Fig. 3. Gas chromatograms of volatile organic emissions from swine manure storage systems representing the four system subtypes. From top to bottom: air sample collected in a deep pit (Type 1), air sample collected over a concrete-lined basin (Type 2), air sample collected over a lagoon (Type 3), and air sample collected over a photosynthetic lagoon (Type 4). Peak reference numbers correspond to organic compounds listed in Table 3