Deposition of Mn from automotive combustion of methylcyclopentadienyl manganese tricarbonyl beside the major highways in the greater Toronto area, Canada

Methylcyclopentadienyl manganese tricarbonyl (MMT) has been used in Canada since 1976 as an antiknock agent in gasoline, completely replacing Pb in 1990. An early study of much higher Mn concentrations in gasoline showed that the combustion of MMT leads to the formation of inorganic manganese oxides, especially Mn3O4. Recent emission testing by Lawrence Livermore National Laboratory for Ethyl Corp. has shown that Mn is primarily emitted as a phosphate or sulfate along with minor amounts of oxides. The main objective of this research was to analyze the deposition of Mn from MMT to the terrestrial environment beside the major highways in the greater Toronto area (GTA), Canada. The results were compared with Pb and other trace elements such as Al, Ca, Fe, Mg, Cu, Zn, Na, and the Cl ion (water extractable) to study the behavior of Mn in soil. The study area was located near major Toronto highways 401 (urban) and 400 (rural), at 43 degrees 67' N and 79 degrees 37' W (latitude and longitude) (278,560 and 47,835 cars/day), respectively. Surface soil samples (0-5 cm depth) were collected at distances up to 40 m from the roadside. Parameters evaluated included total and available Mn and other trace elements, particle size, pH, organic content, and cation exchange capacity. Based on high traffic density along 401, higher Mn deposition was expected. No significant differences were found between the 401 and 400 Barrie (E(+1)) sites, attributable to the natural background levels of Mn or its contribution by other sources such as Mn-enriched road dust or naturally occurring crustal Mn. However, the 400 King City (E(+2)) site had significantly lower Mn levels than did the other three sites, 401 and 400 Barrie. This may be explained by the types of soil along the 401 and 400 sites. The King City site along 400 was found to be higher in sand content than were the 401 sites. A higher sand content could result in higher leaching of Mn to the bottom layer of the soil. Although MMT has been used continuously for approximately 25 years in Canada, its contribution to the terrestrial environment has been very low and has not significantly increased Mn levels along the highways, as demonstrated by this study.     

Effects of sewage effluent discharge on the abundance, condition and mortality of hulafish, Trachinops taeniatus (Plesiopidae)

The effects of sewage effluent on the abundance, condition (length and reproduction) and mortality of hulafish Trachinops taeniatus were investigated at multiple outfall and control locations on the central coast of New South Wales, Australia. Underwater visual surveys found consistently fewer T. taeniatus at locations where sewage was discharged compared to control locations. The condition of T. taeniatus was investigated by comparing mean length and reproductive indices of fish from two outfall and two control locations. Fish from the largest outfall location were significantly smaller in comparison with fish from control locations. Gravid female fish from outfall locations had similar gonadosomatic indices but a significantly greater number of eggs and smaller size of eggs in comparison with fish from control locations. Mortality of T. taeniatus was investigated during 2-week, in situ, caging experiments at multiple locations and times and 80% of fish survived, although mortalities of up to 73% per cage were recorded at one sewage outfall. T. taeniatus may be a suitable environmental indicator species of sewage pollution.     

Increasing UV-B radiation at the earth's surface and potential effects on aqueous mercury cycling and toxicity

In the past two decades, a great deal of attention has been paid to the environmental fate of mercury (Hg), and this is exemplified by the growing number of international conferences devoted uniquely to Hg cycling and its impacts on ecosystem functions and life. This interest in the biogeochemistry of Hg has resulted in a significant improvement of our understanding of its impact on the environment and human health. However, both past and current research, have been primarily oriented toward the study of direct impact of anthropogenic activities on Hg cycling. Besides a few indirect effects such as the increase in Hg methylation observed in acid-rain impacted aquatic systems or the reported enhanced Hg bioaccumulation in newly flooded water reservoirs; changes in Hg transformations/fluxes that may be related to global change have received little attention. A case in point is the depletion of stratospheric ozone and the resulting increase in solar UV-radiation reaching the Earth. This review and critical discussion suggest that increasing UV-B radiation at earth's surface could have a significant and complex impact on Hg cycling including effects on Hg volatilization (photo-reduction), solubilization (photo-oxidation), methyl-Hg demethylation, and Hg methylation. Therefore, this paper is written to provoke discussions, and more importantly, to stimulate research on potential impacts of incoming solar UV-radiation on global Hg fluxes and any toxicity aspects of Hg that may become exacerbated by UV-radiation.     

Lead induced spermatoxicity in mouse and MPG treatment

Protective efficacy of MPG (2-mercaptopropionyl glycine) was studied against the toxic effects of lead acetate in Swiss albino mice. The animals were treated with single dose of lead acetate @ 180, 200 and 250 mg/kg b.wt. in presence and absence of MPG. The results indicated that the body weight was slightly higher in MPG treated groups on day 10 as compared to only respective lead treated groups in all the three dose level. However, significantly lower body weight was observed in both lead treated and lead along with MPG treated groups as compared to control. Patten of mortality is similar in both lead treated and lead plus MPG treated groups. Conspicuous degenerative changes in testicular tissues and elevation in sperm head shape abnormality were observed in both lead treated and lead along with MPG treated groups but the sperm head shape abnormality and damage were more in lead treated groups as compared to lead plus MPG treated groups. But this difference was non-significant between the two groups. These observations suggest that MPG may not be significantly effective against lead induced damage in testicular tissues at cellular level. However, MPG is able to maintain slightly lower level of sperm abnormality in all the three dose level as compared to their respective lead treated groups. Further, studies are needed to find out the optimum dose of MPG for protection against the lower doses of lead induced lethality as MPG is not significantly effective against the higher doses of lead.     

Seasonal ovarian cycle in freshwater teleost, Labeo rohita (Ham.) in Tarai region of Uttaranchal

Seasonal ovarian cycle, based on histophysiological changes, and correlative variations in liver were studied in an Indian major carp, Labeo rohita reared in captivity under ambient environmental conditions in Tarai region of Uttaranchal. The oocyte features used for marking ovarian cycle included nuclear-ooplasmic ratio, yolk vesicle incorporation into ooplasm, number and size of nucleolus and differentiation of follicular layer. Based on these features the ovarian cycle in L. rohita was divided into five phases i.e. resting, preparatory, pre-spawning, spawning and post-spawning/regression. The resting and preparatory phases were characterized by the dominating presence of chromatin-nucleolar and yolk-vesicle stage oocytes. The pre-spawning phase ovary was marked by the prevalence of yolk globule stage oocytes having cortical alveoli and differentiating follicular wall. The oocytes containing densely packed yolk-granules and large masses of yolk vesicles and also exhibiting germinal vesicle movement (GVM) signified the ovary of spawning phase. The ovary in regression phase contained pre-ovulatory atretic oocytes and significant number of oogonia. The histophysiological changes in liver showing augmented biosynthetic activity during preparatory and pre-spawning phases seemed well correlated with the gonadal development. The increasing water temperature and day-length apparently was favourable for the gonadal development in L. rohita.     

Assessment of deposition of MEMC (seed dressing fungicide) in exposed rice grain through study of seedling growth parameters

Rice seed grains exposed to 240 ppm of seed dressing fungicide, MEMC showed increase in deposition of mercury with increase in period of observation (0h to 48h) in 765+/-5 mg of intact endosperm. The gradual increase in mercury deposition in intact endosperm caused simultaneous decrease in mercury content of the seed coat. Exposure periods of 5 to 20 min with 240 ppm of MEMC showed 5.5 to 8.72 microg of mercury deposition in 765+/-5 mg of intact endosperm. Increase in period of exposure (3 to 20 min) to 240 ppm of MEMC and also increase in chronic treatment to lower concentrations (1.5 ppm to 24 ppm) to seed grains have shown similar results in seedling growth parameters. Lower period of exposure or exposure to lower concentrations, both showed a significant inhibition of root growth, however the shoot growth showed stimulation. But higher exposure period or exposure to higher concentrations brought inhibition of both root and shoot growth. The exposure period showing 50% of root growth inhibition of 72h old seedling was calculated to be 10 min So also the chronic treatment showing the 50% of root growth inhibition was calculated to be 9 ppm. Ten min exposure of rice grain to 240 ppm of MEMC showed deposition of 7.11 microg of mercury in 765+/-5 mg of intact endosperm at 48h of observation (optimal phase of germinating process). Regression analysis indicated that by the time of 72h the intact endosperm and developing seedling might have acquired with a minimum amount of 10.23 microg of mercury from the seed coat. Finally it can be said that 10.23 microg of MEMC might be bringing 50% root growth inhibition in 72h old seedlings and 16.71 microg of mercury causing 50% inhibition of both root and shoot growth of 120h old seedlings.     

Trends over time in the risk of driver death: what if vehicle designs had not improved?

OBJECTIVES: Passenger vehicle driver death rates per million vehicle registrations declined steadily during calendar years 1985-2004. The present study sought to separate the effect of vehicle design changes from this trend. METHODS: Restricting the trend to a fixed set of model years removed the vehicle design effects, but there were still effects due to vehicle aging. Risk of driver death was found to increase each year vehicles aged, probably due to changes in vehicle use patterns. RESULTS: After separating out the vehicle design effects and making adjustments for the vehicle age effects, a different picture emerged of trends in death rates over time. Absent the vehicle design changes, the historical decline in driver fatality risk would have ended in 1993, with risk climbing ever since. This underlying trend has been obscured by changes in the vehicle fleet. CONCLUSIONS: The push for vehicle improvements has been worthwhile and can be credited with saving thousands of lives. However, the analysis shows that the gains in occupant protection from vehicle design improvements have been offset partially by an increasingly risky environment in recent years. Therefore, more attention needs to be paid to programs targeting improvement in roadway design and driver behavior.     

Seasonal changes in plasma calcium and inorganic phosphate levels in relation to parathyroid structure of the grey quail, Coturnix coturnix coturnix Linnaeus

Plasma Ca concentration (annual mean) in males Coturnix cotumix coturnix was 10.27 +/- 0.14 mg/100 ml while it was slightly higher (11.85 +/- 0.15 mg/100 ml) among females. Plasma Pi levels (annual mean) in males and females were 5.62 +/- 0.12 mg/100 ml and 6.52 +/- 0.20 mg/100 ml, respectively. While the males did not exhibit marked fluctuation in plasma Ca and Pi levels either in winter or summer, the females did record significant elevation in the levels of both these electrolytes during breeding season. The peak values of plasma Ca (17.66 +/- 0.38 mg/100 ml) and Pi (8.64 +/- 0.22 mg/100 ml) in females were observed during June. Parathyroid gland of the grey quail exhibited hyperactivity (hypertrophy and hyperplasia) during breeding season, however, the activity was more conspicuous among females than in males. The maximum increase in cell and nuclear diameters were observed in females during May-July. The follicles were also filled with AF- and PAS-positive materials during these months. The glands depicted signs of hypoactivity and degeneration during peak winter season (November-December) as evident by decrease in cell and nuclear diameters as well as vacuolation in the chief cells.     

Microbial biomass, P-nutrition, and enzymatic activities of wheat soil in response to phosphorus enriched organic and inorganic manures

Compost was prepared from wheat straw enriched with Rajasthan rock phosphate and Aspergillus awamori. The resulting phospho-compost along with phosphorus enriched FYM, mineral fertilizer (rock phosphate) and super phosphate were evaluated for their individual contribution in improving organic matter status, P availability, and enzymatic activities of soil under wheat crop grown in a micro plot. The results showed that total organic carbon, nitrogen, microbial biomass, and humus content (an index of organic matter status of soil) of soil was highest when farm yard manure (FYM) after its enrichment with 12.5% rock phosphate was applied. Microbial enriched phospho-compost was the product yielding highest soil available phosphorus, phosphorus uptake, urease, and cellulase activities. However, FYM amended with 25% rock phosphate resulted in the greatest enhancement of beta- glucosidase. Measured parameters indicated a sure improvement of chemical and biological activities of soil after the application of phosphorus enriched organic amendments compared to the commercial fertilizer commonly used by the Indian farmers.     

Effects of heavy metals on population growth and metallothionein gene expression in the mosquito Culex quinquefasciatus, from Calcutta, India

Major water bodies in and around the city of Calcutta (India) receive heavy metal contaminated effluents from industries, households, and vehicular traffic through sewage or drainage. We quantified concentrations of Cu, Zn, and Cd from three water bodies at Kalighat, Tangra, and VIP Road, respectively. The concentrations of these heavy metals were significantly greater in the summer than in monsoon when heavy downpours resulted in reduced metal concentrations. Concentrations of metals in the mosquito Culex quinquefasciatus also reflected such seasonal fluctuations. Hatchability and survivorship of C. quinquefasciatus significantly differed among the sites and were reduced significantly from the control. Exposure to heavy metals also induced MT-gene expression in C. quinquefasciatus, likely helping them to survive in the water bodies stressed with heavy metals. MT-gene activity demonstrated significant variation among sites and seasons with the highest activity in the summer in the VIP Road population. This study suggests that C. quinquefasciatus could be used as an ecological indicator of heavy metal pollution by monitoring its MT-gene expression.