Respiration/decomposition

X 10 g(O)/year. Most of this oxygen is removed rather quickly by respiration/decomposition and thus photosynthesis by itself does not account for the net production of oxygen. The production of oxygen results from the physical removal of some of the reduced carbon from contact with oxygen before it has a chance to decompose. This process is known as carbon burial and it represents the difference between photosynthesis and respiration/decomposition. Carbon burial is the removal of fixed carbon to anaerobic sediments where reaction with atmospheric oxygen does not occur until the sediments are returned to the surface by tectonic processes. The rate of carbon burial corresponds to 3.2 x 10 g(O)/ year, less than 1% of the amount of oxygen formed by photosynthesis. 

In our analysis, we will examine only the factors that affect atmospheric oxygen on a time-scale greater than —100 years and neglect the annual "panting" associated with the rapid photosynthetic and respiration/decomposition cycle. 

Maleic Anhydride. The ACGIH threshold limit value in air for maleic anhydride is 0.25 ppm and the OSHA permissible exposure level (PEL) is also 0.25 ppm (181). Maleic anhydride is a corrosive irritant to eyes, skin, and mucous membranes. Pulmonary edema (collection of fluid in the lungs) can result from airborne exposure. Skin contact should be avoided by the use of mbber gloves. Dust respirators should be used when maleic anhydride dust is present. Maleic anhydride is combustible when exposed to heat or flame and can react vigorously on contact with oxidizers. The material reacts exothermically with water or steam. Violent decompositions of maleic anhydride can be catalyzed at high temperature by strong bases (sodium hydroxide, potassium hydroxide, calcium hydroxide, alkaU metals, and amines). Precaution should be taken during the manufacture and use of maleic anhydride to minimize the presence of basic materials. 

PPS dust should be treated as a nuisance particulate. The OSHA permissible exposure limit for respirable dust is 5 mg/m for dust containing no asbestos and less than 1% siUca. The principal decomposition products released during mol ding of PPS and their permissible exposure limits are given in Table 10. Sulfur dioxide and carbonyl sulfide are the most significant off-gases for production of mucous membrane irritation. 

Physical and Chemical Properties - Physical State at 15 X and 1 atm. Solid Molecular Weight 168. Boiling Poira at 1 atm. 556,291,564 Freezing Point 194,90,363 Critical Temperature Not pertinent Critical Pressure Not pertinent Specific Gravity 1.58 at 18°C (solid) Vapor (Gas) Density Not pertinent Ratio of Specific Heats of Vapor (Gas) Not pertinent Latent Heat of Vaporization Not pertinent Heat of Combustion -7,378, -4,099, -171.5 Heat of Decomposition Not pertinent. Health Hazards Information - Recommended Personal Protective Equipment Dust respirator rubber... 

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