Separating salinity increases due to saltwater intrusion from that due to evaporation by a dual-isotope model: a case study in the Shark River Slough Lu Zhai, Rafael Travieso, John Kominoski, Li Zhang, Evelyn Gaiser, Leo Sternberg* Greater Everglades Priority Ecosystem program. Mixing: Saltwater Intrusion Salinity of Coastal Ecosystem Global Warming Evaporation Soil: marsh or beach Water : river or lake Evaporation Freshwater inflow Mixing Inland Saltwater Intrusion Ocean Costal River Evaporation Freshwater inflow Mixing Saltwater Intrusion Costal River Shark River Slough river of grass Evaporation Freshwater inflow Mixing Costal River Saltwater Intrusion Freshwater Mixing Brackish-water Evaporation Final-water Freshwater Mixing Brackish-water: V Evaporation Final-water: V*f Freshwater Mixing Brackish-water: V Evaporation Final-water: V*f Remaining fractionation of water after evaporation. Freshwater Salinity = 0 Mixing Brackish-water Evaporation Final Water Salinity 0 Freshwater Salinity = 0 Salinity Mixing Salinity = SM Mixing Brackish-water Salinity = SM Evaporation Final Water 0 Freshwater Salinity = 0 Evaporation Salinity Mixing Salinity = SM Mixing Brackish-water Salinity = SM Evaporation Final Water Salinity = SME Salinity = SME 0 Freshwater Salinity=0 Mixing Brackish-water: V Salinity=SM Evaporation: (1-f) Final Water: V*f Salinity=SME Salt Mass Balance: V * SM = V * f * SME Freshwater Salinity=0 Salt Mass Balance: V * SM = V * f * SME Mixing Brackish-water: V Salinity=SM Evaporation: (1-f) Final Water: V*f Salinity=SME SM = f * SME Salinity increase from Evaporation: πππΈ β ππ = πππΈ πππΈ β π × πππΈ = πππΈ =1βπ Salinity increase from Mixing: =1β 1βπ =π f can be quantified by a duel-isotope based method Water β Vapor More lighter isotopes evaporate to vapor More heavier isotopes left in the remaining water Ξ΄18O or Ξ΄D of remaining water will increase Rayleigh Distillation: changes of Ξ΄18O and Ξ΄D of remaining water during evaporation πΉπ πΆ = πΉπ πΆ + πΊπΆ β π₯π§ π πΉπ π« = πΉπ π« + πΊπ« β π₯π§ π πΊ is enrichment factor d2H Rainwater Ξ΄2H = 8.6 Ξ΄18O + 11 Surface water from lake or river d18O d2H Ξ΄2H = 8.6 Ξ΄18O + 11 d18O Ξ΄2H = 8.6 Ξ΄18O + 11 d2H deuterium excess (d) = Ξ΄D - 8.6 Ξ΄18O In south Florida, the average d of rainwater is 11. d of surface water will decrease with evaporation. 2 1 d18O d2H d1 deuterium excess (d) = Ξ΄D - 8.6 Ξ΄18O d2 In south Florida, the average d of rainwater is 11. d of surface water will decrease with evaporation. 0 2 1 d18O 0 πΏπ π = πΏ0 π + ππ β ln π πΏπ π· = πΏ0 π· + ππ· β ln π deuterium excess (d) = Ξ΄D - 8.6 Ξ΄18O drain=11 dsample will decrease with evaporation. deuterium excess (di) = Ξ΄Di - 8.6 Ξ΄18Oi πΏπ π = πΏ0 π + ππ β ln π πΏπ π· = πΏ0 π· + ππ· β ln π deuterium excess (d) = Ξ΄D - 8.6 Ξ΄18O drain=11 dsample will decrease with evaporation. deuterium excess (di) = Ξ΄Di - 8.6 Ξ΄18Oi = (πΏ0 π· + ππ· β ln π) β 8.6(πΏ0 π + ππ β ln π) πΏπ π = πΏ0 π + ππ β ln π πΏπ π· = πΏ0 π· + ππ· β ln π deuterium excess (d) = Ξ΄D - 8.6 Ξ΄18O drain=11 dsample will decrease with evaporation. deuterium excess (di) = Ξ΄Di - 8.6 Ξ΄18Oi = (πΏ0 π· + ππ· β ln π) β 8.6(πΏ0 π + ππ β ln π) ππ = π ππ βπΏ0 π·+8.6πΏ018 π / 8.6ππβππ· πΏπ π = πΏ0 π + ππ β ln π πΏπ π· = πΏ0 π· + ππ· β ln π deuterium excess (d) = Ξ΄D - 8.6 Ξ΄18O drain=11 dsample will decrease with evaporation. deuterium excess (di) = Ξ΄Di - 8.6 Ξ΄18Oi =(πΏ0 π· + ππ· β ln π) β 8.6(πΏ0 π + ππ β ln π) ππ = π =π ππ βπΏ0 π·+8.6πΏ018 π / 8.6ππβππ· ππ βπππππ / 8.6ππβππ· πΏπ π = πΏ0 π + ππ β ln π πΏπ π· = πΏ0 π· + ππ· β ln π deuterium excess (d) = Ξ΄D - 8.6 Ξ΄18O drain=11 dsample will decrease with evaporation. deuterium excess (di) = Ξ΄Di - 8.6 Ξ΄18Oi =(πΏ0 π· + ππ· β ln π) β 8.6(πΏ0 π + ππ β ln π) ππ = π =π =π ππ βπΏ0 π·+8.6πΏ018 π / 8.6ππβππ· ππ βπππππ / 8.6ππβππ· ππ β11 / 8.6ππβππ· πΏπ π = πΏ0 π + ππ β ln π πΏπ π· = πΏ0 π· + ππ· β ln π deuterium excess (d) = Ξ΄D - 8.6 Ξ΄18O drain=11 dsample will decrease with evaporation. deuterium excess (di) = Ξ΄Di - 8.6 Ξ΄18Oi = (πΏ0 π· + βπ· β ln π) β 8.6(πΏ0 π + βπ β ln π) ππ βπΏ0 π·+8.6πΏ018 π / 8.6ππβππ· ππ = π ππ βπππππ / 8.6ππβππ· =π ππ β11 / 8.6ππβππ· =π However, in addition to evaporation, saltwater intrusion also can affect Ξ΄O and Ξ΄D values. Stable isotope based model of the mixing and evaporation processes: Visualization dD n Rain d18O dD n Fresh Rain d18O dD Ocean Water Mixing n Fresh Rain d18O Ocean Water Brackish dD Mixing n Fresh Rain d18O Evaporation This is just our model strategy, but does nature work as we think? Field data in October from SRS There are 6 sites along SRS, SRS 1~6. SRS 5 and 6 are brackish water site. Conceptual figure Field data figure Conceptual figure Field data figure Ocean Water Brackish Fresh Rain Conceptual figure Field data figure Ocean Water Brackish Fresh Rain The relative locations of different water match! Begin to calculate the mixing and evaporation based on the isotope-based model Step 1 Fresh Ocean Mixing Water Line: FOMWL (Blue Line) Step 2 Brackish Evaporation Water Line: BEWL (Green Line) Step 2 Same slope Brackish Evaporation Water Line: BEWL (Green Line) Step 3: Intersect of FOMWL and BEWL 18 ππ = πΏπ·π β 8.6 β πΏ π π ππ βπΏ0 π·+8.6πΏ018 π / ππ = π 8.6β18 πββπ· Salinity of SRS6: ~90% from Saltwater intrusion, ~10% form Evaporation in Oct On-going work β’ Collecting river and rain water of SRS . β’ Collecting ocean water from Gulf. β’ SRS weather data. β’ From Oct2016 to Oct2017: cover wet and dry season β’ Long-term simulation of the contribution changes under sea level rise and increasing temperature Thank you!
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