Vertical distribution of heavy metals in soil profile in a seasonally waterlogging agriculture field in Eastern Ganges Basin

Abstract

The accumulation of heavy metals in soil and water is a serious concern due to their persistence and toxicity. This study investigated the vertical distribution of heavy metals, possible sources and their relation with soil texture in a soil profile from seasonally waterlogged agriculture fields of Eastern Ganges basin. Fifteen samples were collected at ~0.90-m interval during drilling of 13.11 mbgl and analysed for physical parameters (moisture content and grain size parameters: sand, silt, clay ratio) and heavy metals (Fe, Mn, Cr, Cu, Pb, Zn, Co, Ni and Cd). The average metal content was in the decreasing order of Fe > Mn > Cr > Zn > Ni > Cu > Co > Pb > Cd. Vertical distribution of Fe, Mn, Zn and Ni shows more or less similar trends, and clay zone records high concentration of heavy metals. The enrichment of heavy metals in clay zone with alkaline pH strongly implies that the heavy metal distributions in the study site are effectively regulated by soil texture and reductive dissolution of Fe and Mn oxy-hydroxides. Correlation coefficient analysis indicates that most of the metals correlate with Fe, Mn and soil texture (clay and silt). Soil quality assessment was carried out using geoaccumulation index (I(geo)), enrichment factor (EF) and contamination factor (CF). The enrichment factor values were ranged between 0.66 (Mn) and 2.34 (Co) for the studied metals, and the contamination factor values varied between 0.79 (Mn) and 2.55 (Co). Results suggest that the elements such as Cu and Co are categorized as moderate to moderately severe contamination, which are further confirmed by I(geo) values (0.69 for Cu and 0.78 for Co). The concentration of Ni exceeded the effects-range median values, and the biological adverse effect of this metal is 87%. The average concentration of heavy metals was compared with published data such as concentration of heavy metals in Ganga River sediments, Ganga Delta sediments and upper continental crust (UCC), which apparently revealed that heavy metals such as Fe, Mn, Cr, Pb, Zn and Cd are influenced by the dynamic nature of flood plain deposits. Agricultural practice and domestic sewage are also influenced on the heavy metal content in the study area.

Effects of drip irrigation on migration and distribution of heavy metals in soil profile

“…The geo-accumulation index (I geo ) introduced by Muller has been used since the late 1960s and has been widely employed in heavy metal studies (Muller 1969;Rajmohan et al 2014). The I geo was used to assess heavy metal contamination in soils by comparing current and pre-industrial concentrations, although it was not always easy to reach pre-industrial sediment layers.…”

Vertical Distribution and Controlling Factors Exploration of Sc, V, Co, Ni, Mo and Ba in Six Soil Profiles of The Mun River Basin, Northeast Thailand

“…The enrichment factor (EF) index and the geoaccumulation index (I geo ) are two important methods to assess the enrichment and contamination of heavy metals in soils [22,23]. The upper continental crust (UCC) is usually chosen as the reference material for the calculation of both indexes [1]. All background values were provided by Wedepohl [24].…”

“…Soil is a huge sink for heavy metals derived from parent rocks and anthropogenic activities, most of which will cause serious contamination once enriched in soils [1]. Because air, water and rocks interface in soil environment, the heavy metals in soils are transported by various carriers, which may lead to the enrichment of heavy metals in some areas [2][3][4].…”

Modelling drivers and distribution of lead and zinc concentrations in soils of an urban catchment (Sydney estuary, Australia)

“…The most significant predictors within the soil landscape covariate were swampy areas prone to soil waterlogging. Waterlogging can alter soil pH and therefore affect heavy metal bioavailability and mobility (Phillips, 1999;Rajmohan et al, 2014). Swampy environments have a direct interaction with waterways, and elevated water table in these areas increase risk of contaminants passing through to the groundwater (Hazelton and Murphy, 2011).…”