In situ and ex situ bioremediation of seleniferous soils and sediments

Abstract

The importance of environmental selenium (Se) research has been increasingly recognized during the last decade (Nancharaiah & Lens, 2015a; Tan et al., 2016). The concerns about Se toxicity began in the 1930s, when symptoms for alkali disease and blind staggers were observed in livestock grazing on grass grown on Se-enriched soil in South Dakota (Tinggi, 2003). On the other hand, Se deficiency was brought to the forefront in the 1960s with identification of a peculiar heart muscle disease symptom, called Keshan’s disease, in China (Chen, 2012). In animals and humans, selenium plays an important role in the redox regulation of intracellular signaling, redox homeostasis and thyroid hormone metabolism (Huawei, 2009; Papp et al., 2007). To avoid deficiency and toxicity, the United States National Academy of Sciences Panel on Dietary Oxidants and Related Compounds recommended a dietary allowance of 55 μg Se day−1 in humans and set an upper tolerable limit of 400 μg Se day−1 (World Health Organization, 2011). The United Kingdom Expert Group on Vitamins and Minerals (2003) recommended a minimum intake of 60 μg Se day−1 for women and 70 μg Se day−1 for men. The amount of selenium in the food chain, and thus in the human diet, depends on the selenium concentrations in the soil. Therefore, soil is the most important part of