Geochemistry of the Cauvery Estuary,East Coast of India     

A. L. Ramanathan  P. Vaithiyanathan  V. Subramanian  B. K. Das 《Estuaries and Coasts》1993,16(3):459-474

Major ion chemistry of water and elemental geochemistry of suspended and surficial sediments collected from the Cauvery Estuary were studied to understand the geochemical processes in this tropical estuarine system. Specific conductance (EC), total dissolved solids (TDS), and total suspended matter (TSM) increased conservatively with increasing chlorinity. In general, SO₄ ^2?, Na, K, Ca, and Mg showed an increasing trend while H₄SiO₄ and PO₄ ^3? showed a decreasing trend toward the sea. Additional removal mechanisms operating for these ions in the Cauvery Estuary have been identified based on observed concentrations. Factor analysis pointed out the sources contributing to the observed trends in estuarine water chemistry. POC and PON decreased toward the high chlorinity zone. TSM in the Cauvery Estuary were mostly of inorganic nature. Stable carbon isotope values showed that the carbon was equally of marine and terrestrial origin and helped to delineate the contribution of river water and seawater. The ? mean size (a logarithmic grain size scale commonly used by sedimentologists) indicated that the surficial sediments were primarily comprised of coarse and silt, whereas suspended sediments were principally silt and clay. Suspended sediments were enriched in clays compared to surficial sediments. Quartz and feldspar were abundant among detritals while chlorite, kaolinite, and montmorillonite were dominant among clays. Silicon was the most abundant element in the sediments followed by Al, Ca, Na, K, Fe, Mn, and P. Heavy metals were enriched in the suspended sediments compared to the surficial bottom sediments as follows: Fe = 3.5, Mn = 7.4, Pb = 1.1, Zn = 15.2, Cu = 7.4, and Cr = 4.0. The levels of Cd, Cr, Zn, and Fe increased up the middle reaches and then decreased toward the sea due to urban effluent and fertilizer input. Size fractionation studies indicated that the metal concentration in the finer fraction was 50% higher by mass than the coarse silt and fine silt fractions. Chemical fractionation studies showed that the abundance of metals were in the order of residual > organic/sulfide > carbonate > Fe/Mn oxide > exchangeable fractions.  相似文献   

Heavy metal distribution in the Godavari River basin     

G. Biksham  V. Subramanian  A. L. Ramanathan  R. Van Grieken 《Environmental Geology》1991,17(2):117-126

Suspended and bed sediments collected from the entire region of the Godavari River basin were analyzed for Fe, Mn, Cr, Cu, Ni, and Zn. There are pronounced temporal and spatial variations in the heavy metal distributions. The concentrations of heavy metals in the suspended sediments are significantly higher than the bed sediments.Throughout the basin heavy metals are enriched in the finer fractions (<2 µm) of the bed sediments. The average heavymetal composition of the sediments is higher when compared to the average Indian river sediments. Heavy-metal concentration in the two shallow cores collected shows, to some extent, the influence of urbanization. When compared to the other tropical Indian rivers such as the Krishna, the Godavari appears to be a significant contributor of heavy metals to the Bay of Bengal. Considering the enormous sediment load of the Godavari River—170 million tons/yr, the heavy metal fluxes to the Bay of Bengal is very significant. Except for the Pranhita, other tributaries of the Godavari do not contribute significant loads of heavy metals. All the metals show high correlation among themselves and the correlation is more pronounced in suspended sediments than in the bed sediments. The heavy-metal distribution, fractionation, and its relationship with total suspended sediments and depth in various parts of the basin are discussed in detail.  相似文献   

Unsteady state of glaciers (Chhota Shigri and Hamtah) and climate in Lahaul and Spiti region,western Himalayas: a review of recent mass loss     

Arindan Mandal  AL. Ramanathan  Thupstan Angchuk  Mohd Soheb  Virendra Bahadur Singh 《Environmental Earth Sciences》2016,75(17):1233

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Assessment of groundwater quality of Lakshimpur district of Bangladesh using water quality indices,geostatistical methods,and multivariate analysis     

Mohammad Amir Hossain Bhuiyan  Md. Bodrud-Doza  A. R. M. Towfiqul Islam  M. A. Rakib  M. Safiur Rahman  A. L. Ramanathan 《Environmental Earth Sciences》2016,75(12):1020

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Waste water management and water quality of river Yamuna in the megacity of Delhi     

M. Parween  AL. Ramanathan  N. J. Raju 《International Journal of Environmental Science and Technology》2017,14(10):2109-2124

The present study aims at assessing water quality of river Yamuna in one of the world’s most polluted and populated megacities, Delhi. Conductivity, salinity and sodium content were within the permissible categories. Chloride concentration exceeded acceptable levels of drinking water guidelines. Water quality was poor at all locations with respect to heavy metal contamination, especially along the lower section of the Delhi stretch. Heavy metal concentrations were manifold higher than the acceptable limits of drinking water according to the BIS guidelines and reached ~29, 4.9, 10, 31, 27, 83, 7.3 and 27 times higher, respectively, for metals aluminum, copper, chromium, cadmium, iron, lead, manganese and nickel. The Najafgarh and the Shahdara drains are major point sources. Low oxidation–reduction potential reflected high organic loads and traces of eutrophication together with significant levels of nitrate and total phosphate. Discharges from agriculture, sewage and power plants could be important sources of high metal concentration. This calls for urgent measures to be taken for prevention of metal contamination in the river, through both, technology as well as implementation of regulations in order to sustain huge populations in megacities like Delhi. Waste water treatment from point sources needs tremendous improvement on the city. Treatment of the entire waste generated up to the tertiary level is required for minimizing dissolved solids, especially toxic metals, and rendering reuse in agriculture suitable. Treatment plants need proper operation, maintenance, uninterrupted power supply and regular monitoring. Various measure and programmes need to be undertaken to ensure safe reuse of wastewater.  相似文献   

Organic matter characterization in a tropical estuarine-mangrove ecosystem of India: Preliminary assessment by using stable isotopes and lignin phenols   总被引：1，自引：0，他引：1  

M. Bala Krishna Prasad  A.L. Ramanathan 《Estuarine, Coastal and Shelf Science》2009,84(4):617-624

In order to characterize the sources and fate of organic matter (OM) in the Pichavaram estuarine-mangrove ecosystem (east coast of India), stable isotope (δ¹³C and δ¹⁵N) ratios and molecular lignin analyses were conducted in plant litter, benthic algae, sediment, particulate matter and in a variety of benthic invertebrate species. The δ¹³C signature of plant litter ranges from −29.75‰ to −27.64‰ suggesting that mangrove trees follow the C₃ photosynthetic pathway. Sedimentary δ¹³C signature (−28.92‰ to −25.34‰) demonstrates the greater influence of plant litter organic matter on sedimentary organic matter. Suspended particulate organic pool was influenced by terrestrial source and also seems to be influenced by the marine phytoplankton. Enriched signature of δ¹⁵N in surface sediments (4.66–8.01‰; avg. 6.69‰) suggesting the influence of anthropogenic nitrogen from agricultural fields and human settlements. Spatial chemical variability in availability of nitrogen and plant associated microbial interactions demonstrate variability in δ¹⁵N signature in mangrove plant litter. Two (lower and higher) trophic levels of invertebrates were identified with and observed >4‰ gradient in δ¹³C signal between these two trophic groups. The observed δ¹³C values suggest that the lower level invertebrates feed on phytoplankton and higher level organisms have a mixed source of diet, phytoplankton, sediment and particulate organic matter. Lignin phenol analyses explain that the benthic surface layer was almost free of lignin. The ratio between syringyl phenols to vanillyl phenols (S/V) is 1.14–1.32 (avg. 1.23) and cinnamyl phenols to vanillyl phenols (C/V) is 0.17–0.31 (avg. 0.24), demonstrate non-woody angiosperm tissues was the major sources of lignin to this ecosystem, while aldehyde to acid ratios (Ad/Al) describe diagenetic nature of sediment and is moderately to less degraded. A two-end-member mixing model indicate that the terrigenous OM was dominant in the estuarine zones, while in the mangrove zone terrigenous supply accounts for 60% and marine input accounts for 40%.  相似文献   

Seismic behaviour of Delhi metro tunnels in liquefiable deposits     

Jishnu  Rama Bhadran  Ayothiraman  Ramanathan 《Natural Hazards》2022,111(3):2261-2280

Natural Hazards - Construction of metro transport networks has been on the ascent in Indian cities like New Delhi, since early 2000s. Metro tunnels in New Delhi traverse through various...  相似文献   

Hydrogeochemical zonation for groundwater management in the area with diversified geological and land-use setup   总被引：1，自引：0，他引：1  

Manish Kumar  Roger Herbert Jr.  AL. Ramanathan  M. Someshwar Rao  Kangjoo Kim  Jyoti Prakash Deka  Bhishm Kumar 《Chemie der Erde / Geochemistry》2013

Despite its limited aerial extent, the National Capital Territory (NCT) Delhi, India, has diversified geological and topographical setup. A geochemical assessment of prevailing conditions of aquifer underlying the NCT was attempted and further classified into different hydrogeochemical zones on the basis of statistical and analyses and its correlation with land use, geological and climatic setting. Mineral phase study and isotopic analyses were used for the verification of performed clustering. Saturation indices (SI) calculated using the geochemical modelling code PHREEQC were used to distinguish the characteristics of four zones, as saturation states of the water does not change abruptly. Four different hydrogeochemical zones were statistically identified in the area: (1) intermediate (land-use-change-impacted) recharge zone, (2) discharge (agriculture-impacted) zone, (3) recharge (ridge) zone, and (4) recharge floodplain (untreated-discharge-impacted) zone. The distinctiveness of hydro-geochemical zones was further verified using stable isotopic (²H and ¹⁸O) signature of these waters. GIS-based flow regime in association with long-term geochemical evidences implied that these zones are being affected by different problems; thus, it necessitates separate environmental measures for their management and conservation. The study suggested that in a diversified urban setup where the complex interactions between anthropogenic activities and normal geochemical processes are functioning, hydrogeochmical zoning based on the integration of various techniques could be the first step towards sketching out the groundwater management plan.  相似文献   

Impact assessment of textile effluent on groundwater quality in the vicinity of Tirupur industrial area, southern India     

Shashi Prabha  Manish Kumar  Alok Kumar  Pallavi Das  AL. Ramanathan 《Environmental Earth Sciences》2013,70(7):3015-3022

Adverse effect of rapid industrialization on groundwater quality and quantity is widely known problem especially in developing countries. Tirupur, which is situated on the bank of Noyyal River in India, is known for intensive textile processing activities. As groundwater is the main water source for drinking water, there is an urgency to assess the groundwater quality. Twenty groundwater samples were collected for each post and pre-monsoon sampling during August 2009 and March 2010, respectively. Chemical and statistical analysis along with numerical modelling has been performed to assess the current status. The hydro-geochemical study revealed that the dominance of Mg–Cl and Na–HCO₃ groundwater type in the upstream region Tirupur industrial hub of Noyyal River basin. Na–Cl groundwater type was found increasing in industrial hub (Kasipalayam) and downstream of the industrial hub (Anaipalayam) sites. The dominance of Na–Cl type of water is mainly due to the impact of salts like NaCl, Na₂SO₄, etc. used in textile processing, which after discharge, percolate and accumulate in the aquifers. Seasonal groundwater quality of Tirupur region as a whole showed the dominance of Ca–HCO₃ ^?, Na–HCO₃ ^? and Na–Cl water types. PHREEQC model output indicates that nearly all the groundwater samples were oversaturated with respect to calcite and dolomite and undersaturated with respect to gypsum and halite. The results obtained in this study were then compared with groundwater quality of the Noyyal River basin for the year 2008–2009. Among the two sites, Kasipalayam was found to be most contaminated due to incessant industrial discharge. But with the advent of new treatment technologies like CETPs having zero liquid discharge system and MBR, there has been slight decline in the concentration of different physicochemical parameters from 2002–2003 to 2008–2009. This study not only makes situation alarming but also calls for immediate attention for sustainable management of water resources.  相似文献   

Hydrochemical characteristics of groundwater in the plains of Phalgu River in Gaya, Bihar, India   总被引：1，自引：0，他引：1  

Rajesh Kumar Ranjan  AL. Ramanathan  Purushothaman Parthasarathy  Alok Kumar 《Arabian Journal of Geosciences》2013,6(9):3257-3267

Assessment of groundwater quality is essential to ensure sustainable use of it for drinking, agricultural, and industrial purposes. The chemical quality of groundwater of Gaya region has been studied in detail in this work to delineate the potable groundwater zones. A total of 30 groundwater samples and 2 surface water samples were collected in and around Gaya district of Bihar. The major cations follow the trend: Ca²⁺?>?Mg²⁺?>?Na⁺?>?K⁺. The domination of calcium ions in the groundwater is due to weathering of rocks. The K⁺ ranged between 0.2 and 47.95 ppm, suggesting its abundance the below desired limit; but some samples were found to be above permissible limit. K⁺ weathering of potash silicate and the use of potash fertilizer could be the source. The major anions abundance followed the order HCO ₃ ^? ?>?Cl^??>?SO ₄ ^2? ?>?NO ₃ ^? ?>?PO ₄ ^3? . Dissolution of carbonates and reaction of silicates with carbonic acid accounts for the addition of HCO ₃ ^? to the groundwater and oxidation of sulphite may be the source of SO ₄ ^2? . Principal component analysis was utilized to reflect those chemical data with the greatest correlation and seven major principal components (PCs) representing >80 % of cumulative variance were able to interpret the most information contained in the data. PC1, PC2 and PC3 reflect the hydrogeochemical processes like mineral dissolution, weathering and anthropogenic sources. PC4, PC5, PC6 and PC7 show monotonic, random and independent relationships.  相似文献