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Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 3/12/2010 Publication Date: 8/2/2010 Citation: Loughrin, J.H., Bolster, C.H., Lovanh, N.C., Sistani, K.R. 2010. A simple device for the collection of water and dissolved gases at defined depths. Applied Engineering in Agriculture. 26(4):559-564. Interpretive Summary: A device, consisting of a jar fitted with an inlet comprised of a gas-tight check valve and an outlet connected via tubing to a portable water pump, was constructed to collect water samples without atmospheric contamination or loss of dissolved gases. A void for dissolved gas analysis was created by enclosing tubing sealed with rubber stoppers within the jar. The device was deployed in a lagoon that served as the main waste recipient of a 2,000 head hog operation as well as a large reservoir. Water samples were analyzed for dissolved methane and common indicators of water quality such as acidity, suspended solids, various ions, and elemental composition. In addition, lagoon wastewater samples were analyzed for malodorous compounds. For reservoir samples, methane concentrations at the bottom of the lake were 3-4 orders of magnitude higher than at the upper levels of the lake while ammonium levels increased steadily with depth. Acidity also steadily increased with depth. Other water quality parameters were similar at each depth. For lagoon samples, ammonium concentration and malodorous compounds declined markedly as temperatures warmed. Results for both reservoir and lagoon sampling indicate that this device affords an expensive yet effective means of water collection for subsequent analysis of both water quality and dissolved gas concentration. Technical Abstract: A device, consisting of a jar fitted with an inlet comprised of a gas-tight check valve and 2-way ball valve outlet connected via tubing to a portable peristaltic pump, was constructed to collect water samples without atmospheric contamination or loss of dissolved gases. A headspace void for dissolved gas analysis was created by enclosing silicone tubing sealed with rubber stoppers within the jar. The device was deployed in a 0.4 ha lagoon that served as the primary waste recipient of a 2,000 head farrowing operation as well as a 4,000 ha impoundment reservoir. Water samples were analyzed for dissolved methane and common indices of water quality such as pH, suspended solids, various ions, and metals concentration. In addition, lagoon wastewater samples were analyzed for malodorous compounds. For reservoir samples, methane concentrations at the bottom of the lake of 0.49 µg L-1 were about three orders of magnitude higher than at the upper levels of the lake while ammonium levels increased from 0.03 mg L-1 at the surface to 1.67 mg L-1 in bottom samples. pH steadily decreased from 8.92 near the surface to 7.40 at the bottom. Other water quality parameters were similar at each depth. For lagoon samples, ammonium concentration and malodorous compounds declined markedly as temperatures warmed. Results for both reservoir and lagoon sampling indicate that this device affords an inexpensive yet effective means of water collection for subsequent analysis of both water quality and dissolved gas concentration. |
