Extraction of TNT from aggregate soil fractions.
Past explosives manufacture, disposal, and training activities have contaminated soil at many military facilities, posing health and environmental risks through contact, potential detonation, and leaching into ground water. While methods have been confirmed for extraction and measuring explosives concentration in soil, no work has addressed aggregate size material (the >2 mm gravel and cobbles) that often occurs with the smaller soil fractions. This paper describes methods and results for extraction and measurement of TNT (2,4,6-trinitrotoluene) in aggregate material from 1/2 to 2-1/1 from a WWII era ammunition plant. TNT was extracted into acetonitrile by both Soxhlet and ultrasonic extraction methods. High pressure liquid chromatography analyses of extracts showed expected variation among samples. Also effective extraction and determination of TNT concentration for each aggregate size fraction was achieved.
Soil Sorption and Plant Uptake of 2,4,6-Trinitrotoluene.
Abstract : Potential environmental hazards are posed by the presence of 2,4,6- Trinitrotoluene (TNT) contamination in soils of US Army Ammunition Plants (AAPs) . Adsorption and desorption studies were conducted on soil samples collected from 13 AAPs. Soils were found to be primarily silt loams, low in organic carbon. TNT reached a steady state of adsorption with test soils within 2 hr of contact. Desorption also reached steady state within 2 hr with more than half of the adsorbed TNT being removed. TNT adsorption correlated most highly with cation exchange capacity, extractable iron, clay content, and percent organic carbon. Sequential desorption indicated that almost all of the adsorbed TNT was desorbed after three sequential desorption cycles. Therefore, soil sorption will not effectively prevent mobility of TNT in the environment unless adsorption increases over extended periods of time or more strongly adsorbing decomposition products are formed. Microbial degradation appeared to be greater in reduced than in oxidized soils, but differences were not significant. Plant uptake of TNT and two of its principal degradation products, 4-amino-2, 6-dinitrotoluene (4ADNT) and 2-amino-4, 6-dinitrotoluene (2ADNT), was also investigated. Results of the study suggest that plant uptake from soils contaminated with 80 micros of the respective treatment compound per gram will not be environmentally significant.
Water Quality Aspects of Irrigation and Drainage: Past History and Future Challenges for Civil Engineers
This paper presents a brief history of irrigation and drainage related to ASCE activities on its Jubilee. This paper discusses legislation and policies that affect irrigation and drainage practices, water quality constituents of increasing concern in irrigation and drainage practices, and presents a prognosis on the future of declining freshwater resources available for irrigated agriculture and growing water quality problems in irrigation and drainage. Civil engineers in ASCE’s Irrigation and Drainage Division have compiled an 80-year history of highly meritorious service and accomplishments. In the next millennium, civil engineers will face a formidable challenge in managing and protecting the precious freshwater resources in the U.S.