The Experts below are selected from a list of 17727 Experts worldwide ranked by ideXlab platform

Henk W. Van Verseveld - One of the best experts on this subject based on the ideXlab platform.

  • Natural Attenuation: What does the subsurface have in store?
    Biodegradation, 2002
    Co-Authors: Wilfred F. M. Röling, Henk W. Van Verseveld
    Abstract:

    Throughout the world, organic and inorganic substances leach into the subsurface as a result of human activities and accidents. There, the chemicals pose direct or indirect threats to the environment and to increasingly scarce drinking water resources. At many contaminated sites the subsurface is able to attenuate pollutants which, potentially, lowers the costs of remediation. Natural Attenuation comprises a wide range of processes of which the microbiological component, which is responsible for intrinsic bioremediation, can decrease the mass and toxicity of the contaminants and is, therefore, the most important. Reliance on intrinsic bioremediation requires methods to monitor the process. The subject of this review is how knowledge of subsurface geology and hydrology, microbial ecology and degradation processes is used and can be used to monitor the potential and capacity for intrinsic bioremediation in the subsurface and to verify degradation in situ. As research on Natural Attenuation in the subsurface has been rather fragmented and limited and often allows only conclusions to be drawn of the site under investigation, we provide a concept based on Environmental Specimen Banking which will contribute to further understanding subsurface Natural Attenuation processes and will help to develop and implement new monitoring techniques.

Liu Peibin - One of the best experts on this subject based on the ideXlab platform.

  • Confirmatory research on the Natural Attenuation capacity of oil pollutants based on in-situ experiment
    Environmental Pollution & Control, 2012
    Co-Authors: Liu Peibin
    Abstract:

    A confirmatory in-situ experiment of oil pollutant Natural Attenuation capacity was carried out to prove the reliability of the field experiments in a representative gas station in Beijing.Both of the concentration of VOCs and profiles of O2,CO2 in the soil presented the same rule as the preliminary experiment.The results show that the primary analysis are reliable and test methods are reasonable,feasible and reproducible for the experiment designed and implemented based on Natural Attenuation method.Early experimental results were verified by further theoretical analysis,drawing conclusions as followed:(1) the ways of Natural Attenuation were proved as both aerobic and anaerobic biodegradation via oxygen and carbon equilibrium calculation.(2) The rates of the Natural Attenuation and half-life of the oil pollutants calculated by the first-order decay model were consistent with previous results.The half-life of petroleum contaminants in contaminated site are about 50 days.(3) Based on the analysis,the capability evaluation of monitored Natural Attenuation and the environmental assessment of all experiments demonstrated that the environmental risk in this gas station had been eliminated under the influence of the Natural Attenuation.

Kuangfei Lin - One of the best experts on this subject based on the ideXlab platform.

  • Natural Attenuation model and biodegradation for 1,1,1-trichloroethane contaminant in shallow groundwater
    Frontiers in microbiology, 2015
    Co-Authors: Zhu Ruili, Jie Yang, Yongdi Liu, Qi-shi Luo, Kuangfei Lin
    Abstract:

    Natural Attenuation is an effective and feasible technology for controlling groundwater contamination. This study investigated the potential effectiveness and mechanisms of Natural Attenuation of 1,1,1-trichloroethane (TCA) contaminants in shallow groundwater in Shanghai by using a column simulation experiment, reactive transport model, and 16S rRNA gene clone library. The results indicated that the majority of the contaminant mass was present at 2-6 m in depth, the contaminated area was approximately 1000 m × 1000 m, and Natural Attenuation processes were occurring at the site. The effluent breakthrough curves from the column experiments demonstrated that the effectiveness of TCA Natural Attenuation in the groundwater accorded with the advection-dispersion-reaction equation. The kinetic parameter of adsorption and biotic dehydrochlorination of TCA was 0.068 m(3)/kg and 0.0045 d(-1). The contamination plume was predicted to diminish and the maximum concentration of TCA decreased to 280 μg/L. The bacterial community during TCA degradation in groundwater belonged to Trichococcus, Geobacteraceae, Geobacter, Mucilaginibacter, and Arthrobacter.

Catherine N. Mulligan - One of the best experts on this subject based on the ideXlab platform.

  • Overview of Natural Attenuation of Sediments
    Journal of ASTM International, 2006
    Co-Authors: Catherine N. Mulligan, Rn Yong
    Abstract:

    Natural Attenuation involves the use of the Natural processes with the soil and groundwater to remediate contamination by physical, chemical, and biological processes to reduce the risk to human health and the environment. Although the use of Natural Attenuation as a treatment process is increasing for remediation of contaminated groundwater, much less research has focused on contaminated soils and sediments. Industrial effluents, agricultural runoff, and sewage discharges are major sources of contaminants for the sediments. In addition, benthic organisms can transport contaminants through bioturbation and there is considerable variability at sites. Organic materials, a particularly important component of the sediments, can sequester the contaminants. Sediment-water partitioning controls the release of the contaminants into pore water and benthic organisms. Fate and transport mechanisms for both organic and inorganic contaminants within the sediments need to be understood to establish protocols for the monitoring and use of Natural Attenuation.

  • Natural Attenuation of contaminated soils.
    Environment international, 2004
    Co-Authors: Catherine N. Mulligan, Raymond N. Yong
    Abstract:

    Natural Attenuation is increasing in use as a low cost means of remediating contaminated soil and groundwater. Modelling of contaminant migration plays a key role in evaluating Natural Attenuation as a remediation option and in ensuring that there will be no adverse impact on humans and the environment. During Natural Attenuation, the contamination must be characterized thoroughly and monitored through the process. In this paper, Attenuation mechanisms for both organic and inorganic contaminants, use of models and protocols, role of monitoring and field case studies will be reviewed.

  • Natural Attenuation of Contaminants in Soils
    2003
    Co-Authors: Raymond N. Yong, Catherine N. Mulligan
    Abstract:

    RAYMOND N. YONG and CATHERINE N. MULLIGAN. CRC Press, Boca Raton, FL. 2003. Hardcover, 336 pp. $149.95. ISBN: 1-56-670617-3. Natural Attenuation is a topic of great practical importance that has gained widespread acceptance by regulatory agencies and entities responsible for site remediation.

Jason Prosser - One of the best experts on this subject based on the ideXlab platform.

  • evaluation of Natural Attenuation rate at a gasoline spill site
    Journal of Hazardous Materials, 2001
    Co-Authors: Jason Prosser
    Abstract:

    Contamination of groundwater by gasoline and other petroleum-derived hydrocarbons released from underground storage tanks (USTs) is a serious and widespread environmental problem. Natural Attenuation is a passive remedial approach that depends upon Natural processes to degrade and dissipate contaminants in soil and groundwater. Currently, in situ column technique, microcosm, and computer modeling have been applied for the Natural Attenuation rate calculation. However, the subsurface heterogeneity reduces the applicability of these techniques. In this study, a mass flux approach was used to calculate the contaminant mass reduction and field-scale decay rate at a gasoline spill site. The mass flux technique is a simplified mass balance procedure, which is accomplished using the differences in total contaminant mass flux across two cross-sections of the contaminant plume. The mass flux calculation shows that up to 87% of the dissolved total benzene, toluene, ethylbenzene, and xylene (BTEX) isomers removal was observed via Natural Attenuation at this site. The efficiency of Natural biodegradation was evaluated by the in situ tracer method, and the first-order decay model was applied for the Natural Attenuation/biodegradation rate calculation. Results reveal that Natural biodegradation was the major cause of the BTEX mass reduction among the Natural Attenuation processes, and approximately 88% of the BTEX removal was due to the Natural biodegradation process. The calculated total BTEX first-order Attenuation and biodegradation rates were 0.036 and 0.025% per day, respectively. Results suggest that the Natural Attenuation mechanisms can effectively contain the plume, and the mass flux method is useful in assessing the occurrence and efficiency of the Natural Attenuation process.