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Petroleum hydrocarbon concentrations (PHC) of surface sediments along the Chennai coast, India, were measured by UV-Fluorescence (UVF) Spectroscopy and the results are expressed in terms of Chrysene equivalents. The concentration of PHC in sediment varies widely (from 1.88 ppm to 39.76 ppm) as compared to the baseline (1.88 ppm) with higher values obtained in the northern part of the study area. The highest magnetic susceptibility (96.8 × 10−8 m3kg−1) value was determined from the Chennai harbour area. The magnetic parameters show that the Chennai coastal sediments are dominated by ferrimagnetic minerals. The positive correlation (r2 = 0.86; p < 0.05) between petroleum hydrocarbon concentrations and magnetic susceptibility suggests that the magnetic minerals and petroleum hydrocarbons along the Chennai coast are derived from the same sources. Factor analysis shows that the magnetic concentration dependent parameters (χ, χARM and SIRM) covary with the petroleum hydrocarbon concentration, suggesting that large amounts of magnetic minerals originate from anthropogenic activities. It is evident that using magnetic measurements may be considered a simple, rapid, cheap and non-destructive method to determine petroleum hydrocarbon concentrations in coastal sediments. Furthermore, this technique may be applied to petroleum exploration studies. Magnetic susceptibility measurements in sediments have been proposed as complementary or alternative means of exploration and assessment of hydrocarbon reservoirs. 相似文献
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Santhiya G Lakshumanan C Jonathan MP Roy PD Navarrete-Lopez M Srinivasalu S Uma-Maheswari B Krishnakumar P 《Marine pollution bulletin》2011,62(11):2537-2542
A survey on the Partially Extracted Trace Metals (PETMs) concentration (Fe, Mn, Cr, Cu, Ni, Co, Pb, Zn, Cd) in beach sediments is reported for the first time from 57 different locations in Chennai Metropolitan City of Southeast coast of India. The concentration of PETMs suggests that they are mainly concentrated with organic matter in the crowded part of the industrial regions in the beaches from the northern part rather than the tourist beaches in the southern part of the city. The comparison on enrichment of trace metals indicates higher values of Pb, Ni in the beaches than lowest effect level (LEL) and effects range low (ERL) than the tourist beaches. 相似文献
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Hema Achyuthan Nagalakshmi Thirunavukarasu 《Journal of the Geological Society of India》2009,73(5):683-696
In this paper we present Quaternary stratigraphy of the area around Chennai based on archaeological findings on the ferricrete
surface, geomorphological observations supplemented by radiocarbon dating. The coastal landscape around Chennai, Tamil Nadu,
has preserved ferruginised boulder gravel deposits, ferricretes and fluvial deposits of varying thickness. The area studied
is approximately 150 km east to west and 180 km north to south with a broad continental shelf towards the seaward. Several
rivers enter the Bay of Bengal along its shores like the Koratallaiyar, Cooum and the Adyar. Precambrian charnockite and Upper
Gondwana sandstone and shale bedrock rim the shelf margin. For the most part, the Upper Pleistocene-Holocene fluvial sediments
overlie an erosion surface that has cut into older Pleistocene sediments and ferricrete surface. Incised valleys that cut
into this erosion surface are up to 5–6 km wide and have a relief of at least 30 m. The largest valley is that cut by the
Koratallaiyar River. Holocene sediments deposited in the incised valleys include fluvial gravels, early transgressive channel
sands and floodplain silts. Older Pleistocene sediments are deposited before and during the 120-ka high stand (Marine isotope
stage 5). They consist of ferricretes and ferricrete gravel formed in nearshore humid environments. Muddy and sandy clastic
sediments dated to the ca. 5 ka highstand suggest that the climate was semi arid at this time with less fluvial transport.
The coarsening up sequence indicates deposition by high intensity channel processes. Pedogenic mottled, clayey silt unit represents
an important tectonic event when the channel was temporarily drained and sediment were sub aerially exposed. Uplift of the
region has caused the local rivers to incise into the landscape, forming degradation terraces. 相似文献
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Anoop A. Krishnan K.S. Yousuf P.L. Kumaran N. Harish B. Anoop V.V. Afsal M. Rajagopalan E. Vivekanandan P.K. Krishnakumar P. Jayasankar 《Estuarine, Coastal and Shelf Science》2008,76(4):909-913
The stomachs of 32 individuals of seven cetacean species incidentally caught in gill net and purseseine fisheries along Mangalore and Chennai coasts (India) between 2004 and 2006 were examined. The whole stomach (fore-gut, mid-gut and hind-gut) was examined in all cases. Prey remains (666 prey items comprising six species of teleosts, one crustacean and one squid species) were found in the stomachs of eight individuals (the remaining 24 stomachs were found to be empty). All cetaceans were found to feed mostly on teleosts with wide range of trophic levels. Based on an index that included frequency of occurrence, percentage by number and by weight, the oil sardine Sardinella longiceps was the main prey in the sample. Cetaceans appear to favour both pelagic as well as demersal prey, possibly indicating surface and benthic feeding habits. 相似文献
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M. Jayaprakash M.P. Jonathan S. Srinivasalu S. Muthuraj V. Ram-Mohan N. Rajeshwara-Rao 《Estuarine, Coastal and Shelf Science》2008
The article presents the results for enrichment of acid-leachable trace metals (ALTMs) from Ennore Creek in north Chennai, a metropolis on the southeast coast of India. ALTMs Fe, Mn, Cr, Cu, Ni, Co, Pb, Zn and Cd along with sediment texture, OC and CaCO3 were analyzed in surface sediments collected during two different seasons, pre-monsoon (PRM) and post-monsoon (POM) seasons to identify and observe the input of trace metals in the creek from various sources in the city limits. The most prominent feature of the ALTMs is the enrichment of Fe, Cr, Cu, Ni, Pb and Zn in the sediments, which is mainly attributed to the intense industrial activities around Chennai, and to the rapid industrialization policies. The ALTMs also indicate their association with the finer fractions, OC and Fe–Mn oxyhydroxides. The enrichment is very well supported by the correlation, grouping and clustering of ALTMs in statistical analysis. The differential behavior of ALTMs in POM season compared to PRM season is possibly due to the excess level of industrial effluents in the channel feeding Ennore Creek. Comparative results of ALTMs with other estuarine regions also indicate that the study area has been enriched with trace metals during the past two decades. The results of the present study suggest the need for a regular monitoring program which will help to improve the quality of Ennore Creek. 相似文献
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Tsunami, the natural disaster, which occurred on December 26, 2004 in the Indian Ocean, caused severe damage to mankind in the coastal areas. Total loss of life and economic loss because of this disaster have been estimated by various agencies but its effect on microbial density has not been probed. With our previous results on microbial populations in four locations of the Chennai coast of the Bay of Bengal, India in the pre‐tsunami period, the change in microbial populations was studied after the tsunami at regular intervals in the same locations. Coastal sediment and seawater samples were collected from four different locations after 5–10 h and thereafter at intervals of every 7 days up to 28 days post‐tsunami. Bacteria, fungi and actinomycetes were isolated from the marine samples by serial dilution on respective media. Before the tsunami, the bacterial population was higher in seawater samples than the sediments, whereas fungi and actinomycetes were recorded only in the sediments. The microbial population remarkably increased 5–10 h post‐tsunami in all the marine samples irrespective of the location. However, it slowly declined in the subsequent days and became similar to that of the population recorded before the tsunami. The population of gram‐positive bacteria increased whereas the gram‐negative bacterial population decreased after the tsunami. Further, populations of pathogenic bacteria such as coliform and vibrios did not increase after the tsunami. It has been observed that the increase in populations of bacteria and actinomycetes even after 28 days of tsunami may be due to the introduction of foreign microorganisms that developed the ability to survive in the extreme environment by exhibiting special characteristics such as pigmentation and production of exopolysaccharides. 相似文献
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《Singapore journal of tropical geography》2018,39(3):454-471
Slums pose a persistent challenge for fast growing urban areas in the global South, despite several decades of policy intervention. While Chennai has adopted several strategies ranging from upgrading to reconstruction, the city has been unable to deliver its target of ‘clearing’ slum settlements. Through an analysis of four enumeration reports and a look at the evolving political contexts and subsequent practices, we illustrate the evolution of slum policy approaches in Chennai since the 1970s. The analysis shows slum practices in Chennai continue to be characterized by an underlying continuity, with relocation as the dominant mode of operation since the nineties. However, approaches to slums have also evolved from paternalistic socialism with in‐situ development in the seventies, to approaches characterized by affordability and cost recovery in the eighties, to the aesthetics of global cities in the nineties, to the technology driven, to slum‐free ‘smart city’ discourse currently in vogue. 相似文献
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