Sedimentation and trace metal distribution in selected locations of Sundarbans mangroves and Hooghly estuary, Northeast coast of India

Abstract

Four sediment cores were collected from selected locations of Sundarbans mangroves and Hooghly estuary, northeast coast of India to establish (210)Pb geochronology and trace metal distribution in sediments. Core sites were chosen to reflect a matrix of variable anthropogenic input and hydrological conditions. The vertical distribution of (210)Pb(xs) ((210)Pb(total)-(226)Ra) provided reliable geochronological age to calculate the mass accumulation rates and historic trace element inputs and their variations. The mass accumulation rates ranged from 0.41 g cm(-2) year(-1) (estuarine region) to 0.66 g cm(-2) year(-1) (mangrove region). Both in mangroves and estuarine systems, Fe-Mn oxy-hydroxides are observed to be a major controlling factor for trace metal accumulation when compared to organic carbon. Core collected from Hooghly estuary shows less contamination when compared to the mangrove region due to high energy and mostly coarse grained. Fe-normalized enrichment factors (EFs) of trace metals were calculated based on crustal trace element abundances. The EFs are typically >1 for Cd, Pb, Co, and Cu indicating that these metals are highly enriched while other metals such as Zn, Ni, Cr, and Mn show no enrichment or depletion. Both Sundarbans mangroves and Hooghly estuary have been receiving considerable pollution loads from anthropogenic sources such as industrial, domestic, and shipping activities in recent times, indicating high concentration of metals in the top few layers. This study suggests that the variation in trace metals content with depth or between mangrove and estuarine system results largely from metal input due to anthropogenic activities rather than diagenetic processes.

Sources and dynamics of sedimentary organic matter in Sundarban mangrove estuary from Indo-Gangetic delta

“…are also dominant plant species in the Indian Sundarbans (Mandal et al 2012). Like other mangrove ecosystems, Sundarban is also highly degraded by anthropogenic activities, like industrial, domestic, and shipping activities (Baneerjee et al 2012, Banerjee et al 2012. Sundarban is rich in biodiversity and is a favorable habitat for the Royal Bengal Tigers.…”

Ecological risk assessments and context-dependence analysis of heavy metal contamination in the sediments of mangrove swamp in Leizhou Peninsula, China

“…Additionally, RDA results also showed that many metals, such as Ni, Cr, Cd and Cu, have a correlation with Fe. Several studies have proved that Fe oxy-hydroxides are a major controlling factor for trace metal accumulation (Banerjee et al, 2012).…”

Evaluation of metals and hydrocarbons in sediments from a tropical tidal flat estuary of Southern Brazil

“…hopanes) ( Table 3). Furthermore, the input of these metals may also be associated with washing of impermeabilized surfaces containing waste of tyres, fuels, lubricants and brake pads, which are carried to the estuary by rainwater runoff (Banerjee et al, 2012) and may be associated with the intense traffic of motor vehicles in the locality. According to Grilo et al (2013), two bridges that cross the Passagem Channel (Camburí and Passagem) were constructed and refurbished, respectively, around 1980, increasing automobile traffic in the region.…”

“…EF ¼ ðM=ScÞ Sample =ðM=ScÞ Background This index is used as a tool for studies of trace metals in order to evaluate the anthropogenic contribution to metal accumulation (Baptista Neto et al, 2000;Karageorgis et al, 2009;Banerjee et al, 2012). Usually, Al or Fe is used as conservative lithogenic marker, however, in this work Sc was used as it is derived only from lithogenic sources (Buat-Menard and Chesselet, 1979) and …”

“…The high enrichment of these metals is possibly due to the use and disposal of fuel vessels (Abu-hilal, 1987), since there is a marina in the P1 region. The enrichment of these metals, along with nickel and chromium, may also be associated with urban runoff (Banerjee et al, 2012). Gajghate and Bhanarkar (2005) also implicate atmospheric deposition of metal by automobile exhaust emissions as an indirect source of Pb to the environment.…”