温度对淀粉酶强化污泥为燃料微生物燃料电池的影响

采用单室无膜悬浮阴极微生物燃料电池(MFC),对比分析了温度变化对淀粉酶强化剩余污泥为燃料的MFC(ESMFC)产电特性和污泥减量化效果的影响.研究表明,在40℃时ESMFC最大功率密度相对于参照组(投加等量失活酶系统)功率密度输出增加最大,为94%;此时CE也最大,为9.2%。这主要是由于在此温度下淀粉酶对系统的促进作用更明显。在45℃时,ESMFC系统中污泥减量化效果最好.当运行温度为45℃时,ESMFC中TCOD去除率为87.2%,投加等量失活淀粉酶的ESMFC中TCOD去除率为55.7%;ESMFC中VSS/TSS从原泥中的67.34%下降到28.07%,对照组则下降到45.61%。此研究对投加淀粉酶的ESMFC实际应用具有一定指导意义。     

不同酶强化污泥为燃料微生物燃料电池特性对比分析

采用单室无膜悬浮阴极微生物燃料电池(MFC),对比分析了蛋白酶和淀粉酶强化剩余污泥为燃料的MFC(ESMFC)产电特性、酶特性和污泥减量化效果。研究表明,投加蛋白酶的ESMFC最大功率密度比对照组增加106.2%,投加淀粉酶时ESMFC最大功率密度比对照组增加48%。蛋白酶作用主要体现在投加后的前12小时,而淀粉酶作用时间则较长,为投加后的前144小时,但在运行前期,由于高温作用,导致系统内的酶活性较强,投加的淀粉酶作用则不明显。投加蛋白酶的系统内TCOD、TSS和VSS去除率分别为82%、65%和85%,而投加淀粉酶的系统内TCOD、TSS和VSS去除率分别达到86%、67%和88%。此研究对于ESMFC中外加酶的选择具有一定意义。     

垃圾渗滤液-沉积污泥微生物燃料电池的产电性能

采用单室沉积型微生物燃料电池(SMFC)处理垃圾渗滤液与沉积污泥,考察电池的产电性能及污染物去除效果。SMFC输出电压呈周期性变化趋势,最大输出电压251 m V,最大功率密度为10.35 mW·m~(-2),功率密度随电流的增加先增大后减小,燃料电池内阻为2 653Ω。COD、氨氮去除率分别达96.18%和80.60%。SMFC的平均输出电压随污染物的降解呈波浪型上升趋势。MLSS、MLVSS去除率分别为24.40%和30.32%。实验结束后,MLVSS/MLSS的比值由0.70降至0.65,在SMFC产电过程中,污泥中的有机物得到有效降解。因此,SMFC可实现污水净化、污泥减量及产电一体化的效果。     

不同运行条件对微生物燃料电池产电性能的影响

以双室微生物燃料电池为研究对象,改变活性污泥MLSS值、营养物质的量、营养物质种类、温度等运行条件,测量24 h内COD值、细菌数目和电压值,进而研究不同运行条件对微生物燃料电池运行初期产电性能的影响。结果表明:在其他同等条件下,只改变MLSS值时,MLSS值越大,产电性能愈佳,只改变葡萄糖浓度时,当葡萄糖浓度为60 mg/m L时,产电性能最佳,最大电压和功率密度可达224.8 m V和505 m W/m3,只改变营养物质种类时,当加入低糖和C源营养物质时,产电性能较佳,只改变运行温度,当温度为37℃时,产电性能最佳,最大电压和功率密度可达231.5 m V和535 m W/m3;改变上述条件时,细菌数目与MFC的产电性能呈显著正相关关系。     

厌氧污泥和Geobacter sulfurreducens接种MFC的产电性能及其修复Cd污染土壤研究

利用混合菌种(厌氧污泥)和单一菌种(Geobacter sulfurreducens)以不同接种方式搭建单室土壤微生物燃料电池(MFC)反应器,考察不同MFC的产电性能及其对Cd污染土壤的修复效果。结果表明,将混合菌种集中接种于阳极碳毡表面的MFC1运行效果最佳,其在2d即可完成启动,输出电压稳定在0.225V左右,最大功率密度为35.00MW/m2,内阻为515.5Ω。土壤修复效果与MFC产电性能相关,MFC1产电性能最佳,因此土壤修复效果最好,稳定运行30d后阴极Cd富集率最高,达19.02%     

光合产电微生物群落构建及光照培养对其产电性能的影响

采用淡水沉积物为接种来源,培养出光合产电微生物群落。将其与藻阴极联用组建了完整的光合作用微生物燃料电池时,功率密度达到(157.5±3.1)m W/m2。采用循环伏安法及电化学阻抗谱对该群落的电化学性能进行了测试。PCR-DGGE及紫外可见吸收光谱分析显示,该群落含有Ectothiorhodospiraceae科及Chloroflexi门不产氧光合细菌、产电菌Arcobacter butzleri、发酵细菌及其他细菌。对该群落进行长期黑暗培养或长期光照培养时,其产电性能均得到了提高,但功率密度测试显示,光照培养微生物燃料电池最大功率密度为(180.1±8.7)m W/m2,高于黑暗培养的微生物燃料电池(160.7±11.4)m W/m2。电化学测试也显示,光照培养的阳极产电性能优于黑暗培养的阳极。     

剩余污泥微生物燃料电池的产电性能及有机物降解与阳极生物分析

构建了以二沉池剩余污泥厌氧发酵上清液为阳极底物的微生物燃料电池(MFC),考察了电池的产电性能、污染物去除效率及阳极微生物种群特征。结果表明,厌氧发酵污泥MFC作为污泥资源化的一种新途径,具有可行性。在厌氧发酵的预处理条件下,MFC体系稳定运行期间输出电压最高可达0.65 V,最大功率密度达86.89 m W·m~(-2),库伦效率为(5.12±0.5)%;与此同时TCOD去除率为(50.6±3.5)%。污泥在厌氧发酵阶段产生大量挥发性脂肪酸(VFAs),它们作为产电微生物易于摄取的阳极底物,能够促进污泥中有机质的去除,进而提高污泥MFC的产电效果。由阳极微生物群落结构可推断:产电和非产电细菌具有协同作用,共同维持MFC的稳定运行。     

微生物燃料电池降解邻苯二甲酸酯及同步产电特性

构建双室微生物燃料电池(MFC)装置,研究了分别以乙酸钠(NaAc)作单一燃料和乙酸钠+邻苯二甲酸酯(PAEs)作混合燃料条件下,MFC的产电性能及其对邻苯二甲酸酯的去除效果。结果显示,微生物燃料电池对邻苯二甲酸酯类废水的化学需氧量(COD)的总去除率可达89%~94%,对邻苯二甲酸酯的去除率均在70%以上。以2 g·L~(-1)NaAc+10 mg·L~(-1)PAEs作混合燃料时,MFC获得最大(面积)功率密度58.78 mW·m~(-2),电池内阻213.50Ω。实验结果表明,MFC能够利用高浓度邻苯二甲酸酯作燃料在实现高效降解的同时稳定地向外输出电能这为环境激素类难降解有机物的高效低耗处理提供了一种新的研究思路。     

人工湿地型微生物燃料电池处理啤酒生产废水

采用人工湿地型微生物燃料电池处理啤酒生产废水,考察了啤酒生产废水中不同COD浓度条件下(475、1 968、5 640 mg·L~(-1))人工湿地型微生物燃料电池对COD和氨氮的去除效果,评估了在此过程中微生物燃料电池的产电性能。研究表明,当COD浓度为1 968 mg·L~(-1)时,人工湿地型微生物燃料电池对COD的去除率最高,达到93.5%;氨氮去除率随COD起始的增加而增加,当进水浓度为5 640 mg·L~(-1)时,氨氮去除率达到70.8%。对产电性能而言,当进水COD浓度为1 968 mg·L~(-1)时,人工湿地型微生物燃料电池产电量最高,其最大电压、功率密度和电流密度分别达到280 mV、24.2 mW·m~(-2)和220 mA·m~(-2)。利用人工湿地型微生物燃料电池处理啤酒生产废水具有一定的可行性,在处理污染物的同时产电,弥补了处理过程中的能源消耗,对废物资源化具有很好的应用前景。     

高盐废水MFCs不同阴极电子受体产电及微生物群落分析

为探查不同电子受体产电性能及对阳极微生物群落的影响,研究了3种电子受体(铁氰化钾、曝气阴极、过硫酸钾),构建了双室榨菜废水微生物燃料电池系统(microbial fuel cells,MFCs),实现了污水处理和能量回收的双重目的,探讨了不同电子受体(铁氰化钾、曝气阴极、过硫酸钾)对榨菜废水MFCs产电性能及阳极微生物群落的影响。结果表明:在产电性能方面,当过硫酸钾作为阴极电子受体时,电池输出电压、库仑效率、功率密度均优于另外2种常用阴极电子受体(铁氰化钾和氧气);在500Ω的外接电阻间歇运行的条件下,其输出电压、库仑效率、功率密度分别为802 mV、(33±1.6)%、697 mW·m~(-2)。阳极生物16S rRNA基因测序分析表明,水解发酵菌为榨菜废水微生物燃料电池阳极核心菌群,铁氰化钾、氧气和过硫酸钾MFCs阳极微生物菌群相对丰度分别为64.3%、63.6%和75.51%,包括Lentimicrobium、Synergistaceae、Sphaerochaeta、Anaerolineaceae、Draconibacteriacea菌属。阴极电子受体不同的MFCs的阳极微生物群落核心菌群类似,但是丰度有所不同。势差较大的电子受体(过硫酸钾)微生物群落多样性和丰富度较高,产电和污染物去除效果较好。     

Radionuclides and trace elements in fish collected upstream and downstream of Los Alamos national laboratory and the doses to humans from the consumption of muscle and bone

Abstract

The purpose of this study was to determine radionuclide and trace element concentrations in bottom‐feeding fish (catfish, carp, and suckers) collected from the confluences of some of the major canyons that cross Los Alamos National Laboratory (LANL) lands with the Rio Grande (RG) and the potential radiological doses from the ingestion of these fish. Samples of muscle and bone (and viscera in some cases) were analyzed for ³H, ⁹⁰Sr, ¹³⁷Cs, ^totU, ²³⁸Pu, ^239,240Pu, and ²⁴¹Am and Ag, As, Ba, Be, Cr, Cd, Cu, Hg, Ni, Pb, Sb, Se, and Tl. Most radionuclides, with the exception of ⁹⁰Sr, in the muscle plus bone portions of fish collected from LANL canyons/RG were not significantly (p<0.05) higher from fish collected upstream (San Ildefonso/background) of LANL. Strontium‐90 in fish muscle plus bone tissue significantly (p<0.05) increases in concentration starting from Los Alamos Canyon, the most upstream confluence (fish contained 3.4E‐02 pCi g^‐1 [126E‐02 Bq kg^‐1]), to Frijoles Canyon, the most downstream confluence (fish contained 14E‐02 pCi g^‐1 [518E‐02 Bq kg^‐1]). The differences in ⁹⁰Sr concentrations in fish collected downstream and upstream (background) of LANL, however, were very small. Based on the average concentrations (±2SD) of radionuclides in fish tissue from the four LANL confluences, the committed effective dose equivalent from the ingestion of 46 lb (21 kg) (maximum ingestion rate per person per year) of fish muscle plus bone, after the subtraction of background, was 0.1 ± 0.1 mrem y^‐1 (1.0 ± 1.0 μSv y^‐1), and was far below the International Commission on Radiological Protection (all pathway) permissible dose limit of 100 mrem y^‐1 (1000 μSv y^‐1). Of the trace elements that were found above the limits of detection (Ba, Cu, and Hg) in fish muscle collected from the confluences of canyons that cross LANL and the RG, none were in significantly higher (p<0.05) concentrations than in muscle of fish collected from background locations.     

Patterns of volatile metabolites and nonvolatile trichothecenes produced by isolates of <Emphasis Type="Italic">Stachybotrys,Fusarium, Trichoderma,Trichothecium</Emphasis> and <Emphasis Type="Italic">Memnoniella</Emphasis>

We reported previously that trichodiene, a volatile trichothecene derivative, was produced by a Stachybotrys isolate, also known to produce highly cytotoxic, non-volatile, macrocyclic trichothecenes (satrotoxins). We investigated the relationship between the production of trichodiene and various non-volatile trichothecenes for several molds. Volatile metabolites were concentrated by adsorption on Tenax TA and analyzed by GC/MS, while non-volatile metabolites were separated by HPLC, derivatized and analyzed by GC/MS. Stachybotrys chartarum isolates producing macrocyclic trichothecenes secreted significantly larger amounts of trichodiene and other sesquiterpenes than isolates which only produced simple trichothecenes. The amounts of secreted trichodiene were relatively small in all cases. With the exception of Memnoniella, which excreted small amounts of sesquiterpenes, the other isolates produced varying amounts of sesquiterpenes, including trichodiene, as well as simple tricothecenes, no detectable trichodiene, but large amounts of griseofulvin derivatives. In Stachybotrys there is apparently a correlation between trichodiene and macrocyclic trichothecene production. In the remaining isolates, there was no simple relationship between trichodiene and non-volatile trichothecene synthesis. Trichodiene is produced in larger amounts by Stachybotrys isolates, which also produce satratoxins, but it will be difficult to utilize this metabolite to detect toxic isolates in buildings due to the relatively small amounts excreted.     

Radionuclides in deer and elk from Los Alamos national laboratory and the doses to humans from the ingestion of muscle and bone

Abstract

This paper summarizes radionuclide concentrations (³H, ⁹⁰Sr, ¹³⁷Cs, ²³⁸Pu, ^239,240Pu, ²⁴¹Am, and ^totU) in muscle and bone tissue of mule deer (Odocoileus hemionus) and Rocky Mountain elk (Cervus elaphus) collected from Los Alamos National Laboratory (LANL), Los Alamos, New Mexico, lands from 1991 through 1998. Also, the committed effective dose equivalent (CEDE) and the risk of excess cancer fatalities (RECF) to people who ingest muscle and bone from deer and elk collected from LANL lands were estimated. Most radionuclide concentrations in muscle and bone from individual deer (n = 11) and elk (n = 22) collected from LANL lands were either at less than detectable quantities (where the analytical result was smaller than two counting uncertainties) and/or within upper (95%) level background (BG) concentrations. As a group, most radionuclides in muscle and bone of deer and elk from LANL lands were not significantly higher (p<0.10) than in similar tissues from deer (n = 3) and elk (n = 7) collected from BG locations. Also, elk that had been radio collared and tracked for two years and spent an average time of 50% on LANL lands were not significantly different in most radionuclides from road kill elk that have been collected as part of the environmental surveillance program. Overall, the upper (95%) level net CEDEs (the CEDE plus two sigma for each radioisotope minus background) at the most conservative ingestion rate (50 lbs of muscle and 13 lbs of bone) were as follows: deer muscle = 0.22 mrem y^‐1 (2.2 μSv y^‐1), deer bone = 3.8 mrem y^‐1 (38 μSv y^‐1), elk muscle = 0.12 mrem y^‐1 (1.2 μSv y^‐1), and elk bone = 1.7 mrem y^‐1 (17 μSv y^‐1). All CEDEs were far below the International Commission on Radiological Protection guideline of 100 mrem y^‐1 (1000 μSv y^‐1), and the highest muscle plus bone net CEDE corresponded to a RECF of 2E‐06, which is far below the Environmental Protection Agency upper level guideline of 1E‐04.     

Leaching of seven pesticides currently used in cotton crop in Mato Grosso State—Brazil

This study aimed to evaluate the leaching of pesticides and the applicability of the Attenuation Factor (AF) Model to predict their leaching. The leaching of carbofuran, carbendazim, diuron, metolachlor, α and β endosulfan and chlorpyrifos was studied in an Oxisol using a field experiment lysimeter located in Dom Aquino – Mato Grosso. The samples of percolated water were collected by rain event and analyzed. Chemical and physical soil attributes were determined before pesticide application to the plots. The results showed that carbofuran was the pesticide that presented a higher leaching rate in the studied soil, so was the one representing the highest contamination potential. From the total carbofuran applied in the soil surface, around 6 % leached below 50 cm. The other pesticides showed lower mobility in the studied soil. The calculated values to AF were 7.06E-12 (carbendazim), 5.08E-03 (carbofuran), 3.12E-17 (diuron), 6.66E-345 (α-endosulfan), 1.47E-162 (β-endosulfan), 1.50E-06 (metolachlor), 3.51E-155 (chlorpyrifos). AF Model was useful to classify the pesticides' potential for contamination; however, that model underestimated pesticide leaching.     

Endosulfan in China 2—emissions and residues

Background, aim, and scope  Endosulfan is one of the organochlorine pesticides (OCPs) and also a candidate to be included in a group of new persistent organic pollutants (UNEP 2007). The first national endosulfan usage inventories in China with 1/4° longitude by 1/6° latitude resolution has been reported in an accompanying paper. In the second part of the paper, we compiled the gridded historical emissions and soil residues of endosulfan in China from the usage inventories. Based on the residue/emission data, gridded concentrations of endosulfan in Chinese soil and air have been calculated. These inventories will provide valuable data for the further study of endosulfan. Methods  Emission and residue of endosulfan were calculated from endosulfan usage by using a simplified gridded pesticide emission and residue model—SGPERM, which is an integrated modeling system combining mathematical model, database management system, and geographic information system. By using the emission and residue inventories, annual air and soil concentrations of endosulfan in each cell were determined. Results and discussion  Historical gridded emission and residue inventories of α- and β-endosulfan in agricultural soil in China with 1/4° longitude by 1/6° latitude resolution have been created. Total emissions were around 10,800 t, with α-endosulfan at 7,400 t and β-endosulfan at 3,400 t from 1994 to 2004. The highest residues were 140 t for α-endosulfan and 390 t for β-endosulfan, and the lowest residues were 0.7 t for α-endosulfan and 170 t for β-endosulfan in 2004 in Chinese agricultural soil where endosulfan was applied. Based on the emission and residue inventories, concentrations of α- and β-endosulfan in Chinese air and agricultural surface soil were also calculated for each grid cell. We have estimated annual averaged air concentrations and the annual minimum and maximum soil concentrations across China. The real concentrations will be different from season to season. Although our model does not consider the transport of the insecticide in the atmosphere, which could be very important in some areas during some special time, the estimated concentrations of endosulfan in Chinese air and soil derived from the endosulfan emission and residue inventories are in general consistent with the published monitoring data. Conclusions  To our knowledge, this work is the first inventory of this kind for endosulfan published on a national scale. Concentrations of the chemical in Chinese air and agricultural surface soil were calculated for each grid cell. Results show that the estimated concentrations of endosulfan in Chinese air and soil agree reasonably well with the monitoring data in general. Recommendations and perspectives  The gridded endosulfan emission/residue inventories and also the air and soil concentration inventories created in this study will be updated upon availability of new information, including usage and monitoring data. The establishment of these inventories for the OCP is important for both scientific communities and policy makers.     

Impact of spiked concentrations of Cd,Pb, As and Zn in growth medium on elemental uptake of Nasturtium officinale (Watercress)

This study is aimed at investigating the impact of water quality on the uptake and distribution of three non-essential and toxic elements, namely, As, Cd and Pb in the watercress plant to assess for metal toxicity. The plant was hydroponically cultivated under greenhouse conditions, with the growth medium being spiked with varying concentrations of As, Cd and Pb. Plants that were harvested weekly for elemental analysis showed physiological and morphological symptoms of toxicity on exposure to high concentrations of Cd and Pb. Plants exposed to high concentrations of As did not survive and the threshold for As uptake in watercress was established at 5 ppm. Translocation factors were low in all cases as the toxic elements accumulated more in the roots of the plant than the edible leaves. The impact of Zn on the uptake of toxic elements was also evaluated and Zn was found to have an antagonistic effect on uptake of both Cd and Pb with no notable effect on uptake of As. The findings indicate that phytotoxicity or death of the watercress plant would prevent it from being a route of human exposure to high concentrations of As, Cd and Pb in the environment.     

Butyltin compounds in sediment and fish from the Polish Coast of the Baltic Sea

Concentrations of mono- (MBT), di- (DBT), and tri-(TBT) butyltin compounds were measured in eggs, liver, and muscle of nine species of fish from four regions of the Baltic Sea - the Firth of Vistula, the Gulf of Gdańsk, Puck Bay, and the mouth of the Vistula River. The overall concentration ranges among all the fish sampled from the four sites were: < 7 to 79 ng/g for MBT, 6 to 1100 ng/g for DBT, 7 to 3600 ng/g for TBT, and 16 to 4800 ng/g for total BTs, on a wet wt basis. The highest concentration of total BTs was found in herring liver from the Firth of Vistula (4800 ng/g, wet wt) and in roach muscle from Puck Bay (3300 ng/g, wet wt), while the least concentration was found in burbot eggs and liver from the Vistula River (39 and 32 ng/g, wet wt, respectively). TBT was the major form of BTs present in most samples analyzed. Sediment samples collected from shipyards in the Gulf of Gdańsk contained butyltin concentrations ranging from 1.2 to 46 μg/g (dry wt) for MBT, 2.0 to 42 μg/g for DBT, and 2.6 to 40 μg/g for TBT. As with the fish, the majority of the BTs in sediment were present as TBT, which suggested recent exposure of the aquatic environment of the region to TBT.     

Malathion-induced sublethal toxicity on the hematology of cricket frog (Fejervarya limnocharis)

The effect of malathion [diethyl(dimethoxythiophosphorylthio)succinate] at sublethal concentration (0.006 ppm) on hematological parameters of the cricket frog (Fejervarya limnocharis) was studied for 24 hrs to 240 hrs of exposure and remarkable hematological alterations were observed. The study on hematological parameters revealed a highly significant decrease (P < 0.01) in the total erythrocytes count in malathion-exposed animals from 24 hours to 96 hrs of exposure as compared to control. Significant decreases (P < 0.01) of hemoglobin and packed cell volume were also observed from 48 hrs to 240 hrs. A significant increase (P < 0.01) in leucocytes count was noted throughout the exposure period. Elevated numbers of lymphocytes and eosinophils as found in the present study revealed lymphocytosis as well as eosinophilia, suggesting that this was a result of direct stimulation of the immunological defense due to the presence of a toxic substance or may be associated with tissue damage. The cytomorphological and cytopathological study of erythrocytes and leucocytes in malathion-exposed frogs at 0.006 ppm concentration revealed various cytotoxic effects at different exposure times. It was noted that the size and the shape of the erythrocytes were subjected to variation in different blood disorders.     

Relation between forest vegetation, atmospheric deposition and site conditions at regional and European scales

Several monitoring programs have been set up to assess effects of atmospheric deposition on forest ecosystems. The aim of the present study was to evaluate effects on the understorey vegetation, based on the first round of a regional (the Netherlands) and a European forest monitoring program. A multivariate statistical analysis showed surprisingly similar results for both data sets; the vegetation appeared to be largely determined by the ‘traditional’ factors soil, climate, and tree species, but there was a small but statistically significant effect of atmospheric deposition. The effects of deposition include a slight shift towards nitrophytic species at high N deposition in the European network, and towards acidophytic species at high S-deposition in the Dutch network. The relatively small effect of atmospheric deposition is understandable in view of the very large natural variation in environmental conditions. Time series of both vegetation and environment are needed to assess deposition effects in detail.