Impact of bioturbation by Arenicola marina on the fate of particle-bound fluoranthene

Abstract

The fate of particle-bound '"Cluoranthene deposited at the sediment-water interface in microcosms with different densities (0 to 300 m-2) of Arenicola marina was followed for 28 d. Worms had a pronounced effect on the degradation rate of fluoranthene. Defecated material quickly buried the surface layer of I4C-fluoranthene into deeper layers of the sediment, where degradation of fluoranthene was much slower than at the more reactive surface sediment in microcosms without A. manna. Only 0.3 and 2.9% of '4C-fluoranthene was mineralised to "CO2 after 28 d i n treatments with and without A. marina, respectively. There was no significant difference between degradation rates among different densities of A. marina, although the mixing of fluoranthene into deeper sediment layers was enhanced at higher worm densities. The D0I4C and PO1'C (particulate and dissolved organic '"C) in the overlying water were negatively related with worm density. The ventilating currents of A. marina may have repositioned 14C-activity from the water into deeper sediment layers, which then acted to filter both dissolved and bound fluoranthene. I4C-activity was high in worms after 28 d, approximately an order of magnitude higher than that mmeralised to 14C02 during this penod. The removal of deposited organic contaminants on sediment surfaces through degradation at the highly reactive sediment-water interface or through local transport by currents or wave action can b e reduced as a result of burial of contaminants by bioturbating organisms. Contaminants may thus persist longer in the sediment environment and will be released from the sediment over a prolonged period of time. Enhanced biological transport of contaminants to depth can lead to increased exposure of infauna.

Effects of sediment organic matter quality on bioaccumulation, degradation, and distribution of pyrene in two macrofaunal species and their surrounding sediment

“…Pyrene is a particle reactive compound , log K OW between 4.50 and 5.32 (Meador et al, 1995), and its distribution is thus highly dependent on forces affecting particle mixing, such as macrofaunal feeding and burrowing. Species-specific differences in bioturbation behaviour often appear to leave finger prints in the distribution of contaminants in the sediment (Holmer et al, 1997, Kure & Forbes, 1997, Gunnarsson et al, 1999a, Gunnarsson et al, 1999b, Sandnes, Forbes, Hansen & Sandnes, 2000. N. diversicolor build, and continuously re-route, extensive burrow galleries (Davey, 1994), while A. filiformis, although sometimes observed to be highly mobile, construct only as much burrow needed for keeping disks buried at ~5 cm depth with 2-4 arms protruding from the sediment for feeding (Woodley, 1975, Jonsson, Broman, Gunnarsson, Lagergren, Larsson, Ohlsson et al, 1997 ( Fig.…”

“…PAH degrading microbes (algae, fungi and bacteria) are largely oxygen dependent (Atlas, 1981, Cerniglia, 1993, and macrofaunal bioturbation (i.e. irrigation and particle mixing) is therefore an important process affecting sedimentary PAH degradation through the oxygenation of deeper sediment layers, and through the transport of contaminated particles between oxic and reduced layers (Gardner, Frez, Cichocki & Parrish, 1985, Bauer, Kerr, Bautista, Decker & Capone, 1988, Holmer, Forbes & Forbes, 1997, Kure & Forbes, 1997. and Granberg et al (2005) furthermore stress the importance of species specific bioturbation patterns for observed differences in microbial degradation and mineralization of pyrene in sediments.…”

Effects of the polychaetes Arenicola marina and Nereis diversicolor on microbial pyrene mineralization

“…In contrast, Kure & Forbes (1997) observed decreased mineralization of fluoranthene in a sediment containing A. marina. In that case, however, the fluoranthene was added as a contaminated top layer that was rapidly buried into anoxic sediment due to the conveyor belt feeding behaviour of A. marina (Kure & Forbes 1997). Our results are consistent with other sediment studies where the pollutants were uniformly distributed throughout the sediment.…”

“…stimulate the degradation of various PAHs, and enhancement factors of between 2 and 3 have been reported (Bauer et al 1988, McElroy et al 1990, Christensen et al 2002. In contrast, Kure & Forbes (1997) observed decreased mineralization of fluoranthene in a sediment containing A. marina. In that case, however, the fluoranthene was added as a contaminated top layer that was rapidly buried into anoxic sediment due to the conveyor belt feeding behaviour of A. marina (Kure & Forbes 1997).…”

“…The few studies examining the effects of macrobenthos on total microbial PAH mineralization indicate that this stimulation also applies to PAH degradation (Bauer et al 1988, McElroy et al 1990, Christensen et al 2002. However, decreased PAH degradation in the presence of polychaetes has also been observed due to transport of PAH-containing material from the surface into deeper anoxic zones (Kure & Forbes 1997, Banta & Andersen 2003.…”