Evaluation of leaching and runoff losses of selenium from seleniferous soils through simulated rainfall

Abstract

Experiments were conducted to study drainage and runoff losses of selenium (Se) from two seleniferous soils (from Simbly containing total Se 850 lg [kg soil] ±1 and from Barwa containing 1310 lg [kg soil] ±1 ) under simulated rainfall (250±260 mm in three rainstorms) conditions. Rainfall intensities ranged from 56 to 120 mm h ±1 with uniformity coefficients ranging from 70.6% to 84.2%. Selenium lost through drainage (sum of drainage from initially saturated soil for 24 h and through dry and wet runs) was 0.15% and 0.11% of total Se content in the two soils. In soils having similar pH and organic-C content, losses of Se through drainage as well as runoff were defined by total Se, water-soluble Se, CaCO 3 content, and texture of the soils. The amount of runoff water was almost two times in the soil with fine texture and less infiltration rate than in the other and that same trend was observed with respect to loss of sediment. The soil with higher CaCO 3 content and water-soluble Se lost more Se with moving water both through leaching and runoff, whereas the other soil with fine texture lost greater amount of Se with the sediment. Total Se lost through drainage as well as runoff was 0.29% of the native Se present in both the soils suggesting that significant amount of Se could be lost from seleniferous soils during irrigation and rainfall events.

Hazardous concentrations of selenium in soil and groundwater in North-West India

“…The map of study area in Punjab can be found in a report by Dhillon and Dhillon [18]. Total rainfall in that area varies from 631 to 1325 mm a −1 and about 80% of the yearly rainfall of approximately 1000 mm occurs in the rainy season, mainly from July to September [24,29]. The soils of the area are mostly loamy and alkaline in reaction and are considered to be formed from the alluvium deposited by Indus rivers system [18].…”

“…The cause of high Se concentrations in the groundwater of this area is still unclear. It was suggested [24,29] that high dissolved Se concentrations in the groundwater could be present due to leaching of Se from seleniferous top soils by rainfall and long-term drainage. In our study, the degree of leaching, however, which was indicated by the Se content in the soil below 15 cm, is probably not sufficient to explain the extremely high Se concentrations in the groundwater at a depth of 76 m. The observed concentrations by far exceeded the Se limits prescribed by the WHO [32].…”

Selenium environmental cycling and bioavailability: a structural chemist point of view

“…Leaching of selenium species from soil to groundwater is another component of selenium hydrological transport. However, processes governing this leaching are poorly understood, due to the heterogeneity of the water/rocks, soils and sediment interfaces (Dhillon et al 2008). Mean residence time of selenium in the deep ocean is about 1,100 years, i.e., is of the order of water residence time (Ihnat 1989).…”

Fate of Selenium in Soils at a Seleniferous Site Recorded by High Precision Se Isotope Measurements

“…Soil Se concentrations range from 0.25 to 6.8 mg kg −1 with a mean value of 3.6 mg kg −1 . 16,17 A 2004 study 18 showed that the dietary intake of Se is greater than 600 μg Se day −1 in this region in excess of the recommended WHO limit. 3 Analysis of human hairs and nails revealed 6 to 9 times higher Se contents compared to background levels.…”