The Ennore Creek system is a complex one, situated north of Chennai, where the average depth rarely exceeds 2 to 5 metres. It is being fed by Kortalaiyar, Buckingham Canal, and a number of small channels. The present study provides a history of accumulation of trace metals and their present level, and the data can be used as a baseline to monitor the estuaries and coast in future. Hence, the present research investigation on the sediments is imperative to assess the environmental degradation of the estuaries as well as the coast.

The Ennore Creek is dominated by coarse fraction of the sediments. There is no marked temporal variation in sediment texture. The mangroves present near the middle of the estuary promote the decomposition of organic matter by microbial activities. The major sources of carbonate materials in the present sediments are the shell fragments of organisms, calcareous tests of organisms and also due to dilution of biogenic calcite by detrital material in the sediments. High organic matter content in the sediments of the riverine part of the estuary is due to fine nature of the sediments, high rate of sedimentation, prevalence of reducing environment and the larger supply of organic matter by river runoff.

The Ennore Creek water is basically alkaline in nature. There are significant enhanced variations in surface water temperature at stations 7 through 9 and 19; this is attributed to the hot water discharge from the North Chennai Thermal Power station (NCTPS). The concentration of nutrients is normal; they are due to higher organic activity in soils as well as faster rates of the chemical weathering reactions in the source region. The concentration of major ions is due to tidal influence; they are increase with salinity and the nutrients do behave non-conservatively due to biogenic removal. The dissolved oxygen content and pH have been intensely affected by anthropogenic activities. The conservative behaviour of trace metals with salinity has been strongly affected by the introduction of these metals by external sources.

Major oxide geochemistry indicates a homogenous and unweathered source for the sediments of the present study. Although the concentrations of Cr and Ni are both relatively higher, the influence on the former is anthropogenic, while that on the latter is more detrital. Copper, lead and zinc in surface sediments have both detrital and nondetrital sources. When compared with other estuaries of the east coast of India, the present study area is relatively more polluted. The trace element study of core samples indicates different characters for different cores. High rate of sedimentation and nondecomposition of OM are characterised by the cores C1, C3 and C5. The influence of anthropogenic input is observed in all cores.

Among the 36 species of foraminifers was identified, 18 are rotaliids, 13 are milliolids, and 5 are textularids. In the Ennore Creek, quite a few tests have been observed to exhibit morphological deformities. These include twisted tests, reduced size of the last chamber, anomalous location of the final chamber, irregular peripheries, dwarfed tests, thin-walled tests, and corroded tests. Ammonia beccarii exhibited highest number of deformed tests. The deformities include aberrant growth of test, reduced size of the last chamber, and twisted coiling in tests. Tests of Quinqueloculina seminulum exhibited aberrant test growth, abnormal location of the last chamber, and widening of apertures; incomplete tests were also common.