Selenium(IV) and (VI) levels in potable, irrigation and waste waters from an industrial zone in southeastern Spain

Selenium in potable, irrigation and waste waters was chemically specified in 62 stations of an industrial zone in southeastern Spain. Hydride generation atomic absorption spectrometry was the method for direct analysis of Se (IV). Prior reduction to Se (IV) by means of HClcc was necessary for measurement of Se (VI). Se (IV) and Se (VI) concentrations ranged respectively from not detectable to 0.380 mu g/l and from not detectable to 0.280 mu g/l. There are no significant differences between the levels of Se (IV) or Se (VI) in the three types of water (P > 0.01). Total Se levels, Se (IV) and Se (VI) of the water in the zone are not affected by human and industrial activity. The low concentrations determined show a low selenium content in those soils through which the water of the zone is leached and drained. Se (TV) concentrations in water are low, but slightly higher than those of Se (VI); for this reason the soluble, bioavailable fraction (mainly present as SeO42-) for the crops in the zone is also low. The daily dietary intake of selenium supplied by drinking water is <0.5 mu g per person.