Persistent organochlorine residues in green mussels from coastal waters of South India     

A. Ramesh  S. Tanabe  A. N. Subramanian  D. Mohan  V. K. Venugopalan  R. Tatsukawa 《Marine pollution bulletin》1990,21(12):587-590

Green mussels (Perna viridis) collected from nine locations along the South Indian coast were used as bioindicator to assess the organochlorine contamination (HCHs, DDTs, and PCBs) in the coastal environment of South India. Concentrations of ΣHCH and ΣDDT were found to be similar, ranging from 3 to 39 ng g⁻¹ on wet wt basis. On the other hand, PCB levels were apparently lower, varying from <1.0 to 7.1 ng g⁻¹ wet wt. The residue pattern of organochlorines in mussels are principally similar to those in Indian human samples, reported earlier. The coastal marine pollution by HCH in India ranks among the highly contaminated areas in the world.  相似文献   

Phosphorus,silicon, and some trace contaminants in the Ganges Estuary     

V. Subramanian 《Estuaries and Coasts》1993,16(3):453-458

Dissolved silica and phosphorous show a highly nonconservative behavior in the Ganges Estuary. In addition, phosphorous also shows seasonal variations, with winter levels higher than the levels in the monsoon. Mineral composition inducates enrichment of coarse quartz grains due to selective removal of finer clays in the estuary, either due to flocculation or due to dredging effects of the Port of Calcutta. Particulate P and Si show strong opposite trends, possibly indicating the presence of P in predominently nondetrial fractions in the sediments. Certain trace contaminants, such as Fe, Mn, Cu, Pb and Zn, show seasonal variability as well as enrichment in suspended particulate material relative to bed sediments. Levels of all these contaminents are still well below those reported for rivers such as the Rhine and other highly man-influenced systems.  相似文献   

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   

Coastal geomorphology and sediment distribution mapping using Landsat—TM digital data —A study in Coastal area of parts of Orissa,India     

S. K. Subramanian  K. Keshavasamy  K. Hanumantha Rao  S. K. Bhan 《Journal of the Indian Society of Remote Sensing》1988,16(3):1-6

An area of about 1100 sq.km forming a part of east coast of India was taken for digital analysis using the VAX 11/780 image analysis computer system. The data used for the analysis is Thematic mapper data of Landsat 5. By using the maximum likelihood algorithm and the existing ground truth, the area was classified geomorphologicall.. In addition a qualitative mapping of suspended sediments of coastal waters in Bay of Bengal around the estuary of Dhamra river in Orissa has been carried out. In seventeen classes, eleven correspond to geomorphic units and six belongs to different categories of sediments concentration in Coastal waters.  相似文献   

Demarcating saline water intrusion pathways using remote sensing,GIS and geophysical techniques in structurally controlled coastal aquifers in Southern India     

Ratnakar Dhakate  S. Sankaran  V. Satish Kumar  B. Amarender  P. Harikumar  S. K. Subramanian 《Environmental Earth Sciences》2016,75(5):363

  相似文献   

Adsorption of Metal Ions onto the Chemically Modified Agricultural Waste     

Ponnusamy Senthil Kumar  Subramaniam Ramalingam  Ramasundaram Vijayakumar Abhinaya  Selvaraj Dinesh Kirupha  Arukkani Murugesan  Subramanian Sivanesan 《洁净——土壤、空气、水》2012,40(2):188-197

This paper discusses about the adsorption of metal ions such as Cu(II), Cd(II), Zn(II), and Ni(II) from aqueous solution by sulfuric acid treated cashew nut shell (STCNS). The adsorption process depends on the solution pH, adsorbent dose, contact time, initial metal ions concentration, and temperature. The adsorption kinetics was relatively fast and equilibrium was reached at 30 min. The adsorption equilibrium follows Langmuir adsorption isotherm model. The maximum adsorption capacity values of the modified cashew nut shell (CNS) for metal ions were 406.6 mg/g for Cu(II), 436.7 mg/g for Cd(II), 455.7 mg/g for Zn(II), and 456.3 mg/g for Ni(II). The thermodynamic study shows the adsorption of metal ions onto the STCNS was spontaneous and exothermic in nature. The kinetics of metal ions adsorption onto the STCNS followed a pseudo‐second‐order kinetic model. The external mass transfer controlled metal ions removal at the earlier stages and intraparticle diffusion at the later stages of adsorption. A Boyd kinetic plot confirms that the external mass transfer was the slowest step involved in the adsorption of metal ions onto the STCNS. A single‐stage batch adsorber was designed using the Langmuir adsorption isotherm equation.  相似文献   

Socioeconomic effect of dust storms in Kuwait     

Ali Al-Hemoud  Mane Al-Sudairawi  Subramanian Neelamanai  Adel Naseeb  Weam Behbehani 《Arabian Journal of Geosciences》2017,10(1):18

Kuwait is an arid country with an annual average rainfall of about 110 to 120 mm. Hence, dust storms have become a common environmental crisis. Although the dry summer months commonly have more dust storms, in recent years, dust storms occur more frequently in the spring season as well. Accumulated data of dust storms in Kuwait for the past 14 years (2001–2014) showed that the month of March had the highest number of dust storms (total 19), which is rather unusual, with an average of 8 dust storms per year (year 2008 had the highest dust storms of total 22). This study explored four socioeconomic effects of dust storms in Kuwait, specifically traffic accident rates, oil export loss due to close out of marine terminals, airline delays due to airport operation shutdown, and agriculture degradation. Statistical analysis using t test and Pearson correlation showed no apparent relationship between dust storms and traffic accident rates or agricultural production; however, loss of oil export and flight delay cost were affected by dust storms. There has been very few published research on the socioeconomic impact of dust storms; this is the first paper that explores the detailed socioeconomic effect of dust storms in Kuwait.  相似文献   

Intervention and assessment of earthquake knowledge at rural schools near the New Madrid seismic zone,USA     

Henson  Harvey  McDaniel  Justin  Subramanian  Rajvee  Edwards  Tishauna 《Natural Hazards》2020,104(2):1315-1329

Natural Hazards - Possible recurrence of large earthquakes such as the 1811–1812 New Madrid sequence presents a significant hazard in the Central United States. The efficacy of earthquake...  相似文献   

Magnetic helicity in stellar dynamos: new numerical experiments     

A. Brandenburg  W. Dobler  K. Subramanian 《Astronomische Nachrichten》2002,323(2):99-122

The theory of large scale dynamos is reviewed with particular emphasis on the magnetic helicity constraint in the presence of closed and open boundaries. In the presence of closed or periodic boundaries, helical dynamos respond to the helicity constraint by developing small scale separation in the kinematic regime, and by showing long time scales in the nonlinear regime where the scale separation has grown to the maximum possible value. A resistively limited evolution towards saturation is also found at intermediate scales before the largest scale of the system is reached. Larger aspect ratios can give rise to different structures of the mean field which are obtained at early times, but the final saturation field strength is still decreasing with decreasing resistivity. In the presence of shear, cyclic magnetic fields are found whose period is increasing with decreasing resistivity, but the saturation energy of the mean field is in strong super‐equipartition with the turbulent energy. It is shown that artificially induced losses of small scale field of opposite sign of magnetic helicity as the large scale field can, at least in principle, accelerate the production of large scale (poloidal) field. Based on mean field models with an outer potential field boundary condition in spherical geometry, we verify that the sign of the magnetic helicity flux from the large scale field agrees with the sign of α. For solar parameters, typical magnetic helicity fluxes lie around 10⁴⁷ Mx² per cycle.  相似文献