Paleolimnology in Roosevelt: Learning from the Past Proposal - - PowerPoint PPT Presentation

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Paleolimnology in Roosevelt: Learning from the Past Proposal - - PowerPoint PPT Presentation

Paleolimnology in Roosevelt: Learning from the Past Proposal Submitted to State of Arizona Water, Economic Development and Sustainability Fund Principal Investigators: Owen K. Davis, UA Susan Fitch, ADEQ Paul Gremillion, NAU


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Paleolimnology in Roosevelt: Learning from the Past

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Proposal Submitted to State of Arizona Water, Economic Development and Sustainability Fund

  • Principal Investigators:

– Owen K. Davis, UA – Susan Fitch, ADEQ – Paul Gremillion, NAU – Vicente Lopes, UA – Peter Van Metre, USGS – David Walker, UA

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Problem Statement

  • In waters without historical water

quality data, it is difficult to predict trends in trophic state.

  • It is impossible to quantify detrimental

effects of land-use activities or natural disturbances unless data has been collected prior to each disturbance or activity.

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Paleolimnology as a Tool

  • Paleolimnological techniques are often

used to assess water quality trends in lakes over time.

  • Incorporated in reservoir sediments is a

record of the organisms that lived in and around the lake, as well as proxy data related to processes occurring in the lake.

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  • Previous studies have examined the

accumulation of watershed-derived pollutants in sediment cores of reservoirs with rapidly urbanizing watersheds.

  • These studies often fail to address the

consequences of these pollutants on aquatic biota or overall ecosystem processes.

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Specifically we propose to;

  • We propose to use paleolimnological

techniques to obtain, date, and analyze sediment cores from Roosevelt.

  • These cores will then be age dated

using Pb210 and/or Cs137 radionuclides.

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Objectives

  • To quantify long-term water quality

trends in Roosevelt and the Salt River watershed

  • Determine how these watershed

determinants define water quality within the reservoir

  • How aquatic biota have responded to

these water quality changes

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Objectives (cont.)

  • Determine watershed vegetation

changes over time and how this has affected, and been affected by, fire cycle frequency and intensity.

  • Determine the effect of

anthropogenic activities in the watershed on water quality in the reservoir.

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  • The focus of this work will be pre-

impoundment, however, local geography indicates a pre- impoundment playa or wetland may have existed (i.e., “Tonto Basin”).

  • We anticipate the cores being long

enough to capture pre-impoundment conditions.

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Analytes and the reason for their analysis.

  • Fossilized pollen grains (palynology)

– To determine watershed vegetative changes which will vary due to climate, wildfire regimen, or human removal. – Decreases in vegetation can reduce transpiration and soil moisture storage which may increase runoff and material transported to the reservoir. – The rate of this transport, in turn, can strongly influence biogeochemical processes within the reservoir.

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  • Fossilized diatom frustules

– Siliceous diatom valves are well-preserved in lake sediments and are a direct reflection of environmental conditions at the time of deposition. – Diatoms contain many species with relatively limited ecological tolerances. – Short life cycles mean they respond rapidly to environmental change. – Have been used to infer changes in pH, salinity, temperature, and nutrient availability.

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  • Fossilized chironomid (midge fly) head

capsules

– Excellent indicators of water quality condition especially of hypolimnetic anoxia. – Chironomids highly sclerotized head capsules are usually well-preserved in sediments. – Chironomid taxa exhibit marked differences in individual responses to water quality degradation leading to anoxia such as nutrient accumulation.

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  • Charcoal Analysis

– To determine past fire cycle, frequency, and intensity. – The consequences of fire on Roosevelt water chemistry is a timely and important issue considering current drought conditions.

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  • Nutrients and heavy metals

– We will obtain samples at select locations of the core for nutrients related to eutrophication and metals associated with wither anthropogenic activities or atmospheric input.

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Questions?