PhD Theses (SACON)
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Item Polycyclic aromatic hydrocarbon contamination in Pallikaranai wetland, Chennai, Tamil Nadu, India; Fish as an Indicator.(SACON, 2020) Mythreyi, D.; Muralidharan, S.Enormous quantities of man-made chemicals are being used every day to meet the ever increasing food, energy, transport and industrial demands. During the past few decades, there has only been a steady increase in the use of these chemicals leading to their excessive presence throughout the global environment. Wetlands, being the most fragile ecosystems have suffered the maximum. Extensive stretches of wetland habitats have been altered and destroyed. Among the gazillion types of chemicals, Persistent Organic Pollutants (POPs) are significant because they are resistant to degradation in the environment and biota. Due to their fat soluble nature and resistance to degradation, ingestion of certain POPs by fauna leads to bioaccumulation throughout their lives, generally in fat tissues, and biomagnification through food chain. Among the POPs, Polycyclic Aromatic Hydrocarbons (PAHs) are highly prevalent in vertebrates, particularly fishes. Polycyclic Aromatic Hydrocarbons (PAHs) are a unique class of POPs constituted by hundreds of individual organic compounds. These ubiquitous environmental contaminants are wide-spread in the air, bonded to particulate matter and readily bioavailable. Studies have demonstrated the carcinogenic, mutagenic and teratogenic behaviour of many of the PAHs. Based on their properties, 16 PAHs are listed as “priority pollutants” by the U.S. Environmental Protection Agency (EPA). These 16 PAHs are being measured and monitored in different environmental components in ecosystem throughout the globe.Item Polychlorinated Biphenyl (PCB) residues in marine fishes available in Coimbatore market and their suitability for human consumption(SACON, 2011) Alaguraj, A.; Muralidharan, S.Seven species of marine fishes totalling 732 individuals caught at Cochin and Rameshwaram coasts, and sold in Ukkadam fish market. Coimbatore between October 2004 and October 2006 were analysed for residues of 32 individual congeners, including six indicator PCBs (PCB 28, 52, 101, 138, 153 and 180) with Gas Chromatograph coupled with Mass Selective Detector. Fishes included in the present study are Indian Mackerel (Rastrelliger kanagurta), Japanese Threadfin Bream (Nemipterus japonicus), Oil Sardine (Sardinela Iongiceps), Great Barracuda (Sphyraena barracuda), Malabar Travelly (Carangoides malabaricus), Tongue Sole (Cyanoglossus macrolepidotus) and King Seer (Scomberomollus commersonil)' Selection was based on human consumption (preference), commercial value and availability throughout the year in both the locations.Item Organochlorine Pesticide Residues in the Marine Fishes of Coimbatore Market – Suitability for Human Consumption(SACON, 2012) Jayanthi, P.; Muralidharan, S.The current study has attempted to document the organochlorine pesticide residues in select species of commercially important marine fishes, received from Cochin and Rameshwararn, and sold at Coimbatore market. A total of 716 fish samples belonging to seven species, namely Carangoides malabaric, Cynoglossus macrolepidotus, Nemipterus japonicus, Rastrelliger kanagurta, Sardinella longiceps, Scomberomorus commersonn and Sphyraena barracuda caught at Cochin and Rameshwaram were collected from the Coimhatore market. The samples were collected with regular intervals during the study period (October 2004 . September 2006) which fell into eight quarters, with three months being one quarter.Item Heavy metal contamination in the fishes of Inland wetlands of India.(SACON, 2007) Jayakumar, R.; Murlidharan, S.Heavy metals are one of the most toxic, persistent and widespread group of contaminants in aquatic systems. Their effects may often occur and remain unrecognized at the individual level but slowly, over a period of time, show up at population level. It is well known that heavy metals measured in tissues of aquatic organisms can reflect past exposures. They can also be a reasonable measurement for public health standards and in the point of view of animals' health. Over a few decades globally there has been growing interest to determine levels of heavy metals in the aquatic environment and public food supplies, particularly fish due to their known hazards. In India heavy metals although have not created any major problems, varying magnitudes of heavy metal contamination do exist in various biotic and abiotic components. Information on heavy metal contamination in fishes lay scattered and many of them do illustrate the toxic effects at laboratory conditions. Further information on the suitability of fishes for human consumption, in the perspective of metal contamination, is limited. The current study has attempted to document the heavy metal contamination status of select wetlands spread across the country using fish as an indicator. Altogether 8S9 fishes comprising 19 species were collected from 90 wetlands spread across 10 states in the country and examined for heavy metal contamination, Further, biomarkers of metal contamination, namely Metallothionein and Glutathione were also quantified in a few species of fishes collected from select wetlands in Tamil Nadu. Biomarkers are expected to indicate the stress in fishes and serve as an early warning signal. Suitability of fishes for human consumption was evaluated as it will help assess the impact on human beings in tong run.