Foliar injury and leaf diffusive resistance of rice and white bean in response to SO2 and O3, singly and in combination

Plants of rice (Oryza sativa) and white bean (Phaseolus vulgaris) were exposed to 524 microg m(-3) SO2, 392 microg m(-3) O3 and a mixture of both gases, i.e. 524 microg m(-3) SO2 and 392 microg m(-3) O3 to determine the visible foliar injury and leaf diffusive resistance. Response of leaf diffusive resistance was measured on upper and lower surfaces of leaves, i.e. the two unifoliate leaves of bean and the first, second and third primary leaves of rice. The difference in the response may be due to sensitive guard cells causing stomatal closure in the presence of O3, whilst a low concentration of SO2 caused the stomata to open. Thus, SO2 alone is known to decrease, and O3 tends to increase leaf diffusive resistance. However, exposure to both gases increases or decreases the resistance, depending on the species response.     

Carbon capture,storage, and usage with microalgae: a review

Environmental Chemistry Letters - Global warming is induced partly by rising atmospheric carbon dioxide levels, calling for sustainable methods to sequester carbon. Here we review carbon capture,...     

Sediment accumulation and bio-diffusion mixing rates derived from excess <Superscript>210</Superscript>Pb and <Superscript>137</Superscript>Cs profiles in sediment cores of Mumbai Harbor Bay

Bio-diffusion mixing rates (D_b) were estimated from depth profiles of excess ²¹⁰Pb and ¹³⁷Cs in three sediment cores collected from Mumbai Harbour Bay (MHB) using a steady state vertical advection - diffusion model. The mean of ²¹⁰Pb and ¹³⁷Cs derived D_b values along the studied area were obtained to be about 23 and 36 cm²y^?1 respectively. These derived values were within the range of literature values reported for other equivalent environment internationally. The relatively higher D_b values for ¹³⁷Cs profiles demonstrated that particles have diffused more intensely within the surface layer of sediments over 1 year. Conversely, low D_b values for ²¹⁰Pb indicate slow mixing rates in the sediment profile which might be resulted from low ²¹⁰Pb flux and diffusion of ²²²Rn to the seafloor. The significant differences between ²¹⁰Pb and ¹³⁷Cs derived D_b values among cores indicate that there appeared to be as regional differences in sediment properties and local variability in the intensity of seafloor mixing. Furthermore, D_b values also depend on differences in characteristic time and depth scales of radionuclides in cores, benthic fauna abundances, organic carbon flux to the sediments and primary production in overlying surface waters. Comparison of ²¹⁰Pb derived D_b values with those calculated from ¹³⁷Cs distributions reveals better agreement for core 2 than core 1 and 3. The agreement may be fortuitous because ¹³⁷Cs appears significantly deeper than ²¹⁰Pb in all cores. It was also observed that D_b values increases as sediment accumulation rate increases for both radionuclide.     

Heavy metal contamination of soil,and bioaccumulation in vegetables irrigated with treated waste water in the tropical city of Varanasi,India

The present study was conducted to determine the heavy metal contamination in soil with accumulation in plants in waste water irrigated areas. Results revealed that waste water contained lower concentrations of Cr, Zn, Cu, and Pb except Cd (0.03) than the permissible limits prescribed by the World Health Organization. The maximum metal concentrations occurred in Brassica oleracea (Zn 63.80, Cu 12.25, Cr 10.65, Pb 3.63, and Cd 0.56 mg Kg^?1).The metal enrichment (EF of Cd 1.9, Cr2.9, Zn 4.8, Cu 6.5, and Pb 15.5) and degree of contamination (CF of Cd 2.9, Cr 2.0, Zn 2.3, Cu 2.7, and Pb 2.2) showed that accumulation of the five toxic metals increased during sewage irrigation as compared with the reference values, other Indian regions and globally. However, based on WHO standards for heavy metal contamination of soil and irrigation water, our data does not ensure safe levels for food.     

Impact of rhizobacteria on growth and chromium accumulation in Scirpus lacustris L. grown under chromium supplementation

Four chromate tolerant rhizobacterial strains viz., RZB-01, RZB-02, RZB-03 and RZB-04 were isolated from rhizosphere of Scirpus lacustris collected from Cr-contaminated area. These strains characterized at morphological and biochemical levels. The most efficient chromate tolerant strain RZB-03 was inoculated to fresh plant of S. lacustris and grown in 2 microg ml(-1) and 5 microg ml(-1) of Cr+6 supplemented nutrient solution under controlled laboratory condition. The effects of rhizobacterial inoculation on growth and chromium accumulation in S. lacustris were evaluated. The inoculation of rhizobacteria increased biomass by 59 and 104%, while total chlorophyll content by 1.76 and 15.3% and protein content increased by 23 and 138% under 2 microg ml(-1) and 5 microg ml(-1) concentrations of Cr+6, respectively after 14 d as compared to non-inoculated plant. Similarly, the Cr accumulation also increased by 97 and 75% in shoot and 114 and 68% in root of inoculated plants as compared to non inoculated plants at 2 microg ml(-1) and 5 microg ml(-1) Cr+6 concentrations, respectively after 14 d. The chromate tolerant rhizobacteria which play an important role in chromium uptake and growth promotion in plant may be useful in development of microbes assisted phytoremediation system for decontamination of chromium polluted sites.     

Study of bio-physico-chemical parameters of Mothronwala swamp, Dehradun (Uttarakhand)

Aquatic biodiversity is one of the most essential characteristics of the aquatic ecosystem formaintaining its stability and a means of coping with any environmental change. The entire stretch of the Mothronwala swamp has rich riparian vegetation for providing conducive environment for the growth of aquatic organisms. The present work has been undertaken to study the bio-physico-chemical characteristics of the swamp. The data on physico-chemical environmental variables (temperature, total dissolved solutes, size and composition of substratum, pH, dissolved oxygen, alkalinity chlorides, and hardness) have been given under the present contribution. A total of 16 genera of aquatic insects belonging to orders Trichoptera, Coleoptera, Hemiptera, Ephemeroptera, Odonata and Phylum Mollusca represented the macroinvertebrates of Mothronwala swamp. The fresh water swamp of Mothronwala is under threat due to human interference and other anthropogenic activities. Some of the natural and anthropogenic environmental problems of the Mothronwala swamp have been identified and the ameliorative measures for the protection of aquatic environment and the conservation measures for the swamp have been suggested. The qualitative study revealed the present status of the aquatic biodiversity of the swamp and also about the physico-chemical parameters, which would be very helpful for policy makers to take precautionary measures to save the swamp.     

Temperature related seasonal changes in Golgi complex of brain, heart and intestine of a teleost

Impact of temperature related seasonal changes in density of Golgi complex were studied in brain, heart and intestine of the freshwater catfish, Clarias batrachus (Linnaeus). The density of Golgi complex was more in these organs of the fish acclimatized to a lower temperature (20 degrees C) than that to a higher temperature (29 degrees C). This suggests that lower temperature induces secretory activity in cells to cope up with the changes in surrounding environment. It could be a kind of histophysiological adaptation in poikilothermic animal.     

Ameliorating effect of N-acetylcysteine and curcumin on pesticide-induced oxidative DNA damage in human peripheral blood mononuclear cells

Endosulfan, malathion, and phosphamidon are widely used pesticides. Subchronic exposure to these contaminants commonly affects the central nervous system, immune, gastrointestinal, renal, and reproductive system. There effects have been attributed to increased oxidative stress. This study was conducted to examine the role of oxidative stress in genotoxicity following pesticide exposure using peripheral blood mononuclear cells (PBMC) in vitro. Further possible attenuation of genotoxicity was studied using N-acetylcysteine (NAC) and curcumin as known modulators of oxidative stress. Cultured mononuclear cells was isolated from peripheral blood of healthy volunteers, and exposed to varying concentrations of different pesticides: endosulfan, malathion, and phosphamidon for 6, 12, and 24 h. Lipid peroxidation was assessed by cellular malondialdehyde (MDA) level and DNA damage was quantified by measuring 8-hydroxy-2'-deoxyguanosine (8-OH-dG) using ELISA. Both MDA and 8-OH-dG were significantly increased in a dose-dependent manner following treatment with these pesticides. There was a significant decrease in MDA and 8-OH-dG levels in PBMC when co-treated with NAC or/and curcumin as compared to pesticide alone. These results indicate that pesticide-induced oxidative stress is probably responsible for the DNA damage, and NAC or curcumin attenuate this effect by counteracting the oxidative stress.     

Oxidative stress in Scenedesmus sp. during short- and long-term exposure to Cu2+ and Zn2+

Algae are exposed to elevated levels of heavy metals in water bodies generally for a long-term, and occasionally for a short-term duration. The present study deals with oxidative stress in Scenedesmus sp., commonly found in nutrient-rich freshwaters, during short- (6h) and long-term (7d) exposure to Cu(2+) and Zn(2+). The cells accumulated almost 2- and 4-times more Cu(2+) and Zn(2+) inside the cells during long-term than during short-term exposure to these metals. But the data on photosynthetic O(2) evolution and cell viability suggest that Scenedesmus sp. experienced lesser metal stress in long-term than in short-term experiment. Although malondialdehyde content was slightly higher in the long-term experiment, the amount produced by one unit intracellular metal was significantly lower than that in the short-term experiment. Superoxide dismutase activity of Scenedesmus sp. was >30% higher during long-term than during short-term exposure to Cu(2+) and Zn(2+). But, catalase and ascorbate peroxidase activities increased only at 2.5 microM Cu(2+) and 25 microM Zn(2+) when oxidative stress was mild, but were inhibited at 10 microM Cu(2+) under intense oxidative stress. Cu(2+) and Zn(2+) reduced glutathione reductase activity and total SH content of Scenedesmus sp. in both the experiments, with greater reduction occurring in the long-term experiment. The depletion of total thiol was positively related with the intracellular level of metals. Thiols might have helped Scenedesmus sp. in overcoming metal-induced oxidative stress, but depletion of thiol pool is known to make cells vulnerable to oxidative stress. The study suggests that antioxidant enzymes play a role only under mild oxidative stress. An increased accumulation of proline seems to be an important strategy for alleviating metal-induced oxidative stress in Scenedesmus sp. The study shows that Scenedesmus sp. could acclimatize during long-term exposure to toxic concentrations of the test metals.