Annable, Michael D.

Bjerg, Poul Løgstrup

Cremeans, Mackenzie

McKnight, Ursula S.

Rønde, Vinni Kampman

Sonne, Anne Thobo

Online Research Database In Technology

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Downloaded from orbit.dtu.dk on: Mar 30, 2019Attenuation of a discharging chlorinated ethene (CE) plume: use of streambed pointvelocity probes (SBPVP), streambed passive flux meters (SBPFM) and contaminantmass discharge (CMD)Rønde, Vinni Kampman; McKnight, Ursula S.; Annable, Michael D.; Cremeans, Mackenzie; Sonne, AnneThobo; Bjerg, Poul LøgstrupPublication date:2017Document VersionPublisher's PDF, also known as Version of recordLink back to DTU OrbitCitation (APA):Rønde, V. K., McKnight, U. S., Annable, M. D., Cremeans, M., Sonne, A. T., & Bjerg, P. L. (2017). Attenuation ofa discharging chlorinated ethene (CE) plume: use of streambed point velocity probes (SBPVP), streambedpassive flux meters (SBPFM) and contaminant mass discharge (CMD). Poster session presented at 2017 AGUFall Meeting, New Orleans, United States.StreambedStreamActivated carbon mixed with alcohols inside slotted pipeStudy site: Grindsted stream, DK (Fig. 1)• Geology: sandy• Average annual discharge: 2000 L/s. • Impacted by contaminated site 1.5 km north of streamAttenuation of a discharging chlorinated ethene (CE) plume: use of streambed point velocity probes (SBPVP), streambed passive flux meters (SBPFM) and contaminant mass discharge (CMD)Vinni Rønde (1), Ursula S. McKnight (1), Michael D. Annable (2), John F. Devlin (3), Mackenzie Cremeans (3), Anne Th. Sonne (1), and Poul L. Bjerg (1)OBJECTIVES1) Compare bank, streambed and in-stream CMD estimates obtained from:• CE concentrations and Darcy’s law,• CE concentrations and SBPVP data• SBPFM data2) Assess the attenuation of a CE plume discharging to a stream by including CMD calculations. (1) Department of Environmental Engineering, Technical University of Denmark, Kgs. Lyngby, Denmark, (2) Department of Environmental Engineering Sciences, University of Florida, Gainesville, FL, United States, (3) Department of Geology, University of Kansas, Lawrence, KS, United StatesEmail: vikar@env.dtu.dkStream bank fluxCombining concentrations and water fluxes from Darcy’s law and PVPs along CP1 (Fig. 2), using Eq.1 [1]:Streambed fluxSBPVP (Fig 3A): Combining concentrations and SBPVP seepage velocities in coloured area in Fig 2, using Eq.1 [2].SBPFM (Fig 3B): SBPFM contaminant fluxes along plume core transect (Fig. 1 & 2), using Eq.2 [4]:Based on tracer removal, Darcy fluxes were obtained from an analogue to Eq.2. In-stream CMDObtained from stream concentrations and corresponding stream discharge at fully mixed conditions (Fig 2) [1].Contaminant input from culverts (Fig 1) and upstream of plume discharge zone were subtracted.tracer linedetector wiresdetectorsinjection portflow upward or downwardFig. 3: Principles of the SBPVP (A), modified from [3], and SBPFM (B). Residence times from bank to streambedShort residence times from bank to streambed (Table 2)  no time for degradation.α = convergence coefficientA = area of control planec = concentrationJ = contaminant fluxm = sorbed massn = porosityr = radius of sorbent column t = test timev = seepage velocityq = Darcy flux Q = stream dischargeIntroduction MethodsConclusionsFig. 4: CE conc. based on water samples (coloured contour), SBPFMs (coloured rectangles) and hydraulic head (m asl) (line contours). Lower graph: SBPFM Darcy fluxes (blue curve), CE fluxes (green), conc. of cis-DCE (orange) and VC (red).Plume core discharge to streamSpatial pattern of SBPFM-derived concentrations agree with water samples (Fig 4).Highest CE fluxes occurred at high concentration zones  CE flux is controlled by concentrations (Fig. 4). CE conc. (µg/L, PCEeq)culvertFig. 1: Field work at plume core transect.𝐽 = 𝑐𝑞 = 𝑐𝑣𝑛 (1)𝐽 =𝑚α𝜋𝑟2𝑡(2)𝐶𝑀𝐷 = 𝑐𝑄 (4)From contaminant flux to CMD1) Rønde, V., Mcknight, U.S., Sonne, A.T., Balbarini, N., Devlin, J.F., & Bjerg, P.L. (2017). Contaminant mass discharge to streams: comparing direct groundwater velocity measurements and multi-level groundwater sampling with an in-stream approach. Journal of Contaminant Hydrology. 206: 43-542) Cremeans, M. & Devlin, J.F. (accepted). Application of new point measurement device to quantify groundwater-surface water interactions. Journal of Contaminant Hydrology3) Cremeans, M. & Devlin, J.F. (2017). Validation of a new device to quantify groundwater-surface water exchange. Journal of Contaminant Hydrology 206:75-80 4) Layton, L., Klammler, H., Hatfield, K., Cho, J., newman, M.A. & Annable, M.D. (2017). Development of a passive sensor for measuring vertical cumulative water and solute mass fluxes in lake sediments and streambeds. Advances in Water Resources 105: 1-12Assessment of attenuation through CMDPlume core and total CMD estimates at the streambed are comparable to  corresponding bank CMD estimates (Table 1). no/limited mass loss from bank to streambed.In-stream CMD is comparable to total bank and streambed CMD estimates (Table 1)  no/limited mass loss from bank to fully mixed point.Similar molar ratios for bank, streambed and in-stream CMD (Fig. 5)  no/limited dechlorination, despite favorable redox conditions.𝐶𝑀𝐷 = 𝐴𝐽 (3)• Total SBPVP-based CMD is comparable to bank estimates.• Plume core SBPFM-based CMD is comparable to bank estimates.  SBPVP and SBPFM are promisingtools for estimation of streambed CMD• Total CMD at bank, streambed and in stream are comparable. No/limited mass loss• No/limited shift in molar ratios of specific CE  No/limited degradation• Short streambed residence time is thought to cause the lack/limited degradation despite favorable redox condition. • In-stream mixing is the dominant attenuation process.Table 1: Preliminary CMD at plume core transect (along 1m stream reach) and total CMD (along entire plume width) for CE at the bank, streambed and in stream.Fig. 2: SBPVP-based CE flux (coloured contour, data from [2]), and locations of CP1, plume core transect and point of fully mixed conditions.BAMethod Darcy flux(m/d)residence time(d)SBPVP 2.2 ± 1.6 1.7SBPFM 0.14 ± 0.11 27Darcy 1.0 3.7Table 2: Average Darcy fluxes (± standard deviation) and residence times from bank to streambed at plume core transect. Assumptions: n=0.37 [1], travel distance=10 m.In-stream mixingStream water concentrations are non-uniformly distributed at plume core transect (Fig. 4).Transverse in-stream mixing occurs to point of fully mixed conditions 200 m further downstream (Fig 6). Implications for stream water sampling strategy.Fig. 6: In-stream concentrations in transects across the stream [1].Funding: The innovation Fund Denmark & The Region of Southern Denmark3020100 Darcyflux(cm/d)CE flux(g/m2/d, PCEeq)cis-DCE/VCconc. (mg/L, PCEeq)Distance from south bank (m)0          2          4           6         8         10        12Chlorinated ethenes (CE) are common groundwater contaminants and pose risk to groundwater and surface water. To conduct proper risk assessment at stream sites, knowledge on CE attenuation is essential, but these processes are still not fully understood. An approach to assess CE attenuation of discharging plumes is CMD calculations. These require CE fluxes, which can be obtained by streambed SBPFM data or by combining concentrations and SBPVP data. Preliminary resultsMethod CMD plume core(kg/y, PCEeq)Total CMD(kg/y, PCEeq)PVP (mean q) 8.6 204Bank PVP (varying q) 7.7 269Darcy 13 372SBPVP 63 310Streambed SBPFM 10 pendingDarcy 23 pendingIn-stream From GW - 5583020100 62%38%56%44%60%39%PCE: 1%Stream bank(PVP, varying q)Streambed(SBPFM)In-stream(from GW)Fig. 5: Molar ratios  of CMD (grey: cis-DCE, yellow: VC) at bank, streambed and in-stream. Methods not shown suggest similar trend.  

Attenuation of a discharging chlorinated ethene (CE) plume: use of streambed point velocity probes (SBPVP), streambed passive flux meters (SBPFM) and contaminant mass discharge (CMD)

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Attenuation of a discharging chlorinated ethene (CE) plume: use of streambed point velocity probes (SBPVP), streambed passive flux meters (SBPFM) and contaminant mass discharge (CMD)

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