Sulfur-containing functional groups in dissolved organic matter (DOM) interact with trace metals, which in turn affects trace metal mobility and bioavailability in aquatic environments. Typical methods for identification and quantification of sulfur in DOM are costly, complex, and time intensive. Triple quadrupole inductively coupled plasma tandem mass spectrometry (ICP-MS/MS) is capable of part per billion-level sulfur quantification in environmental samples and is a more accessible analytical technique compared with other available methods. This study is the first published investigation of ICP-MS/MS for the direct quantification of sulfur in freshwater DOM. Sulfur ( 32 S) detection occurs at a mass-to-charge ratio of 48 as 32 S 16 O + after removal of interferences and reaction with oxygen gas. We compare three commonly used DOM preparation methods to assess variability among replicate samples. Preparation of freshwater DOM samples by solid phase extraction followed by evaporation overnight and dissolution in 2% nitric acid results in the most accurate quantification of sulfur. Analysis of sulfur in Suwannee River Fulvic Acid standard serves as method validation, measuring a carbon-normalized sulfur concentration that is ∼20% higher than previously reported methods. We apply the ICP-MS/MS analysis method to determine sulfur concentrations in DOM from nine lakes in the northern Midwest. Carbon-normalized sulfur concentrations in the selected lakes are in general agreement with previously reported percentages of sulfur-containing formulas in DOM found by Fourier transform-ion cyclotron resonance-mass spectroscopy.

Inorganic mercury in sediments is a potential source of bioaccumulative methylmercury in the aquatic food web; however, in many cases, total mercury concentrations in the sediment alone cannot predict methylmercury production and distribution. Fish that primarily feed in the St. Louis River Estuary, a Great Lakes coastal wetland, have higher concentrations of methylmercury in their tissues than fish that primarily feed upriver or in Lake Superior; however, the exact sources of mercury to methylating microorganisms and methylmercury to fish remain unknown. Solid-phase mercury pools, sediment and porewater chemistry, and sediment–porewater partitioning are assessed here to obtain a more detailed understanding of the role of sediments in methylmercury production. We show that in sediments where concentrations of reduced sulfur groups in dissolved organic matter in the porewater approach or exceed aqueous inorganic sulfide, there are higher concentrations of total mercury in the porewater. Reduced sulfur groups in dissolved organic matter raise the fraction of total mercury in the porewater where it may be more accessible for methylation and uptake to the food web. In the St. Louis River Estuary, conditions which facilitate greater partitioning of total mercury to the porewater correspond to sediments with lower sediment total mercury concentrations, highlighting that absolute total mercury concentration in the sediment alone cannot accurately assess the potential for mercury mobility and bioaccumulation. This study elucidates factors, mainly the presence of reduced sulfur groups in dissolved organic matter in the porewater, which facilitate the partitioning of total mercury to the porewater.

Wetlands provide unique habitat functions that benefit society by provisioning food, recreation, and ecosystem sustainability. Warfare affects the habitats of wetland‐dependent reptiles, amphibians, and birds in both positive and negative ways, and opportunities exist to improve the management of wildlife habitat using a warfare ecology framework. Recent events in Ukraine highlight these relationships and provide stimulus to further consider the implications of current events for natural resources. In response, this commentary highlights both degradational and positive impacts of warfare on wetland fauna during the cyclical preparation, active conflict, and recovery phases. For example, the active conflict phase often initiates ecological disturbance regimes that couple large‐scale landscape alteration with the release of chemicals and other materials into wetlands, leading to reduced reproductive potential and population declines in wetland‐dependent species (e.g., amphibians, waterfowl) along with decreased overall wetland biodiversity and habitat quality. In contrast, wetland‐dependent wildlife can benefit from (1) conservation activities occurring on military installations maintained to support training activities and (2) restoration efforts initiated after the cessation of combat. For example, many threatened and endangered reptiles and amphibians find refugia on military lands in the USA and internationally, and international protections for wetland resources (including the Ramsar Convention) have been established to promote their sustainability and wise use. Additional research is needed to improve the protection of valuable wetland resources by further enhancing ongoing conservation and planning efforts and improving strategies to mitigate the negative impacts of warfare on wetland dependent species throughout each phase of the warfare ecology cycle. Integr Environ Assess Manag 2023;00:1–9. Published 2023. This article is a US Government work and is in the public domain in the USA. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).