title: Development and mapping of seleniferous soils in northwestern India.
abstract: Periodic surveys were undertaken to identify and characterize Se-contaminated soils in northwestern India. Total Se content varied from 0.023 to 4.91mgkg(-1) in 0-15cm surface soil and 0.64-515.0mgkg(-1) in samples of vegetation. Selenium-contaminated land occupying an area of 865ha was classified into different categories based on total Se content of soils as moderately contaminated (0.5-2.0mg Sekg(-1)) and highly contaminated (>2.0mg Sekg(-1)). The normal soils contained <0.5mg Sekg(-1). The soil map was prepared using village level cadastral maps. Se-contaminated soils were silty loam to silty clay loam in texture and tested pH 7.9-8.8, electrical conductivity 0.3-0.7dSm(-1), calcium carbonate 0.1-4.1% and organic carbon 0.4-1.0%. Selenium was present throughout the soil profile up to 2m depth; 0-15cm surface soil layer contained 1.5 to 6.0 times more Se than in subsurface layers. Selenium content in rock samples collected from lower and upper Shiwalik sub-Himalayan ranges varied from 1864 to 2754 and 11 to 847μgkg(-1), respectively. The sediments transported through seasonal rivulets linking the Shiwalik ranges to affected sites contained 0.57-2.89mg Sekg(-1). The underground water containing 2.5-69.5μg SeL(-1) used for irrigating transplanted rice grown in Se-contaminated area resulted in a net Se addition in soil up to 881gha(-1)y(-1); possibly further aggravating the Se-toxicity problem. Presence of substantial amount of Se in rock samples and sediments of seasonal rivulets suggests that Se-rich materials are being transported from Shiwalik hills and deposited in regions where seasonal rivulets end up.
authors.affiliation: Department of Soil Science, Punjab Agricultural University, Ludhiana 141 004, Punjab, India. Electronic address: dhillon_karaj@yahoo.com.
authors.forename: Karaj S
authors.initials: KS
authors.lastname: Dhillon
authors.affiliation: Department of Soil Science, Punjab Agricultural University, Ludhiana 141 004, Punjab, India. Electronic address: surjitdhillon1948@yahoo.com.
authors.forename: Surjit K
authors.initials: SK
authors.lastname: Dhillon
mesh_terms: D000383:Agriculture; D004784:Environmental Monitoring / Q000379:methods*; D007194:India; D012275:Oryza; D012643:Selenium / Q000032:analysis*; D012987:Soil / Q000737:chemistry*
chemical_list: D012987:Soil; D012643:Selenium
keywords: Distribution map; Rocks; Seasonal rivulets; Sediments; Seleniferous soils; Shiwaliks