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81.
82.
Teuchies J de Deckere E Bervoets L Meynendonckx J van Regenmortel S Blust R Meire P 《Environmental pollution (Barking, Essex : 1987)》2008,155(1):20-30
A historical input of trace metals into tidal marshes fringing the river Scheldt may be a cause for concern. Nevertheless, the specific physicochemical form, rather than the total concentration, determines the ecotoxicological risk of metals in the soil. In this study the effect of tidal regime on the distribution of trace metals in different compartments of the soil was investigated. As, Cd, Cu and Zn concentrations in sediment, pore water and in roots were determined along a depth profile. Total sediment metal concentrations were similar at different sites, reflecting pollution history. Pore water metal concentrations were generally higher under less flooded conditions (mean is (2.32 ± 0.08) × 10−3 mg Cd L−1 and (1.53 ± 0.03) × 10−3 mg Cd L−1). Metal concentrations associated with roots (mean is 202.47 ± 2.83 mg Cd kg−1 and 69.39 ± 0.99 mg Cd kg−1) were up to 10 times higher than sediment (mean is 20.48 ± 0.19 mg Cd kg−1 and 20.42 ± 0.21 mg Cd kg−1) metal concentrations and higher under dryer conditions. Despite high metal concentrations associated with roots, the major part of the metals in the marsh soil is still associated with the sediment as the overall biomass of roots is small compared to the sediment. 相似文献
83.
Kraigher H Al Sayegh Petkovsek S Grebenc T Simoncic P 《Environmental monitoring and assessment》2007,128(1-3):31-45
Mycorrhiza is the main spatial and temporal linkage between different constituents in a forest ecosystem. The functional compatibility
and stress tolerance of ectomycorrhizal types is species specific, and therefore the information on the ectomycorrhizal community
structure can add to the understanding of processes in forest ecosystems and can also be applied as tools for bioindication
of pollution stress in forest soils. We have studied the effects of pollution (N and S) on trees and forest soils by: (1)
quantification of ECM types diversity as in situ indicators in forest stands, (2) determination and quantification of pollution-sensitive or -insensitive ECM types as passive
monitors, (3) root growth and development of ECM on nonmycorrhizal spruce seedlings, planted at the studied sites (active
monitors), and (4) ECM infection (a bioassay based on mycorrhizal inoculum potential) of seedlings in an experimental set-up
as ex situ testers. ECM species richness for Norway spruce trees (Picea abies) showed higher values in unpolluted sites than in polluted ones, while the differences were not significant for European
beech trees (Fagus sylvatica). As pollution-sensitive or -insensitive ECM species in spruce forests, we suggest Hydnum rufescens (sensitive) and Paxillus involutus (unsensitive). Mycorrhizal potential in Norway spruce seedlings as a bioassay for soil N and S pollution was effective, and
is suggested as an additional, standardized and widely comparable system in bioindication of soil pollution. 相似文献
84.
Impact of Bioaugmentation with a Consortium of Bacteria on the Remediation of Wastewater-Containing Hydrocarbons (5 pp) 总被引:1,自引:0,他引:1
Domde P Kapley A Purohit HJ 《Environmental science and pollution research international》2007,14(1):7-11
Goals, Scope and Background It has been observed that hydrocarbon treated wastewaters still contain high COD and a number of intermediates. This suggests
that the required catabolic gene pool for further degradation might be absent in the system or, that its titer value is not
significant enough. By providing the desired catabolic potential, the overall efficiency of the treatment system can be improved.
This study aims to demonstrate this concept by bioaugmentation of a lab-scale reactor treating refinery wastewater with a
consortium having the capacity to complement the alkB genotype to the available microbial population.
Methods Two reactors were set up using activated biomass collected from a refinery treatment plant and operated at a continuous mode
for a period of 8 weeks. The feed to both reactors was kept constant. Crude oil was spiked regularly. One reactor was bioaugmented
with a consortium previously described for crude oil spill remediation. The efficiency of the bioaugmented reactor was demonstrated
by reduced COD. The changes in the microbial population over a period of time were analyzed by RAPD. Catabolic activity of
the biomass in both reactors was monitored by PCR. The presence of the catabolic loci was confirmed by Southern Hybridization.
Results and Discussion 52.2% removal of COD was observed in the bioaugmented reactor while only 15.1% reduction of COD was observed in the reactor
without bioaugmentation. The change in microbial population can be seen from the 4th week, which also corresponds to improved
catabolic activity. The presence of the bedA locus was seen in all samples, which indicates the presence of aromatic degraders,
but the appearance of the alkB locus, from the 6th week onwards, which was observed only in the samples from the bioaugmented
reactor. The results suggest that the gene pool of the bioaugmented reactor has catabolic loci that can degrade accumulated
intermediates, thus improving the efficiency of the system.
Conclusions In this study, improvement of efficiency of bioremediation was demonstrated by addition of catabolic loci that are responsible
for degradation. Bioaugmentation was carried out in biomass that was collected from an ETP (effluent treatment plant) treating
hydrocarbon containing wastewater to study the strategies for improvement of the treatment system. Biostimulation, only marginally
improved the efficiency, when compared to bioaugmentation. The improved efficiency was demonstrated by COD removal. The presence
of the alkB locus suggests the importance of a catabolic gene pool that acts on accumulated intermediates. It is well documented
that straight chain aliphatics and intermediates of aromatic compounds after ring cleavage, accumulate in refinery wastewater
systems, thereby hindering further degradation of the wastewater. Supplementation of a catabolic gene pool that treats the
lower pathway compounds and alkanes will improve the overall efficiency. In this study, results suggest that the alkB locus
can also be used to monitor the degradative mode of the activated biomass.
Recommendations and Perspective . Pollution from petroleum and petroleum products around the globe are known to have grave consequences on the environment.
Bioremediation, using activated sludge, is one option for the treatment of such wastes. Effluent treatment plants are usually
unable to completely degrade the wastewater being treated in the biological unit (the aerator chambers). The efficiency of
degradation can be improved by biostimulation and bioaugmentation. This study demonstrates the improved efficiency of a treatment
system for wastewater containing hydrocarbons by bioaugmentation of a consortium that supports degradation. Further experiments
on a pilot scale are recommended to assess the use of bioaugmentation on a large scale. The use of molecular tools, like DNA
probes for alkB, to monitor the system also needs to be explored. 相似文献
85.
生命周期评价理论与方法作为一种量化环境影响的工具,在诸多领域中得到了广泛的应用。在垃圾处理领域,生命周期评价最早在20世纪90年代得到应用。生命周期评价与城市生活垃圾处理的有效结合,将促进城市生活垃圾的减量化、资源化、无害化目标的实现。总结了生命周期评价理论与方法在城市生活垃圾处理中的应用现状。对国内不同城市生活垃圾处理方式环境影响因子进行比较分析,诸如全球变暖潜力、酸化潜力和富营养化潜力等因子。针对其目标范围定义、数据收集、评价方法的选择、结果解释及工艺改进等方面指出了目前研究的局限性和不足。并对未来城市生活垃圾处理生命周期评价的发展方向进行展望。 相似文献
86.
以比阻(SRF)、过滤时间(TTF)和泥饼含水率作为评价污泥脱水性能的指标,考察2种阳离子聚丙烯酸酯CPAL-1和CPAL-2对污泥脱水性能的影响,并与阳离子絮凝剂三氯化铁(FeCl3)、聚合氯化铝(PAC)、阳离子聚丙烯酰胺(CPAM)和阳离子表面活性剂十六烷基三甲基溴化铵(CTAB)的作用效果进行比较.还测定了Zeta电位(ZP)和滤液中胞外聚合物(EPS)含量的变化来探讨CPAL的作用机理.实验结果表明,经CPAL-1调理的污泥脱水效果优于CPAM、PAC和FeCl3,明显优于CPAL-2和CTAB.当CPAL-1的投加剂量为0.200 g/g干基时,SRF、TTF和泥饼含水率降至最低,依次为5.37 ×1011m/kg、70 s和75.73%.CPAL主要通过电中和、吸附架桥作用和溶出EPS等来改善污泥的沉降脱水性能. 相似文献
87.
本研究采用原子力显微镜(AFM)结合自制的膜探针以及Zeta电位仪通过分别测量不同有机污染物,即腐殖酸(HA)、牛血清蛋白(BSA)和海藻酸钠(SA)与微滤膜之间的粘附力以及相应污染物的Zeta电位,对高岭土在不同有机物微滤过程的影响进行了系统性研究。结果表明,高岭土对污染膜通量衰减的影响主要发生在膜过滤的初期阶段,其存在使HA污染膜的初期通量衰减幅度增加,BSA和SA污染膜的初期通量衰减幅度减缓;清洗后HA污染膜的通量恢复率降低,而BSA和SA污染膜的通量恢复率增大。而且,高岭土的存在使膜-HA之间的粘附力变大以及HA溶液的Zeta电位变小,膜-BSA、SA之间的粘附力变小以及相应污染物的Zeta电位都增大。因此,膜-污染物之间粘附力以及溶液的Zeta电位的变化可以指示膜污染的变化趋势。 相似文献
88.
采用在活化硅酸制备过程中加入适量Ti Cl4的方法,试制了一种新型无机高分子助凝剂—聚硅酸钛。研究了不同[Si]/[Ti]条件下制备的聚硅酸钛在固定p H值的水中分散物的粒径和Zeta电位随着活化时间的变化趋势,并与活化硅酸作比较。结果表明,在Si/Ti=20,活化48 h的条件下能制备出较为稳定的聚硅酸钛。与活化硅酸相比,聚硅酸钛在水中的分散物具有较大的粒径和更高的Zeta电位。通过对比制备的活化硅酸和聚硅酸钛的红外图谱发现,聚硅酸钛中有TiO-Si键,证明钛离子参与了聚合反应,新生成的化学键提高了它的聚合度和稳定性。采用硫酸铝为混凝剂,聚硅酸钛为助凝剂进行混凝除浊实验。测定了絮凝体的Zeta电位和混凝沉淀后的上清液浊度,研究了硫酸铝投加量和混凝p H对聚硅酸钛助凝效果的影响。结果表明,投加适量的聚硅酸钛助凝剂,明显提高了混凝除浊效果且拓宽了有效混凝p H值的范围。 相似文献
89.
对比研究了AlC13和3种不同碱化度的聚合氯化铝(PACl)在不同pH与投量下除氟效果,并对不同形态铝盐除氟机理进行了初步探讨.结果表明,pH对絮凝剂水解后铝形态分布及其除氟效果有重要影响.pH 5 ~6时,Al3+和Al2、Al3等低聚态铝为AlCl3主要形态,且AlCl3更易水解生成可将溶解态氟转化为颗粒态氟的Al(OH)3,从而较PACl具有更佳除氟效果.pH >7时,PACl较AlCl3具有更佳除氟效果,且增大PACl碱化度可促进氟的去除,这主要是由于具有较高Al13含量的PACl更容易与电负性F-结合所致;且絮凝剂混凝除氟絮体ζ电位越高,越利于F-在絮体表面吸附. 相似文献
90.
AbstractThe roles of PM2.5-induced mitochondrial damage and oxidative stress on mast cell degranulation were examined in vitro. Mast cells were treated with suspensions of PM2.5 in Dulbecco’s modified Eagle’s medium at concentrations from 25 to 200?mg/L in the absence or presence of 10?mmol/L N-acetyl-L-cysteine. Biological effects and mitochondrial function were assessed by determining cell viability, β-hexosaminidase release, interleukin-4 secretion, reactive oxygen species generation, adenosine triphosphate production, potential alteration of mitochondrial membrane, and activities of mitochondrial electron transport chain complexes I and III. Exposure of mast cells to PM2.5 induced reduction of adenosine triphosphate production, collapse of mitochondrial membrane potential, and inhibition of the activity of complex III. Co-treatment of mast cells exposed to PM2.5 with N-acetyl-L-cysteine attenuated cytotoxicity and the production of reactive oxygen species, and decreased the release of β-hexosaminidase and interleukin-4. Evidently, PM2.5-induced oxidative stress plays an essential role in mitochondrial toxicity and mast cell activation. 相似文献