Foliar responses of five plant species to ozone and a sulphur dioxide/ozone mixture after a sulphur dioxide pre-exposure

Plants that were pretreated with 0.15 ppm SO₂ for either 2 or 3 d before an intermittent O₃ or SO₂/O₃ exposure exhibited differences in per cent visible foliar injury that often varied significantly from plants that received no SO₂ pretreatment. Differences that were observed could not be explained on the basis of leaf diffusive resistance alone. The SO₂ pretreatment for 2 d caused a decrease in visible O₃ injury in white bean, an increase in visible O₃ injury in cucumber and radish, and had no effect on soybean and tomato. The same pretreatment caused an increase in visible injury from the SO₂/O₃ mixture in white bean, a decrease in visible injury for cucumber and tomato, and had no effect on soybean and radish. However, these same trends did not occur when the SO₂ pretreatment was increased to 3 d. Pretreatment with sub-acute levels of SO₂ can significantly alter a plant's response to O₃ or a mixture of SO₂/O₃, the change in response being sensitive to the pretreatment SO₂ dosage. The nature of the visible injury symptoms from O₃ or the pollutant mixture were not altered for any of the plant species regardless of the length of time of the SO₂ pretreatment and, generally, the onset of visible injury was not greatly altered.     

Yield responses of different crop species to long-term fumigation with sulphur dioxide in open-top chambers

Potted plants of commercial cultivars of rape (Brassica napus L., cv. 'callypso'), summer barley (Hordeum vulgare L., cvs. 'arena' and 'hockey') and bush beans (Phaseolus vulgaris L., cvs. 'rintintin' and 'rosisty') were continuously exposed in open-top chambers to sulphur dioxide (SO(2)) for the whole growing season in order to assess effects of this pollutant on growth and various yield parameters. Treatments consisted of charcoal-filtered air (CF) and CF supplemented with four levels of SO(2), resulting in mean exposure concentrations (microg m(-3)) of approximately 8, 50, 90, 140 and 190. With the exception of the 1000 seeds weight, which was slightly reduced, dry matter production and yield parameters of rape remained unaffected by all SO(2) concentrations or were even stimulated. Compared to CF vegetative growth of both bean cultivars was reduced by 10-26% at all SO(2) levels; however, with significant effects only for cv. 'rintintin'. While all SO(2) additions reduced significantly the yield (dry weight of pods) of the bean cultivar 'rosisty' between 17% and 32%, cv. 'rintintin' showed a significant reduction of up to 42% only at the two highest pollutant concentrations. Dry matter production of the barley cultivars was mainly impaired at SO(2) concentrations > 100 microg m(-3) with a reduction of 30-52%. While nearly all yield parameters of cv. 'hockey' reacted similar to the dry matter production, the yield of cv. 'arena' was reduced already at the low SO(2) levels. At a treatment concentration of 90 microg SO(2) m(-3) a significant yield loss of 30% was recorded. A reduction of the 1000 grains weight mainly contributed to these yield losses observed for both barley cultivars. From these results, it may be assumed that SO(2) concentrations within the range 50-90 microg m(-3) are potentially phytotoxic to some crop species.     

Comparison of different physiological parameter responses in Lemna minor and Scenedesmus obliquus exposed to herbicide flumioxazin

The sensitivity of different physiological parameters in Scenedesmus obliquus and Lemna minor exposed to herbicide (flumioxazin) was investigated to indicate the most convenient and sensitive parameter. To assess toxicity of flumioxazin, we used a panel of biomarkers: pigment contents, chlorophyll fluorescence parameters and antioxidative enzyme activities. Algae and duckweed were exposed to 48-h IC50 for growth rate. In L. minor, the sensitivity of the parameters was as follows: QN > Oxygen emmision > phiS(PSII) > QP > phi(PSII) > CAT, GR > Pigment> APO > Growth. For S. obliquus, this ranking was as follows: CAT > Oxygen emission > QP > APO > GR > Pigment > phiS(PSII) > Growth > phi(PSII) > QN (from the greatest to the least sensitive). The results demonstrated that the observed toxicity is related not only to interspecific variations but also to the selected parameter.     

Toxicological responses of earthworm (Eisenia fetida) exposed to metal-contaminated soils

The aim of this study was to evaluate the toxicological responses of earthworm (Eisenia fetida) induced by field-contaminated, metal-polluted soils. Biochemical responses and DNA damage of earthworm exposed to two multi-metal-contaminated soils in a steel industry park and a natural reference soil in Zijin Mountain for 2, 7, 14, and 28 days were studied. Results showed that three enzyme activities, including superoxide dismutase (SOD), acetylcholinesterase (AChE), and cellulase, in earthworm in metal-contaminated soils were significantly different from those of the reference soil. Cellulase and AChE were more sensitive than SOD to soil contamination. The Olive tail moment of the comet assay after 2-day exposure increased 56.5 and 552.0 % in two contaminated soils, respectively, compared to the reference soil. Our findings show that cellulase and DNA damage levels can be used as potential biomarkers for exposure of earthworm to metal-polluted soils.     

The effects of prior exposure to sulphur dioxide and nitrogen dioxide on the water relations of timothy grass (Phleum pratense) under drought conditions

Studies of the growth and water relations of the grass Phleum pratense L. (Timothy) were made after simultaneous exposure to SO(2) and NO(2) at concentrations ranging from 80 + 57.4 microg m(-3) to 240 + 172.2 microg m(-3) (SO(2) + NO(2)). Decreased partitioning to the roots was evident during exposure to the pollutants, but when the plants were returned to clean air restrictions in root growth did not persist. Shoot to root partitioning was, however, complicated by the additional factor of changes in the nutritional status of the soil after additional columns of fresh soil were attached to the original tubes. The rate of use of soil water was nevertheless substantially increased by the pollution treatment and after a period of 23 days in which water was withheld, a clear pollution x water stress interaction was seen. The ability of polluted leaves to conserve water under severe water stress was tested by excising the leaves and measuring their water loss over time. The results from this second experiment showed that conservation of water by the leaves was appreciably affected after exposure to 80 + 57.4 microg m(-3) or 133.3 + 95.6 microg m(-3) SO(2) + NO(2). It seems likely that damage to the cells in the epidermal layer, leading to malfunctioning of stomata, is mainly responsible for the reduced ability to conserve water under conditions of extreme stress.     

Multi-biomarker responses in green mussels exposed to PFCs: effects at molecular,cellular, and physiological levels

Perfluorinated chemicals (PFCs) are extremely persistent and have been found extensively in the environment and wildlife. Oceans are the final sink for many persistent organic pollutants (POPs) including PFCs. However, to date, there has been a lack of studies that investigated the environmental consequences of PFCs on marine organisms. To fill in this gap, environmental toxicity of two dominant PFCs, perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA), was examined in a sentinel species, green mussel Perna viridis, using a series of biomarkers corresponding to different biological levels (molecular, cellular, and physiological). Correlations among these biomarkers were also investigated. The results showed that the tested compounds can induce a series adverse effect at different biological levels, including oxidative stress, DNA damage, membrane instability, suppressed filtration rate, and reduced body weight. Correlation analysis revealed that excess production of reactive oxygen species could be the major toxic pathway. An indirect mode of toxic action was also explored where adverse impacts could be secondary effects of PFC exposure. The joint analysis of biomarkers from multiple biological levels resulted in a comprehensive understanding of how PFC exposure can influence the health of organisms. The correlations of these biomarkers also provided a new perspective of the ecological consequences of PFCs.     

The wet deposition of sulphate and its relationship to sulphur dioxide emissions

The factors that need to be considered when comparing rainfall data with emission data are summarized, and it is indicated that trend analysis cannot be done properly without the use of a transport model. An optimization procedure is then used to fit the Fisher statistical model to European sulphate in rain data. This indicates moderately efficient to efficient wet removal of sulphate on average across Europe which is consistent with limited aqueous oxidation close to major source areas and a more linear behaviour at greater distances. At such distances, particularly in remote high rainfall areas, the results demonstrate the importance of ‘background’ sulphate. The results are all consistent with the latest U.K. rainfall data.     

Evaluation of rational sulphur dioxide abatement in China

Sulphur dioxide (SO₂) abatement is attracting wide attention, with its generation increasing rapidly in China. In this paper, we calculate the SO₂ rational abatement ratio (SRAR) of 30 regions in China from 1990 to 2005, by applying Data Envelopment Analysis (DEA) based on the regional own production frontier. Results show that, the more developed area is, the lower SRAR is. The eastern, central and western areas have the lowest, medium and highest 1990-2005 average SRAR (22.17%, 46.99% and 58.28%), respectively. Chinese government should emphasise particularly on SO2 abatement in central and western area. More investment in SO2 management, introducing advanced technology as well as popularising clean coal technology are the urgent tasks for central and western area to improve SO2 emission efficiency.     

The functional and physiological status of Gammarus fossarum (Crustacea; Amphipoda) exposed to secondary treated wastewater

Climate change scenarios predict lower flow rates during summer that may lead to higher proportions of wastewater in small and medium sized streams. Moreover, micropollutants (e.g. pharmaceuticals and other contaminants) continuously enter aquatic environments via treated wastewater. However, there is a paucity of knowledge, whether extended exposure to secondary treated wastewater disrupts important ecosystem functions, e.g. leaf breakdown. Therefore, the amphipod shredder Gammarus fossarum was exposed to natural stream water (n = 34) and secondary treated wastewater (n = 32) for four weeks in a semi-static test system under laboratory conditions. G. fossarum exposed to wastewater showed significant reductions in feeding rate (25%), absolute consumption (35%), food assimilation (50%), dry weight (18%) and lipid content (22%). Thus, high proportions of wastewater in the stream flow may affect both the breakdown rates of leaf material and thus the availability of energy for the aquatic food web as well as the energy budget of G. fossarum.     

Biomarker responses at different levels of biological organisation in crabs (Carcinus aestuarii) experimentally exposed to benzo(alpha)pyrene

The aim of this study was to validate a multi-trial biomarker approach for the evaluation of toxicological risk due to benzo(alpha)pyrene. Carcinus aestuarii, exposed to increasing concentrations of B(alpha)P in the water, was used as the bioindicator organism. A set of biomarkers were tested in order to: identify biological materials for biomarker and residue analysis; determine a group of sensitive techniques for the assessment of PAH contamination; investigate correlation between responses at different levels of biological organisation. The results underlined that BPMO activities in hepatopancreas and gills were a good biomarker of exposure to PAH-type compounds. B esterases activities in hemolymph and porphyrin patterns in excreta could be proposed as a non-destructive approach for evaluating chemical exposure in this species.     

Study of iron(III) catalysed sulphur dioxide oxidation in aqueous solution over a wide range of pH

Iron catalysed sulphur dioxide oxidation in aqueous solution at atmospheric concentrations has been investigated in the range of pH 3–8. S(IV) oxidation rate increases proportionally to Fe(III) concentration in the solution. The reaction shows a maximum rate at pH 4, that is explicable considering the solution chemistry of both S(IV) and Fe(III) as a function of pH. The reaction order with respect to S(IV) concentration varies from one at pH 3–4 to two at pH 5–8.     

The oxidation and long-range transport of sulphur dioxide in a remote region

The flux of sulphur dioxide has been measured in the plume of a remotely situated smelter (Mount Isa, Australia) at distances of up to 1000 km from the source. These measurements were made with an airborne correlation spectrometer in plumes ranging in age from 1.0 to 42.5 h, the latter corresponding to a photolytic age of almost two periods of daylight. Ground-based experiments were also performed to determine the rate of dry deposition of sulphur dioxide in the area situated about 500 km from the source.The implications of an error in the deposition velocities, reported by Milne J.W., Roberts D.B. and Williams D.J. (Atmos. Envir. 13, 373–380, 1979.), are considered. The average velocity for the Mount Isa region is higher than that previously employed by Roberts D. B and Williams D.J. (Atmos. Envir. 13, 1485–1489, 1979). Along with a reassessment of the diurnal model and the average mixing height encountered by Roberts and Williams, this necessitates a reduction in the estimate of the photochemical oxidation rate of sulphur dioxide from 0.25 to 0.15%h⁻¹, when averaged over 24 h.It is shown in this study that the rate of loss of sulphur dioxide from the plume out to the furthest distances measured can be accounted for by the combined processes of atmospheric oxidation and dry deposition, as determined by Roberts and Williams for much shorter distances (< 260 km). The lifetime of sulphur dioxide in the region under study is shown to be fourteen days, with about half of the loss being due to atmospheric oxidation.     

Antioxidative responses in relation to growth of mustard (Brassica juncea cv. Pusa Jaikisan) plants exposed to hexavalent chromium

Effect of hexavalent chromium (Cr6+) was seen on Brassica juncea cv. Pusa Jaikisan grown for 15 days in hydroponic culture supplemented with 0.2, 2 and 20 microM Cr. The inhibitory response of Cr6+ on growth of B. juncea was concentration and time dependent. The stimulation of plant growth, observed in response to exposure to 0.2 microM Cr6+, during initial 5 days was reversed on prolonged treatment and at higher Cr6+ concentrations (2 and 20 microM Cr6+). Despite reduction in growth, chlorophyll content increased substantially on 15 days exposure to 20 microM Cr6+. Significant increases in lipid peroxidation and tissue concentration of H2O2 occurred in plants exposed to 2 and 20 microM Cr6+. Effect of Cr6+ on antioxidative enzymes in roots and leaves was differential. SOD and CAT activities at lower levels of Cr6+ supply remained higher all through the treatment. While APX was very susceptible to excess Cr6+, GR and GST increased at elevated levels of Cr6+. The results suggested Cr6+ induced depression in plant growth of B. juncea to be a function of increased cellular accumulation of Cr despite increase in the activities of some of the antioxidative enzymes.     

Electrolyte solution theory and the oxidation rate of sulphur dioxide in water

A theoretical assessment of the effect of ionic strength on the thermodynamics and kinetics of sulphite ions in aqueous solution is made. It is concluded that in the range up to 0.1 M ionic strength substantial effects on the equilibria and reaction rates would be anticipated, especially at low pH, but the available experimental data are inadequate to confirm or to deny these possibilities.     

Dissolved sulphur dioxide and sulphate in urban and rural precipitation (Norfolk,U.K.)

Sulphur dioxide washout and total sulphate scavenging by precipitation at a rural and urban site have been measured in Norfolk (easternmost part of U.K.) over a period of one year. The basic sampling period was one day although, on occasions, more intensive sampling was undertaken. Estimates have been made of the role of sulphur dioxide washout in the total sulphur removal process. Because the “same” rainfall was collected in the urban and rural locations, attempts have been made to compare city and rural sulphur dioxide washout and sulphate scavenging rates in relation to precipitation amount, intensity, atmospheric sulphur dioxide, rainfall pH and weather-type. There is a greater difference between urban and rural sulphur dioxide washout levels than between the respective precipitation sulphate levels. The field measurements of sulphur dioxide solubilities agree reasonably well with some previous theoretical work.     

Effects of sulphur dioxide (SO2) on growth and flowering of SO2-tolerant and non-tolerant genotypes of Phleum pratense

The objective of this study was to compare the growth and interaction of clipping and sulphur dioxide (SO(2)) exposure on SO(2)-tolerant and non-tolerant genotypes of Phleum pratense at two field sites along an SO(2)-concentration gradient. Sulphur-dioxide-tolerant and non-tolerant genotypes of Phleum pratense were identified from indigenous populations that had been collected along the same SO(2)-concentration gradient in southern Alberta, Canada. Physiological differences between the two genotypes were confirmed by supplying leaves with (14)CO(2) and examining the assimilate partitioning between the genotypes. For the field experiment, clones of each genotype and seedlings grown from commercial seed were planted at two different field sites along an SO(2)-emission gradient. There were no differences in growth between the genotypes at the two field sites after the first year except that the SO(2)-tolerant clones had a greater percentage of root length colonised by vesicular-arbuscular (VA) mycorrhizal fungi. After the second growing season, there was a significant decrease in the number of inflorescences produced by plants exposed to SO(2), particularly by the non-tolerant genotype. The added stress of defoliation appeared to increase the sensitivity of flowering to SO(2), again particularly in the non-tolerant genotype. The results of the field study showed that flowering as opposed to vegetative plant growth was more sensitive to long-term low-concentration SO(2) exposure and that this sensitivity was compounded by the stress interaction of defoliation.     

Effect of gender on physiological and behavioural responses of Gammarus roeseli (Crustacea Amphipoda) to salinity and temperature

The importance of potentially interacting factors in organisms responses to a stress are often ignored or underestimated in ecotoxicology. In laboratory experiments we investigated how gender, temperature and age influence the behaviour and the physiology of the freshwater amphipod Gammarus roeseli under salinity stress. Our results revealed a significant higher sensitivity of females in survival, ventilation and ionoregulation whereas no inter-age differences were reported. Water temperature also exerted a significant effect in survival and ventilation of G. roeseli. Some of those factors appeared to interact significantly. This study provides evidence that gender can affect organisms responses to a stressor and consequently has to be considered while assessing a stress impact. We discussed the potential relationships between biological and behavioural responses.     

Meteorological effects on smoke and sulphur dioxide concentrations in the Manchester area

Observations of mean daily concentrations of smoke and of sulphur dioxide, obtained from several National Survey sites in the Manchester area, have been correlated with meteorological data and with certain other variables. Two periods have been examined, one from May 1975 to March 1977, the other from October 1978 to April 1979; the second, shorter period was more closely analysed. The model adopted for analysis differed from the power-law form selected by most previous investigators; it appears physically more satisfactory and in practice gave better correlation with sulphur dioxide observations. For the long period, the relatively crude analysis explained about two-thirds of the variance: for the shorter period, using more detailed meteorological data, the proportion explained ranged from 72 to 93 %.