Biogeochemical facsimile of the organic matter quality and trophic status of a micro-tidal tropical estuary

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.…”

Thematic Issue: Water of the Taihu Lake

“…Quality of surface waters is a severe problem worldwide (Dimberg and Bryhn 2014;Harmon et al 2014;Christia et al 2014;Renjith et al 2013;Sedlacek et al 2013;Antunes et al 2013;Rinke et al 2013;Watchorn et al 2013;George et al 2013) but particularly important to China because of the water resources use from the huge rivers originating in the Tibetan plateau flowing through the North China Plain into the Pacific Ocean. The water quality issue includes nutrients Wu et al 2013), in particular phosphorus (Chen and Zhao 2014;Yuan et al 2014;Zhu et al 2013;Liu and Chang 2013) and many other pollutants.…”

Thematic issue: water of the Erhai and Dianchi Lakes

“…Eutrophication of surface waters is a severe problem worldwide (Dimberg and Bryhn 2014;Harmon et al 2014;Christia et al 2014;Renjith et al 2013;Sedlacek et al 2013;Antunes et al 2013;Rinke et al 2013;Watchorn et al 2013;George et al 2013;Ivashechkin et al 2004) but particularly important to China because of the use of water resources from the huge rivers originating in the Tibetan plateau flowing through the North China Plain into the Pacific Ocean. The water quality issue includes nutrients (Ji et al 2014;Wu et al 2013) and phosphorus (Chen et al 2014;Yuan et al 2014;Zhu et al 2013;Liu and Chang 2013;Marjore et al 2013).…”