Influence of soil type and properties on distribution and changes in arsenic contents of different paddy soils in Bangladesh

Distribution and changes in heavy metal contents of paddy soils in different physiographic units of Bangladesh

“…A total of 66 surface soil samples (22 from 1967 and 44 from 1995 sampling) were used in this study. According to the Soil Survey Staff (1975), the soils have been tentatively correlated with the USDA soil taxonomy classification (Ali et al 1997a(Ali et al , 2003. They belong to the order Inceptisols except for the Chandra (Barind Tract; BT), Belabo (BT), and Noadda series (Madhupur Tract; MT) which belong to the order Ultisols (UNDP /FAD 1971).…”

“…Standard methods were used for the determination of the soil pH with a glass electrode (Mclean 1982), total carbon content with Sumigraph NC-80 (Surnitomo Chemical Co. Ltd., Osaka, Japan) (Nelson and Sommers 1982). Effective cation exchange capacity (ECEC) was calculated based on the sum of the amounts of neutral 1 N NH 4 0Ac-extractable bases (Na, K, Ca, and Mg) plus 1 N KCl-extractable acidity (H + AI) and the clay content by using the pipette method (Gee and Bauder 1986), as reported in our earlier papers (Ali et al 1997a(Ali et al , b, 1998(Ali et al ,2003.…”

“…This study was based on air-dried archived Bangladesh soil samples collected in 1967 and 1995, which were used in our previous studies (Ali et al 1997a(Ali et al , b, 1998(Ali et al , 2003. Based on the first (1967) soil sampling conducted during the period from December 1967to January 1968(Kawaguchi and Kyuma 1977, in the second (1995) sampling, the soils were collected similarly in June 1994 and April-May 1995 from the same sites/ series as in 1967.…”

“…The hydrological regimes are considerably influenced by the heterogeneity in the topographic elements and exert major impacts on the soils of different physiographic units. Remarkable changes in cropping practices and the use of agricultural inputs, especially crop types, irrigation and fertilizer application, were observed during the period 1967-1995 (Ali et al 1997a(Ali et al , 2003.…”

“…In a previous paper (Ali et al 2003), we described the distribution and changes in the relationship between the As content and selected soil properties during the period 1967-1995. In the current paper, we attempted (i) to determine the background contents of heavy metals and the factors regulating the distribution characteristics in the soils of different physiographic units, and (ii) to evaluate the changes in heavy metal contents during the period 1967 -1995 in Bangladesh.…”