States <i>x</i>₁ and <i>x</i>₂ with <i>sat</i>(<i>u</i>).

States x1 and x2 with sat(u).</p

S1 File -

(ZIP)</p

Response curves of the saturated control input <i>sat</i>(<i>u</i>).

Response curves of the saturated control input sat(u).</p

Response curves of the output feedback signal.

Response curves of the output feedback signal.</p

Response curve of the saturated control input <i>sat</i>(<i>u</i>).

Response curve of the saturated control input sat(u).</p

States <i>x</i>₁ and <i>x</i>₂ with disturbance and <i>sat</i>(<i>u</i>).

States x1 and x2 with disturbance and sat(u).</p

Nonlinear circuit system.

Nonlinear circuit system.</p

Response curve of the output feedback signal.

Response curve of the output feedback signal.</p

States <i>x</i>₁ and <i>x</i>₂ with disturbance and without <i>sat</i>(<i>u</i>).

States x1 and x2 with disturbance and without sat(u).</p

Bioaccumulation and Trophic Transfer of Emerging Organophosphate Flame Retardants in the Marine Food Webs of Laizhou Bay, North China

Despite the increase in production, usage, and discharge of organophosphate flame retardants (OPFRs), little information is available about their bioaccumulation and trophic transfer in the marine food web. In this study, seawater, sediment, and marine species (10 fish and 9 invertebrate species) collected from Laizhou Bay, North China, were analyzed to investigate the levels, bioaccumulation, and biomagnification of OPFRs in a marine food web. Of 20 OPFRs screened for, 17 were quantifiable in seawater, sediment, and organisms. The ∑OPFRs concentrations ranged from 0.2 to 28.4 ng/L in seawater, 0.1–96.9 ng/g dry weight in sediment, and 21.1–3510 ng/g lipid weight in organisms. Benthic fish accumulated more OPFRs than pelagic fish and invertebrates. A linear and significant increase of bioaccumulation factors with increasing lipophilicity of OPFRs was observed (R2 = 0.63, p < 0.05), and the biota-sediment accumulation factors increased with hydrophobicity up to log KOW = 4.59 and then decreased with increase in log KOW. Trophic magnification factors of OPFRs ranged from 1.06 to 2.52, indicating biomagnification potential of OPFRs in a marine food web. This study provides important insight into the biomagnification potential of OPFRs and suggests further investigation on this group of chemicals