1 / 12

Selenium and the Kesterson Reservoir

Selenium and the Kesterson Reservoir. Kayla Carpenter. San Joaquin Valley: Lots of farming Poorly drained Built drain to the San Francisco Bay. San Luis Drain. Built 1968-1975 by Bureau of Reclamation Originally from Five Points, CA, to Bay Reservoir = controlling reservoir, midpoint.

vanig
Télécharger la présentation

Selenium and the Kesterson Reservoir

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Selenium and the Kesterson Reservoir Kayla Carpenter

  2. San Joaquin Valley: • Lots of farming • Poorly drained • Built drain to the San Francisco Bay

  3. San Luis Drain • Built 1968-1975 by Bureau of Reclamation • Originally from Five Points, CA, to Bay • Reservoir = controlling reservoir, midpoint

  4. SELENIUM! • Water: 300 ppb from drain vs. <10ppb natural • Soil: above 100 ppm in evaporation ponds

  5. Deformity and death of waterfowl leads to closure

  6. 1988 • 500 ha site, 60% filled in • 15-150 cm uncontaminated soil • Wetland  upland grassland • PHYTOREMEDIATION! • Inexpensive, enviro friendly, rather effective • Brought in over 20 spp common weedy plants • Volatilized to atmosphere, dimethyl selenide • Aided by microorganisms, esp. in rhizosphere

  7. 4 Depositional Environments • Dryer northern ponds • Saltgrass (Distichlis) & alkali weed (Cressa) • Accumulates loose layer of organic detrius • “Playas” • Flooded in winter & spring, little organic matter • Ruppia spp then filamentous algae • Flooded & wet • Cattails (Typha) & alkali bulrush (Scirpus spp) • Stay wet  peat-like material • Submerged • Algae dominant (Chara, then filamentous & diatoms) • Thick organic ooze deposits in open waters

  8. Miscellaneous Findings • pH 6.5 –8.0 • Selenate, selenite, organic Se • Amount & speciation changed over time • Sharp decrease in water-extractable soil Se, esp top soil • Correlation between vegetation & water extractable Se • Plant roots can take up Se from lower soil profile  good news for aquifer • Food chain contamination less with upland than wetland • Plants in irrigated soils have higher Se concentrations • More volatilization in warm months & wet areas

  9. Rate of Removal • At current conditions, volatilization of 1-5% total selenium in top 60 cm • 5%: half gone 14 yrs, all gone 46 yrs • 1%: half gone 69 years, all gone 230 yrs • Further aided by irrigation, application of carbon & protein source (glucose & casein), aerobic conditions, and pH 8.0

  10. Conclusions • It is working • It’s slow • Still impacts food chain • Volatilized selenium

  11. Questions?

More Related