organic matter from salt marsh plant and sediment

The effects of allochthonous dissolved organic matter (DOM) on the growth and photosynthesis of Phaeodactylum tricornutum were investigated. P. tricornutum incubated in f/2 medium was exposed to DOM additives, which were extracted from the plant and sediment samples of a salt marsh in North Branch of the Yangtze estuary, China. During 12 days incubation, the chlorophyll fluorescence parameters of P. tricornutum were measured by a Phyto-PAM phytoplankton analyzer. Spectral properties of DOM in algae filtrates were also observed. The concentrations of chlorophyll a, active chlorophyll a, and the maximum quantum yield of photosystem II significantly decreased after four days of incubation, suggesting that the growth and photosynthetic e ciency of P. tricornutum were inhibited. After adding sediment-DOM extract, both a250/a365 (the ratio of the absorption coe cients at 250 and 365 nm) and S values (spectral slope coe cients) of algae filtrates declined in the first two days, which demonstrated a loss of low molecular weight DOM. Parallel factor analysis of fluorescence spectra of DOM in algae filtrates revealed that DOM could be classified into two humic-like and two protein-like components. The fluorescence intensity of tyrosine-like component originating from algae increased significantly during incubation. This study supports the hypothesis that allochthonous DOM derived from salt marsh plant and sediment have a strong influence on the adjacent aquatic ecosystems.     

Response of antioxidase in viscera of Pagrosuma major larvae to water soluble fraction of hydrocarbons in No.0 diesel oil

Pagrosomus major larvae were to the water-soluble fraction of hydrocarbon in No.0 diesel oil(corresponding to No.2 fuel oil) at concentration of 0,0.17,1.22 and 8.82mg/L for up to 15 days.Larvae were sampled on days 9 and 15 of the experiment.Supernatants of viscera tissue extractions were assayed for biochemical response in terms of oxidative stress-superoxide dismutase(SOD),activity of selenium-dependant glutathione peroxidase(Se-GPx) and catalase(Ca),and the concentration of reduced glutathione(CSH).On day 9 of exposure ,statistically significant dose-related increases in Se-GPx and SOD activity,and GSH concentration were observed in all cases except for Se-GPx activity under the highest dosage of hydrocarbon.However,on day 15 of exposure, a similar dose-related in all cases except for Se-GPx activity under the highest dosage of hydrocarbon.However,on day 15 of exposure, a similar dose-related response was only observed for Se-GPx activity.GSH concentration decreased and SOD activity showed no statistical difference as compared to controls.However, a significant decrease in compared to day 9 Se-GPx activity and GSH concentration, in contrast to increase SOD activity at day 15 as indicates an accelerated accumulation of H2O2 and potential oxidative damage under long term exposure of larvae to hydrocarbons.No statistical changes were observed in Ca activity throughout the experiment, possibly owing to the high efficiency of Se-GPx.A recovery experiment was performed on indicating that the response of antioxidants measured tending to returm to return to their control levels.These results prove the function of the antioxidant defense system of the larvae to the water-soluble fraction of hydrocarbons in No.0 diesel oil.     

Response of antioxidase in viscera of Pagrosuma Major larvae to water soluble fraction of hydrocarbons in No.0 diesel oil

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Effects of sludge dredging on the prevention and control of algae-caused black bloom in Taihu Lake, China

Algae-caused black bloom (also known as black water agglomerate) has recently become a critical problem in some Chinese lakes.It has been suggested that the occurrence of algae-caused black bloom was caused by the cooperation of nutrient-rich sediment with dead algae,and sludge dredging was adopted to control black bloom in some lakes of China.In this article,based on the simulation of black bloom using a Y-shape apparatus for modeling natural conditions,both un-dredged and dredged sites in three areas of Taihu Lake,China were studied to estimate the effects of dredging on the prevention and control of black bloom.During the experiment,drained algae were added to all six sites as an additional organic load;subsequently,the dissolved oxygen decreased rapidly,dropping to 0 mg/L at the sediment-water interface.Black bloom did not occur in the dredged sites of Moon Bay and Nan Quan,whereas all three un-dredged sites at Fudu Port,Moon Bay and Nan Quan experienced black bloom.Black bloom also occurred at the dredged site of Fudu Port one day later than at the other sites,and the odor and color were lighter than at the other locations.The color and odor of the black water mainly result from the presence of sulfides such as metal sulfides and hydrogen sulfide,among other chemicals,under reductive conditions.The color and odor of the water,together with the high concentrations of nutrients,were mainly caused by the decomposition of the algae and the presence of nutrient-rich sediment.Overall,the removal of the nutrient-rich sediment by dredging can prevent the occurrence and control the degree of algae-caused black bloom in Taihu Lake.     

淡水水体底泥厌氧氨氧化菌的初步富集培养与氨氧化特性

对已通过16SrRNA基因方法检测到厌氧氨氧化菌(anammox菌)的江苏新沂河底泥样品在厌氧生物反应器中进行连续培养,研究这种新发现的anammox菌的生长特性,及其厌氧氨氧化效应.培养试验历时49d.经25d的启动期,反应器中氨氮和亚硝酸氮开始同时降低,并与厌氧氨氧化反应的化学计量关系类似.此后,反应器的氮转化量呈上升趋势(最大值接近0.17kg.m-.3d-1).底泥经培养后,anammox菌得到了富集,其数量从1%提高到5.6%,其倍增时间为12d.研究还发现反应器生物量的流失,出水中含有与anammox菌特异性基因探针杂交并正进行增殖的细菌细胞,但其生物特性有待深入研究.     

生物海绵铁体系降解硝基苯的特性及机理初探

采用硝基苯（NB）模拟废水对生物海绵铁体系进行驯化,考察了NB初始浓度、海绵铁投加量、初始pH值、温度等因素对生物海绵铁体系降解NB的影响,初步探讨了生物海绵铁体系高效降解NB的机理.结果表明：生物海绵铁体系较普通活性污泥系统对NB适应性及氧化作用更强,驯化至第28d对300mg/L NB废水去除率稳定在98%以上,驯化周期比普通活性污泥体系缩短28d;海绵铁的加入大大促进了微生物对NB的降解,NB初始浓度及pH值对生物海绵铁体系降解速率影响较大,该体系适宜的温度范围较广,10~40℃均能高效降解NB,生物海绵铁体系对NB的降解符合零级反应动力学规律;生物海绵铁体系中活性氧化物（ROS）含量明显高于海绵铁体系及污泥体系,尤其是介入铁泥的生物海绵铁体系ROS含量更高,为体系发生较强类Fenton效应提供了条件.在实验确定的最佳工况下,经NB驯化的铁泥与海绵铁形成的生物海绵铁体系,NB降解速率为31.49min^-1,6hNB降解率及TOC去除率分别高达92.0%和63.1%,较单独海绵铁体系与单独铁泥体系降解率的叠加值分别高出22.3%和11.4%.本研究为经济有效地处理NB废水提供了新思路.     

短期暴露于城市污水处理厂尾水的文蛤抗氧化酶响应

为研究城市污水处理厂(STPs)尾水是否会引起海洋生物的氧化逆境,将取自青岛市李村河污水处理厂的尾水用海水稀释到不同浓度(0%、1%、5%、10%、20% V/V), 对文蛤(Meretrix meretrix)暴露培养15d, 分析其内脏中超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、谷胱甘肽过氧化物酶(GPx)、谷胱甘肽还原酶(GR)的活性. 结果表明:SOD活性随尾水暴露时间延长基本表现为“抛物线型”的响应特征,体积比10%、20%的尾水暴露6~12d期间,文蛤体内SOD活性均受到诱导,最大增幅为15.88%;CAT和GPx对尾水的主要响应特征是抑制效应,分别在暴露9d、12d时最为明显,最大抑制率分别为64.38%和52.39%;较高浓度(20%)的尾水能够持续抑制GR活性,而其他处理组中,GR对尾水表现为“抛物线型”的响应特征,即:暴露3d或6d时活性增加,而后显著降低.GR活性的最大诱导出现在暴露3d和6d时,分别比对照组上升81.47%和80.91%.研究结果进一步表明STPs不能有效降解有害化学物质以消除尾水的毒性, 文蛤内脏SOD、CAT、GPx和GR活性能够敏感指示尾水诱导的氧化逆境.     

光照、温度和藻类对底泥释放磷的影响

在悬浮底泥与藻类体系中,不同温度和光照条件对底泥释放磷的影响方面的研究,尚未见到过报道。现对此进行了研究,并得出下述结论:有藻存在时底泥的释放量大于无藻存在时底泥的释放量。光照度大时(一定限度下),底泥的释放量稍有增加;温度升高时,底泥的释放量加大;水柱中含泥量大时,则磷的释放量也大。此工作对在不同条件下浅湖的内负荷量计算提供了基础。     

光照、温度和藻类对底泥释放磷的影响

在悬浮底泥与藻类体系中,不同温度和光照条件对底泥释放磷的影响方面的研究,尚未见到过报道。现对此进行了研究,并得出下述结论:有藻存在时底泥的释放量大于无藻存在时底泥的释放量。光照度大时(一定限度下),底泥的释放量稍有增加;温度升高时,底泥的释放量加大;水柱中含泥量大时,则磷的释放量也大。此工作对在不同条件下浅湖的内负荷量计算提供了基础。     

底泥不同悬浮方式对水体生物有效磷的影响

以太湖月亮湾底泥为材料,通过室内模拟实验研究了底泥不同悬浮方式(底泥扰动、底泥曝气)对水体中生物有效磷的影响。结果表明:底泥再悬浮导致颗粒态磷生物有效性呈下降趋势,10 d时,藻类可利用磷(AAP)占总磷(TP)的百分比仅为初始状态(39.86%)时的34.75%(底泥扰动)和17.03%(底泥曝气)。内源磷形态分析表明,悬浮物中Fe/Al-P含量、非闭蓄态Fe/Al-P(AAP)占Fe/Al-P的比重均有下降的趋势。这主要与底泥再悬浮导致溶解氧融入(溶解氧从2.59 mg/L(初始状态)分别增加至5 mg/L(底泥扰动)和6 mg/L(底泥曝气)左右)和pH改变(pH值从8.07(初始状态)分别降至7.4(底泥扰动)和7.3(底泥曝气))有关。实验结束时颗粒态磷生物有效性突然升高,出现这种现象的原因较复杂,可能与底泥再悬浮状态下底泥的物理化学变化和水中微生物的作用有关,还需要进一步探究。底泥再悬浮导致水体中可被利用颗粒态磷(BAPP)和溶解态磷(DTP)含量降低,从而导致上覆水中生物有效磷(BAP)含量降低。     

底泥疏浚对湖泊沉积物的生态毒性效应的影响

采用淡水沉积物质量基准和微生物毒性试验方法,对疏浚前后五里湖沉积物提取液和全底泥沉积物的生态毒性进行了研究与分析.结果表明,疏浚后,沉积物中各重金属污染物的总体含量均显著降低,但是铬、铅和镍的含量仍然分布在阈值效应低值(TEL)和可能效应水平值(PEL)之间的灰色区域,仍可能对水体生态系统产生不良影响;疏浚后1个月,沉积物提取液中发光菌发光试验的EC50值降低约50%,毒性增加近1倍;与疏浚前相比,全底泥沉积物的细菌毒性试验的EC₅₀值降低11%～30%;全底泥月芽藻毒性试验的EC₅₀值也有显著降低.     

沉积物中三丁基锡对铜锈环棱螺肝胰脏抗氧化防御系统的影响

以铜锈环棱螺(Bellamya aeruginosa)为试验对象,采用人工添加TBT的自然沉积物对铜锈环棱螺进行静态暴露实验,研究了沉积物中不同浓度TBT长期暴露(30 d)对铜锈环棱螺肝胰脏的超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和谷胱甘肽(GSH)的影响,以揭示TBT对它们影响的浓度效应关系。结果表明,沉积物中低浓度(100 ng/g)TBT对SOD、CAT和GSH没有影响。当TBT浓度为500～1000 ng/g时,SOD活性呈现浓度依耐性的升高。当TBT浓度为200～1000 ng/g时,CAT活性表现为浓度依耐性的升高。高浓度(2000 ng/g)TBT则导致SOD和CAT活性急剧下降,分别比对照下降了67.33%和54.87%。当TBT浓度为200～1000 ng/g时,GSH含量呈现浓度依耐性的下降,高浓度(2000 ng/g)TBT导致GSH含量急剧下降,比对照下降了76.87%。环境水平的TBT长期暴露对铜锈环棱螺肝胰脏产生了氧化胁迫,高浓度的TBT长期胁迫使肝胰脏受到了严重的氧化损伤。CAT和GSH可以用作环境水平TBT长期暴露的有效生物标志物。     

金属离子及盐度对硝基苯厌氧生物降解过程的影响

以硝基苯废水处理反应器内的污泥为菌源,采用间歇反应的方法分别考察Fe3+,Ni2+,Zn2+,Al3+,Cr(Ⅵ)和Cu2+ 6种金属离子及盐度对硝基苯厌氧生物降解过程的影响.结果表明,适宜质量浓度的Fe3+,Ni2+,Zn2+,Al3+和Cr(Ⅵ)可促进硝基苯的降解. 当ρ(Fe3+)为5 mg/L,ρ(Ni2+),ρ(Zn2+)和ρ(Al3+)为1.0 mg/L及ρ〔Cr(Ⅵ)〕为0.50 mg/L时,硝基苯的降解速率提高5%～23%. 当ρ(Fe3+),ρ(Ni2+),ρ(Zn2+),ρ(Al3+),ρ〔Cr(Ⅵ)〕和ρ(Cu2+)分别大于50,10.0,5.0,5.0,5.0和0.25 mg/L时,金属离子开始对硝基苯降解菌产生抑制作用,毒性顺序为Cu2+>Cr(Ⅵ)>Al3+>Zn2+>Ni2+>Fe3+. 硝基苯降解菌生长的最佳盐度为0.25%～1.00%.