Oxygen-release compounds increase the oxygen content of contaminated areas, enhancing biological activity and thus promoting natural attenuation. The specific compound used will depend on soil chemistry, concentration of target organics, type of target organics and cleanup levels. Parameters of interest are release rate of oxygen at different effective partial pressures and ratio of oxygen released to amount of oxygen applied. Researchers studied the solid oxidants below with respect to dissolution rate and ease of movement through other media:

• --Na₂CO₃-1.5H₂O₂ encapsulated sodium percarbonate
• --Free sodium percarbonate crystals
• --CaO₂, calcium peroxide
• --MgO₂, magnesium peroxide

Oxygen movement

Oxygen movement in the subsurface is influenced by：

• --Soil heterogeneity
• --Moisture content, which can hinder O₂ movement
• --Pore size——a function of sediment age and history
• --Tortuosity, caused by small pore sizes, which increases O₂ path distance

Soil morphology directly influences O₂ diffusion through the soil and soil redox potential, and the biological degradation that will occur at interfacial areas. In the interstitial pores, microbes are protected from toxic compounds. "Interstitial pore space attachment also makes predation more difficult. Solid oxidants can exhibit slow dissolution and fall into a reaction-limited domain. Conversely, these compounds can release oxygen from their surfaces rapidly, exhibiting transport limitations. Researchers predicted that the encapsulated Na₂CO₃ +1.5H₂O₂'s release of O₂ was by diffusion-limited transport while the other studied oxidants were controlled by chemical reaction kinetics of dissolution. The kinetics of dissolution have both chemical and thermodynamic limitations. Reactions are as follows：

2H₂O + MgO₂ ↔ Mg(OH)₂(s) + H₂O₂ 

2H₂O + CaO₂(s) + ↔ Ca(OH)₂(s) + H₂O₂ 

4Na₂CO₃•1.5H₂O₂ ↔ 8Na+ + 4CO₃- + 6H₂O₂ 

H₂O₂ + H₂O₂ ↔ O₂ + 2H₂O 

Some of the reaction products produced-Mg(OH)₂ and Ca(OH)₂ -have solubility values lower than the ions added. Such precipitates may coat reactant particles and block pores in both the soil and reactant particles, limiting transport of reacting ions and particles. Sodium percarbonate would release O₂ by diffusion-limited transport whereas chemical kinetic reactions would control dissolution rate of other oxidants. Release rates of MgO₂ and CaO₂ could be limited because of self-encapsulation. 

Experiments and results：The unencapsulated Na₂CO₃• 1.5H₂O₂ had the most rapid release rate, followed by CaCO₂, and encapsulated Na₂CO₃•1.5H₂O₂. MgO₂ had the slowest O₂ release by several orders of magnitude. However, the large size of both forms of Na₂CO₃-1.5H₂O₂ slows transport of bulk particles. CaO₂ and MgO₂ both have fractions small enough to permit migration where soil particles, and thus pore spaces, are larger than the particles of soil oxidant. In some cases, lack of movement of oxidant particles may be desirable in establishing stationary oxidative zones. Adding oxidants to water also changes the water's pH, usually in the range of 10 to 12. Shifts to high pH conditions generally have a negative effect on indigenous bacteria, but soils can have a buffering capacity to counteract or neutralize the pH shifts. 

Other conclusions：Release rates that are too rapid for biological uptake rates will prevent the utilization of all O₂. Oxygen release rates below optimum may result in reduced aerobic metabolism or failure to maintain aerobic respiration. Of the oxidants tested, MgO₂ has the widest application based on 

• --O₂ release rate, which was the longest
• --pH shift, which was lowest
• --O₂ release per mass, which was highest

Oxygen release compound, commonly known as magnesium peroxide (MgO₂), raises the dissolved oxygen concentration of aquifers, thereby creating conditions which may stimulate indigenous, petrophilic microbes to aerobically degrade petroleum contamination to carbon dioxide and water. 

* Oxygen generation: Magnesium peroxide, when hydrated, releases oxygen per the following reaction: MgO₂+H₂O -> 1/2 O₂+ Mg(OH)₂

*  Application methods: Magnesium peroxide can be introduced to an aquifer by either the retrievable filter sock method or by direct-push injection as a slurry. In situations where there is an open excavation as a result of either an underground storage tank removal, or remediation via excavation, magnesium peroxide as a dry powder can be mixed with low level contaminated soil before backfilling. Typically, the amount of compound applied to the soil is at least about 100 grams per metric ton of soil and preferably from about one to ten kilograms of compound per metric ton of soil.

* Uses: Some noteworthy uses of magnesium peroxide in the remediation of petroleum are: 

（1）At sites where adequate nutrients for bioremediation already exist in an aquifer, and dissolved oxygen is all that is needed to accelerate the rate of contaminant biodegradation

（2）As an oxygen barrier for groundwater contamination plume control 

（3）As a polishing step to meet target rehabilitation contaminant levels when active site remediation, such as pump-and-treat or other physical methods, is no longer cost-effective

（4） As the oxygen supplier, in combination with other injected bioremediation products that directly introduce either nutrients and/or microbes into aquifers

Bioremediation refers broadly to the use of microbiological populations to participate in the biodegradation, transformation or sequestration of a given environmental pollutant. A prerequisite for this process are the microbes found in the soil or groundwater that consume the harmful organic materials and remove them from the environment. The microbes leave behind carbon dioxide and water as decomposition products.

In-situ bioremediation is in-place bioremediation, (aerobic and anaerobic) without excavation of contaminated soil. Excess oxygen is required for an accelerated in situ bioremediation; this means that there must be aerobic conditions in the area to be cleaned up. The microbes will grow, reproduce and consume an ever increasing amount of harmful organic materials under aerobic conditions and with the optimal addition of nutrients.

When bioremediation is used, it is therefore essential to maintain aerobic conditions. The location to be cleaned up must be supplied with oxygen over a long period. Magnesium peroxide is primarily used as the main oxygen source for in situ bioremediation. The reason for this is related to the specific properties of magnesium peroxide. Magnesium peroxide in powdered form is stable over a long period. The total O₂ release period will last from three months to one year, however, this is a site specific issue that is primarily dependent on contaminant load and groundwater velocity. Field experience has indicated that at most hydrocarbon contaminated groundwater sites magnesium compound continues to release oxygen for a period of at least 6 months' time.

Magnesium peroxide is a non-toxic compound with no potential adverse effects to the aquifer. The by-products of magnesium peroxide's reaction with water are oxygen and ordinary magnesium hydroxide, which is virtually insoluble. Thus, magnesium liberates only oxygen into the aquifer. The magnesium hydroxide is insoluble and remains as an inert faction of the soil or in the application of filter socks, the magnesium hydroxide is contained within the cloth and is removed from the well. It should be noted that magnesium peroxide and magnesium hydroxide are safe for human consumption as they are both used as anti-acids in common drug store products.

Magnesium peroxide is a fine, odorless and tasteless, white powder. When the pH shifts toward neutral, magnesium peroxide slowly releases oxygen via intermediate formation of hydrogen peroxide. Magnesium peroxide is primarily used as the main oxygen source for in-situ bioremediation. It also finds use in oxygenating the lower parts of artificial or natural lakes, as well as wastewater and effluent, in coating seeds to improve germination and seedling survival rates, in oxygenating the roots of plants, and as the bleach agent in personal formulations.