The objectives of this research were to examine potential chemical and physical effects on sorption/desorption of explosives in soil and sediments; determine toxicity effects of explosive-contaminated soil and sediments for organisms, and assess ecological risks of explosive-contaminated soils and sediments. Four target compounds including 2,4-dinitrotoluene (2,4-DNT), 2,4,6-Trinitrotoluene (TNT), cyclotrimethylene-trinitramine (RDX) and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) were selected. Batch and column experiments were designed to assess contamination potential of explosives in the subsurface environment. Sediment testing intermittent renewal system were used to evaluate toxicity of explosives. Test species including Neocaridina shrimp (Neocaridina denticulata), amphipod (Hyalella azteca), carp (Carassius auratus), silkworm (Tubifex hattai), and earthworm (Eisenia fetida) were used in acute toxicity test.  HMX had the highest sorption coefficient among the target compounds. TNT had the least tendency to sorb onto soil. With the increased organic carbon content in soil, desorption of target compound was less. The empirical relationship between sorption coefficient (Koc) and water solubility was established.  Results of column experiments indicated that HMX had the highest retardation factor. It had the highest tendency to resist leaching-out effect of groundwater. RDX had the highest tendency to leach out by groundwater from results of column experiments. Overall 2,4-DNT and TNT tend to dissolve and degrade by surface water and groundwater.<br/>The results of toxicity tests illustrated that 2,4-DNT and TNT had higher toxicity which was revealed by low lethal concentration. In contrast HMX has low toxicity onto biota. Low ecological risk were found when test species exposed to 2,4-DNT and TNT. Results showed that as 2,4-DNT at concentration level of 5.13 mg/L, the aquatic species might be affected. Also TNT at concentration level of 0.79 mg/L may pose ecological risk for 5% aquatic species in the ecosystem. This study provided a basis to predict fate and transport of explosives in the environment.

Environmental fate and ecotoxicity of explosives in contaminated sites

2019 Spring National Meeting

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