Phthalates and Nonylphenols in Roskilde Fjord

More documents

Recommendations

Info

The diffusivity of a molecule depends on the random movements(Brownian motion) which again is dependant on the kinetic (or internal)energy. The kinetic energy is defined as ½ ⋅ m ⋅ v 2 stating that largermolecules have lower mean velocities than smaller molecules, givenequal energy levels. Furthermore the increased cross sectional areas reducethe mean free path in the carrier medium resulting in a lower mobilityof larger molecules compared to smaller molecules.This relationship between molecular size and diffusivity can be used topredict diffusivities of compounds from known diffusivities of othercompounds based alone on the molecular masses, cf. Equation 7(Schwarzenbach et al., 1993)DDunknownknownmassknown≈ (7)massunknownThis requires that the carrier media are the same and that the chemicalstructures are related. Benzene can be used as a model compound forcalculating the diffusivity of DEHP that also contain a benzene ring inaddition to the alkyl chains and ester groups. Schwarzenbach et al.(1993) have found a diffusion coefficient in water for benzene (M w = 78g ⋅ mol -1 ) of approximately 10 -9 m 2 ⋅ sec -1 .DDEHP= Dbenzene⋅mmbenzeneDEHP=1 ⋅ 10-92msec.⋅78391= 5 ⋅ 10-102msec.Fick’s 1st law can describe the vertical substance flux in the sedimentdCS⎡ mg ⎤sz= θ ⋅ Ddisp,sz ⋅dz ⎢⎣m⋅ sec. ⎥(8)⎦N2where θ is the porosity of the sediment and D disp,sz is the dispersion coefficient,defined as2⎡ m ⎤Ddisp, sz= α ⋅ vp+ Dsz⎢ ⎥(9)⎣sec.⎦where α is the longitudinal dispersivity, v p is the advective pore watervelocity (≈ 0) and D sz is the molecular diffusion coefficient.Schwarzenbach (1993) suggests the following empirical relationshipD=D=5100.55=2102msec.1.5-101.5-10(10)disp, szszAdditionally, under favourable conditions, the redistribution of sedimentparticles by benthic macro fauna can occur by a variety of processes.This bioturbation can influence the transport and fate of hydrophobic xenobioticsin the surface layer. The particle reworking and the pumping ofpore water can create a mixed layer where the adsorbed and dissolved62
substances migrate more rapidly than can be accounted for by moleculardiffusion.The extension of the mixing layer is dependent on the macro organism.For lugworm Arenicola marina, which is the predominant benthic organismin the inner Fjord, a 5 to 10 cm bioturbation zone in depths of approximately15 cm can be expected. However, the sediment core wasextremely hard and therefore it is expected that the influence from bioturbationis negligible. This is confirmed by the DEHP concentrationprofile in the sediment core.Thus neglecting the influence from bioturbation, the horizontal concentrationgradient is much smaller than the vertical concentration gradientand the horizontal diffusion can be omitted in the mass balance for amodel sediment volume.6.1.5 Horizontal transport in the waterThe hydraulic effect from the sea will cause a high flow through the narrowparts in the middle of the Fjord. This combination of saline intrusionsand fresh water discharges causes a salinity gradient ranging from20 ‰ in the northern entrance to 14.5 ‰ in the inner parts of the Fjord(Harremoës et al., 1990).In the preceding section it is assumed that the convective flow in thesediment is zero. This excludes the influence of percolation of groundwaterthrough the sediment into the Fjord. This is an assumption that willnot hold at local spots where freshwater intrusions will enter the salineFjord and lower the salinity on a local scale. The approach in this work isto consider net deposition, streams and anthropogenic outlets as the onlyfreshwater sources to the fjord.Due to an effective large scale mixing of the water volumes, which enhancesthe vertical transport of dissolved and particulate matter, the verticalconcentration gradient is negligible, resulting in a mean depth integratedconcentration in the water column. The large scale mixing, whichis caused by a combination of turbulence and convection, is also the predominantprocess in the horizontal transport of water and substances inthe shallow Fjord.The salinity mixing data can be used to calculate an effective longitudinaldispersion coefficient for the narrow part of the Fjord. Assuming auniformly distributed freshwater supply along the shore of 1.16 ⋅ 10 -4 m 3 ⋅(m ⋅ sec) -1 , a mean cross sectional area of 2610 m 2 , a length of 28 km andsalinities of 20 ‰ in the northern entrance and 14.5 ‰ in the Bredning,the effective dispersion coefficient can be calculated from the salinitygradient (Harremoës et al., 1990)Dwx=-4 m1.16 ⋅ 10 ⋅sec.22 ⋅ 2610 m ⋅2( 28000 m)20.0ln14.52=542msec.(11)63
Page 2 and 3:
[Blank page]
Page 4 and 5:
Data sheetTitle:Phthalates and Nony
Page 6 and 7:
6.2 Sources 646.3 Model parameters
Page 8 and 9:
The physico-chemical processes in t
Page 10 and 11:
De fysisk-kemiske processer i fjord
Page 13: 2 PurposeThe aim of the study has b
Page 16 and 17: In Table 3 the flow in the streams
Page 18 and 19: 3.3 Samples of fjord sedimentFinall
Page 21 and 22: 4 AnalyticalThe following substance
Page 23 and 24: 4.5 Standards and spikesThe labelle
Page 25 and 26: In Table 9 the results of the test
Page 27: The analysis was carried out as des
Page 30 and 31: 100Concentration ng/l90807060504030
Page 32 and 33: 400300DBP ng/l2001000JunJunSepDecMe
Page 34 and 35: 5.1.3 Monthly samples in Roskilde V
Page 36 and 37: 5.1.4 Analysis of varianceTo evalua
Page 38 and 39: Table 15 Correlations at Stations 2
Page 40 and 41: 500r = 0.86 (p=0.01)400DEHP ng/l al
Page 42 and 43: Table 16 Concentrations in fjord se
Page 44: tion levels off, ultimately approac
Page 47 and 48: 200NPNPDEConcentration, ng/g d.m.15
Page 49 and 50: was observed in the flow direction
Page 51 and 52: 1000800meanConcentration, ng/g dw60
Page 53 and 54: NPDE and DEHP in the Hove Å system
Page 55 and 56: µg/m²/y000800600400200013-Nov27-N
Page 57 and 58: 6 Mathematical data interpretationI
Page 59 and 60: 6.1.2 Sorption and solvationIn the
Page 61 and 62: Different standard methods can be u
Page 63: Introducing the concentration of se
Page 67 and 68: • In 1969 in connection with work
Page 69 and 70: SeaDispersion modelBox-modelsIsefjo
Page 71 and 72: AtmosphericdepositionxdxN wx + ∂
Page 73 and 74: tWater gridxo• • •i+1 i i-1x
Page 75 and 76: 6.4.3 Dynamic solution to the diffu
Page 77 and 78: The two diffusion curves and the tw
Page 79 and 80: Fluxsedimentation /Fluxtotal1,00,90
Page 81 and 82: µg DEHP / sec10008006004002000-200
Page 83 and 84: 7 ConclusionsDEHP was the most abun
Page 85 and 86: 8 ReferencesBerger, W.H. & Heath, G
Page 87: Smith, R. (1986): Mixing and Disper
Page 90 and 91: NPNPDENPEPAEPFKPhthalatesdSIMSpikeS
Page 92 and 93: dzD benzeneD DEHPVertical step in s
Page 94 and 95: Ptt sedzαθ sProduct from bio-degr
Page 97 and 98: 12 Appendix A.Analytical performanc
Page 99 and 100: 4000NPDE3000Mean + - sdRegression l
Page 101 and 102: 300250DEHPMean + - sdRegression lin
Page 103 and 104: and mass-spectrometrical characeris
Page 105 and 106: 1000800BBPMean + - sdRegression lin
Page 107 and 108: National Environmental Research Ins
Page 109: The aim of the study has been to in
show all

Phthalates and Nonylphenols in Roskilde Fjord

Create successful ePaper yourself

Delete template?

Save as template?