Sources of Sediment and Trace Metals to Lake Worth Lagoon

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Stanley Gilmore
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1 Downstream of S155 Structure, September 7, 2008 Sources of Sediment and Trace Metals to Lake Worth Lagoon John H. Trefry and Robert P. Trocine Florida Institute of Technology LWL Symposium, PBAU, May 15, 2013 Integrating Science, Restoration, and Research for the Benefit of the Lagoon

2 Muck and Metals in LWL Distribution Sources

3 S5A C-51 Canal S155A Suspended particles and bottom sediment were collected along the C-51 Canal and in LWL S155 Lake Worth Lagoon

170 55 150 180 50 Sediment Distribution 120 50 C-51 30 S155 Depths of muck layers (cm) LWL 0 50 20 50 30 70 70 20 0 0 0

5 Sediment Distribution C S155 Depths of muck layers (cm) LWL Sediment distribution patchy with some hard sand (0) and some muck layers thicker than 1 m 0

6 Metal Distribution Natural = 12 μg/g 28 C S Effects Range Low = 50 μg/g 46 LWL Effects Range Median = 218 μg/g Lead (Pb) in μg/g = parts per million

8 Sources of Organic Matter, Sediment and Metals to LWL

$Determining the fractions of land-derived (terrestrial) and lagoon-produced (plankton, algae, sea$

9 Determining the fractions of land-derived (terrestrial) and lagoon-produced (plankton, algae, sea grass) organic matter Centric diatom from LWL Station L38, September 7, 2008 Sources of Organic Matter

$Determine fractions of terrestrial and lagoonal organic matter (OM) δ 13 C [( 13 C/ 12 C) ratio of sample relative to standard] δ 13 C for 100% terrestrial OM = -26.$

10 Determine fractions of terrestrial and lagoonal organic matter (OM) δ 13 C [( 13 C/ 12 C) ratio of sample relative to standard] δ 13 C for 100% terrestrial OM = δ 13 C for 100% lagoonal OM = (0% Terr OM) % Terr OM % Terr OM % Terr OM If the δ 13 C of organic matter from LWL is -24.3, the sample contained 65% terrestrial organic matter

11 On average, sediments in LWL obtain 64 ± 10% of their organic matter from terrestrial (land-derived) sources. Near station C74, June 24, 2008

12 Sources of Sediment to LWL

13 We sampled 9 Source Areas for Sediment to LWL L-8 D Wellington M-1 E-1 E-2 E-3 Stub E-4 Sampled suspended and bottom sediment and 7 different sod samples from farms/distributors

13 ratios (8 different metals) for sediments from LWL with RSD<15% LWL Seds. Sod Fe/Al 0.9 ± 0.1 2.6 ± 0.3 Cr/Fe 25 ± 1 7 ± 2 Cu/Zn 0.40 ± 0.03 1.1 ± 0.3 Zn/Al 52.

14 13 ratios (8 different metals) for sediments from LWL with RSD<15% LWL Seds. Sod Fe/Al 0.9 ± ± 0.3 Cr/Fe 25 ± 1 7 ± 2 Cu/Zn 0.40 ± ± 0.3 Zn/Al 52.2 ± ± 103 Results show common source for these LWL metals and/or good mixing of incoming sediments from a variety of sources during transport to and burial in LWL.

15 Mathematically Mixed Different Source Sediments and/or Sod to Get Best Match for LWL Sediments (just like a puzzle) Calculated percentage of sod and L8-type sediment that need to be mixed to create the composition of LWL sediments. Ratio % Floritam Sod % L8-type material Cu/Al Cu/Fe Cu/Zn As/Al Zn/Al Mean* 9* 91* *All 13 ratios

16 Water Discharge (acre feet/yr) Data show that 75% of the water that passes through S155 structure comes from west of the S-155A structure; 25% is derived within C-51 east. S5A C-51 West S155A C-51 East S155 L8 + EAA miles C51 West C51 East STA 1 East Conboy (2009) using data from DBHYDRO

17 Sources of Metals Zn Pb Hg Ag

18 C120 C118 C117 C97 C96 C95 C93 C92 C75 C74 C73 C72 C69 C45 C44 C42 C30 C27 C26 C25 C24 C8 C4 C2 LWL Background Mean (C-51) Zinc L8 (20-Mile Bend) Royal Palm Beach Lake Clarke Shores US 95 LWL Airport Zn/Al

19 C120 C97 C96 C95 C93 C92 C75 C74 C73 C72 C69 C45 C44 C42 C30 C27 C26 C25 C24 C8 C4 C4 #1 C2 LWL Background Mean (C-51) Lead L8 (20 Mile Bend) Royal Palm Beach Airport Lake Clarke Shores US 95 LWL Pb/Al

20 C120 C97 C96 C95 C93 C92 C75 C74 C73 C72 C69 C45 C44 C42 C30 C27 C26 C25 C24 C8 C4 C2 LWL Background Mean (C-51) Mercury L8 (20 Mile Bend) Royal Palm Beach Airport Lake Clarke Shores US 95 LWL Hg/Al

Ag (Silver in µg/g) 0.5 0.4 0.3 0.2 0.1 LWL Bot Sed What s C51 Bot Sed up with L38 L43 Mercury? L38 L38 0.

21 Ag (Silver in µg/g) LWL Bot Sed What s C51 Bot Sed up with L38 L43 Mercury? L38 L Background Hg (Mercury in µg/g) Dental amalgams typically contain 43-54% Hg and 20-35% Ag

$Sod probably contributes <10% of the inorganic fraction of the muck sediment to LWL, but probably 25-50% of the sediment found in tributary creeks such as E-1 to E-4.$

22 Conclusions: Organic matter makes up ~20% S155A of Structure the sediment in LWL; ~65% of this organic matter is from terrestrial sources. Sod probably contributes <10% of the inorganic fraction of the muck sediment to LWL, but probably 25-50% of the sediment found in tributary creeks such as E-1 to E-4. >70% of the sediment in LWL seems to be derived from source areas west of Loxahatchee in the western reaches of the C-51 basin. Cu, Hg, Pb and Zn in LWL muck sediments exceed State of Florida Guidelines for >70% of samples. Sources seem to be urbanized or heavily travelled areas of Palm Beach County.

Just upstream of S155, June 2008 What can we do? Increase public awareness about impacts of discharging lawn cuttings and debris into the canals. Support decrease in flow at the S155A structure.

23 Just upstream of S155, June 2008 What can we do? Increase public awareness about impacts of discharging lawn cuttings and debris into the canals. Support decrease in flow at the S155A structure. Support continued monitoring and dredging of C-51 Canal where it turns east and passes under the US 95. Support capture of sediment at S155 structure by re-engineering present structure or creating an additional adjacent structure.

Downstream of S155 Structure Discussion Acknowledgements: Financial support from Palm Beach County and SFWMD Alessandra Medri, Julie Bishop, Paul Davis, Tom Conboy of

24 Downstream of S155 Structure Discussion Acknowledgements: Financial support from Palm Beach County and SFWMD Alessandra Medri, Julie Bishop, Paul Davis, Tom Conboy of Palm Beach County Rod Braun, Nenad Iricanin and Dan Haunert of the SFWMD Full Report at or contact

25 APPENDICES

26 Natural = 30 ng/g C Effects Range Low = 150 ng/g LWL Effects Range Median = 710 ng/g Mercury (Hg) in ng/g = parts per billion

27 Sediment Geochronology (Age Dating) (a) 137 C s (dpm /g) (b) 210 P b A ctivity (dpm /g) D epth (cm ) S = 30 cm /58 yr = 0.5 cm /yr C ore L38 S edim ent D epth (cm ) Y = X r = 0.97 ln excess P b210 Total P b210 S = 0.4 cm /yr C ore L38 Age-dating of sediments shows that we collected sediments that date back 50 years or more. Thus, we were able to characterize LWL sediments for the present and back several decades.

28 Lead (μg/g) State of Florida Sediment Guidelines 10 3 C 51 Lead (µg/g) LW L Aluminum (%) as proxy for clay content A lum inum (µg/g) 49 of 72 sediment samples had Pb concentrations that exceeded the State of Florida guidelines.

29 Sod Type H 2 O (%) Dirt (%) Grass & Roots (%) Silt + Clay (% of dirt) Floritam Bermuda

30 Fraction of organic matter in surface suspended sediment that was derived from a terrestrial source. 58% Terr. OM C-51 S155 98% Terr. OM 86% Terr. OM 58% Terr. OM

31 (Cu/Zn) LWL seds. = ± (RSD = 7%) LW L sed Clays are enriched in Al and metals C u (µg/g) Sand and shell are low in Al and metals Zn (µg/g) Y = 0.40X r = 0.98, n = 31 (C u/zn) = ± (R S D = 7% )

32 Percentages of Floritam Sod and L8-type (C121b) sediment that need to be mixed to create the composition of E-3 (C74b) sediments. Ratio % Sod % L8 type material Cu/Al Cu/Fe Cu/Zn Zn/Al Mean 41 59

Final Report to Palm Beach County and the South Florida Water Management District for Contract R

Final Report to Palm Beach County and the South Florida Water Management District for Contract R2008-0985 SEDIMENT SOURCING STUDY OF LAKE WORTH LAGOON AND C-51 BASIN, PALM BEACH COUNTY Upstream of S155