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

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

“…The dominance of DDD's over DDE's clearly supports the reductive dechlorination of DDT's to DDD under anaerobic conditions and similar observations reported earlier (Barakat et al, 2002). The results of anoxic behavior of sediments from the study area was in good concurrence with the previous work of Akhil et al, 2013 andManju et al, 2013. The total P OCI contamination in sediment was 1170 ng/g (2009) and 1087 ng/g (2011) in the entire study region.…”

Geochemical characterization of mangrove sediments of the Zuari estuarine system, West coast of India

“…High TOC percentage in the core collected from the upper middle estuary that coincided with clay is attributed to the enhanced adsorption of organic carbon onto the clay minerals in the low salinity regimes (Akhil et al, 2013). Increased TOC percentage along with silt in the upper sections of the core in Cumbharjua canal may be due to the rapid burial of organic matter.…”

Fate and source distribution of organic constituents in a river-dominated tropical estuary

“…Typically TOC/S ratios >5 has been categorized as oxic sediment with oxygenated bottom water, TOC/S = 1.5-5 indicates sediments deposited under periodic anoxia and TOC/S <1.5 reflect anoxic sediments with anoxic water (Raiswell et al 1987). The estimated TOC/S values (range: 0.30-9.52) pointed out that most of the stations were under the influence of periodic anoxia, where sediments undergo sulphate reduction below an oxygenated water column (Niffy Benny 2009;Renjith et al 2012;Akhil et al 2013).…”

“…Biochemical composition serves not only as a valid methodology to determine the origin of organic matter (Colombo et al 1996), but also as a useful tool to evaluate the nutritional quality of organic materials as available food for benthic consumer organisms (Dell'Anno et al 2000;Rossi et al 2001;Rossi and Lardicci 2002;Cividanes et al 2002;Joseph et al 2008). Composition of OM in sediments has been recognized as the major factor affecting metabolism, distribution and dynamics of benthic organisms (Grant and Hargrave 1987;Graf 1989;Duineveld et al 1997) and has been widely employed to evaluate the trophic state of both marine and estuarine ecosystems (Cloern 2001;Renjith et al 2012;Akhil et al 2013). The portion of sedimentary OM which are more readily available to benthic consumers (labile fraction), has usually been assessed by estimation of the main biochemical classes of organic compounds (Fichez 1991;Danovaro et al 1993;Fabiano et al 1995;Dell'Anno et al 2002).…”

“…Even though the estuary has been found to be a site of positive net ecosystem production (Qasim 2003), a seasonal shift in net pelagic production to heterotrophic conditions owing to terrestrial input of OM has also been reported (Thottathil et al 2008). Even though, information regarding the organic geochemical aspects of sediments in the Cochin estuarine system is available (Aneeshkumar and Sujatha 2012;Gireeshkumar et al 2012;Renjith et al 2012;Akhil et al 2013), a long term monitoring and detailed description of the sedimentary variables is yet to be attempted. All these investigations have repeatedly demonstrated the role of industrialisation, urbanisation and other anthropogenic interventions, creating alterations in the biogeochemical aspects and ecological functioning of this sensitive ecosystem.…”