Metal fractionation study on bed sediments of Hussainsagar Lake, Hyderabad, India

Hussainsagar Lake in the heart of Hyderabad City (India) receives toxic substances through five streams draining from a catchment area of 245 km². Of particular interest are heavy metals received from urban runoff as well as municipal sewage and industrial effluents. Heavy metals entering the lake get adsorbed onto the suspended sediments, which eventually settle down in the bottom of the lake. In this study, fractionation of metal ions has been studied on the bed sediments of Hussainsagar Lake in order to determine the ecotoxic potential of metal ions. Comparison of sediments with average shale values indicated anthropogenic enrichment with copper, nickel, lead, cadmium, and zinc. The risk assessment code as applied to the present study reveals that 10–17% of manganese, 10–18% of nickel, 14–24% of chromium, 10–19% of lead, 21–30% of cadmium, and 18–28% of zinc exist in exchangeable fraction and, therefore, comes under medium risk category and may enter into food chain. The association of these metals with the exchangeable fraction may cause deleterious effects to aquatic life. The present database will help in formulating guidelines for carrying out dredging operations under restoration programs in the Hussainsagar Lake.     

Accumulation of total trace metals due to rapid urbanization in microtidal zone of Pallikaranai marsh, South of Chennai, India

The article presents the results for enrichment of total trace metals (TTMs) from Pallikaranai salt marsh in South Chennai, a metropolis on the southeast coast of India. TTMs Fe, Mn, Cr, Cu, Ni, Co, Pb, Zn, Cd, Sr, V, and Hg along with sediment texture, OC, and CaCO₃ were analyzed in 36 surface sediments collected during August 2008 to recognize and observe the input of TTMs in the marsh from various sources in the city limits. In view of the rapid urbanization and industrialization in Chennai City, especially on the southern side, uncontrolled input of sewage, garbage, and industrial effluents into the Pallikaranai marsh land, the elevated concentrations are not surprising. The level of enrichment of TTMs has also increased by 20% to 60% for most of the elements when compared with all other ecosystems in the world as well as the nearby area. The results also indicate that the marshy region is more heavily contaminated with Cd, Hg, Cr, Cu, Ni, Pb, and Zn than other regions on the southeast coast of India. The Enrichment Factor, Contamination Factor, and I _geo indexes are calculated, and these values are useful to assess the degree of pollution in sediments. The spatial distributions of TTMs are also controlled by other factors like geochemical, precipitation, and flocculation of particulate substances in the marsh. The results of the present study suggest the need for a regular monitoring and management program which will help to improve the quality of Pallikaranai pristine marsh land.     

Estimation of pollutant partition in sandy soils with different water contents

The objectives of this work were: (1) to identify an isotherm model to relate the contaminant contents in the gas phase with those in the solid and non-aqueous liquid phases; (2) to develop a methodology for the estimation of the contaminant distribution in the different phases of the soil; and (3) to evaluate the influence of soil water content on the contaminant distribution in soil. For sandy soils with negligible contents of clay and natural organic matter, contaminated with benzene, toluene, ethylbenzene, xylene, trichloroethylene (TCE), and perchloroethylene (PCE), it was concluded that: (1) Freundlich’s model showed to be adequate to relate the contaminant contents in the gas phase with those in the solid and non-aqueous liquid phases; (2) the distribution of the contaminants in the different phases present in the soil could be estimated with differences lower than 10% for 83% of the cases; and (3) an increase of the soil water content led to a decrease of the amount of contaminant in the solid and non-aqueous liquid phases, increasing the amount in the other phases.     

Evaluation of groundwater quality and its suitability for drinking and agricultural use in Thanjavur city, Tamil Nadu, India

As groundwater is a vital source of water for domestic and agricultural activities in Thanjavur city due to lack of surface water resources, groundwater quality and its suitability for drinking and agricultural usage were evaluated. In this study, 102 groundwater samples were collected from dug wells and bore wells during March 2008 and analyzed for pH, electrical conductivity, temperature, major ions, and nitrate. Results suggest that, in 90% of groundwater samples, sodium and chloride are predominant cation and anion, respectively, and NaCl and CaMgCl are major water types in the study area. The groundwater quality in the study site is impaired by surface contamination sources, mineral dissolution, ion exchange, and evaporation. Nitrate, chloride, and sulfate concentrations strongly express the impact of surface contamination sources such as agricultural and domestic activities, on groundwater quality, and 13% of samples have elevated nitrate content (>45 mg/l as NO₃). PHREEQC code and Gibbs plots were employed to evaluate the contribution of mineral dissolution and suggest that mineral dissolution, especially carbonate minerals, regulates water chemistry. Groundwater suitability for drinking usage was evaluated by the World Health Organization and Indian standards and suggests that 34% of samples are not suitable for drinking. Integrated groundwater suitability map for drinking purposes was created using drinking water standards based on a concept that if the groundwater sample exceeds any one of the standards, it is not suitable for drinking. This map illustrates that wells in zones 1, 2, 3, and 4 are not fit for drinking purpose. Likewise, irrigational suitability of groundwater in the study region was evaluated, and results suggest that 20% samples are not fit for irrigation. Groundwater suitability map for irrigation was also produced based on salinity and sodium hazards and denotes that wells mostly situated in zones 2 and 3 are not suitable for irrigation. Both integrated suitability maps for drinking and irrigation usage provide overall scenario about the groundwater quality in the study area. Finally, the study concluded that groundwater quality is impaired by man-made activities, and proper management plan is necessary to protect valuable groundwater resources in Thanjavur city.     

Hydrogeochemical characterization of fluoride rich groundwater of Wailpalli watershed, Nalgonda District, Andhra Pradesh, India

The groundwater of Nalgonda district is well known for its very high fluoride content for the past five decades. Many researchers have contributed their scientific knowledge to unravel causes for fluoride enrichment of groundwater. In the present paper, an attempt has been made to relate the high fluoride content in the groundwater to hydrogeochemical characterization of the water in a fracture hard rock terrain—the Wailpally watershed. Groundwater samples collected from all the major geomorphic units in pre- and post-monsoon seasons were analyzed for its major ion constituents such as Ca^2?+?, Mg^2?+?, Na^?+?, K^?+?, CO $_{3}^{-}$ , HCO $_{3}^{-}$ , Cl^???, SO $_{4}^{-2}$ , NO $_{3}^{-}$ , and F^???. The groundwaters in the watershed have the average fluoride content of 2.79 mg/l in pre-monsoon and 2.83 mg/l in post-monsoon. Fluoride concentration in groundwater does not show perceptible change neither with time nor in space. The ionic dominance pattern is in the order of Na^?+? > Ca^2?+??> Mg^2?+??> K^??? among cations and HCO $_{3}^{-}\:\,>$ Cl^????> SO $_{4}^{-2} >$ NO $_{3}^{-} >$ F^??? among anions in pre-monsoon. In post-monsoon, Mg replaces Ca^2?+? and NO $_{3}^{-}$ takes the place of SO $_{4}^{-2}$ . The Modified Piper diagram reflect that the water belong to Ca^?+?2–Mg^?+?2–HCO $_{3}^{-}$ to Na^?+?–HCO $_{3}^{-}$ facies. Negative chloralkali indices in both the seasons prove that ion exchange between Na^?+? and K^?+? in aquatic solution took place with Ca^?+?2 and Mg^?+?2 of host rock. The interpretation of plots for different major ions and molar ratios suggest that weathering of silicate rocks and water–rock interaction is responsible for major ion chemistry of groundwater in Wailpally watershed. Chemical characteristics and evolution of this fluoride-contaminated groundwater is akin to normal waters of other hard rock terrain; hence, it can be concluded that aquifer material play an important role in the contribution of fluoride in to the accompanying water. High fluoride content in groundwater can be attributed to the continuous water–rock interaction during the process of percolation with fluorite-bearing country rocks under arid, low precipitation, and high evapotranspiration conditions.     

Effects of drill cuttings discharge on meiofauna communities of a shelf break site in the southwest Atlantic

The present study investigates the effects of drill cutting discharges on the structure of meiofauna communities in an area of the shelf break at Campos Basin, Southeast Brazil. Drilling activities were operated, in a first phase, with water-based fluid and, in a second phase, with synthetic fluid paraffin-based (NAF-III). A total of 135 samples taken at a pre-drilling situation (MS1) and two post-drilling moments (MS2 and MS3—3 and 22 months post-drilling, respectively) were analyzed. Effects on meiofauna were dependent on two main factors: 1—the impact received during drilling operation, if water-based or synthetic/water-based drilling fluid and 2—the background state, if it already presented signs of previous drilling activities or not. Based on univariate and multivariate analysis, there were evidences that the most affected area after drilling was those under the influence of synthetic-based fluid and that already had signs of previous drillings activities. The region impacted only by water-based fluid was less affected and the only one that completely recovered after 22 months. Nematodes and copepods had different responses to the impact. While copepods flourish in the impacted area and recovered 22 months after drilling, nematodes were adversely affected shortly after drilling and the community structure only recovered where hydrocarbons had been depleted.     

Study on the hydrogeochemical characteristics in groundwater, post- and pre-tsunami scenario, from Portnova to Pumpuhar, southeast coast of India

Natural hazards cause great damage to humankind and the surrounding ecosystem. They can cast certain indelible changes on the natural system. One such tsunami event occurred on 26 December 2004 and caused serious damage to the environment, including deterioration of groundwater quality. This study addresses the groundwater quality variation before and after the tsunami from Pumpuhar to Portnova in Tamil Nadu coast using geochemical methods. As a part of a separate Ph.D. study on the salinity of groundwater from Pondicherry to Velankanni, water quality of this region was studied with the collection of samples during November 2004, which indicated that shallow aquifers were not contaminated by sea water in certain locations. These locations were targeted for post-tsunami sample collection during the months of January, March and August 2005 from shallow aquifers. Significant physical mixing (confirmed with mixing models) within the aquifer occurred during January 2005, followed by precipitation of salts in March and complete leaching and dissolution of these salts in the post-monsoon season of August. As a result, maximum impact of tsunami water was observed in August after the onset of monsoon. Tsunami water inundated inland water bodies and topographic lows where it remained stagnant, especially in the near-shore regions. Maximum tsunami inundation occurred along the fluvial distributary channels, and it was accelerated by topography to a certain extent where the southern part of the study area has a gentler bathymetry than the north.     

Seasonal air quality profile of inorganic ionic composition of PM10 near Taj Mahal in Agra, India

Atmospheric aerosols and their impacts on the environment particularly on human health is an issue of significant public and governmental concern. Though studies on air quality related to total suspended particulate matter have done by various authors in India, yet respirable suspended particulate matter (PM₁₀) is not characterized so far particularly in a historical and world heritage city like Agra. This study presents seasonal variation in mass levels of PM₁₀ and its ionic composition. PM₁₀ samples were collected in the proximity of Taj Mahal and subjected to chemical analysis using ion chromatography technique. The preliminary findings reveal that the 24-h average of PM₁₀ mass level varies from 115 to 233, 155 to 321, and 33 to 178 μg/m³, respectively, in summer, winter, and rainy seasons indicating critical pollution situation. These values are very much higher than the National Ambient Air Quality Standards of 75 μg/m³ (prescribed by Central Pollution Control Board, India) in both of summer and winter seasons whereas quite near the permissible limits in rainy season. The equivalent ratios of NH₄ ⁺ to nonsea salt SO₄ ^2? and NO₃ ^? and ∑Cations to ∑Anios were found to be greater than unity indicating high source strength of ammonia and alkaline nature of aerosols. The study suggests the need for continuous and long-term systematical sampling and detailed physiochemical analysis of PM₁₀ and also to know the characteristics of PM in background areas for better understanding of the emission sources.     

Determination of some organochlorine pesticide residues in honeys from Konya, Turkey

In this study, 24 organochlorine pesticide residues in 109 different honey samples collected from stores and open markets in Konya, Turkey were analyzed by gas chromatography-electron capture detection. Aldrin, cis-chlordane, trans-chlordane, oxy-chlordane, 2,4^′ -DDE, and 4,4^′ -DDE were found in all honey samples. The mean value was 0.0540 μg g^???1 for oxy-chlordane. In the 55 samples of 109, levels of organochlorine pesticide residues of oxy-chlordane were determined as higher than those of Turkish Alimentarius Codex maximum residual limits (MRLs). Other organochlorine pesticide residues also exceeded MRLs except for cis-heptachlor epoxide and α-hexachlorocyclohexane. Since all of the honey samples are found contaminated and most of these samples exceeded MRLs, a control of organochlorine pesticide residues in honey is necessary for consumer health.     

Bacteria with dual resistance to elevated concentrations of heavy metals and antibiotics in Nigerian contaminated systems

Samples of soil, water, and sediments from industrial estates in Lagos were collected and analyzed for heavy metals and physicochemical composition. Bacteria that are resistant to elevated concentrations of metals (Cd^2?+?, Co^2?+?, Ni^2?+?, Cr^6?+?, and Hg^2?+?) were isolated from the samples, and they were further screened for antibiotic sensitivity. The minimum tolerance concentrations (MTCs) of the isolates with dual resistance to the metals were determined. The physicochemistry of all the samples indicated were heavily polluted. Twenty-two of the 270 bacterial strains isolated showed dual resistances to antibiotics and heavy metals. The MTCs of isolates to the metals were 14 mM for Cd^2?+?, 15 mM for Co^2?+? and Ni^2?+?, 17 mM for Cr^6?+?, and 10 mM for Hg^2?+?. Five strains (Pseudomonas aeruginosa, Actinomyces turicensis, Acinetobacter junni, Nocardia sp., and Micrococcus sp.) resisted all the 18 antibiotics tested. Whereas Rhodococcus sp. and Micrococcus sp. resisted 15 mM Ni^2?+?, P. aeruginosa resisted 10 mM Co^2?+?. To our knowledge, there has not been any report of bacterial strains resisting such high doses of metals coupled with wide range of antibiotics. Therefore, dual expressions of antibiotics and heavy-metal resistance make the isolates, potential seeds for decommissioning of sites polluted with industrial effluents rich in heavy metals, since the bacteria will be able to withstand in situ antibiosis that may prevail in such ecosystems.