Chemical response of the lichen Punctelia subrudecta (Nyl.) Krog transplanted close to a power station in an urban-industrial environment

The lichen Punctelia subrudecta (Nyl.) Krog was transplanted to 22 biomonitoring sites in a northwestern area of Córdoba city, Argentina and tested for chlorophyll a, chlorophyll b, phaeophytin a, soluble protein, hydroperoxy conjugated dienes (HPCD), malondialdehyde (MDA) concentration and sulphur accumulation. A pollution index (PI) was calculated for each biomonitoring site. The biomonitoring sites were set according to (1) traffic levels, (2) industrial density and (3) distance of the power station close to each site. The biomonitor's chemical response was associated with industries as well as power stations. Significant differences were observed in sulphur content, MDA concentration and PI values in lichen material transplanted to sites with different industrial densities. The higher values for these parameters were found at sites with high industrial levels. At the same time, significant differences were detected for sulphur content in samples at different distances from the power station, with higher accumulation in samples located far from the power plant. For MDA concentration, effect of different levels of industrial density was observed only at points close to the power station, probably because of higher levels of humidity near the power plant. For PI significantly higher values were observed in samples at points far from the power station and with high industrial density. This shows the additive effect of the principal emission sources that act on the response of P. subrudecta to air pollutants.     

U- and Th-series radionuclides in snowshoe hare (Lepus americanus) taken near U mill tailings close to Elliot Lake, Ontario, Canada

Snowshoe hare (Lepus americanus) trapped near U tailings had higher concentrations of (226)Ra in their bones (250 +/- 94 mBq g(-1) dry wt) than those from local control sites 3-15 km from the tailings (20-30 mBq g(-1) dry wt) and those from a distant control site 880 km away from the U mining area, which were below the detection limit (DL) (3.7 mBq g(-1) dry wt). Most chyme (stomach content) samples contained 226Ra below DL. Concentration ratios of 226Ra from tissues of local plants, considered important in the hare's diet, to bone ranged from 0.22 to 8.60. Concentrations of 210Pb and 210Po (95-245 mBq g(-1) dry wt) were not significantly different among tailings and control site populations. Disequilibrium between these isotopes and their precursors was noted. No significant accumulation of U and Th was noted at any site. Higher concentrations of 228Th compared to 232Th are attributed to accumulation of 228Ra in a manner similar to that of 226Ra. Based on bone 226Ra and 210Po contents, the maximum internal dose rates to the skeleton and the maximum life-time dose of hare living near tailings were 3.9 x 10(-5) Gy d(-1) and 4.2 x 10(-2) Gy, respectively. These rates were below the threshold required to produce osteosarcoma in other mammals and were considered unlikely to adversely affect hare during their lifetime. Radionuclide uptake by the animals was concluded to have no environmental significance in the transport of radionuclides from tailings to other locations.     

Surfactant solubilization of hydrophobic compounds in soil and water

The soil/water partition coefficient (K_d) of hexachlorobenzene (HCB) ranged from 220 1/kg to 1800 1/kg for eight soils having a wide range of physico-chemical properties. K_d normalised to soil organic carbon (K_oc) was found to be 28000 ± 4800 1/kg. Anionic surfactant dodecylsulphate (DS) present at concentrations above the critical micellar concentration (CMC) caused reductions in the apparent soil/water partition coefficient (K_d ^*) in the range of 3–26 times for most soils and up to 36–91 times for sandy soils. Below CMC, at environmentally relevant surfactant concentrations, K_d ^* was reduced by a factor of 1–13. For clay and calcareous soils significant adsorption/complexation/precipitation of DS occurred. At the lowest DS concentration this produced a two-fold increase in K_d ^*. At increasing DS concentrations this effect was shielded by the solubihzing effect from DS. Monomer (K_mn) and micellar (K_mc) surfactant/water partition coefficients for HCB were determined to be, 980 ± 190 1/kg and 21000 ± 1600 1/kg, respectively.     

Lead levels of feral pigeons (Columba livia) from Madrid (Spain)

Tissue lead data are presented for populations of feral pigeons (Columba livia) from three locations in Madrid (Spain). The lead present in the lungs and digestive tract of pigeons increased progressively with traffic density and in parallel with atmospheric and ground lead values. The contribution of the respiratory route of Pb intake to the pigeons was about three times greater than the digestive route. The highest Pb values were found in bones. It is suggested that the pigeons gave a greatly magnified picture of lead pollution in cities than indicated by atmospheric lead concentrations.     

Long-term trends and spatial variability in nitrate leaching from alpine catchment-lake ecosystems in the Tatra Mountains (Slovakia-Poland)

Relationships between catchment characteristics of 31 alpine lakes and observed trends in lake water concentrations of nitrate were evaluated in the Tatra Mountains. Nitrate concentrations increased from background levels <4 microeql(-1) in the 1930s to maxima (up to 55 microeql(-1)) in the 1980s, after which they declined to 4-44 microeql(-1) by the late 1990s. In-lake nitrate concentrations correlated negatively with parameters characterising catchment-weighted mean pools (CWM; kgm(-2)) of soil, i.e. with percent land cover with meadow and soil depth, and positively with grade of terrain, annual precipitation, and the highest elevation in the catchment. The CWM pool of soil and annual precipitation explained together 65% of the current spatial variability in nitrate concentrations. Denitrification and direct N deposition on surface area explained 14% of the variability. Increased atmospheric N deposition and declining net N retention in soils were responsible for long-term changes in nitrate concentrations. Long-term decline in %N retention in soils decreased along with the estimated decline in C:N ratios (from 21 to 18 on average during the last 70 years). An empirical model linking nitrate concentrations in different types of alpine Tatra Mountain lakes to four independent variables (CWM soil pool, annual precipitation, increased N deposition, and average trend in soil C:N ratios) explained 80% of the observed spatial and temporal nitrate variability over the period 1937-2000.     

Kinetics of mass and DNA decomposition in tomato leaves

This laboratory study investigated the kinetics of leaf and DNA content decomposition in two varieties of tomato (Palmiro and Admiro) after incubation in soil for 35 days. Results revealed that the decrease of dry matter in leaves in both varieties did not follow a single exponential function and was better described by a double exponential model. Composite half-decrease times were 3.4 and 2.4 days for Palmiro and Admiro respectively. The same pattern was observed for DNA mass loss, although this was closer to a single exponential model with composite half-decrease times of 1.5 and 1.4 days. Genomic analysis showed that DNA in dried leaves at room temperature (not inoculated in the soil), remains intact or presents a weak degradation, and DNA extracted from leaves inoculated in non-sterile soil showed degradation after two days. These results indicate that before release an important quantity of DNA may be degraded inside plant tissues during decomposition in soil.     

Selection of an electrolyte to enhance the electrochemical decolourisation of indigo. Optimisation and scale-up

The investigation presented here focussed on the electrochemical decolourisation of a commercial, textile indigo dye, in an undivided electrochemical cell using graphite electrodes. The decolourisation values obtained employing halide salts--sodium chloride, potassium bromide and potassium iodide--and a reductive agent--sodium meta-bisulphite--as electrolytes are higher than those attained when no electrolyte was used. The highest decolourisation value at a low level of electric power consumption was obtained with sodium chloride. Besides, this electrolyte is usually found in the coloured wastewaters of textile industry. Thus, a detailed study was carried out to determine the influence of electrolyte--sodium chloride--and dye concentration on the efficiency of the process expressed in terms of energy consumption and extension of the decolourisation reaction. The scale-up of the treatment with sodium chloride was satisfactorily tested in a 20 l cell.     

Influence of air pollution on the incidence of respiratory tract neoplasm

To evaluate the possible influence of air pollutants on the incidence of respiratory tract neoplasm we studied 12 S?o Paulo City districts where air pollution is observed. We collected data on pollutants from 1981-1990 and correlated it with the incidence of larynx and lung neoplasms in 1997. Ozone was the pollutant that best correlated with the incidence of neoplasm. The correlation coefficients were 0.7234 (p=0.277) and 0.9929 (p=0.007) for lung and larynx cancer, respectively. There may be a relationship between air pollution and the incidence of respiratory tract neoplasm. This study, however, does not allow us to conclude that there is a causal relationship.     

Content of aliphatic hydrocarbons in limpets as a new way for classification of species using artificial neural networks

It is demonstrated that biological species like limpets can be classified according to their level of n-alkanes when artificial neural networks are applied. Marine intertidal and subtidal limpets of the Canary Islands (Spain), Patella piperata, Patella candei crenata and Patella ulyssiponensis aspera were selected as bioindicator organisms. Samples were collected at four stations on the coasts of Fuerteventura. Concentration of n-alkanes in the soft tissues of the limpets has been determined by gas chromatography. Data were treated with artificial neural networks (ANNs) and it was found that using suitable architecture of a supervised artificial neural network, the limpets can be successfully distinguished (classified) up to 98%.     

Electrochemical decolourisation of structurally different dyes

The electrochemical decolourisation of structurally different dyes (bromophenol blue, indigo, poly R-478, phenol red, methyl orange, fuchsin, methyl green and crystal violet) by means of the application of DC electric current was assessed. It was found that the electrochemical process allowed a colour removal of all dyes studied, although the decolourisation rate largely depended on the chemical structure of the different dyes. Nearly complete decolourisation was achieved for bromophenol blue followed by methyl orange and methyl green, whereas phenol red was hardly decolourised (30% in 60 min). In mixtures of two dyes, the decolourisation rate became similar for both dyes. However, the addition of a redox mediator, (Co(2+/3+)) clearly enhanced the degradation rate of all tested dyes, but the simplest dye molecules were attacked firstly, followed by dyes with more complex chemical structures. The results revealed the suitability of the process to effectively decolourise wastewaters from dyeing process.