Mercury Flux in an Urban Watershed System

Mercury Flux in an Mercury Flux in an Urban Watershed Urban Watershed

SystemSystem

Joseph T. BusheyJoseph T. Bushey11, Peter M. Groffman, Peter M. Groffman22, , Charles T. DriscollCharles T. Driscoll11, Gary T. Fisher, Gary T. Fisher33

11Syracuse University Dept. of Civil & Syracuse University Dept. of Civil & Environmental EngineeringEnvironmental Engineering

22Institute of Ecosystem Studies, Institute of Ecosystem Studies, 33US US Geological SurveyGeological Survey

October 19, 2006October 19, 2006

OverviewOverview

BackgroundBackground ObjectivesObjectives ResultsResults

UrbanizationUrbanization Storm EventsStorm Events

ConclusionsConclusions

Why?Why? NeurotoxinNeurotoxin BioaccumulationBioaccumulation potential potential

What?What? Gaseous HgGaseous Hgoo

HgHg2+2+ (RGM, ionic, particulate) (RGM, ionic, particulate) Methyl Hg – BAD GUYMethyl Hg – BAD GUY, bioaccumulates, bioaccumulates

Where?Where? Paints, pesticides, scientific/medical, Paints, pesticides, scientific/medical,

electricalelectrical Manufacturing (e.g. chlorine)Manufacturing (e.g. chlorine) Utilities/fossil fuels → atmospheric Utilities/fossil fuels → atmospheric

depositiondeposition

(Cartoon from: www.grinningplanet.com)

Why Urban?Why Urban? Increased anthropogenic inputsIncreased anthropogenic inputs Altered ecosystem processesAltered ecosystem processes

AddedAdded

exposureexposure

ObjectivesObjectives Quantify the effect on Hg species flux Quantify the effect on Hg species flux

with respect to:with respect to: Urbanization/Land use changesUrbanization/Land use changes Elevated discharge eventsElevated discharge events

Assess the impact of ecosystem Assess the impact of ecosystem alterations on Hg transport and alterations on Hg transport and transformation processestransformation processes

11 Sites associated with Gwynns Falls 11 Sites associated with Gwynns Falls LTERLTER

Mercury: THg, MeHg, filtered vs. unfilteredMercury: THg, MeHg, filtered vs. unfiltered Ancillary chemistry: e.g. DOC, TSS, SOAncillary chemistry: e.g. DOC, TSS, SO44

2-2-, DO, DO

Main Main BranchBranch

ForestSuburban

Urban

Suburban Boundary

PB GB VN CPForest

ReferenceSuburbanHeadwater

SuburbanBoundary

UrbanOutlet

THg 1.10 0.50 0.73 0.85

MeHg 0.045 0.011 0.019 0.020

DOC 0.70 0.66 0.88 1.39

TSS 2.23 1.21 2.04 1.73

Main Stem Chemical Main Stem Chemical FluxFlux(Units: THg, MeHg – (Units: THg, MeHg – g mg m-2-2 yr yr-1-1; DOC, TSS – g m; DOC, TSS – g m-2-2 yr yr-1-1))

What are effects of What are effects of urbanization?urbanization?- Hg mobility -- Hg mobility -

THg ↑ with THg ↑ with urbanization urbanization WRTWRT

DOCDOC TSSTSS

Effect of Effect of runoff runoff

Particulate Particulate Hg Hg important important for flux for flux

What are effects of What are effects of urbanization?urbanization?

- Methylation potential -- Methylation potential - MethylationMethylation

De-coupling of De-coupling of Hg-DOC Hg-DOC

Decreased Decreased effect of biotic effect of biotic activity on Hg activity on Hg mobilitymobility

AnthropogeniAnthropogenic DOC c DOC source? Oxic source? Oxic conditions?conditions?

What are effects of elevated What are effects of elevated events?events?

Base

Forest

Suburban

Urban

ConclusionsConclusions

Urbanization alters Hg-DOC Urbanization alters Hg-DOC relationship and effects on relationship and effects on Hg mobilityHg mobility

THg and MeHg flux ↓ under THg and MeHg flux ↓ under base flow conditions for base flow conditions for developed ecosystemsdeveloped ecosystems

Importance of particulate Importance of particulate and high flow events on THg and high flow events on THg fluxflux

Future WorkFuture Work Examine link between urban Examine link between urban

DOC and Hg mobilityDOC and Hg mobility Study the effect of the short-Study the effect of the short-

circuiting of ecosystem circuiting of ecosystem processes on Hg mobilityprocesses on Hg mobility

Investigate the interaction Investigate the interaction between the urban canopy between the urban canopy cover and Hg loadingcover and Hg loading

Explore the potential for Explore the potential for diurnal variationsdiurnal variations

Funding: Funding: The Dreyfus FoundationThe Dreyfus Foundation US Environmental Protection AgencyUS Environmental Protection Agency National Science Foundation (LTER Program)National Science Foundation (LTER Program)

Support: Support: Baltimore Co. Dept. of Envir. Protection & Baltimore Co. Dept. of Envir. Protection &

Mgmt.Mgmt. USGS Cooperative Water ProgramUSGS Cooperative Water Program City of Baltimore Dept. of Public WorksCity of Baltimore Dept. of Public Works Dan Dillon, Tara Krebs (IES)Dan Dillon, Tara Krebs (IES) M. Montesdeoca, J. Flagg, J. Hanley, M. M. Montesdeoca, J. Flagg, J. Hanley, M.

Bushey (SU)Bushey (SU)

AcknowledgementsAcknowledgements

““Every Cloud Every Cloud has a has a

Quicksilver Quicksilver Lining”Lining”

PB GL MD RH

Forest Suburban Ag Urban

THg 1.10 0.46 0.33 2.02

MeHg 0.045 0.013 0.017 0.028

DOC 0.70 0.82 0.36 2.07

TSS 2.23 2.05 0.71 3.36

Land Use Chemical Land Use Chemical FluxFlux(Units: THg, MeHg – (Units: THg, MeHg – g mg m-2-2 yr yr-1-1; DOC, TSS – g m; DOC, TSS – g m-2-2 yr yr-1-1))

PB GL MD RH RH-SC

Forest Suburban Ag UrbanUrbanStorm

THg 1.10 0.46 0.33 2.02 6.72

MeHg 0.045 0.013 0.017 0.028 0.108

DOC 0.70 0.82 0.36 2.07 2.40

TSS 2.23 2.05 0.71 3.36 14.6

Effect of High Flow Effect of High Flow on Fluxon Flux(Units: THg, MeHg – (Units: THg, MeHg – g mg m-2-2 yr yr-1-1; DOC, TSS – g m; DOC, TSS – g m-2-2 yr yr-1-1))