C H Sujatha

Determination and distribution of endosulfan and malathion in an indian estuary

Abstract A field survey was conducted to determine the spatial and seasonal distribution of two very common pesticides, Endosulfan and Malathion, in Cochin estuary, India. Six sampling stations along the estuary were identified and analyses were carried out during premonsoon, monsoon and postmonsoon seasons. Pesticide levels were higher during the premonsoon period than during the postmonsoon season. Throughout the monsoon season, the estuary remained largely free of the pesticides except at the mid-estuarine region which was characterized by prominent agricultural runoff. One of the sampling sites located in the riverine area was designated as “pesticide-loading site” in view of its proximity to the pesticide-manufacturing unit.

Chemometric study on the trace metal accumulation in the sediments of the Cochin Estuary―Southwest coast of India

The distribution and accumulation of trace metals in the sediments of the Cochin estuary during the pre-monsoon, monsoon and post-monsoon periods were investigated. Sediment samples from 14 locations were collected and analysed for the metal contents (Mg, Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd and Pb), organic carbon, total nitrogen, total sulphur and grain size. The data were processed using statistical tools like correlation, factor and cluster analysis. The study revealed an enrichment of Cd and Zn in the study area particularly at station 2, which is confirmed by enrichment factor, contamination factor and geoaccumulation index. The factor analysis revealed that the source of Cd and Zn may be same. The study indicated that the spatial variation for the metals like Mg, Cr, Fe, Co, Ni, Cu, Zn, Cd and Pb were predominant unlike Mn which shows a temporal variation. The strong association of trace metals with Fe and Mn hydroxides and oxides are prominent along the Cochin estuary. The anthropogenic inputs of industrial effluents mainly control the trace metals enrichment in the Cochin estuary.

Spatial budgetary evaluation of organochlorine contaminants in the sediments of Cochin Estuary, India

This paper presents the first detailed investigation on the residual levels of organochlorine insecticide (OCI) concentrations in the Cochin estuarine sediment. It aims in elucidate their distribution and ecological impact on the aquatic system. Concentrations of persistent organochlorine compound (OC) were determined for 17 surface sediment samples which were collected from specific sites of Cochin Estuarine System (CES) over a period of November 2009 and November 2011. The contaminant levels in the CES were compared with other worldwide ecosystems. The sites bearing high concentration of organochlorine compounds are well associated with the complexities and low energy environment. Evaluation of ecotoxicological factors suggests that adverse biological effects are expected in certain areas of CES.

Core sediment biogeochemistry in specific zones of Cochin Estuarine System (CES)

Geochemical composition is a set of data for predicting the climatic condition existing in an ecosystem. Both the surficial and core sediment geochemistry are helpful in monitoring, assessing and evaluating the marine environment. The aim of the research work is to assess the relationship between the biogeochemical constituents in the Cochin Estuarine System (CES), their modifications after a long period of anoxia and also to identify the various processes which control the sediment composition in this region, through a multivariate statistical approach. Therefore the study of present core sediment geochemistry has a critical role in unraveling the benchmark of their characterization. Sediment cores from four prominent zones of CES were examined for various biogeochemical aspects. The results have served as rejuvenating records for the prediction of core sediment status prevailing in the CES.

Distribution of organochlorine pesticides in a tropical waterway: HCH isomers

Pesticide residue levels in the aquatic systems are scattered and fragmentory in India. A systematic analysis of the distribution pattern of the common organochlorine pesticide Hexachlorocyclohexane (HCH) and its isomers in the waters of the tropical positive estuarine system (the Cochin Estuarine System) has been carried out for the first time. The average concentrations of HCH ranged between 0.013 and 1.125 μg 1−1. α‐HCH was found to be at an appreciable concentrations throughout the study area and formed the highest percentage (90%) of all isomers of the HCH family

Behaviour of REEs in a tropical estuary and adjacent continental shelf of southwest coast of India: Evidence from anomalies

The distribution and accumulation of the rare earth elements (REE) in the sediments of the Cochin Estuary and adjacent continental shelf were investigated. The rare earth elements like La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and the heavy metals like Mg, V, Cr, Mn, Fe, Cu, Zn, U, Th were analysed by using standard analytical methods. The Post-Archean Australian Shale composition was used to normalise the rare earth elements. It was found that the sediments were more enriched with the lighter rare earth elements than the heavier ones. The positive correlation between the concentrations of REE, Fe and Mn could explain the precipitation of oxyhydroxides in the study area. The factor analysis and correlation analysis suggest common sources of origin for the REEs. From the Ce-anomalies calculated, it was found that an oxic environment predominates in all stations except the station No. 2. The Eu-anomaly gave an idea that the origin of REEs may be from the feldspar. The parameters like total organic carbon, U/Th ratio, authigenic U, Cu/Zn, V/Cr ratios revealed the oxic environment and thus the depositional behaviour of REEs in the region.

Trace metal enrichment and organic matter sources in the surface sediments of Arabian Sea along southwest India (Kerala coast)

The geochemical distribution and enrichment of trace metals (Cd, Co, Cu, Fe, Mn, Ni, Pb and Zn) were determined in the surface sediments of Arabian Sea, along southwest India, Kerala coast. The results of geochemical indices indicated that surficial sediments of five transects are uncontaminated with respect to Mn, Zn and Cu, uncontaminated to moderately contaminated with Co and Ni, and moderately to strongly contaminated with Pb. The deposition of trace elements exhibited three different patterns i) Cd and Zn enhanced with settling biodetritus from the upwelled waters, ii) Pb, Co and Ni show higher enrichment, evidenced by the association through adsorption of iron-manganese nodules onto clay minerals and iii) Cu enrichment observed close to major urban sectors, initiated by the precipitation as Cu sulfides. Correlation, principal component analysis (PCA) and cluster analysis (CA) were used to confirm the origin information of metals and the nature of organic matter composition.

Organophosphorus pesticide adsorption variability in diverse estuarine sediments

This paper reports on the sorption variabilities of two Organophosphorus pesticides, namely Malathion (MT) and Methyl parathion (MPT) in three distinctly different estuarine sediment types. The adsorption capacity of the pesticide has been quantified in terms of the Sorptive index, S for varying exposure times. An equilibrium/partition model has been proposed to characterize the pesticide, sediment interactions.

Prevalence of organochlorine pesticide residues in groundwaters of Kasargod District, India

The Kasargod District is the northernmost district of Kerala State and is bound between the north latitudes 12°02′27″ and 12°47′35″ and east longitudes 74°51′54″ and 75°25′25″. The present study highlights the contamination levels of organochlorine pesticides in open wells of the Kasargod District from 2010 to 2011. Maximum contamination of organochlorine pesticides (OCPs) was observed for endosulfan followed by hexachlorobenzene (BHC). Contamination levels of α-endosulfan were higher at Panathur (58 µg L−1) and next to Periya (37 µg L−1) in the postmonsoon season of 2010. During premonsoon 2011, the residue levels of α-endosulfan were higher at Panathady (56 µg L−1) followed by Rajapuram (40 µg L−1). Contamination levels of the BHC isomers exhibit the order of γ-BHC > α-BHC > β‐BHC, showing that γ-BHC represents 62% of the total OCP residues in premonsoon 2010. Among the studied OCPs, concentration levels of DDT were below detection limit. Maximum concentrations of the sum of all OCP residues were observed at Mulleria and Cheemeni (premonsoon 2010), followed by Panathur and Periya (postmonsoon 2010), and lowest in Panathady and Rajapuram (premonsoon 2011). Residues of OCPs were lowest in Paettikundu and Cheravatur in all the three seasons.

Heavy metal distribution and contamination status in the sedimentary environment of Cochin estuary

Heavy metals (Fe, Mn, Cr, Zn, Ni, Pb, Cu, Co and Cd) in the surface sediments of Cochin estuary, Southwest coast of India were analyzed to understand the spatio-temporal variation and contamination status via six sampling campaigns. Pollution indices like enrichment factor, geoaccumulation index and pollution load index inferred that the sediments of the northern arm of the estuary exhibited severe trace metal accumulation. Numerical sediment quality guidelines were applied to assess adverse biological effects of the trace metals, suggesting that occasional biological effect may occur due to Cr, Cu, Ni and Pb. Correlations between metals, organic carbon, silt and clay suggested that both fine grained sediment and organic matter were important carriers for these metals. Multivariate statistics indicated that the sources of Cu and Ni resulted primarily from natural weathering processes, whereas enriched levels of Cd, Cr, Zn and Pb were mainly attributed to anthropogenic activities.