Lead detoxification by coontail (Ceratophyllum demersum L.) involves induction of phytochelatins and antioxidant system in response to its accumulation

Coontail (Ceratophyllum demersum L.) plants when exposed to various concentrations of Pb (1-100microM) for 1-7days, exhibited both phytotoxic and tolerance responses. The specific responses were function of concentration and duration. Plants accumulated 1748mugPbg(-1) dw after 7d which reflected its metal accumulation ability, however most of the metal (1222microgg(-1) dw, 70%) was accumulated after 1d exposure only. The toxic effect and oxidative stress caused by Pb were evident by the reduction in biomass and photosynthetic pigments and increase in malondialddehyde (MDA) content and electrical conductivity with increase in metal concentration and exposure duration. Morphological symptoms of senescence phenomena such as chlorosis and fragmentation of leaves were observed after 7d. The metal tolerance and detoxification strategy adopted by the plant was investigated with reference to antioxidant system and synthesis of phytochelatins. Protein and antioxidant enzymes viz., superoxide dismutase (SOD, EC 1.15.1.1), guaiacol peroxidase (GPX, EC 1.11.1.7) ascorbate peroxidase (APX, EC 1.11.1.11), catalase (CAT, EC 1.11.1.6) and glutathione reductase (GR, EC 1.6.4.2) showed induction at lower concentration and duration followed by decline. All enzymes except GPX showed maximum activity after 1d. An increase in cysteine, non-protein thiols (NP-SH) and glutathione (GSH) content was observed at moderate exposure conditions followed by decline. Phytochelatins (PC(2) and PC(3)) were synthesized to significant levels at 10 and 50microM Pb with concomitant decrease in GSH levels. Thus production of PCs seems important for the detoxification of metal, however it may lead to depletion of GSH and consequently oxidative stress. Results suggest that plants responded positively to moderate Pb concentrations and accumulated high amount of metal. Due to metal accumulation coupled with detoxification potential, the plant appears to have potential for its use as phytoremediator species in aquatic environments having moderate pollution of Pb.     

Concentrations of heavy metals and aquatic macrophytes of Govind Ballabh Pant Sagar an anthropogenic lake affected by coal mining effluent

Five heavy metals Cu, Cd, Mn, Pb and Hg were found in high concentration from three sampling sites located in Asia’s largest anthropogenic lake Govind Ballabh Pant GBP Sagar. Concentrations of these heavy metals were measured in Water, bottom sediment and in different parts of the aquatic macrophytes collected from the reservoir. Plants collected from the lake were Eichhornia crassipes, Azolla pinnata, Lemna minor, Spirodela polyrrhiza, Potamogeton pectinatus, Marsilea quadrifolia, Pistia stratiotes, Ipomea aquqtica, Potamogeton crispus, Hydrilla verticillata and Aponogeton natans. These plants have shown the high concentrations of Cu, Cd, Mn, Pb and Hg in their different parts due to bioaccumulation. In general plant roots exhibited higher concentrations of heavy metals than corresponding sediments. A comparison between different morphological tissues of the sampled plants reveled the metal concentration in following order roots > leaves. Analyses of bottom sediment indicated the higher concentrations of Cd, Mn, Cu and Pb. Strong positive correlations were obtained between the metals in water and in plants as well as between metal in sediment and in plants. Indicating the potential of these plants for pollution monitoring of these metals.     

Governance, institutions and the environment-income relationship: a cross-country study

This paper examines the environment-income relationship in the context of the Environmental Kuznets Curve (EKC), and explores the possible role that factors like governance, political institutions, socioeconomic conditions, and education play in influencing this relationship. The results suggest that the EKC exists for carbon dioxide emissions for cross-country data over the period 1984–2002. However, there is nothing automatic about this relationship; policies designed to protect the environment may be responsible for this phenomenon. Two other significant findings are: one, countries with better quality of governance, stronger political institutions, better socioeconomic conditions and greater investment in education have lower emissions; and two, only around 15% of the countries in the dataset have reached income levels high enough to be associated with an unambiguous decline in emissions. The implications of these results are discussed within the context of the international environmental policy arena and the Kyoto Protocol. One of the main objectives of this paper is to bridge the gap between studies conducted on the EKC and developments in the international environmental policy arena. As a final note this paper emphasizes that one needs to connect the body of knowledge on the EKC hypothesis to the international environmental policy arena, despite the apparent difficulty of doing so. One hopes that future studies will further build on this line of thought.

Impact of degradation on nitrogen transformation in a forest ecosystem of India

A study was performed selecting one protected forest and an adjacent degraded forest ecosystem to quantify the impact of forest degradation on soil inorganic nitrogen, fine root production, nitrification, N-mineralization and microbial biomass N. There were marked seasonal variations of all the parameters in the upper 0–10 and lower 10–20 cm depths. The seasonal trend of net nitrification and net N-mineralization was reverse of that for inorganic nitrogen and microbial biomass N. Net nitrification, net N-mineralization and fine root biomass values were highest in both forests during rainy season. On contrary, inorganic nitrogen and microbial biomass N were highest during summer season. There was a marked impact of forest degradation on inorganic nitrogen, fine root production nitrification, N-mineralization and microbial biomass observed. Soil properties also varied with soil depth. Fine root biomass, nitrification, N-mineralization and microbial biomass N decreased significantly in higher soil depth. Degradation causes decline in mean seasonal fine root biomass in upper layer and in lower depth by 37% and 27%, respectively. The mean seasonal net nitrification and N-mineralization in upper depth decreased by 42% and 37%, respectively and in lower depth by 42.21% and 39% respectively. Similarly microbial biomass N also decreased by 31.16% in upper layer 33.19% in lower layer.     

Long-term leaching of uranium from different waste matrices

A semi-dynamic leaching test was carried out for metallurgical wastes and ore samples from the uranium and copper mining industry over a 142 day period using distilled water and 0.1N NaNO(3) as solvents. Laser fluorimetry was used as the analytical technique to determine the total uranium content in the leachates. The cumulative leach fraction (CLF) of uranium release from the samples was calculated to be 0.22, 0.22, 0.07 and 0.39% for rock, uranium tailings, copper kinker ash samples and copper tailings respectively using distilled water as solvent and 0.31, 0.27, 0.05 and 0.59% for the same matrices using 0.1N NaNO(3). The release of mobile uranium fraction was very slow, being faster in the initial stage and then attained a near steady state condition. The diffusion coefficient and bulk release of uranium from the samples have been calculated. The processes governing the release of uranium from these matrices have been identified to be surface wash-off and diffusion. Hence the use of weak solvents (leach out the mobile/exchangeable fraction of uranium) under semi-dynamic conditions aids the determination of leaching parameters and identification of the leaching mechanism for mobile uranium fraction from different matrices by slow leaching processes.     

Impact of alphamethrin on antioxidant defense (catalase) and protein profile of a catfish

The toxic effects of alphamethrin on catalase (CAT) and protein profile in liver, heart, kidney, and intestine of the freshwater catfish Clarias batrachus have been investigated. CAT activity and specific activity decreased in liver, heart, kidney, and intestine on exposure of sublethal concentration of alphamethrin for 14 days. Similarly, protein content declined in different tissues of the fish exposed to alphamethrin. Maximum decline in CAT activity was in liver, while minimum decrease was in intestine. Maximum reduction in CAT specific activity was in kidney and minimum in heart. Protein content declined maximum in liver and minimum in heart. Alphamethrin-induced reduction in CAT activity and specific activity might be due to binding of pesticide with enzyme or by inhibiting the enzyme synthesis. The reduction in protein content might be due to extensive proteolysis. The results suggested alphamethrin-induced reduction in oxidative defense and protein profile of the catfish.     

Interacting effects of pyrethroid and hormone on catalase and protein for toxicity amelioration in the freshwater fish, <Emphasis Type="Italic">Clarias batrachus</Emphasis>

Ameliorating effects of cortisol and T₃ on alphamethrin-dependent changes in the catalase (CAT) and protein profile of the freshwater catfish, Clarias batrachus, were studied. CAT activity and specific activity decreased in the liver, heart, kidney, and intestine after exposure to alphamethrin for 14 days. The administration of cortisol to alphamethrin-exposed fish brought the activity and specific activity of CAT up to their control values. The protein content decreased in different tissues of the fish after exposure to alphamethrin. The administration of T₃ to alphamethrin-exposed fish reduced the protein content to the control value. Therefore, it can be suggested that cortisol and T₃ may be used to ameliorate the toxicological effects of alphamethrin in fish.     

Supplemental UV-B radiation induced changes in growth, pigments and antioxidant pool of bean (Dolichos lablab) under field conditions

Present study is conducted to evaluate the response of bean (Dolichos lablabcv . pusa early prolific) plants to supplemental UV-B (sUV-B: 280-315 nm: 7.2 kJ m(-2) d(-1)) radiation. UV-B caused alteration in biomass translocation pattern with more retention of biomass in below ground parts leading to an increment in root shoot ratio. Specific leaf area (SLA) which is the measure of leaf thinness, increased in plants under sUV-B exposure by 95.7 and 82.3% after 15 and 30 days after germination. Photosynthetic machinery of bean plants was the potential target of UV-B as photosynthetic rate was decreased by 88.6% at 30 days after germination. sUV-B lead to the formation of reactive oxygen species thus generating oxidative stress. Stimulation of antioxidant defense system (enzymatic and non-enzymatic) was observed due to sUV-B radiation. Phenolic content decreased (34.7 and 18.6%) but protein showed varied response, increased initially (34%) thereafter declined (10.2%) under sUV-B radiation.     

An empirical investigation of nuclear energy and environmental pollution nexus in India: fresh evidence using NARDL approach

Environmental Science and Pollution Research - Environmental pollution caused by carbon emissions is an emerging issue to study among researchers. The nexus between environmental pollution and...     

Hexavalent chromium reduction and plant growth promotion by Staphylococcusarlettae strain Cr11

Cr(VI), a mutagenic and carcinogenic pollutant in industrial effluents, was effectively reduced by an indigenous tannery effluent isolate Staphylococcus arlettae strain Cr11 under aerobic conditions. The isolate could tolerate Cr(VI) up to 2000 and 5000 mg L⁻¹ in liquid and solid media respectively. S. arlettae Cr11 effectively reduced 98% of 100 mg L⁻¹ Cr(VI) in 24 h. Reduction for initial Cr(VI) concentrations of 500 and 1000 mg L⁻¹ was 98% and 75%, respectively in 120 h. The isolate was also positive for siderophore, indole acetic acid, ammonia and catalase production, phosphate solubilization and biofilm formation in the presence and absence of Cr(VI). The isolate showed halotolerance (10% NaCl) and cross tolerance to other toxic heavy metals such as Hg²⁺, Ni²⁺, Cd²⁺ and Pb²⁺. Bacterial inoculation of Triticum aestivum in controlled petri dish and soil environment showed significant increase in percent germination, root and shoot length as well as dry and wet weight in Cr(VI) treated and untreated samples. This is the first report of simultaneous Cr(VI) reduction and plant growth promotion for a S. arlettae strain.