In situ measurements of explosive compound dissolution fluxes from exposed munition material in the Baltic Sea

Underwater munitions containing millions of tons of toxic explosives are present worldwide in coastal marine waters as a result of unexploded ordnance and intentional dumping. Dissolution flux of solid explosives following corrosion of metal munition housings controls exposure of biological receptors to toxic munition compounds (MC; including TNT: 2,4,6-Trinitrotoluene, RDX: 1,3,5-Trinitro-1,3,5-triazinane, and DNB: 1,3-Dinitrobenzene). Very little is known about the dissolution behavior of MC in the marine environment. In this work, we exploit a unique marine study site in the Baltic Sea with exposed solid explosives to quantify in situ MC dissolution fluxes using dissolved MC gradients near the exposed explosive surface, as well as benthic chamber incubations. The gradient method gave dissolution fluxes that ranged between 0.001 and 3.2, 0.0001 and 0.04, and 0.003 and 1.7 mg cm-2 d-1 for TNT, RDX, and DNB, respectively. Benthic chamber incubations indicated dissolution fluxes of 0.0047-0.277, 0-0.11, and 0.00047-1.45 mg cm-2 d-1 for TNT, RDX, and DNB, respectively. In situ dissolution fluxes estimated in the current study were lower than most dissolution rates reported for laboratory experiments, but clearly demonstrated that MC are released from underwater munitions to the water column in the Baltic Sea

Quantification of munition compounds in the marine environment by solid phase extraction – ultra high performance liquid chromatography with detection by electrospray ionisation – mass spectrometry

Highlights • High resolution mass spectrometry used to detect munition compounds. • Isotope dilution used for accurate quantification of TNT. • Seven explosives and metabolites detected in seawater at ng L−1 concentrations. • Ten explosives and metabolites detected in marine biota from a contaminated site. Abstract As a consequence of World War II, large amounts of munition have been deposited in coastal waters. Deterioration of the mines and bombs is resulting in a release of munition compounds (MCs) like trinitrotoluene to the surrounding marine environment, with potential implications to ecosystems. Analytical methods have thus far been unable to detect these compounds reliably in seawater. We present a highly sensitive method for the analysis of MCs in the marine environment. We combine preconcentration and sample clean up by solid phase extraction with separation and detection by ultra-high performance liquid chromatography – electrospray ionisation – mass spectrometry (UHPLC-ESI-MS) for the detection of MCs dissolved in filtered (< 0.2 µm) seawater. For biota, dried and ground samples were extracted in acetonitrile and analysed after simple dilution. Eleven MCs were detected by UHPLC-ESI-MS with limits of detection between 0.01 and 25 pg. For the first time, we used heavy isotopes of trinitroluene and dinitrobenzene to improve quantification in environmental samples. We detected 7 MCs in waters sampled at a known munition disposal site in the Baltic Sea after a 1000-fold preconcentration and using an injection volume of 25 µL. Trinitrotoluene and dinitrobenzene were the most abundant MCs, occurring at concentrations between 0.1 and 11.8 ng L−1. We observed 10 MCs at concentrations up to 24 µg g−1 dry weight in benthic organisms sampled from the site. The enhanced sensitivity of our method allowed us to detect MCs at concentrations relevant for assessment and management of munitions disposal sites in the marine environment

Spread, Behavior, and Ecosystem Consequences of Conventional Munitions Compounds in Coastal Marine Waters

Coastal marine environments are contaminated globally with a vast quantity of unexploded ordnance and munitions from intentional disposal. These munitions contain organic explosive compounds as well as a variety of metals, and represent point sources of chemical pollution to marine waters. Most underwater munitions originate from World Wars at the beginning of the twentieth century, and metal munitions housings have been impacted by extensive corrosion over the course of the following decades. As a result, the risk of munitions-related contaminant release to the water column is increasing. The behavior of munitions compounds is well-characterized in terrestrial systems and groundwater, but is only poorly understood in marine systems. Organic explosive compounds, primarily nitroaromatics and nitramines, can be degraded or transformed by a variety of biotic and abiotic mechanisms. These reaction products exhibit a range in biogeochemical characteristics such as sorption by particles and sediments, and variable environmental behavior as a result. The reaction products often exhibit increased toxicity to biological receptors and geochemical controls like sorption can limit this exposure. Environmental samples typically show low concentrations of munitions compounds in water and sediments (on the order of ng/L and μg/kg, respectively), and ecological risk appears generally low. Nonetheless, recent work demonstrates the possibility of sub-lethal genetic and metabolic effects. This review evaluates the state of knowledge on the occurrence, fate, and effect of munition-related chemical contaminants in the marine environment. There remain a number of knowledge gaps that limit our understanding of munitions-related contaminant spread and effect, and the need for additional work is made all the more urgent by increasing risk of release to the environment