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Resolving sources of dissolved organic matter in the Sacramento-San Joaquin Delta by radiocarbon dating James O. Sickman Soil and Water Science Department,

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Presentation on theme: "Resolving sources of dissolved organic matter in the Sacramento-San Joaquin Delta by radiocarbon dating James O. Sickman Soil and Water Science Department,"— Presentation transcript:

1 Resolving sources of dissolved organic matter in the Sacramento-San Joaquin Delta by radiocarbon dating James O. Sickman Soil and Water Science Department, University of Florida Carol DiGiorgio California Department of Water Resources M. Lee Davisson Lawrence Livermore National Laboratory Delores Lucero University of Florida Erin Waites Department of Water Resources Presented at: October 2004 CALFED Science Conference

2 Who am I? I am an interdisciplinary scientist working in and across the fields of biogeochemistry, limnology and watershed science My research program is focused on biogeochemical cycling of C, N and P in lakes, rivers and wetlands In these terrestrial and aquatic ecosystems I utilize standard watershed analysis along with application of isotopes ( e.g.,  15 N and  18 O of nitrate,  13 C,  14 C of dissolved organic matter) to solve environmental problems Watersheds Biogeochemistry Limnology My Research

3 Education and Work History Education: Ph.D., Ecology, Evolution and Marine Biology (emphasis in biogeochemistry and limnology) University of California, Santa Barbara, 2001 M.A., Aquatic and Population Biology University of California, Santa Barbara B.A., Aquatic Biology, University of California, Santa Barbara Work Experience: 2004 – present: Assistant Professor. Soil and Water Science Department, University of Florida-IFAS. Biogeochemistry of rivers, lakes and wetlands 2003 – 2004: Assistant Professor. Department of Geology and Geophysics. University of New Orleans. Watershed biogeochemistry and ecosystem restoration in the Mississippi Delta and Sacramento River Delta 2001 – 2003: Senior Environmental Scientist - California Department of Water Resources, Division of Environmental Services, Sacramento, California. Carbon biogeochemistry, AMS carbon dating, aquatic ecological processes and water-quality investigations of the Sacramento-San Joaquin River Delta and State Water Project 1983 – 2001: Staff Research Associate IV. Donald Bren School of Environmental Science and Management, University of California, Santa Barbara. Global-change research on biogeochemistry, aquatic ecology and hydrology of the Sierra Nevada and Rocky Mountains.

4 Current Research: California C&N Biogeochemistry of Montane Watersheds Aquatic Ecology of Oligotrophic Lakes DOM Sources and Fate in Rivers and Estuaries Effects of Seasonal Transitions on Biogeochemistry of Chaparral

5 Causes of macroalgae blooms in Florida springs (J. Stevenson, A. Pinowska MSU; R. Reddy UF) Impacts of Melaleuca quinquenervia invasion on soil biogeochemical properties (M. Martin UF, P. Tipping USDA) Sources of DOM to St Johns and Caloosahatchee Rivers (M. Fisher SJRMD, TJ Evens USDA) Current Research: Florida

6 Teaching: Current Courses (1) Spring 2005: SOS 6456 Advanced Biogeochemistry (3 credits) TOPIC: Biogeochemical Cycles and Global Change: Sustaining Biodiversity and Ecosystem Services in Soils and Sediments PREREQUISITES: Graduate standing, BSC 2011 and 2011L (population biology) or equivalent, AND SOS 3022 (soil chemistry ) or equivalent COURSE DESCRIPTION: This course will present an in-depth treatment of global elemental cycles in the context of Global Change. Topics that will be covered include properties of and transfers between the key reservoirs of C, N, S & P, coupling of biogeochemical cycles and climate, and human modification of the Earth System. Discussion of ecosystem services provided by soils and sediments in terrestrial and aquatic ecosystems will be emphasized

7 Teaching: Current Courses (2) Fall 2005: SOS 4932 Environmental Biogeochemistry (3 credits) PREREQUISITES: BSC 2010 and 2010L (general biology) or equivalent, AND CHM 2045 and 2045L (general chemistry) or equivalent COURSE DESCRIPTION: This course will examine the biogeochemical systems of the Earth for the past 5 billion years. We will consider the effects of life on the Earth's chemistry on a global scale, emphasizing the impact of humans in altering the global biogeochemical cycles of C, N, S, and P. The course will examine several important, but complex questions regarding the Earth System: 1) How did the Earth System operate in the absence of significant human influence? 2) How can human-driven effects on global biogeochemical cycles be discerned from those due to natural variability? 3) What are the implications of changes in the Earth’s biogeochemical systems for human well-being? 4.) How robust are the Earth’s biogeochemical systems in the face of anthropogenic forcings? Topics that will be covered include element cycling, coupled biogeochemical cycles, and solutions for global change including economic valuation of natural ecosystem functions.

8 Teaching: Planned Course (3) SOS 4XXX/5XXX: Watershed Science and Analysis COURSE DESCRIPTION: Given the interconnectedness of watersheds and the integrating influence of hydrology, watersheds are a fundamental scale at which to study and manage ecosystems. Watershed science is an interdisciplinary field that incorporates fundamental and applied knowledge of natural sciences (hydrology, geomorphology, chemistry, biology, geology) and social sciences (law, environmental policy and resource economics). This course will provide advanced training in concepts, tools and methods for solving watershed-scale problems. It will consist of a combination of lecture, field work and laboratory analyses. A local watershed will be used as the focus of the course. Topics to be covered: 1.Introduction to watershed science 2.Field/lab methods in watershed analysis 3.Remote sensing and GIS 4.Geomorphology 5.Hydrologic and hydrochemical modeling 6.Biogeochemistry of watersheds 7.Use of environmental isotopes in watershed science 8.Watersheds in environmental policy and regulation 9.Environmental monitoring, databases and analysis John Wesley Powell, renowned explorer of the Grand Canyon defines a watershed as "that area of land, a bounded hydrologic system, within which all living things are inextricably linked by their common water course and where, as humans settled, simple logic demanded that they become part of a community”

9 Isotopes of Carbon and Their Abundance IsotopeProtonsNeutronsProportionHalf life 12 C6699% stable 13 C671% 14 C680.0000000001%5568 years

10 Radiocarbon Basics

11 History of Radiocarbon Dating Invented by Willard F. Libby of the University of Chicago after the end of World War 2. Libby later received the Nobel Prize in Chemistry in 1960 for the radiocarbon discovery Shroud of Turin (AD 1260-1390)

12 Flow in and through the Delta: Comprises 70% of annual California runoff Supplies drinking water to 23 million people Maintains agricultural vitality of California economy Evolving concerns over past 50 years: Primary conduit for state water project flows Expanding role for environmental flows Increasing degradation of water quality Principal quality problems related to: Salinity, agricultural wastes, local land use, and conflicting flow management strategies California’s Delta region exhibits elements common to agricultural/urban areas of Florida Managing water quality and the ecological health of the Delta affects all of California

13 How do we restore habitat, without: high organic loads leading to carcinogenic by-products formed during drinking water treatment  carcinogen levels increase proportionally with organic matter content  natural wetlands have 5-10X more organic matter than Delta today  EPA STAGE 1 D/DBP RULE ON THE HORIZON bioaccumulating toxic metals that impact fish:  wetland chemistry promotes bioavailability of mercury and selenium Increasing salinity in municipal and agricultural supplies  2-5X increase in bromide renders chlorinated water undrinkable Promoting land subsidence The CALFED Restoration mission is to balance ecological, agricultural, and urban demands, but Carbon runoff from agricultural practices is a growing concern for water quality Restoration of Delta may have unwanted consequences for water quality

14 Wetland Forest Agricultural Grasses Historic Today Urban Organic-rich soils Wetland DOM is a precursor to disinfection byproducts in finished drinking water DOM likely originates from modern and historical sources Relative proportions of different sources will vary during water year The Dynamic Delta Landscape Presents Unique Challenges for Drinking Water Quality Banks Pumping Plant CO 2 DOC

15 Determination of Delta Island DOM Influence at Banks Can Isotopic fingerprinting determine if: Delta island peat is a significant source of C loading to the State Water Project? C inputs from Delta island peat vary through time depending on seasonal and hydrologic conditions?

16 Simple Conceptual Model for DOM Sources to the State Water Project Riverine DOMPeat-derived DOM State Water Project

17 Sampling and Analysis Monthly sampling:   Rivers   Ag drains Periodic sampling:   Urban runoff DOM Fractionation Measurements:   AMS carbon dating   C, N and S isotopes   SUVA   THMFP Water fingerprinting using DSM2 model Emphasis to date has been on DOM fractionation and radiocarbon measurements

18 DOM Fractionation Procedure After Aiken et al. (1992) Fractionation favors isolation of hydrophobic compounds (humics) which tend to be more refractory Longer environmental persistence of these hydrophobic compounds may correlate to radiocarbon age. Isolation Columns Combustion/Extraction isotopes measured

19 Fractionation Data

20 Radiocarbon Comparison of Surface DOM and Soil Organic Matter Accelerator Mass Spectrometry fraction modern carbon SourceDOCXAD-8 Sacramento R1.07, 1.10 San Joaquin R1.09, 1.10 Old R1.08, 1.53 Cache Cr0.89 Missouri R0.94-1.14 0.87-0.99 Mississippi R1.06-1.09 *Hudson R0.84-0.96 Others1.06-1.11 0.77-1.40 Delta Island Soil Organic Matter 0.38-0.89 from Davisson (2002) * from Raymond and Bauer (2000) 2.00 1.90 1.80 1.70 1.60 1.50 1.40 1.30 1.20 1.10 1.00 Fraction Modern Carbon (fmc) (Fraction Modern Carbon)

21 River XAD-8 Fractions Are Younger Than Ag Drain Water April-Oct 2003 Whole Water XAD 8

22 Calculated 14 C abundance in non-XAD-8 DOC fractions indicate old or possibly fossil carbon sources

23 Sac. River and Aqueduct 14 C abundance of XAD-8 fraction closely track each other Jones Tract Breach June 2003 Sac. RiverAqueduct

24 Simple Mass Balance Mixing Model Tends to Under- Predict 14 C abundance of XAD-8 DOC Fraction * Based on DSM2 daily mass flow estimates for all major Delta inflows *Input Flows Sac. River SJ River Ag Drains Other Streams linear mixing model

25 Implications from Simple Mass Balance Modeling Delta Island agricultural drainage has minimum influence on DOC at Banks Increasing flow contributions from eastside of Delta or San Joaquin River cannot account for 14 C discrepancy Modern-aged carbon is added to the XAD-8 fraction between Hood and Banks SUVA (L/mg-m)THMFP (µmol/mmol C) Sac. River2.13 7.45 Aqueduct2.83 9.08

26 For Sacramento and San Joaquin rivers, whole water DOM predominantly has lower radiocarbon content than corresponding XAD-8 fractions The non-XAD-8 portion of DOM in these river waters suggest old or fossil carbon inputs Sacramento River and San Joaquin River have younger XAD-8 fractions than Delta Island agricultural drain waters A conservative mixing model for DOM at Banks predicts older carbon than is observed for most samples thus far Results suggest young carbon is added between Hood and Banks, which may explain increases in SUVA and THMFP Conclusions

27 Funding provided by the CALFED Bay Delta Program, State Water Project Contractors and Department of Water Resources Acknowledgements Twitchell Island Banks Pumping Plant

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