Monitored natural recovery

Forstner, U. and Apitz, S. (2007) Sediment remediation US focus on capping and monitored natural recovery, J. Soils and Sediments, 1, pp. 351-358. 

Monitored natural recovery, which is based on the assumption that, while sediments pose some risk, it is low enough that natural processes can reduce risk over time in a reasonably safe manner. 

U.S. EPA defines MNA as the reliance on natural processes, within the context of a carefully controlled and monitored site cleanup approach, to achieve site-specific remediation objectives within a time frame that is reasonable compared to that offered by other more active methods. The natural processes include biodegradation, dispersion, dilution, sorption, volatilization, stabilization, and transformation. These processes reduce site risk by transforming contaminants to less toxic forms, reducing contaminant concentrations, and reducing contaminant mobility and bioavailability. Other terms for natural attenuation in the literature include intrinsic remediation, intrinsic bio-remediation, passive bioremediation natural recovery, and natural assimilation. 30... 

Fate-and-transport studies using computer modeling and mathematical calculations can effectively evaluate the potential for contaminant migration and degradation through the natural and anthropogenic processes active at the site. Often a brief fate-and-transport study early in the project can lead to optimal placement of monitor and recovery wells, and selection of sample analytical procedures. 

Sometimes the best response to an oil spill on a shoreline may be to leave the oil and monitor the natural recovery of the affected area. This would be the case if more damage would be caused by cleanup than by leaving the environment to recover on its own. This option is suitable for small spills in sensitive environments and on a beach that will recover quickly on its own such as on exposed shorelines and with non-persistent oils such as diesel fuel on impermeable beaches. This is not an appropriate response if important ecological or human resources are threatened by long-term persistence of the oil. 

Education about the nature of anxiety helps engagement and improves recovery. Models have been described for most anxiety disorders in both the biological and psychological dimensions, and patients benefit from an explanation, tailored to their level of understanding, in each dimension. This can be reinforced by the use of educative hterature (Dannon et al. 2002). Patients should be encouraged to record and monitor their symptoms, as this can improve treatment efficacy (Febbraro and Glum 1998). 

An alternative to the trap and special oven method is the use of small-diameter extraction tubes that can be introduced directly into a modified GC injector. Recovery is considered to be satisfactory when it attains 60%, although it is often quantitative with this device. This principle is also applied to badges used in industrial hygiene for monitoring pollution in the workplace or the environment (Fig. 20.3). In the latter application, air flows through the badge in a natural fashion to trap the analyte. 

Reticulum ATPase [105,106], Owing to the long-lived nature of the triplet state, Eosin derivatives are suitable to study protein dynamics in the microsecond-millisecond range. Rotational correlation times are obtained by monitoring the time-dependent anisotropy of the probe s phosphorescence [107-112] and/or the recovery of the ground state absorption [113— 118] or fluorescence [119-122], The decay of the anisotropy allows determination of the mobility of the protein chain that cover the binding site and the rotational diffusion of the protein, the latter being a function of the size and shape of the protein, the viscosity of the medium, and the temperature. 

Another tool that enables us to evaluate analytical accuracy of organic analyses is surrogate standards. These are compounds that do not naturally occur in the environment and that are similar in chemical nature and behavior to target analytes. In organic compound analysis, known amounts of surrogate standards are added to each sample prior to extraction. The comparison of surrogate standard recoveries to laboratory control limits permits the laboratory to monitor the efficacy of extraction and to measure the accuracy of analysis for each individual sample. 

Despite the dramatic recovery of Lake Erie through point-source reductions, the lake remains enriched in phosphoms. Over half of the external load of total phosphoms to Lake Erie is from tributaries draining cultivated land. Therefore, attainment of the desired total phosphoms load will depend on further nonpoint-source controls (Dolan, 1993). Lake Erie must be monitored regularly because of its dynamic nature due to heavy use as an international shipping route. Following its introduction to the Great Lakes about 20 years ago and prolific expansion, the zebra mussel (Dreissena spp.) has been partly... 

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