Geochemical variability in the soils of Bangladesh as affected by sources of irrigation water and inundation land types

Abstract

Paddy soils in Bangladesh experience extensive irrigation with groundwater and surface water, both having variable geochemical constituents. The soils also have topological variations across the landscape. To understand the geochemical variability in the soils as affected by the different sources of irrigation water and the topographical variability, cultivation zones of paddy soils irrigated with both groundwater (n = 904) and surface water (n = 281) across Bangladesh were sampled and analyzed for a suit of seventeen geochemical elements. This study also assessed the extent and distribution of arsenic and the other geochemical elements in the paddy soils (n = 1209) as well as in a set of neighboring non-paddy soils (n = 235) within the different inundation land types (highland, medium highland-1, medium highland-2, medium lowland, lowland and very lowland) of Bangladesh. The mean concentrations of aluminum (26,000 mg/kg), cobalt (13 mg/kg), copper (32 mg/kg), iron (28,250 mg/kg), lead (18 mg/kg), magnesium (8050 mg/kg), molybdenum (1.02 mg/kg), nickel (41 mg/kg), potassium (4870 mg/kg), sodium (750 mg/kg) and zinc (70 mg/kg) in the surface water-irrigated paddy soils were found to be significantly (0.001 ≥ p ≤ 0.05) higher compared to the concentrations in the soils irrigated with groundwater (23,400; 12; 28; 25,650; 17; 7000; 0.96; 36; 4350; 600; and 62 mg/kg, respectively). Therefore, surface water used for paddy irrigation could increase the inputs of a number of toxic elements in the paddy soils having potential risk of crop contamination. Arsenic in the paddy and non-paddy soils varied significantly (F = 24.74, p < 0.001 and F = 3.42, p < 0.01, respectively) within the inundation land types, the very lowland (9.95 and 6.72 mg/kg, respectively) and lowland (8.33 and 5.20 mg/kg, respectively) having the highest mean arsenic concentrations and the medium highland-1 (5.27 and 5.17 mg/kg, respectively) having the lowest. The concentrations of the other geochemical elements analyzed were also observed to be higher, in general, in the soils of very lowland and lowland. Since the low-level lands are predominantly used for paddy cultivation, higher concentrations of various toxic elements, particularly arsenic, in such soils pose an increased risk of rice toxicity in Bangladesh. The results of this study present an inimitable geochemical database for the surface soils across Bangladesh which can be used in any future studies on the geomorphologically variable agricultural and non-agricultural Bangladeshi soils, providing a basis for environmental pollution assessment and sustainable mitigation approaches.

Errors in agricultural practices increase the toxicity of heavy metals in the food chain at Ishwardi Upazila in Bangladesh

“…A wide range of values for metal concentrations was observed among the sampling sites. Factors such as salinity, geomorphological setup, farming process, and land runoff might have played a crucial role in the variation of metals [ 36 ]. As shown in Table 1 , concentrations of heavy metals at some sites were much higher than others because these sites are located downstream of the river, with extensive discharging of urban waste, excessive use of agrochemicals, and use of poultry litter (Composed of poultry feed, waste, and blending of rice husk) as organic fertilizer.…”

Human health implications of trace metal contamination in topsoils and brinjal fruits harvested from a famous brinjal-producing area in Bangladesh

“…Kormoker et al 47 collected agricultural field soils from 58 sites of the Jhenaidah and Kushtia districts, Bangladesh, and the mean concentration of Pb, Ni, Cd, Cr, and Cu was 19.20, 21.00, 1.20, 5.78, and 31.80 µg g -1 , respectively. On the other hand, Chowdhury et al 48 analyzed 1209 paddy soils collected from 57 Upazilas (sub-districts) of 17 districts in Bangladesh and found that the mean concentrations of Pb, Ni, Cu, Fe, and Zn were 18.0, 41.0, 32.0, 28250, and 70.0 µg g -1 , respectively. For comparison with geochemical background concentration, the mean concentrations of all trace elements studied were lower than the average shale value 49 , soil toxicity reference values 50 , and soil quality guideline values of Canada 51 , and the Netherlands 52 (Table 2 Suppl.).…”

Alleviation of arsenic accumulation in rice by applying silicon-rich rice husk residues in Bangladesh soil

“…The addition of silicon-rich rice husk residues has been reported to increase plant-available silicon in soil porewater, which limitsthe uptake of arsenite by suppressing the expression of the Low silicon 1 (Lsi1) and 2 (Lsi2) genesin roots (Ma et al, 2006;Ma and Yamaji, 2015), and enhance the competition of silicon with arsenite for uptake (Bogdan and Schenk, 2008;Seyfferth and Fendorf, 2012). Thereduced uptake of arsenic by roots, along with the reducedadsorption of arsenic onto soil solids due to enhanced competition with the released silicon from FRH and RHA in soil porewater (Luxton et al, 2006), increases the concentration of arsenic available in soil porewater that may undergo redistribution and remobilisation through irrigation/ monsoon flooding (Roberts et al, 2010) depending on the land topographical condition (Chowdhury et al, 2021). However, the mobilization and retention of arsenic and silicon in paddy soils are also affected by a a number of other factors related to the properties and composition of the soil, such as temperature, pH, redox potential, clay and organic matter content, ionic constituents as well as the microbially mediated biogeochemical interactions that control the biogeochemical cycling of the elements in the soil (Bissen and Frimmel, 2003;Mahimairaja et al, 2005;Sommer et al, 2006;Moreno-Jiménez et al, 2012;Pati et al, 2016).…”