View abstract View article PDF The potential impacts of climate change on crop productivity are of widespread interest to those concerned with addressing climate change and improving global food security. Two common approaches to assess these impacts are process-based simulation models, which attempt to represent key dynamic processes affecting crop yields, and statistical models, which estimate functional relationships between historical observations of weather and yields. Examples of both approaches are increasingly found in the scientific literature, although often published in different disciplinary journals.
A set of standards used in Europe exists and is often called the Dutch standards. The European Union EU is rapidly moving towards Europe-wide standards, although most of the industrialised nations in Europe have their own standards at present.
In Canadamost standards for remediation are set by the provinces individually, but the Canadian Council of Ministers of the Environment provides guidance at a federal level in the form of the Canadian Environmental Quality Guidelines and the Canada-Wide Standards Canada-Wide Standard for Petroleum Hydrocarbons in Enviromental movement matrix.
Often nearby sites owned by the same company or which are nearby and have been reclaimed, levelled or filled are also contaminated even where the current land use seems innocuous. For example, a car park may have been levelled by using contaminated waste in the fill.
Also important is to consider off site contamination of nearby sites often through decades of emissions to soilgroundwaterand air. Ceiling dust, topsoilsurface and groundwater of nearby properties should also be tested, both before and after any remediation.
This is a controversial step as: No one wants to have to pay for the cleanup of the site; If nearby properties are found to be contaminated it may have to be noted on their property title, potentially affecting the value; No one wants to pay for the cost of assessment.
Often corporations which do voluntary testing of their sites are protected from the reports to environmental agencies becoming public under Freedom of Information Actshowever a "Freedom of Information" inquiry will often produce other documents that are not protected or will produce references to the reports.
Other countries have other mechanisms and commonly sites are rezoned to "higher" uses such as high density housing, to give the land a higher value so that after deducting cleanup costs there is still an incentive for a developer to purchase the land, clean it up, redevelop it and sell it on, often as apartments home units.
Ex-situ methods involve excavation of affected soils and subsequent treatment at the surface as well as extraction of contaminated groundwater and treatment at the surface. In-situ methods seek to treat the contamination without removing the soils or groundwater.
In-situ technologies include but are not limited to: During the process a desorber volatilizes the contaminants e. After that the contaminants can either be collected or destroyed in an offgas treatment system.
Recent advancements in bioaugmentation and biostimulation of the excavated material have also proven to be able to remediate semi-volatile organic compounds SVOCs onsite. Recently, ExSitu Chemical oxidation has also been utilized in the remediation of contaminated soil. This process involves the excavation of the contaminated area into large bermed areas where they are treated using chemical oxidation methods.
This technology is also successful when utilized as the initial step in a multi faceted remedial approach utilizing SEAR then In situ Oxidation, bioremediation enhancement or soil vapor extraction SVE. For petroleum-contaminated sites this material is usually activated carbon in granular form.
Chemical reagents such as flocculants followed by sand filters may also be used to decrease the contamination of groundwater. Air stripping is a method that can be effective for volatile pollutants such as BTEX compounds found in gasoline.
With fluidized bed bioreactors it is possible to achieve very low discharge concentrations which will meet or exceed discharge requirements for most pollutants. However, pump and treat is typically not the best form of remediation.
It is expensive to treat the groundwater, and typically is a very slow process to clean up a release with pump and treat. It is best suited to control the hydraulic gradient and keep a release from spreading further. Other methods include trying to increase the dissolved oxygen content of the groundwater to support microbial degradation of the compound especially petroleum by direct injection of oxygen into the subsurface, or the direct injection of a slurry that slowly releases oxygen over time typically magnesium peroxide or calium oxy-hydroxide.
In situ oxidation[ edit ] New in situ oxidation technologies have become popular for remediation of a wide range of soil and groundwater contaminants. Remediation by chemical oxidation involves the injection of strong oxidants such as hydrogen peroxideozone gas, potassium permanganate or persulfates.
One disadvantage of this approach is the possibility of decreasing anaerobic contaminant destruction natural attenuation where existing conditions enhance anaerobic bacteria which normally live in the soil prefer a reducing environment.
In general though, aerobic activity is much faster than anaerobic and overall destruction rates are typically greater when aerobic activity can be successfully promoted.
In these cases, injections downgradient of groundwater flow may provide adequate microbial destruction of contaminants prior to exposure to surface waters or drinking water supply wells.Bid Form Supplements: Allowance Form Alternate Form Bid Security Form Bid Submittal Checklist Estimated Quantities Form Proposed Products Form Proposed Subcontractors Form.
Conservationist Admits Enviromental Movement is Founded on Assumption and Hearsay Environmentalists Organizations Exposed 'Jurassic Coast' becomes World Heritage Site.
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Also for: S, S Due to commercial, safety, enviromental, quality and processing reasons, there is a huge number of quality parameters and related test methods for crude oils used by different actors. Environmental remediation deals with the removal of pollution or contaminants from environmental media such as soil, groundwater, sediment, or surface water.
This would mean that once requested by the government or a land remediation authority, immediate action should be taken as this can impact negatively on human health and the .