Field validation of POCIS for monitoring at underwater munitions sites

Abstract

The present study evaluated polar organic chemical integrative samplers (POCIS) for quantification of conventional munitions constituents, including trinitrotoluene (TNT), aminodinitrotoluenes, diaminonitrotoluenes, dinitrotoluene, and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) in a field setting. The POCIS were deployed at varying distances from the commonly used explosive formulation composition B (39.5% TNT, 59.5% RDX, 1% wax) in an embayment of Santa Rosa Sound (Pensacola, FL, USA). Time-weighted averaged water concentrations from a 13-d deployment ranged from 9 to 103 ng/L for TNT and RDX, respectively, approximately 0.3 to 2 m from the source. Concentrations decreased with increasing distance from the source to below quantitation limits (5-7 ng/L) at stations greater than 2 m away. Moderate biofouling of POCIS membranes after 13 d led to a subsequent effort to quantify potential effects of biofouling on the sampling rate for munitions constituents. After biofouling was allowed to occur for periods of 0, 7, 14, or 28 d at the field site, POCIS were transferred to aquaria spiked with munitions constituents. No significant differences in uptake of TNT or RDX were observed across a gradient of biofouling presence, although the mass of fouling organisms on the membranes was statistically greater for the 28-d field exposure. The present study verified the high sensitivity and integrative nature of POCIS for relevant munitions constituents potentially present in aquatic environments, indicating that application at underwater military munitions sites may be useful for ecological risk assessment. Environ Toxicol Chem 2018;37:2257-2267. Published 2018 Wiley Periodicals Inc. on behalf of SETAC. This article is a US government work and, as such, is in the public domain in the United States of America.

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

“…Similar to what was observed for flume experiment 1, the concentrations of 2-and 4-ADNT were below detection levels for the field study . Cleaved artillery shells containing TNT and RDX exposed to seawater in situ for up to 3 yr showed minor visual evidence of mass loss (Ek et al 2006), corroborating the findings of the present study and those of Rosen et al (2018).…”

“…This finding corroborates mathematical predictions (Wang et al 2013) and demonstrates the high influence of degree of exposure to flow on rate of dissolution. Concentrations in the water resulting from the slow release of approximately 1.6 g of MC from Composition B fragments were orders of magnitude higher in a large flume (closed system, present study) than in a coastal embayment (open system, 0.3 m from the source; Rosen et al 2018), likely as a result of the dilution effect of hydrodynamic transport. Results from the present study and previous experimental and site characterization studies indicate that the release of MC from leaking munitions is likely to result in water column concentrations <100 µg/L, which are below concentrations reported to cause toxic effects to most species of aquatic organisms investigated .…”

“…The percentage of loss of Composition B mass observed for flume experiment 1 (16.5% in 10 d) was higher than the mass loss into Santa Rosa Sound (11% in 13 d; Rosen et al ). The lower mass loss for the field study is likely at least in part explained by the higher containment provided by the placement of Composition B fragments in stainless steel bags inside a canister and by the lower flow velocity (Rosen et al ). Contrasting with the relatively minor differences in mass loss during deployment and the relative concentration of TNT and RDX in the water column, major differences in the concentration of MC in the water column were observed between the closed system deployment in the present study and the field deployment (Rosen et al ).…”

“…The lower mass loss for the field study is likely at least in part explained by the higher containment provided by the placement of Composition B fragments in stainless steel bags inside a canister and by the lower flow velocity (Rosen et al ). Contrasting with the relatively minor differences in mass loss during deployment and the relative concentration of TNT and RDX in the water column, major differences in the concentration of MC in the water column were observed between the closed system deployment in the present study and the field deployment (Rosen et al ). The combined loss of 1.724 g of TNT and RDX in flume experiment 1 resulted in the sum TNT and RDX concentration of 36 µg/L, whereas the combined loss of 1.535 of TNT and RDX in the field resulted in an average sum TNT and RDX concentration of 0.16 µg/L approximately 0.3 m from the source (Rosen et al ).…”

“…Underwater sites around the world are known to contain underwater military munitions (UWMM) as a result of military activities or historic disposal events. Munitions constituents (MC) including 2,4,6‐trinitrotoluene (TNT) and 1,3,5‐trinitro‐1,3,5‐triazine (RDX) may be released into the surrounding aquatic environments as a result of UWMM corrosion and breaching of the munition's outer casing (Lewis et al ; Rosen and Lotufo ; Wang et al ; Li et al ; Voie and Mariussen ; Rosen et al ; Beck et al ). Release may also occur from fragments of explosives formulations that become exposed following low‐order (incomplete) detonations resulting in fully breached munitions (Beck et al ).…”