San Joaquin Valley

Another contaminant of concern for the Delta is Se. Selenium occurs in high concentrations in the soils of the western San Joaquin Valley associated with salts that have accumulated in this region [10]. Selenium is recycled through agricultural retom flows to the river and transported to the Delta and San Francisco Bay. The Se is transformed into a more bioavailable form by microbial communities and aquatic plants. The Se is passed through the foodweb with particular concern for bottomfeeding migratory waterfowl and predatory fishes. The hydrodynamics of water from the San Joaquin River is an important consideration in the intensity and distribution of Se contamination within the Delta. 

California San Joaquin valley September-November 1986 whole fish ... 

Saiki, M.K., M.R. Jennings, and T.W. May. 1992. Selenium and other elements in freshwater fishes from the irrigated San Joaquin valley, California. Sci. Total Environ. 126 109-137. 

Saiki, M.K. and CJ. Schmitt. 1986. Organochlorine chemical residues in bluegills and common carp from the irrigated San Joaquin Valley floor, California. Arch. Environ. Contam. Toxicol. 15 357-366. 

Nakamoto, R.J. and T.J. Hassler. 1992. Selenium and other trace elements in bluegills from agricultural return flows in the San Joaquin Valley, California. Arch. Environ. Contamin. Toxicol. 22 88-98. 

Ohlendorf, H.M.R.L. Hothem, and T.W. Aldrich. 1988. Bioaccumulation of selenium by snakes and frogs in the San Joaquin Valley, California. Copeia 1988 704-710. 

Presser, T.S. and H.M. Ohlendorf. 1987. Biogeochemical cycling of selenium in the San Joaquin Valley, California, USA. Environ. Manage. 11 805-821. 

Saiki, M.K. and D.U. Palawski. 1990. Selenium and other elements in juvenile striped bass from the San Joaquin Valley and San Francisco estuary, California. Arch. Environ. Contamin. Toxicol. 19 717-730. Sandholm, M. 1973. Biological Aspects of Selenium Uptake of Selenium by SH-Groups and Different Organic Materials in the Ecosystem. Thesis, Dept. Medicine, Coll. Veterin. Medic., Helsinki, Finland. 35 pp. 

The characteristic example of Se-enriched regions is the San Joaquin Valley in California, USA (Figure 1). 

The irrigation systems were constructed in this valley in 1930-1960s. It was found afterward that irrigation drainage water from parts of the San Joaquin Valley contains levels of selenium and other trace elements that have been implicated in bird deformations in the Kesterson Reservoir. Depending on location and season, the drainage water contains 100-1400 pg/L Se, predominantly as selenate (SeO 2, Se-IV), the most soluble form, whereas the California State Water Resources Control Board has recommended an interim maximum mean monthly selenium concentration of 2-5 pg/L in receiving waters and wetlands. 

The deposits of the San Joaquin Valley are derived from the Sierra Nevada on the East and the Coast Range on the West. The Sierra Nevada, a fault block that dips... 

Figure 1. Location and geographic features of the western San Joaquin Valley (Deverel et al., 1994).

THE SAN JOAQUIN VALLEY AND ADJACENT SIERRA NEVADA MOUNTAINS... 

Li A, Andren AW, Yalkowsky SH (1996) Choosing a cosolvent Solubilization of naphthalene and cosolvent properties. Environ Toxicol Chem 15 2233-2239 Lin ZQ, Schemenauer RS, Cervinka V, Zayed A, Lee A, Terry N (2000) Selenium volatilization from a sod-plant system for the remediation of contaminated water and soil in the San Joaquin Valley. J Environ Quality 29 1048-1056 Lindsay WL (1979) Chemical equilibria in soils. Wiley, New York... 

DBCP has been found In ground water In Hawaii, California, Arizona, South Carolina, and Maryland (5-7,19,77-79). Typical positives are 0.02-20 ppb. Areas with the highest frequency of positives and the highest well concentrations are the San Joaquin Valley In California and the region southwest of Phoenix, Arizona. The Hawaii contamination has occurred despite several hundred feet of overburden between the basal aquifer and the surface. One set of California soil core results show that ppb amounts of DBCP has leached about 15 m through the unsaturated zone ( ), whereas DBCP was not detected In another set of California soil cores sampled as deep as 10 m and five years after the last application (80). The latter results can possibly be explained by rapid movement of DBCP down the soil profile to depths greater than 10 m. 

LI, M. All, S. Burau, R. Crosby, D. Hatsfleld, J. Hsleh, D. Kilgore, W. Painter, W. Selber, J. In "A Systems Approach to Controlling Pesticides In the San Joaquin Valley" Ecosystems Studies of National Science Foundation, University of California, Davis, CA, 1979. 

Consequently, soil samples from feedlots have a dual origin of toco-pherols. This is illustrated with the GC-MS data of a study done in the San Joaquin Valley of California (Fig. 5b, ). The y-tocopherol is derived exclusively from the vegetation fodder, while a-tocopherol is derived from both vegetation and the hydrolysis of the tocopheryl acetate feed supplement. Excess a-tocopherol acetate, not hydrolyzed in the animal gut, is also present. Because a-tocopherol acetate is relatively stable, its presence in soil dust samples indicates the level of its usage as a feed supplement. A significant metabolite of a-tocopherol elutes after the acetate and the... 

Ames RG, Gregson J Mortality following cotton defoliation San Joaquin Valley, California, 1970-1990.7 Occup Environ Med 37(7) 812-819, 1995... 

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