http://nopr.niscpr.res.in/handle/123456789/38649 Fri, 09 Oct 2026 08:44:57 GMT 2026-10-09T08:44:57Z http://nopr.niscpr.res.in/handle/123456789/39288 Title: Chemical Variation & Element Correlation in Manganese Nodules from a Dredge Haul in the Central Pacific Authors: Roonwal, G S; Friedrich, G H Abstract: Local variations in composition of Fe-Mn nodules from the nodule belt of the central Pacific Ocean indicate that these variations are similar to those seen on the regional scale. Mn varies from 8.4-23.4% and Fe 5.8-14%. Heavy metal content also shows a corresponding trend. C.orrelation between major and minor elements shows that to a large extent the minor elements follow the major elements, viz. eu and Ni follow Mn, and Co, Pb and Ti follow Fe. Interelement relationship shows that Zn and Mo tend to follow Ni, and Cu-Ni show a mutual relationships. Nodules show Mn/Fe ratio 1.4 to 3 and a relatively higher concentration of heavy metals. They are predominantly todorokite rich and also show high barium content. On the Bonatti diagram, they occupy the central field of hydrogenous type. Page(s): 235-239 Mon, 01 Dec 1980 00:00:00 GMT http://nopr.niscpr.res.in/handle/123456789/39288 1980-12-01T00:00:00Z http://nopr.niscpr.res.in/handle/123456789/39287 Title: Chemical Oceanography of the Arabian Sea. Part V - Hydrochemical Characteristics Off the Central West Coast of India Authors: Gupta, R Sen; Braganca, Analia; Noronha, R J; Singbal, S Y S Abstract: Data from Arabian Sea cruises 46 (December 1978) and 59 (October 1979) of R V Gaveshani have been used to calculate rates of denitrification at intermediate depths (72-1200 m). About 34% of the available nitrate-nitrogen is depleted by denitrification. The 'standing crop' of denitrified nitrogen is 70 g m-2. Combining the rates of denitrification at an intermediate depth with the photosynthetic productivity at the euphotic zone, the mean residence time of the watermass is between 13 and 54 yr. Page(s): 240-245 Mon, 01 Dec 1980 00:00:00 GMT http://nopr.niscpr.res.in/handle/123456789/39287 1980-12-01T00:00:00Z http://nopr.niscpr.res.in/handle/123456789/39286 Title: Diel Variations in Some Organic Constituents of Particulate Matter in Vellar Estuary Authors: Subramanian, B R; Venugopalan, V K Abstract: Diel variations of particulate organic carbon (POC), nitrogen (PON), phosphorus (POP), carbohydrate (PCHO) and chlorophyll a (chl a) were studied during a 24 hr tidal cycle. POC, chl a and PCHO exhibited day and night time variations. Increase in POC and PCHO during day was attributed to photosynthesis by phytoplankton and the decrease of the same during night to algal respiration. Decrease in chl a during night was related to zooplankton grazing. All the parameters except POP, showed no significant variation between surface and bottom waters. Page(s): 246-249 Mon, 01 Dec 1980 00:00:00 GMT http://nopr.niscpr.res.in/handle/123456789/39286 1980-12-01T00:00:00Z http://nopr.niscpr.res.in/handle/123456789/39285 Title: General Expression for Spectrum of Magnetic Anomaly due to Long Tabular Body & Its Characteristics Authors: Mishra, D C; Murthy, K S R; Rao, T C S Abstract: A general expression for spectrum of magnetic anomalies-vertical, horizontal and total intensity - due to a long tabular body is derived which is used to estimate the body parameters. The analysis is extended to a marine magnetic anomaly recorded over the outer shelf off Visakhapatnam, Andhra Pradesh, India. The results obtained show good correlation with those from methods of curve matching and characteristic curves. Page(s): 250-252 Mon, 01 Dec 1980 00:00:00 GMT http://nopr.niscpr.res.in/handle/123456789/39285 1980-12-01T00:00:00Z