Mobilization, Adsorption, and Bioavailability of Pt and Pd in Coastal Sediments: The Role of the Polychaete, Arenicola marina

Abstract

The biogeochemical behavior of Pt and Pd in coastal sediments has been examined in a series of microcosms, both in the presence and absence of the deposit-feeding invertebrate, Arenicola marina. When metals were introduced to the overlying water column as solutes from acidified standards, A. marina dramatically enhanced their sorption to sediment throughout the core depth (14 cm) compared with an unfaunated control by exposing a greater surface area of particles to more rapidly ventilating contaminated water. After a 10 day incubation period, the assimilation efficiency (AE) by A. marina was about 10% for Pt and 1% for Pd. Calculations based on either partition constants or operational measures of metal bioaccessibility in sediment (using the protein, BSA) suggested that both aqueous and dietary sources of metal were important When Pt and Pd were introduced to the sediment-water interface as components of ground catalytic converter particles, significant subduction was effected by A. marina, and metals were solubilized to a greater extent than in an unfaunated control. AE in these experiments was < 0.1% for Pt and about 1% for Pd, and the most important vector for assimilation appeared to be from the aqueous phase via partial solubilization of metal from catalytic material. The findings of this study improve our understanding of the availability, cycling, and fate of Pt and Pd in contaminated estuaries and coastal waters.

Metal fate and effects in estuaries: A review and conceptual model for better understanding of toxicity

“…Particulate metals are also released as a result of chemical changes caused by aquatic plants (Greger et al, 1995) and benthic organisms (French and Turner, 2008). The organic matter provided by biota detritus and roots exudates plays an important role as food source for microorganisms, which catalyse a series of redox reactions in the presence of electron acceptors.…”

“…Indeed, French and Turner (2008) found that platinum metals introduced via water show increased sorption behaviour when sediments are colonized by the deposit feeder Arenicola marina. On the other hand, the same species increased pore water metal concentrations up to 2 orders of magnitude by remobilizing contaminated sediment (French and Turner, 2008). Relocation of metals as faecal pellets might also affect their distribution.…”

“…Relocation of metals as faecal pellets might also affect their distribution. Assimilation rates about 10% of Pt from water and sediment imply that 90% of ingested metal is transferred to faecal pellets (French and Turner, 2008). The high filtration capabilities of some molluscs also have a potential to significantly affect sedimentation of particles at whole estuary scale.…”

The English Channel: Contamination status of its transitional and coastal waters

“…Kinetic constraints on the partitioning of Pt suggested that sorption of the dissolved metal to particles would be favoured in longer residence time coastal waters (Cobelo-Garcia et al, 2008). Studies using water, sediment and the polychaete Arenicola marina from the Erme Estuary (SWRBD) showed these benthic organisms potentially have an important role in the cycling and fate of both dissolved and catalytic convertor particle PGE in estuarine environments (French and Turner, 2008). There have been few toxicity studies of PGE undertaken on marine organisms.…”

Synthesis of palladium colloids within polydimethylsiloxane and their use as catalysts for hydrogenation

“…However, free colloidal catalytic particles, which can be both expensive and toxic, pass through conventional filters and could end up in a consumer product or in the environment. There is growing evidence that colloids released into the environment find their way into biological systems [4,5]. These concerns have led to proposed limits on the use of free colloidal particles in environmental settings [6].…”