Trace element concentration in groundwater of Pesarlanka Island, Krishna Delta, India

Abstract

There is a growing concern over the potential accumulation of trace element concentration in groundwater of coastal aquifer owing seawater encroachment in the last several decades. A total of 29 groundwater samples collected from Pesarlanka Island, Krishna delta, Andhra Pradesh, India were analyzed for 13 trace elements (B, V, Mn, Fe, Ni, Co, Cu, Zn, As, Sr, Cd, Ba, and Pb) using inductively coupled plasma mass spectrometry. The results reveal that B, Fe, Ni, As, Sr, and Pb vary from 11.22 to 710.2, 1.25 to 684.6, 0.02 to 37.33, 27.8 to 282.3, 164.1 to 7,009, and 1.97 to 164.4 microg/l, respectively. Ba, Cd, Co, Cu, Ni, V, and Zn are almost within permissible limits for drinking water, but As, Fe, Mn, Pb, B, and Sr are above the permissible limit. The toxic element Pb is 1.64 times more than the maximum permissible limits of drinking water. The minimum value of As is also 2.78 times more, whereas the maximum is 28.2 times the permissible limit. The spatial distributions of alkaline earths (Sr, Ba), transition metals (V, Co, Ni, Fe), metallic elements (Cu, Pb), and (As) were found in considerable variation in the entire Island. Good cross-correlations were found between As, B, Co, and Sr with total dissolved solids and among other trace elements such as B, As, Co, and Sr. The variability observed within the groundwater samples is closely connected to the sea spray input; hence, it is primarily a consequence of geographical and meteorological factors, such as distance from the ocean and time of year. The trace element levels, in particular those of heavy metals, are very low, suggesting an origin from natural sources rather than from anthropogenic contamination. A few trace elements (Sr and B) are found as sensitive parameters responding to changes in fresh to saline groundwater environment. The highly elevated trace elements in this area which may be attributed to marine sediments or death and decay of plants are presented in this paper.

Impacts of sediment retention by dams on delta shoreline recession: evidences from the Krishna and Godavari deltas, India

“…The situation in the Krishna delta is much worse as widespread seawater intrusion is transforming the fresh groundwater to brackish/saline water (Saxena et al, 2004), even in the channel islands like Potharlanka (Mondal et al, 2008) and Pesarlanka (Mondal et al, 2009), which are located within the braided course of the Krishna River as far as 50 km inland from the shore. Lowering of the water-table due to groundwater extraction for irrigating long-duration crops like sugarcane, turmeric and banana grown in these areas (Nageswara Rao and Vaidyanadhan, 1981) and lack of recharge due to reduced river fl ows for most of the year might be leading to seawater intrusion into the delta, which is evident from the presence of trace elements like strontium and boron in the groundwater here (Saxena et al, 2004;Mondal et al, 2009). The condition is perhaps further exacerbated by possible coastal subsidence and relative sea-level rise due to diminishing sediment supplies in the recent decades pushing, in turn, the freshwater-seawater interface landward.…”

Groundwater arsenic contamination and their variations on episode of drought: Ter River delta in Catalonia, Spain

“…Another important clue to support the previous hypothesis is the geologic characteristics and morphology of Baix Emporda aquifer; the delta is an area where sea and land coexist, this aquifer is formed by a big number of deposit of different size materials; the origin of (As) could be a deposit of sediments rich in iron and manganese oxides from antic marine deposits (prehistoric wetlands) which now are part of the aquifer (Montaner and Subiranas 2009;Mondal et al 2010). The increase in arsenic associates to site 17, because the well is drawing water from a specific deposit of sediments rich in arsenic oxides, as are explained for Montaner and Subiranas (2009) …”

Hydrochemical characteristic of coastal aquifer from Tuticorin, Tamil Nadu, India

“…11). In general, the Sr and B concentrations are low in fresh groundwater (Mondal et al 2010b), but high in brackish and saline waters (see Table 5). …”

“…Thus, one of the most common methods for assessing seawater intrusion through an aquifer in coastal belts is a periodic analysis of groundwater chemistry (Todd 1980;Sukhija et al 1996;Saxena et al 2003;Beddows et al 2007;Sarwade et al 2007;Kim et al 2009). When seawater intrusion is a main cause of high salinity, groundwater generally exhibits high concentrations not only in total dissolved solids (TDS) but also in major cations and anions (Richter and Kreitler 1993) as well accumulation of selective trace elements (Saxena et al 2004;Mondal et al 2010b).…”