Distribution of selenium in a mini-landscape of Yutangba, Enshi, Hubei Province, China

Yutangba. where a sudden incidence Se poisoning occurred in 1963, is located in the northern part of Shuanghe Town of Enshi City in the SW of Hubei Province. China. In a small area of 0.01 km(2) in Yutangba, the mean concentrations of Se in soil and corn were. soil, 4.06 +/- 1.24 mug g(-1); total corn, 6.47 +/-4.29 mug g(-1): root, 4.36 +/-3.27 mug g(-1); stalk, 3.06 +/-2.24 mug g(-1); leaf, 9.79 +/-7.62 mug g(-1): and seed. 8.07 +/- 5.02 mug g(-1), the spatial distribution of Se in soil and corn is significantly uneven. Selenium is an active element in the supergene moderate-strong chemical weathering environment. relatively low-Se, median-Se and high-Se subregions can be distinguished according to St: concentrations in soil and corn. Microtopographic features and leaching conditions are the primary factors affecting Se content and distribution in soil and corn. Increased incidence of Se poisoning is likely to occur in the low-Se subregions where Se easily accumulates. Selenium concentrations differ significantly among the organs of corn and decrease in the following order: tassel (male flower), silk (female flower)> leaf > seed > root > stalk > leafy husk of the ear. The Se concentrations in the upper leaves and stalks were greater than in their lower cognates and the outer leafy husk of the ear had a greater Se concentration than the inner leafy husk. This distribution not only indicates that Se is probably an essential element for corn, but also that, under high-Se background and no Se-accumulating indicator plant occurrence. these plant organs with relatively high Se concentrations may be used as a sensitive indicator of Se levels in the environment. :(C) 2001 Elsevier Science Ltd. All rights reserved.