A Nitrogen Isotopic Study of Greater Biscayne Bay: Implication for Sources of Nutrients

Transcription

1 A Nitrogen Isotopic Study of Greater Biscayne Bay: Implication for Sources of Nutrients Swart, Peter K., Anderson, W., Drayer, C. Devlin, Q. Altabet, M. and Bellmund S. RSMAS, University of Miami, Miami Fl Department of Geology, FIU U.Mass Dartmouth BNP, Homestead Fl Funding from SFC CESU/BNP

2 Take Home Message In Biscayne Bay there is a clear signature of isotopically positive N derived from anthropogenic sources in the Nitrate, POM, algae, sponges, seagrasses, and sediments. No temporal trends in any of the components measured suggesting the contamination is a permanent feature This signature is only present close to the land and is not agricultural in origin

3 Biscayne Bay An area of outstanding water in which the flora and fauna has declined over the past century as a result of the input of sewage, dredging, pollution and other activities Adjacent to a pollution of ~5 million people who create waste. Adjacent to large land fill Mount Trashmore and Black Point Sewage Treatment Plant

4 What are the Ranges? N / N ( / ) 1* sample δ N 00 = N / Ns tan dard

5 +ve What do different values mean? 12 You are what you eat plus a few per mille Nitrogen Isotopes Trophic Level or Food Chain

6 Atm N 2 Denitrification = 28 N 2 O Nitrogen Fixation N 2 + 8H + + 8e ATP = 2NH 3 + H ADP + 16 Pi = 0 NO NH 3 NO 2 Organic Matter NO 3 - Assimilation = ~2-4 PON Volatilization = ~0 Nitrification NO 2 - Mineralization DON NH 4 = 0 DON Assimilation and = ~2-4 NH 4+ NH 3 = 20 = NH 4 + Lamb 2006

7 Nitrogen as Indicator of Sewage Numerous papers have been published which report the use of stable isotopes in benthic organisms in order to distinguish sewage (Heikoop et al. 2000a,b; Sammarco et al., 1999; Risk and Erdmann, 2000; Costanzo et al., 2001, 2004). N Risk and Erdman 2000 Distance from Source (km)

8 Measured δ 15 N values in Codium sp. from Jupiter Inlet Values reached to almost +12 during summer which he concluded was a result of freshwater bringing high δ 15 N nitrogen from animal waste. Lapointe (1997) Nitrogen (ppt) May June July September August

9 Miami Gulf of Mexico Key Largo Florida Bay Florida Keys Dry Tortugas Key West Atlantic Ocean

10 0 Florida Reef Tract δ 13 C ( ) δ 15 N ( ) Data from Lamb et al. (In Prep.)

11 0 Florida Reef Tract δ 13 C ( ) Thalassia Mangrove δ 15 N ( ) Data from Lamb et al. (In Prep.)

12 0 Florida Reef Tract -5 1 δ 13 C ( ) Thalassia 2 Coral Tissue 3 Zooxanthellae 6 Mangrove δ 15 N ( ) Data from Lamb et al. (In Prep.)

13 Florida Reef Tract δ 13 C ( ) Thalassia 2 Coral Tissue 3 Zooxanthellae 5 Fish 6 Mangrove 7 Sponges 8 Halimeda δ 15 N ( ) Data from Lamb et al. (In Prep.)

14 Florida Reef Tract δ 13 C ( ) Thalassia 2 Coral Tissue 3 Zooxanthellae 4 POM 5 Fish 6 Mangrove 7 Sponges 8 Halimeda δ 15 N ( ) Data from Lamb et al. (In Prep.)

15 0 Florida Reef Tract -5 Seagrass -10 δ 13 C ( ) Mangrove δ 15 N ( ) Data from Lamb et al. (In Prep.)

16 0 Florida Reef Tract -5 Seagrass -10 δ 13 C ( ) Higher trophic level waste Nitrogen Fixation Mangrove δ 15 N ( ) Data from Lamb et al. (In Prep.)

17 20 Florida Reef Tract 15 Nitrogen Isotope Composition (ppt) Birds Fish Data from Lamb et al. (In Prep.) POM Sponge Dictoyota Halimeda Mangrove Thallasia Turf DIN KLC

18 Average salinity from (Data from FIU) Salinity

19 Average NOx from (Data from FIU) Mean NOx (µm)

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21 POM δ 15 N Nitrogen

22 Green Algae δ 15 N Penicillus sp. Udotea sp. Rhipocephalus sp. Avrainvillea sp. Caulerpa sp. Ulva sp. Acetabularia sp. Nitrogen

23 Seagrass δ 15 N Nitrogen

24 Red Algae δ 15 N Laurencia sp. Murrayella sp. Galaxaura sp. Also Brown Algae Sponges Nitrogen

25 Sedimentary Organic Material δ 15 N Nitrogen

26 δ 15 N

27 14.00 Longtitude Green Algae Seagrasses Sponges POM Red Algae δ 15 N (o/oo)

28 Dissolved Nitrate Biscayne Bay Atmospheric Input δ 18 O ( ) Biscayne Waterway 0 Fixation and Fertilizer Higher Trophic Input δ 15 N ( )

29 The Growing Human Footprint on Coastal and Open-Ocean Biogeochemistry Scott Doney Science x 10 6 kg to Biscayne Bay in a year

30 20 15 Nitrogen Isotopic Composition (ppt) Green Algae POM Seagrass Red Algae DIN CGW

31 20 15 Nitrogen Isotope Composition (ppt) Birds Fish Data from Lamb et al. (In Prep.) POM Sponge Dictoyota Halimeda Mangrove Thallasia Turf DIN KLC

32 20 15 Nitrogen Isotope Composition (ppt) Birds Fish Data from Lamb et al. (In Prep.) POM Sponge Dictoyota Halimeda Mangrove Thallasia Turf DIN KLC

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35 Conclusions In Biscayne Bay there is a clear signature of isotopically positive N derived from anthropogenic sources in the Nitrate, POM, algae, sponges, seagrasses, and sediments. No differences in the trends between any of these components Appears to be a constant source This signature is only present close to the major sources of N and is not agricultural in origin