Definitions - o

Ocean Acidification

Ocean Acidification (OA) is a term used to describe changes to the chemistry of the ocean.

It occurs when carbon dioxide gas (or CO2) is absorbed by the ocean and reacts with seawater to produce acid. Although CO2 gas naturally moves between the atmosphere and the oceans, the increased amounts of CO2 gas emitted into the atmosphere, mainly as a result of human activities (e.g. burning fossil fuels), has been increasing the amount of CO2 absorbed by the ocean, which results in seawater that is more acidic.

Note: the water being more acidic does not mean its actually acid, rather it is less alkaline or base, seawater pH is typically limited to a range between 7.5 and 8.4 - with 7 being pH neutral.

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Ocean Fertilization

Ocean fertilization is a proposed form of geo-engineering that involves the introduction of iron particles to the upper ocean to stimulate a phytoplankton bloom.

In theory, the phytoplankton will then absorb CO2 before dying and sinking to the bottom of the ocean where the carbon will be sequestered.

An experiment in early 2009 in the Southern Ocean dampened hopes for widespread uptake of the technology after crustacean zooplankton fed on the bloom before it died and reintroduced the extracted CO2 into the atmosphere.

However, some scientists maintain that ocean fertilization could prove a cost effective means of reducing concentrations of CO2 in the atmosphere. Environmental groups counter that large scale ocean fertilization projects could have unexpected consequences on maritime food chains.

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Off Grid

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Off-Gassing

Materials may give off gases, some of which are toxic. Implicated in a variety of ailments, some people are more sensitive than others to these gases.

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Oligotrophic Lakes

Deep clear lakes with few nutrients, little organic matter and a high dissolved-oxygen level.

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Onconogenicity

The capacity to induce cancer.

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One-Axis Tracking

A system capable of rotating about one axis to track the sun.

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Opportunity Cost

The cost of an economic activity foregone by the choice of another activity.

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Orbital Forcing

Theory that proposes large scale climate changes are due in part to the variations in precession, eccentricity and obliquity that affects the amount of solar radiation received by the earth.

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Organic Farming

Organic farming is the form of agriculture that relies on techniques such as crop rotation, green manure, compost, biological pest control, and mechanical cultivation to maintain soil productivity and control pests on a farm. Organic farming excludes or strictly limits the use of synthetic fertilizers and synthetic pesticides, plant growth regulators, livestock antibiotics, food additives, and genetically modified organisms.

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Organic Flow Battery

Compared to traditional aqueous inorganic redox flow batteries such as vanadium redox flow batteries and Zn-Br2 batteries, that have been developed for decades, organic redox flow batteries have emerged in last few years (since 2009) and hold great promise to overcome major drawbacks preventing economical and extensive deployment of traditional inorganic redox flow batteries. The primary merit of organic redox flow batteries lies at using sustainable and tunable organic redox active molecules, free of resources limit and enabling unlimited combinations of anode and cathode materials.

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Organic Food

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Orographic Rainfall

Precipitation that results when moist air is lifted over a topographic barrier such as a mountain range.

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Oxygen Cycle

Cyclic movement of oxygen in different chemical forms from the environment, to organisms, and then back to the environment.

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Ozone

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Ozone Depleting Substance

A family of man-made compounds that includes, but are not limited to, chlorofluorocarbons (CFCs), bromofluorocarbons (halons), methyl chloroform, carbon tetrachloride, methyl bromide, and hydrochlorofluorocarbons (HCFCs). These compounds have been shown to deplete stratospheric ozone, and therefore are typically referred to as ODSs.

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Ozone Precursors

Chemical compounds, such as carbon monoxide, methane, non-methane hydrocarbons, and nitrogen oxides, which in the presence of solar radiation react with other chemical compounds to form ozone, mainly in the troposphere.

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