Biogeochemical Cycling of Cu Associated with Particulate Matter

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Biogeochemical Cycling of Cu Associated with Particulate Matter in Lake Superior Jaebong Jeong Environmental

Biogeochemical Cycling of Cu Associated with Particulate Matter in Lake Superior Jaebong Jeong Environmental Engineering Michigan Technological University 1

KITES Project (Keweenaw Interdisciplinary Transport Experiment in Superior) Keweenaw Current Thermal Bar f in

KITES Project (Keweenaw Interdisciplinary Transport Experiment in Superior) Keweenaw Current Thermal Bar f in arg s-m os Cr Of re o sh Courtesy of Judy Budd, MTU rt po ns tra ar e N re o sh 2 (NOAA Coast. Watch L. Superior Surface Temperature Imagery)

My project: Cu cycling associated with particles (SP and mine tailings). Eagle Harbor Freda

My project: Cu cycling associated with particles (SP and mine tailings). Eagle Harbor Freda and Redridge Copper Harbor Gay Houghton Portage Canal & Torch Lake Ontonagon Keweenaw Peninsula 3

Gay, MI 4 Courtesy of Dave Bolgrien, EPA

Gay, MI 4 Courtesy of Dave Bolgrien, EPA

Freda Old Smelter Site 5

Freda Old Smelter Site 5

Freda Stamp Sands 6

Freda Stamp Sands 6

] Copper (Cu) F Copper is a trace metal essential to healthy life of

] Copper (Cu) F Copper is a trace metal essential to healthy life of plants and animals (micro-nutrient). F The elevated copper concentrations have toxic effects on animal and plant communities. ] Particulate matter (PM) F Particles play an important role in regulating trace metals (sink and source terms). Ø It is important to understand copper cycling associated with particles in this area. 7

Objectives 1. Characterize the source sediments (Freda Stamp Sands, Ontonagon sediments, Wisconsin red clay).

Objectives 1. Characterize the source sediments (Freda Stamp Sands, Ontonagon sediments, Wisconsin red clay). 2. Investigate transport of suspended particles and sediments redistribution. 3. Investigate the spatio-temporal patterns of dissolved Cu. 4. Identify the factors controlling biogeochemical cycling of Cu. 8

Intensive Shipboard Sampling (1998~2000) 9 The RV Laurentian (U of Michigan)

Intensive Shipboard Sampling (1998~2000) 9 The RV Laurentian (U of Michigan)

Methodology ] Sediment and Suspended Particles ]Total Suspended Particles (TSP): GFF filters ]Particle Size

Methodology ] Sediment and Suspended Particles ]Total Suspended Particles (TSP): GFF filters ]Particle Size of Sediments: Sieve & Particle Counter ]Mineralogical Composition: XRD ]Chemical Composition: Chemical Extractions & ICP and AAS ]Organic Carbon and Nitrogen of Suspended Particles: TOCA ] Water ]Dissolved Cu: Ultraclean Technique (Teflon) ]Cu analysis: Atomic Absorption Spectrophotometer (AAS) ]Cations and Anions: Ion Chromatography ]Alkalinity: PC-Titrate. TM Autotitrator ]CTD data: Conductivity, Temperature, Chlorophyll a, & Transmissivity 10

Major Sampling Sites Wisconsin red clay EH Transect Eagle Harbor HN Transect Ontonagon Copper

Major Sampling Sites Wisconsin red clay EH Transect Eagle Harbor HN Transect Ontonagon Copper Harbor Surface Sediment sampling Sites FR Transect Freda CH Transect Core Sediment (MCA 2) Redridge Freda stamp sands Ontonagon River sediments 11

Depth Profile of Cu in the Core Sediment MCA 2 -Surf [Cu]Tot (mmol/g sediment)

Depth Profile of Cu in the Core Sediment MCA 2 -Surf [Cu]Tot (mmol/g sediment) MCA 2 -Cu Mean Mass Diameter (mm) MCA 2 -BG v The background level of Cu is 0. 1 mmol/g Sediment. v The Core Sediment shows the maximum Cu concentration at 2. 5~3 cm depth and slightly high Cu in the surface. 12

Longshore Transport ? Or Dissolution and Precipitation? Or Algae Uptake & Sink? MCA 2

Longshore Transport ? Or Dissolution and Precipitation? Or Algae Uptake & Sink? MCA 2 Copper Harbor Eagle Harbor Redridge Freda Original dumping site of stamp sands Ontonagon 13

Characterization of Sediments v Glycerol-treated X-ray diffraction patterns of clay-size particles of the three

Characterization of Sediments v Glycerol-treated X-ray diffraction patterns of clay-size particles of the three source materials. 14

Mineralogical Composition v Ternary phase diagram (Illite-Smectite-Chlorite system) of clay minerals v Three sediment

Mineralogical Composition v Ternary phase diagram (Illite-Smectite-Chlorite system) of clay minerals v Three sediment source materials (triangle) and near Freda lake sediments (circle) including a core sediment. 15

Longshore & Cross-margin Transport Source Materials 7. 06 (mg/g) Settling Particles & Sediments In

Longshore & Cross-margin Transport Source Materials 7. 06 (mg/g) Settling Particles & Sediments In Lake Superior Total [Cu] (mg/g) Under water Longshore transport Cross-margin transport Cu peak Surface Back Ground Settling Particles Freda Ontonagon River Wisconsin Stamp Sands Sediments red clay Offshore @ the HN transect Core Sediments v Concentrations of total Cu in the different particles. 16

Sediment Trap Samples Copper Harbor Eagle Harbor s os Cr n gi ar -m

Sediment Trap Samples Copper Harbor Eagle Harbor s os Cr n gi ar -m HN Transect rt o sp an Tr Freda Ontonagon 17

Cu Concentrations in Surface Sediments Total Cu Concentrations Grain Size of Sediments (mm) 1974

Cu Concentrations in Surface Sediments Total Cu Concentrations Grain Size of Sediments (mm) 1974 Freda Kraft (mg/kg) Redridge North Entry Bathymetry (m) 2000 Freda North Entry Redridge Our Data (mg/g) Freda North Entry Redridge 18

Original Dumping Site Dissolved Cu Concentrations ? Contaminated Sediments with High Cu Normal Lake

Original Dumping Site Dissolved Cu Concentrations ? Contaminated Sediments with High Cu Normal Lake Sediments How the contaminated sediments in neashore contribute the dissolved Cu concentrations in the water column? 19

Spatial Variations of Dissolved Cu Transect v Nearshore/offshore gradients in concentrations of dissolved Cu

Spatial Variations of Dissolved Cu Transect v Nearshore/offshore gradients in concentrations of dissolved Cu were found due to the dissolution of Cu-rich tailings and river inputs. v These values are low due to rapid mixing and dispersing. 20

Nearshore/offshore gradients (HN Transect) What are the controlling factors for the gradients? 21

Nearshore/offshore gradients (HN Transect) What are the controlling factors for the gradients? 21

The Vertical Profiles of Dissolved Cu Bruland, K. W. , 1980 (North Pacific, Sept.

The Vertical Profiles of Dissolved Cu Bruland, K. W. , 1980 (North Pacific, Sept. 1977) Our data (L. Superior, Aug. 2000) v Unlike Cu cycling in the Oceans, biological uptake and regeneration seem not to be the major processes of Cu cycling in L. Superior. 22

Cu: C ratios in Settling Particles Our data 2000 Log Cu: C Shafer and

Cu: C ratios in Settling Particles Our data 2000 Log Cu: C Shafer and Armstrong 1990 Sigg 1987 Sunda and Susan 1995 v High Cu: C ratios in suspended particles give strong evidence that dissolved copper concentrations may be controlled by particles via sorption. 23

DCM and BNL HN 210, 2000 DCM BNL HN 110, August 22, 1999 Deep

DCM and BNL HN 210, 2000 DCM BNL HN 110, August 22, 1999 Deep chlorophyll maximum (DCM) and Benthic nepheloid layer (BNL) are cooccur during summer due to biological activity and resuspension of sediments. 24

Particle Scavenging @DCM TSP (mg/L) Transmissivity/100 (%) Particulate Cu (Fp, %) @ BNL ON

Particle Scavenging @DCM TSP (mg/L) Transmissivity/100 (%) Particulate Cu (Fp, %) @ BNL ON 210, August 2000 Particulate Cu fractions are closely related to particle resuspension in the BNL. 25

Conclusions (Particle Transport) ] Copper tailings are distinguishable from other sediment sources and usable

Conclusions (Particle Transport) ] Copper tailings are distinguishable from other sediment sources and usable as tracers for particle transport and sediment redistribution. ] The Keweenaw Current is responsible for the longshore transport of fine particles, whereas wave action causes the lateral transport of the coarse deposits along the shore. ] Bathymetry also plays an important role for movements of resuspendable sediments. ] Some cross-margin transport occurs as evidenced by Cu-rich particles in surface sediments and sediment traps in offshore stations. 26

Conclusions (Cu Cycling) ] Continuous dissolution of Cu from the Cu-rich mine tailings causes

Conclusions (Cu Cycling) ] Continuous dissolution of Cu from the Cu-rich mine tailings causes high Cu concentrations found in the nearshore zones. ] Tributaries containing high Cu concentrations contribute to spatial variation in dissolved Cu in the Ontonagon area. ] Uniform depth profile and high Cu: C ratios in the settling particles suggest that dissolved Cu is controlled by the suspended particles via sorption rather than biological activity. ] Also, physical processes (i. e. , the fast mixing of the entire water body and transport by currents) appear to be significant factors regulating the dissolved copper. 27

Questions? 28

Questions? 28