Response of two cultivars of Triticum aestivum L. to simulated acid rain

The present experiment was aimed at assessing the impact of simulated acidic precipitation (SAR) on growth, biomass accumulation and yield of two cultivars of wheat (Triticum aestivum L.), Malviya 206 and 234, varying in cuticular thickness and leaf area. Wheat cultivars were exposed to simulated rain acidified to pH 5.6 (control), 5.0, 4.5, 4.0 and 3.0 from 30 days of age, twice a week for five weeks. The plants received ambient precipitation of unknown acidity, as well as the acid rain treatments. Growth parameters such as shoot height, root length, and leaf area were reduced significantly in treated plants at different growth stages. Above and below-ground biomass also decreased significantly in the plants treated with acidic precipitation. Relative to control, the number of grains per plant and yield per m(2) declined significantly at all SAR treatments. The hypothesis that the variety with thinner cuticle and greater leaf area would be more susceptible to acidic precipitation was not supported by the present study.     

Radium-226 in cattails, Typha latifolia, and bone of muskrat, Ondatra zibethica (L.), from a watershed with uranium tailings near the city of Elliot Lake, Canada

Radium-226 concentrations were measured in the main food plants (cattails, Typha latifolia) and bone of adult muskrats (Ondatra zibethica (L.)), taken from a study area near Quirke Lake in the Serpent River drainage basin. This watershed receives drainage containing radionuclides from the U tailings near the City of Elliot Lake, Ontario, Canada. Two control sites (one local, one 130 km distant) were also sampled. Radium-226 levels in cattails varied by plant part and place of collection. Roots sampled in the study area had the highest mean (226)Ra level (1135.0 mBq g(-1)), stems and leaves had 284.2 and 275.9 mBq g(-1), respectively (dry-weight basis, n = 6 in all cases). Local and distant control cattails carried much lower (226)Ra levels (20.2 and 15.2 mBq g(-1) dry weight, respectively, using pooled equal portions of all plant parts, n = 3 in both cases). Muskrats from waters with mean total (226)Ra levels in the period, 1984-1987 greater than 75.0 mBq litre(-1) ('study-high' sites), near U tailings within 10 km of Quirke Lake, had a mean (geometric) bone level of (226)Ra of 344.9 mBq g(-1) (dry-weight basis, n = 36); those from nearby waters, containing < 75.0 mBq litre(-1) of (226)Ra ('study-low' sites), had a mean bone level (80.3 mBq g(-1), n = 9) similar to animals taken in unaffected local control areas 20 km from the tailings (79.1 mBq g(-1), n = 12); animals from the distant control area, near Sudbury, Ontario, had the lowest mean burden (11.5 mBq g(-1), n = 24). Levels were unrelated to age or sex of the animals. Dry-weight based (226)Ra concentration ratios (bone concentration/plant tissue concentration) were calculated to range from 0.3-1.4 in the study-high area to 2.4-6.3 in the local control area. Wet-weight based concentration ratios were about 4.3 times higher. Concentration ratios were similar to values calculated for other species and in general agreement with values calculated for humans. The muskrat is judged to be a useful indicator (biomonitor) of environmental (226)Ra levels as there is a highly significant positive correlation coefficient (r = 0.74) between bone and ambient (water) concentrations of the radionuclide (F79 = 95.04, P < 0.0001) Estimated yearly (226)Ra intake by people eating muskrats was calculated to be below the current allowable level set by Canadian regulatory authorities.     

Persistent organochlorines in beluga whales (Delphinapterus leucas) from the St Lawrence River estuary--I. Concentrations and patterns of specific PCBs, chlorinated pesticides and polychlorinated dibenzo-p-dioxins and dibenzofurans

Blubber samples from beluga whales (Delphinapterus leucas) in the St Lawrence River estuary were analysed for PCB congeners (ortho- and non-ortho-substituted) and other persistent organochlorines as well as chlorinated dibenzo-dioxins/furans (PCDD/Fs). Major individual components (mean concentrations > 1 microg g(-1)) were 4,4'-DDE, -DDD and -DDT, T12 (a toxaphene-related compound), trans-nonachlor, oxychlordane, mirex, HCB, tris(p-chlorophenyl) methane and dieldrin. Concentrations of SigmaPCBs (8.3-412 microg g(-1)), SigmaDDT (3.36-389 microg g(-1)) and mirex (0.18-6.8 microg g(-1)) were particularly elevated relative to other odontocetes in Canadian waters. SigmaDDT, PCBs (as Aroclor), mirex and T12 concentrations were positively correlated with age of adult females (> 10 years) but only weakly, or not significantly, correlated with age of adult males. PCDD/Fs were present at low ng kg(-1) levels and consisted mainly of penta- and hexachlorofurans, and hepta- and octachlorodioxin. CB126 (3,3',4,4',5-PCB) was the most prominent non-ortho-substituted PCB congener in beluga blubber. Total TCDD toxic equivalents averaged 330 ng kg(-1) in females and 1400 ng kg(-1) in males and were dominated by CB126, and the mono-ortho-substituted congeners CB105 and CB118. Biomagnification factors (BMFs) for mirex and SigmaPCB from fish to beluga ranged from 11 to 16, and were similar to BMFs in Arctic animals, indicating that elevated levels in St Lawrence animals are a consequence of relatively high levels of recalcitrant organochlorines in prey of the beluga in the St Lawrence river system.     

Effects of the phenylurea herbicide isoproturon on periphytic diatom communities in freshwater indoor microcosms

The toxic effects of the phenylurea herbicide Isoproturon -IPU: (3-(4-isopropylphenyl)-1, 1-dimethylurea)-were studied on the colonization of periphytic diatom communities, within indoor microcosms consisting of a mixed biotope (water column and natural sediment) and two biological species-rooted macrophyte cuttings (Elodea densa) and benthic bivalve molluscs (Corbicula fluminea). The periphyton, essentially composed of diatoms, was collected on artificial substrata (glass slides) in the upper layers of the water column, after two periods of exposure (34 and 71 days). IPU was initially added in the water or in the sediment compartment, at two nominal concentrations (L1 and L2 levels) for each contamination source-5 and 20 microg litre(-1) and 100 and 400 microg kg(-1) in sediment (w/w) respectively. The effects of IPU on the density and community structure of periphytic diatoms are described. A marked reduction in the diatom density was observed after 34 days exposure to the lower concentration of IPU in the water (5 microg litre(-1)). For the L2 levels, the very small number of live cells present did not permit quantification of the diatom density. After 71 days, recovery in community parameters occurred for the two contamination levels of the sediment and water column sources. Samples collected in the experimental units contaminated with the L2 levels were dominated by heterotrophic and smaller diatom species, such as Sellaphora seminulum. Data treatment based on factorial discriminant analysis enabled us to distinguish the different contamination conditions, with only 11 species from the 130 taxa identified.     

Effects of ethylenediurea (EDU) on ozone-induced acceleration of foliar senescence in potato (Solanum tuberosum L.)

Experiments were conducted to examine the effects of the anti-ozonant ethylenediurea (EDU) and chronic ozone (O3) exposure on leaf physiology and senescence in an O3-sensitive potato cultivar (Solanum tuberosum L. cv. Norland). A dose-response experiment showed that an EDU concentration of 15 mg l(-1) soil (given as a soil drench) provided complete protection from accelerated foliar senescence induced by exposure to 0.1 microl l(-1) O3 for 5 h day(-1) for 11 days. EDU doses of 45 and 75 mg active ingredient l(-1) soil also gave protection but were associated with symptoms of toxicity and delayed senescence. In further experiments, plants were given 0 or 15 mg EDU l(-1) soil and exposed to clean air or 0.1 microl l(-1) O3 for 5 h day(-1) for 14 days. Chronic O3 exposure in the absence of EDU resulted in accelerated foliar senescence, characterized by early declines in net photosynthesis and Rubisco quantity in O3-treated plants relative to controls. EDU in the presence of O3 gave complete protection against symptoms of accelerated senescence. Senescence was not delayed in plants that received EDU in the absence of O3, and no symptoms of EDU toxicity were evident. The results suggest that EDU-induced tolerance to O3 was not based on 'anti-senescent' properties of this anti-ozonant.     

Chemical fractionation of copper, lead and zinc in ombrotrophic peat

Measurement of operationally defined chemical fractions in ombrotrophic peat samples provides information not obtained by total metal extractions. Examination of such sequential data permits interpretation of process dynamics. Results for copper, lead and zinc chemical fractionation of peat profiles from Ringinglow Bog, near Sheffield, Great Britain, are reported and discussed. Lead and zinc share similar patterns of partitioning. A considerable proportion of these records is in a form predisposed to transformation and mobilisation. In contrast, much of the copper is comparatively immobile, it being associated with the more chemically intractable fractions. The results suggest that peat copper deposition records may be used for reconstruction of pollution history. The use of lead and zinc records for these purposes is problematic.     

Effect of ozone on net photosynthesis in oat (Avena sativa) and duckweed (Lemna gibba)

Short exposure to ozone depressed photosynthesis in both oat and duckweed at concentrations above 140 microg m(-3) and 300 microg m(-3), respectively. The effect on exposed oat flag leaves was age-dependent, with maximum susceptibility to ozone 10-20 days after emergence of the panicle. In duckweed, photosynthesis was more sensitive to differences in ozone concentration than to differences in duration of exposure.     

The total carbohydrate: organic carbon ratio as an indicator of sewage-derived organic matter in Burbo Bight sediments, Liverpool Bay, UK

Sediments from the Burbo Bight, Liverpool Bay, were analysed for their total carbohydrate (TCH) and organic carbon (TOC) contents, and the TCH:TOC ratio (when the TCH is expressed as a percentage of the TOC) was used to give an indication of the amount of sewage-derived organic matter in the sediments. The %TCH values found ranged from 17-68 with an average of 40, indicating that sewage-derived organic matter constituted a significant fraction of the organic matter in the sediment. This appears likely to have been derived mainly from the Mersey Estuary outflow and the sewage sludge dumped in Liverpool Bay, but these two sources cannot be distinguished using this technique. It is suggested that further studies are required on the carbohydrates in sewage sludge and coastal sediments to satisfactorily establish this technique.     

Heavy metal concentrations in the liver of three duck species: influence of species and sex

To investigate interspecific and intersex differences in heavy metal levels, we analysed concentrations of cadmium, cobalt, chromium, copper, lead, mercury, manganese, nickel and zinc in the livers of male and female black duck (Anas rubripes), mallard (A. platyrhynchos) and greater scaup (Aythya marila) collected in Raritan Bay, New Jersey in December 1980 and January 1981. Certain metal levels varied significantly by species and sex. In all species, Zn and Cu had the highest concentrations, and Cd, Co, and Hg were lowest in all three species. Scaup had significantly higher levels of Cu than black ducks and mallards, and mallards had significantly higher levels of Mn and Zn than black duck and scaup. Overall, eight of nine metal levels were higher in male than female black duck. In scaup, females had significantly higher levels of Pb and Mn than males. In black ducks, males had significantly higher levels of Cu, Mn and Zn than females. The sample of mallard was too small to test intersex differences.     

The effect of pH on zinc adsorption equilibria and exchangeable zinc pools in soils

Zinc adsorption equilibria were measured in soils differing in pH but with similar textures and total zinc concentrations, using adsorption isotherm and isotopic exchange techniques. The results suggested that the equilibrium between solution and exchangeable zinc was strongly pH dependent and the active zinc species in adsorption was single charged (e.g. Zn(OH)(+)). The size of the exchangeable zinc pool was not strongly pH dependent. Similar results were obtained when zinc was added to the soils, either as Zn(NO(3))(2) or in sewage sludge.