In situ monitoring of the mutagenic effects of the gaseous emissions of a solid waste incinerator in metropolitan São Paulo, Brazil, using the Tradescantia stamen-hair assay

The present work was designed to determine the potential genotoxicity at the vicinity of a solid waste incinerator in the metropolitan area of S?o Paulo, using the Tradescantia stamen-hair bioassay. Experiments were carried out between December 1998 and April 1999 in four regions (40 pots of plants per site) selected on the basis of their pollution levels predicted by theoretical modeling of the dispersion of the incinerator's plume. The exposure sites were defined as follows: highest level (incinerator); a high level (museum) located 1.5 km from the emission point; a moderate level (school, at a distance of 3.5 km from the incinerator); and a control (at Jaguariúna countryside). The difference in genotoxicity among the groups was statistically significant (p < 0.001). The frequency of mutations observed in the countryside was significantly lower [2.25 +/- 1.55, mean +/- SD (standard deviation)] than that of the sites close to the incinerator. The frequency of mutations measured at the school (3.70 +/- 1.36) was significantly lower than that measured at both the museum (4.89 +/- 1.12) and the incinerator (5.69 +/- 1.34). In conclusion, we found a positive correlation between the spatial distribution of the emissions of the incinerator located in an urban area and the mutagenic events measured by the Tradescantia stamen-hair assay. The in situ approach employed in this study was simple, efficient, and of low cost. No air or chemical extraction of pollutants was necessary for genotoxicity testing as required by other assays.     

The use of mosses and pine needles to detect persistent organic pollutants at local and regional scales

Polycyclic aromatic hydrocarbons (PAHs) were analysed in mosses (Hypnum cupressiforme) and pine needles (Pinus sylvestris) collected in the Czech Republic between 1988-94 at a regional background site in Kosetice, south Bohemia (1988-94) and two industrial sources. One industrial site (sampled 1989-91) in middle Moravia, was near a factory producing PAHs, carbon black and phthalates, the other (sampled 1991-93) near a coal and gas fuel production plant in western Bohemia. Selected chlorinated pesticides and polychlorinated biphenyl congeners were also analysed in samples at the regional background site. This study clearly shows that vegetation sampling can be used to show spatial differences in the atmospheric burden of a range of persistent organic pollutants with differences in the mixtures of compounds reflecting differences in their regional or local use/atmospheric emission.     

Organochlorine contamination in bird's eggs from the Danube Delta

In this study we report the levels of organochlorine compounds in eggs of aquatic birds from the Danube Delta, a major European wetland. The eggs were collected in 1997 and belonged to the following species: the mallard (Anas platyrhynchos), the greylag goose (Anser anser), the mute swan (Cygnus olor), the coot (Fulica atra), the glossy ibis (Plegadis falcinellus), the spoonbill (Platalea leucorodia), the little egret (Egretta garzetta), the night heron (Nycticorax nycticorax), the grey heron (Ardea cinerea), the great white egret (Egretta alba), the red-necked grebe (Podiceps griseus), the Dalmatian pelican (Pelecanus crispus), the Pygmy cormorant (Phalacrocorax pygmaeus) and the common cormorant (Phalacrocorax carbo). Dichlorodiphenyltrichloroethane (DDT) levels were higher in eggs of the little egret, the great white egret, the cormorant and the Pygmy cormorant with respect to the other species (48,399, 13,613, 12,400 and 10,417 ng/g dry wt., respectively). Hexachlorobenzene (HCB) levels were lower than 1393 ng/g dry wt. in all species while polychlorinated biphenyl (PCB) concentrations in the Pygmy cormorant (2565 ng/g dry wt.) were higher than in the other species. The toxicity evaluation was based on 2,3,7,8-TCDD toxic equivalent factors (TEF) and non-ortho PCB congeners contributed much more than mono-ortho PCBs in most of species. A further aim of this study was to evaluate the possible differences of organochlorine levels in bird eggs collected in the same area in 1982 and in 1997; generally speaking the levels detected in the latter period were lower than those detected in the earlier one.     

Acute and chronic impacts caused by aromatic hydrocarbons on bacterial communities at Boa Viagem and Forte do Rio Branco Beaches, Guanabara Bay, Brazil

The bacterial community presented significantly different hydrocarbonoclastic activity under acute and chronic impacts. Benzoic acid, toluene, benzene and xylene were used in final concentrations of 5, 10 and 15 mM and bacterial biomass was quantified through protein dosage. Under acute impact, the highest biomass percentages occurred between the 11th and 14th days; under chronic impact, between the 20th and 29th days. Under acute and chronic impacts, the bacterial biomass presented higher nutritional specialization at Boa Viagem Beach, using the aromatic hydrocarbons up to a concentration of 15 mM. Under acute impact, the concentration of the hydrocarbons constituted a critical factor for the bacterial flora from Forte do Rio Beach, because biomass increases only occurred in concentrations of 5 mM; under chronic impact, the aromatic hydrocarbons induced the specialization and increased bacterial biomass for 15 mM toluene. Benzoic acid (15 mM) was used by the bacteria from Boa Viagem and Forte do Rio Branco Beaches.     

Seedling insensitivity to ozone for three conifer species native to Great Smoky Mountains National Park

Field symptoms typical of ozone injury have been observed on several conifer species in Great Smoky Mountains National Park, and tropospheric ozone levels in the Park can be high, suggesting that ozone may be causing growth impairment of these plants. The objective of this research was to test the ozone sensitivity of selected conifer species under controlled exposure conditions. Seedlings of three species of conifers, Table Mountain pine (Pinus pungens), Virginia pine (Pinus virginiana), and eastern hemlock (Tsuga canadensis), were exposed to various levels of ozone in open-top chambers for one to three seasons in Great Smoky Mountains National Park in Tennessee, USA. A combination of episodic profiles (1988) and modified ambient exposure regimes (1989-92) were used. Episodic profiles simulated an average 7-day period from a monitoring station in the Park. Treatments used in 1988 were: charcoal-filtered (CF), 1.0x ambient, 2.0x ambient, and ambient air-no chamber (AA). In 1989 a 1.5x ambient treatment was added, and in 1990, additional chambers were made available, allowing a 0.5x ambient treatment to be added. Height, diameter, and foliar injury were measured most years. Exposures were 3 years for Table Mountain pine (1988-90), 3 years for hemlock (1989-91), and 1 and 2 years for three different sets of Virginia pine (1990, 1990-91, and 1992). There were no significant (p<0.05) effects of ozone on any biomass fraction for any of the species, except for older needles in Table Mountain and Virginia pine, which decreased with ozone exposure. There were also no changes in biomass allocation patterns among species due to ozone exposure, except for Virginia pine in 1990, which showed an increase in the root:shoot ratio. There was foliar injury (chlorotic mottling) in the higher two treatments (1.0x and 2.0x for Table Mountain and 2.0x for Virginia pine), but high plant-to-plant variability obscured formal statistical significance in many cases. We conclude, at least for growth in the short-term, that seedlings of these three conifer species are insensitive to ambient and elevated levels of ozone, and that current levels of ozone in the Park are probably having minimal impacts on these particular species.     

Interactive effects of elevated ozone and carbon dioxide on growth and yield of leaf rust-infected versus non-infected wheat

Spring wheat (Triticum aestivum L. cv. Turbo) was grown from seedling emergence to maturity (129 days) in chambers simulating the physical climate and ozone pollution of a field site in Northern Germany from 1 April to 31 July with a mean 1-h daily maximum of 61.5-62.4 nl l(-1) ozone compared to a constant low level of 21.5-22.8 nl l(-1) ozone. The two ozone levels were combined with either a current (374.1-380.2 microl l(-1)) or enriched (610.6-615.0 microl l(-1)) CO(2) atmosphere. Additionally, a leaf rust epidemic (Puccinia recondita f. sp. tritici) was induced at tillering stage by repeated re-inoculations with the inoculum formed on the plants. Leaf rust disease was strongly inhibited by ozone, but largely unaffected by elevated CO(2). Ozone damage on leaves was strongly affected by CO(2) and infection. On infected plants, ozone lesions appeared 2-4 weeks earlier and were up to fourfold more severe compared to non-infected plants. Elevated CO(2) did not delay the onset of ozone lesions but it significantly reduced the severity of leaf damage. It also enhanced the photosynthetic rate of flag leaves and increased the water use efficiency, biomass formation and grain yield. The relative increases in growth and yield induced by CO(2) were much larger on ozone-stressed than on non-stressed plants. Both ozone and fungal infection reduced biomass formation, number of grains per plant, thousand grain weight and grain yield; however, adverse effects of leaf rust infection were more severe. Elevated CO(2) largely equalized the negative effects of ozone on the photosynthetic rate, growth and yield parameters, but was not capable of compensating for the detrimental effects of fungal infection. The data imply that the impact of ozone in the field cannot be estimated without considering the predisposing effects deriving from fungal infections and the compensating effects deriving from elevated CO(2).     

Surface water acidification in the South Pennines II. Temporal trends

Data for eight reservoirs in the South Pennines covering the period 1980-98, and for 1988-98 at the River Etherow Acid Waters Monitoring Network site, have been analysed for temporal trends using the Seasonal Kendall test. Rising trends in pH were identified at seven of the eight reservoirs, generally accompanied by declining aluminium levels. Nitrate concentrations have, however, increased sharply at the two reservoirs for which adequate data were available. Data for a wider range of determinands at the Etherow suggest that pH increases in the region can be attributed to declining sulphate concentrations, as a result of reductions in sulphur deposition. Nitrate concentrations have again increased at this site. Results are significant in a national context in that pH recovery, although widely believed to have taken place in the UK since the 1970s, has rarely been shown to have occurred. For the South Pennine region, which has been severely acidified by historically high acid deposition levels, there have clearly been improvements over the last 18 years, although many surface waters remain acidic. Observed trends for nitrate suggest that some of the pH recovery resulting from reduced sulphur deposition may have been offset by nitrogen saturation in the region, due in part to continued high levels of nitrogen deposition.     

Suitability of process-based tree growth models for addressing tree response to climate change

Empirical models of tree growth have been used for many years to predict timber yields and other properties of trees. However, such models rely on measured relationships between tree growth and historic environmental conditions. As anthropogenic actions alter the environment, especially atmospheric composition, empirical models become less reliable and process-based models become more useful. Process-based models are challenged to simulate growth of structurally and physiologically complex organisms using explicit mathematical expressions to capture growth response to environmental conditions. In this review we summarize the physiological requirements of process-based models and examine the capabilities of six published models (CARBON, ECOPHYS, PGSM, TREE-BGC, TREGRO, W91) for simulating tree response to changes in environmental conditions (elevated temperature, increased CO(2) concentration, and enhanced concentrations of tropospheric ozone). These analyses indicate that current models are reliable integrators of environmental effects on individual processes (e.g. photosynthesis), but may be less reliable where physiological acclimation occurs or when extrapolated to growth of specific tree compartments.     

Mercury levels in muscle of two fish species and sediments from the Cartagena Bay and the Ciénaga Grande de Santa Marta, Colombia

Mercury (Hg) content in sediments and muscle from two fish species were determined in Cartagena Bay and Ciénaga Grande de Santa Marta, an industrialized bay and an unpolluted estuary in the Caribbean coast of Colombia. Sampling was conducted four times during March-November 1996, including both the dry and rainy seasons. Significant differences in Hg concentration were detected both for fish and sediments between the two waterbodies. Hg values ranged from 94 to 10,293 microg/kg dry weight (dw) in sediments from Cartagena Bay and between 20 and 109 microg/kg dw in Ciénaga Grande de Santa Marta. Highest Hg concentrations were observed for the omnivorous species Eugerres plumieri, and lowest concentrations were found in the detritivorous Mugil incilis. High Hg concentrations in sediments of Cartagena Bay were detected in front of the sewage discharge of an extinct chlor-alkali plant, with decreasing concentrations in stations far from the source. Our results suggest that Hg can be persistent in the sediments of previously exposed ecosystems and that the use of their biological resources should be avoided until decontamination programs guarantee safe levels of the metal in the environment.     

In situ sequential treatment of a mixed contaminant plume

Groundwater plumes often contain a mixture of contaminants that cannot easily be remediated in situ using a single technology. The purpose of this research was to evaluate an in situ treatment sequence for the control of a mixed organic plume (chlorinated ethenes and petroleum hydrocarbons) within a Funnel-and-Gate. A shallow plume located in the unconfined aquifer at Alameda Point, CA, was found to contain up to 218,000 μg/l of cis-1,2 dichloroethene (cDCE), 16,000 μg/l of vinyl chloride (VC) and <1000 μg/l of 1,1 dichloroethene (1,1 DCE), trans-1,2 dichloroethene (trans-1,2 DCE) and trichloroethene (TCE). Total benzene, toluene, ethylbenzene and xylenes (BTEX) concentrations were <10,000 μg/l. Contaminated groundwater was funneled into a gate, 3.0 m wide, 4.5 m long and 6.0 m deep (keyed into the underlying aquitard) where treatment occurred. The initial gate segment consisted of granular iron, for the reductive dechlorination of the higher chlorinated ethenes. The second segment, the biosparge zone, promoted aerobic biodegradation of petroleum hydrocarbons and any remaining lesser-chlorinated compounds, stimulated by dissolved oxygen (DO) and carbon dioxide (CO₂) additions via an in situ sparge system (CO₂ was used to neutralize the high pH produced from reactions in the iron wall). Groundwater was drawn through the gate by pumping two wells located at the sealed, downgradient, end. Over a 4-month period an estimated 1350 g of cDCE flowed into the treatment gate and the iron wall removed 1230 g, or 91% of the mass. The influent mass of VC was 572 g and the iron wall removed 535 g, corresponding to 94% mass removal. The other chlorinated ethenes had significantly lower influent masses (3 to 108 g) and the iron wall removed the majority of the mass resulting in >96% mass removal for any of the compounds. In spite of these high removal percentages, laboratory column tests indicated that at these levels of chlorinated contaminants, surface saturation of the iron grains likely contributed to lower than expected reaction rates. In the biosparge zone, mass removal of cDCE appeared to occur predominantly by biodegradation (65%) with volatilization (35%) being an important secondary process. The dominant removal process for VC was volatilization (70%) although significant biodegradation was also indicated (30%). Laboratory microcosm results confirmed the potential for aerobic biodegradation of cDCE and VC. When average influent field concentrations for cDCE and VC were 220,000 and 46,000 μg/l, respectively, the sequential treatment unit removed 99.6% of the total mass and when the influent concentrations decreased to 26,000 and 19,000 μg/l for cDCE and VC, respectively, >99.9% removal within the treatment gate was attained. BTEX compounds were found to be significantly retarded in the iron treatment zone. Although they did eventually break through the granular iron, and into the gravel transition zone, none of these compounds was detected in the biosparge zone. No noticeable interferences between the anaerobic (reductive) and aerobic parts of the system occurred during testing. The results of this experiment show that in situ treatment sequences are viable, although further work is needed to optimize performance.