Silicones as tracers for anthropogenic additions to sediments

Pellenbarg, Robert E.

doi:10.1016/0025-326x(79)90484-3

Cited by 42 publications

(13 citation statements)

References 5 publications

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“…The fate of silicones in soil is not yet understood, but an early study showed that when polydimethylsiloxane (PDMS) fluids were coated on air-and oven-dried soils, the silicone polymers rearranged to small oligomers, with the reaction inhibited by small amounts of moisture [I]. This inhibition of degradation by moisture is supported by the fact that silicones have been judged stable enough in marine sediments to be used as markers of human activity [2].…”

Section: Introductionmentioning

confidence: 99%

Degradation of silicone polymers in soil

Lehmann

Varaprath

Frye

1994

Enviro Toxic and Chemistry

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Silicone polymers (polydimethylsiloxanes, or PDMS) are used in numerous personal care and household products, eventually enter wastewater treatment plants, and are later applied to the land as a component of sludge. The fate of silicones in soil is largely unknown, but this study shows that in a moist (0.2 MPa = 12% moisture) Londo sandy clay loam, 200 centi‐stoke (cs)14C‐labeled PDMS degraded slowly over six months to yield about 3% of applied 14C as low‐molecular‐weight, water‐soluble products. When the soil was allowed to dry in one week from 12 to 3% moisture, the degradation rate was much more rapid, and after several days at 3 % moisture about half of the applied 14C was water desorbable. HPLC‐GPC of tetrahydrofuran (THF) soil extracts showed that PDMS had been degraded to low‐molecular‐weight molecules of the general formula HO‐[Si(CH3)2O]n‐H. The range of moistures in this experiment was measured in a field of Londo sandy clay loam during the summer of 1992, indicating that PDMS should be unstable in the soil environment. Further work on the identification and biological degradation of these small products is ongoing.

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Section: Introductionmentioning

confidence: 99%

Degradation of silicone polymers in soil

Lehmann

Varaprath

Frye

1994

Enviro Toxic and Chemistry

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“…These results confirm the ecological acceptability of demethylated silicon moieties, demonstrate that the accompanying D and T structures have no significant toxicity for diatoms, and show that even monomethyl silicon moieties are not utilized as silicic acid sources by diatoms. Studies by Pellenbarg [4,5] have demonstrated "silicones to be a ubiquitous component of the sediments and of the water-surface microlayer of widely spaced and differing aqueous compartments." Because of the adsorptive tendencies of methylsilicones and their resistance to hydrolysis, their extensive environmental persistence as ecologically benign aquatic sedimentary components is anticipated.…”

Section: Diatom Studiesmentioning

confidence: 99%

Photolytic Oxidative Demethylation of Aqueous Dimethylsiloxanols

Buch

Lane

Annelin

et al. 1984

Environ Toxicol Chem

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Dimethylsilanediol and other water-soluble dimethysiloxanols undergo aqueous photolytic oxidative demethylation with tropospheric ultraviolet radiation in the presence of suitable chromophores, such as nitrogen oxides, to give silicic acid and carbon dioxide. The "bio suitability" of the resulting silicic acid was demonstrated by monitoring the growth of diatoms (Nuviculu pelliculosa) in the irradiated aqueous media. Thus, a plausible route for the further degradation of such water soluble hydrolysis products of poly(dimethy1-siloxane) to naturally occurring materials was conclusively demonstrated. Furthermore, di-and monomethyl silanol species were shown not to be utilized by the diatom colony, even when present as completely water soluble components.

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“…Previous work [1][2][3][4] has clearly established the utility of silicones as tracers for the movement of surficial sediments in a variety of aquatic systems. Indeed, silicones appear to collect preferentially on sedimentary particles, probably as a manifestation of their surface-active properties.…”

Section: Introductionmentioning

confidence: 99%