Temporal processes that contribute to nonlinearity in vegetation responses to ozone exposure and dose

Ozone interacts with plant tissue through distinct temporal processes. Sequentially, plants are exposed to ambient O₃ that (1) moves through the leaf boundary layer, (2) is taken up into plant tissue primarily through stomata, and (3) undergoes chemical interaction within plant tissue, first by initiating alterations and then as part of plant detoxification and repair. In this paper, we discuss the linkage of the temporal variability of apoplastic ascorbate with the diurnal variability of defense mechanisms in plants and compare this variability with daily maximum O₃ concentration and diurnal uptake and entry of O₃ into the plant through stomata. We describe the quantitative evidence on temporal variability in concentration and uptake and find that the time incidence for maximum defense does not necessarily match diurnal patterns for maximum O₃ concentration or maximum uptake. We suggest that the observed out-of-phase association of the diurnal patterns for the above three processes produces a nonlinear relationship that results in a greater response from the higher hourly average O₃ concentrations than from the lower or mid-level values. The fact that these out-of-phase processes affect the relationship between O₃ exposure/dose and vegetation effects ultimately impact the ability of flux-based indices to predict vegetation effects accurately for purposes of standard setting and critical levels. Based on the quantitative aspect of temporal variability identified in this paper, we suggest that the inclusion of a diurnal pattern for detoxification in effective flux-based models would improve the predictive characteristics of the models. While much of the current information has been obtained using high O₃ exposures, future research results derived from laboratory biochemical experiments that use short but elevated O₃ exposures should be combined with experimental results that use ambient-type exposures over longer periods of time. It is anticipated that improved understanding will come from future research focused on diurnal variability in plant defense mechanisms and their relationship to the diurnal variability in ambient O₃ concentration and stomatal conductance. This should result in more reliable O₃ exposure standards and critical levels.     

Rainfall trends in twentieth century over Kerala,India

Attempts were made to study temporal variation in monthly, seasonal and annual rainfall over Kerala, India, during the period from 1871 to 2005. Longterm changes in rainfall determined by Man-Kendall rank statistics and linear trend. The analysis revealed significant decrease in southwest monsoon rainfall while increase in post-monsoon season over the State of Kerala which is popularly known as the “Gateway of summer monsoon”. Rainfall during winter and summer seasons showed insignificant increasing trend. Rainfall during June and July showed significant decreasing trend while increasing trend in January, February and April. Hydel power generation and water availability during summer months are the concern in the State due to rainfall decline in June and July, which are the rainiest months. At the same time, majority of plantation crops are likely to benefit due to increase in rainfall during the post-monsoon season if they are stable and prolonged.     

Seasonal variation of HCH isomers in open soil and plant-rhizospheric soil system of a contaminated environment

Background, aim, and scope  

Lindane, technically 1, 2, 3, 4, 5, 6-hexachlorocyclohexane (γ- HCH), is the most commonly detected organochlorine pesticide from diverse environmental compartments. Currently, India is the largest consumer and producer of lindane in the world. The production of lindane results in the generation of large quantities of waste HCH isomers (mainly α-, β- and δ-). All these isomers are toxic and have a long-range environmental transport potential. The aim of this study was to monitor the seasonal variation of HCH isomers in an open soil–plant–rhizospheric soil system of a contaminated industrial area. For this, selected plant species and their rhizospheric soil (soil samples collected at a depth range of 0–45 cm near to the root system) and open soil samples (soil samples collected (0–30 cm depth) from 1–1.5 m away from the plant root system) were collected for 2 years (two summer seasons and two winter seasons).     

First REP-LECOTOX Workshop—ecotoxicogenomics: the challenge of integrating genomics/proteomics/metabolomics into aquatic and terrestrial ecotoxicology

Environmental Science and Pollution Research -     

Atmospheric composition change research: Time to go post-normal?

For more than two decades a number of frameworks for scientific knowledge production are being proposed by science and technology researchers. They all advocate an extended involvement of non-specialists, in particular when it comes to knowledge production applicable to practical societal problems. We look to what extent these new frameworks have taken ground within a particular research community: the ACCENT Network of Excellence which coordinates European atmospheric chemistry and physics research applicable to air pollution and climate change. We did so by stimulating a debate through a “blog”, a survey and in-depth interviews with ACCENT scientists about the interaction between science, policy making and civil society, to which a great deal of ACCENT member contributed in writing or verbally. Most of them had interactions with policy makers and/or the general public, and they generally believe that interactions with spheres other than the scientific are needed. While such interactions give personal insight and satisfaction, they seem to have little impact on the goals and the practice of the scientific work itself. Extended frameworks of science production that go beyond the disciplinary mode seem to emerge at the level of individual scientists, yet they still need to find their way to the level of scientific project management. In this paper we discuss the justifications and barriers to implement a higher degree of extended knowledge integration in applied science projects such as ACCENT. It is felt that the community of atmospheric chemists and physicists is mature for such an implementation and recommendations are given to help and make this happen.     

Heavy metal deposition in the Italian “triangle of death” determined with the moss Scorpiurum circinatum

In this study, a biomonitoring project using the moss Scorpiurum circinatum was carried out to evaluate the deposition and biological effects of heavy metals in the area of Acerra (Naples, S Italy), one of the vertices of the sadly called “Italian triangle of death” owing to the dramatic increase in tumours. The results clearly indicated that the study area is heavily polluted by heavy metals, a large proportion of which is likely present in the atmosphere in particulate form. The ultrastructural organization of exposed samples was essentially preserved, but cell membrane pits, cytoplasm vesicles and concentric multilamellar/multivesicular bodies, probably induced by pollution, were found, which may be involved in the tolerance mechanisms to metal pollution in this moss species. Although severe biological effects were not found at the ultrastructural level in the exposed moss, effects on humans, especially after long-term exposure, are to be expected.     

Bait-lamina assay as a tool to assess the effects of metal contamination in the feeding activity of soil invertebrates within a uranium mine area

As part of the tier 2 of a site-specific risk assessment, this study was the first reporting an intensive in situ application of the bait-lamina assay; two exposure periods (7 and 14 days) were tested during four seasons in ten different sites, within a uranium mine area and at two different depths. The most contaminated sites (by deposition of sludge from the effluent treatment pond) were discriminated after 14 days of exposure because extremely low percentages of feeding activity were recorded. Previous sub-lethal ecotoxicological assays, already had demonstrated that the habitat function of these soils is compromised. Nevertheless, seasonality has proved to have a significant influence on responses. Thus to strength conclusions about the impact of contaminants, the in situ bait-lamina assay should be performed on different annual seasons, at least for temperate regions. It was also found that some environmental parameters (e.g. soil moisture and litter) can act as confounding factors in the bait-lamina assay.     

Validation studies of turbulence closure schemes for high resolutions in mesoscale meteorological models – A case of gas dispersion at the local scale

This work is a contribution to a large project, aimed at the development of an advanced environmental assessment modelling system to be used in Japan. The modelling system here considered consisted of the RAMS and HYPACT coupled models. The RAMS code was modified to properly simulate local scale phenomena using a fine mesh size of 250 m. In this direction, the main aim here was to investigate the effect of the choice of the turbulence closure scheme on the dispersion of pollutants. Our modified version of the RAMS/HYPACT model chain was validated using field experiments which were carried out by the Japan Atomic Energy Research Institute (JAERI) in the area of Mt. Tsukuba (Japan). The mean flow, turbulence and concentration fields obtained using two alternative turbulence closure schemes are compared. A discussion on the different performances of the turbulence closures is presented and the influence of the closure schemes over the plume dispersion is investigated.     

Petroleum hydrocarbon concentrations in eight mollusc species along Tamilnadu coast, Bay of Bengal, India

Eight mollusc species and sediment samples collected from three different stations along Tamilnadu coast, Bay of Bengal, India were analysed for the levels of petroleum hydrocarbons to elucidate the status of the petroleum residues in mollusc meant for human consumption. The concentrations of petroleum hydrocarbons in sediments along Tamilnadu coast varied from 5.04–25.5 g/g dw (dry weight). High concentration of petroleum hydrocarbons in the sediment of Uppanar estuary (25.5 1.45 g/g dw) was perhaps land and marine based anthropogenic sources of this region. The petroleum hydrocarbon residues in eight mollusc species collected from Uppanar, Vellar and Coleroon estuaries varied between 2.44–6.04 g/g ww (wet weight). Although the concentration of petroleum hydrocarbons in sediment of the Uppanar region was markedly higher than the background, the petroleum hydrocarbon residues in mollusc collected from Uppanar estuary did not suggest bioaccumulation. The results signified that industrial growth has affected the aquatic environments and regular monitoring will help to adopt stringent pollution control measures for better management of the aquatic region.