Review and synthesis of evidence regarding environmental risks posed by munitions constituents (MC) in aquatic systems

Abstract

Underwater military munitions (UWMM) may pose a risk to aquatic environments because they typically contain munitions constituents (MC) such as 2,4,6-trinitrotoluene (TNT) and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX). If UWMM become corroded or breaches, the fill material may leak or dissolve into the surrounding environment, which could potentially adversely affecting affect the exposed biota. In large part, because of the high cost and complexity associated with sampling MC at UWMM sites, detailed and reliable information about MC in water, sediment, and biota is available for only a few sites, and therefore temporal and spatial uncertainties persist. Examination of available data indicates that concentrations of MC in water and sediment were largely below detection or were relatively low (e.g., parts per billion), with higher concentrations being highly localized and typically near a point source. These findings were in accordance with predictive modeling and with fate studies. Available toxicity data derived for a variety of freshwater and marine species were compiled and used to derive interim water quality criteria and protective values derived from species sensitivity distributions. Toxicity varied widely across a diversity of MC and species. For most aquatic sites, MC contamination in sediment and in the watercolumn presents low risk to the resident biota.

Field validation of POCIS for monitoring at underwater munitions sites

“…In addition to TNT and RDX measured both inside and outside the canister, time-weighted average concentrations were quantified for ADNTs inside the source canister volume only, whereas DANTs were not detected in any case. Both 2-ADNT and 4-ADNT were 2 orders of magnitude lower than the parent TNT compound, and likely formed rapidly by microbial degradation, which is well documented for TNT (e.g., Elovitz and Weber 1999;Rosen and Lotufo 2005;Lotufo et al 2017). In our estimation, the source canister served as a surrogate for the inside cavity of a munition, where munitions constituent potentially present at high concentrations inside the cavity is released through one or more breaches.…”

“…Based on the quantitation limits and BCFs just given, detection of TNT in oysters by POCIS was expected at concentrations of ≥16 μg/L. Concentrations of this magnitude have been reported at underwater military munitions sites (Lotufo et al ), and therefore, the potential for detection of munitions constituents justified their deployment along with POCIS.…”

“…In open water environments, munitions constituents dissolve and are released to the overlying water to be carried away from the source by currents, readily diluted, and subjected to similar transformative processes in the water column. Overall, munitions constituent persistence in the environment is a key determinant of exposure (Lotufo et al ).…”

Release of Munitions Constituents in Aquatic Environments Under Realistic Scenarios and Validation of Polar Organic Chemical Integrative Samplers for Monitoring

“…The highest concentration sum TNT and RDX concentration in the field was over 300 times lower than the concentration in the flume water. Although processes such as sorption onto particulates and degradation (Smith et al ; Lotufo et al ; Ariyarathna et al ) certainly served as removal pathways for TNT and RDX released at a coastal embayment, hydrodynamic transport (e.g., near‐field current‐driven water exchange and bay‐wide tidal exchange) was likely the primary factor governing the distribution of MC released from the composition B fragments in the field and the resulting low concentration (Wang et al ; Voie and Mariussen ; Lotufo et al ; Beck et al ). Similar to what was observed for flume experiment 1, the concentrations of 2‐ and 4‐ADNT were below detection levels for the field study (Rosen et al ).…”

“…These parameters have been used in mathematical models to estimate the amount of MC introduced into the surrounding aquatic environment from an uncovered single breached shell (Wang et al , ). Subsequent to the breaching event, concentrations in the surrounding environment are expected to fluctuate over time because of release kinetics dependence on the above parameters, hydrodynamic conditions leading to dilution effects, sorption to suspended particles, phototransformation, and other factors leading to loss from the aquatic compartment (Voie and Mariussen ; Lotufo et al ). Overall, MC persistence in the environment is a key determinant of exposure (Lotufo et al ).…”