Relationship of arsenic accumulation with irrigation practices and crop type in agriculture soils of Bengal Delta, India

S H Farooq,W Dhanachandra,K Ram,D Chandrasekharam

doi:10.1007/s13201-019-0904-1

Abstract

The present study investigates the current state and distribution of As in the upper soil horizons (i.e. rhizospheric zone, 0–15 cm) of two different agricultural fields: (1) paddy-cultivating agricultural field that was irrigated with groundwater containing 137 µg/L of As and (2) wheat-cultivating agricultural field that was irrigated with groundwater having 67.3 µg/L of arsenic. Results clearly indicate different levels of As accumulation in the upper soil horizons of both profiles. In paddy field, although significantly higher quantity of As-contaminated groundwater was used for irrigation, still lesser than expected As concentration in soils was found [average As concentration 16.0 mg/kg (measured) vs. 29.0 mg/kg (calculated)]. The imbalance between higher influx of As and its relatively lower accumulation in soils indicates the existence of a mechanism (organic carbon mechanism, elaborated in the main text) that is responsible for continuous removal of As, and ultimately prevents the expected shoot-up of As in the paddy soils. On the other hand, although lesser quantity of less contaminated groundwater is used in wheat field, still wheat field soils show relatively higher As accumulation [average As concentration 22.5 mg/kg (measured) vs. 12.2 mg/kg (calculated)]. Such accumulation of As happens when there is continuous influx of As through irrigation water and/or other sources, and an effective (natural) mechanism to remove As from the wheat soil is absent. Adoption of distinct harvesting methods is responsible for existence of different mechanisms in paddy and wheat fields, which ultimately cause the differential accumulation of As in paddy and wheat soils.

Highlights

Arsenic contamination in the groundwater is probably the worst case of mass poisoning in the history of mankind and poses a severe threat to the worldwide groundwater resources (Chatterjee et al 1995)
Concentration of As and other elements in the groundwater samples was measured by high-resolution ICP-MS (Axiom, Thermo/VG Elemental, UK)
The fractions of mineral phases plus organic matter were summed up, and the fraction of clay minerals comprising minerals such as smectites, vermiculites and chlorites was determined by taking the difference from total sample (i.e. 100%)

Summary

Introduction

Arsenic contamination in the groundwater is probably the worst case of mass poisoning in the history of mankind and poses a severe threat to the worldwide groundwater resources (Chatterjee et al 1995). Many countries in the world are facing problems of As contamination in the groundwater This problem is most severe in many Southeast Asian countries including India, Bangladesh, Cambodia, Vietnam, etc. Over 50 million people in BDP are routinely exposed to As poisoning through drinking of contaminated groundwater, and around 45% of the total population living in As-affected areas of West Bengal is severely affected (Fewtrell et al 2005; Smith et al 2000). Different aspects of As contamination of groundwater have been investigated by various researchers around the globe (Berg et al 2007; Charlet et al 2007; Guo et al 2007; McArthur et al 2001; Mukherjee et al 2008; Nath et al 2008; Norra et al 2012; Smedley and Kinniburgh 2002; Stüben et al 2003; van Geen et al 2006), but still several gaps exist in scientific knowledge

Methods

Results

Discussion

Conclusion