Water, Air and Soil Pollution: Focus

Urban concentration fields are extremely inhomogeneous andtheir gradients are very high. It results in specificproblems when modelling air pollution at the urban scalethat are analysed in this paper. Some examples ofmisrepresentation of the urban concentration field,computed with the use of the source-receptor type models,are given here. They can help in understanding the natureof the problems we face and reveal deficiencies of thecomputational technologies in use. Filtering of thecomputed fields is suggested as an instrument for improvingtheir quality. Its efficiency is proved on the test runs.An algorithm for refinement of the filtered fields isintroduced in this paper.

Since October 1998 two DOAS instruments were installed at the level of the first floor and at the top of a building located in St. Petersburg at Pestelya Street. The collected datacovers the time period of December 1998–March 2001, and include concentrations of benzene, toluene, NO and NO2, ozone and SO2. There is also an additional information about the traffic intensity and meteorological conditions. The results of the analysis of this data set, using the OSPM model, are presented here with the goal to understand the features of the air pollution dispersion in this street canyon and to analyse the information about the emission factors of the vehicles. In particular, the model results are used for the solution of the inverse problem of reconstructing the emission factors from measured concentrations. The results obtained indicate that most of the concentrations are well inside the Russian standards with the only exception of NO2 (mean and 98-th percentile are equal to 57.8 and 119.2 μg m-3 for the street level). The same values for benzene are 18.5 and 62.6, respectively. Emission estimates show that there is a possibility that the NOx and benzene basic emission factors recommended by the Russian national guidelines could result in overestimating the traffic emissions. These considerations are supplemented with the model sensitivity tests carried out in connection with the problem of predictability of NO2 concentrations in the street canyon. Tests indicate that NO2 concentrations are not very sensitive to NOx emissions because of the usually low urban background ozone levels.

Concentrations and isotopic compositions of NO3 - from the Oldman River (OMR) and some of its tributaries (Alberta, Canada) have been determined on a monthly basis since December 2000 to assess temporal and spatial variations of riverine NO3 - sources within the OMR basin. For the OMR sites, NO3 --N concentrations reached up to 0.34 mg L-1, δ15N-NO3 - values varied between –0.3 and +13.8‰, and δ18O-NO3 - values ranged from –10.0 to +5.7‰. For the tributary sites, NO3 --N concentrations were as high as 8.81 mg L-1, δ15N-NO3 - values varied between –2.5 and +23.4‰, and δ18O-NO3 - values ranged from –15.2 to +3.4‰. Tributaries in the western, relatively pristine forested part of the watershed add predominantlyNO3 - to the OMR with δ15N-NO3 - values near +2‰ indicative of soil nitrification. In contrast, tributariesin the eastern agriculturally-urban-industrially-used part of the basin contribute NO3 - with δ15N-NO3 - valuesof about +16‰ indicative of manure and/or sewage derived NO3 -. This difference in δ15N-NO3 - values of tributaries was found to be independent of the season, but rather indicates a spatial change in the NO3 - source, which correlates with land use changes within the OMR basin. As a consequence of tributary influx, δ15N-NO3 - values in the Oldman River increased from <+3‰ to >+6‰ in the downstream direction (W to E), although [NO3 --N] increased only moderately (generally <0.5 mg L-1). This study demonstrates the usefulness of δ15N-NO3 - and δ18O-NO3 - values in identifying the addition of anthropogenic NO3 - to riverine systems.

Field experiments were carried out in the vicinity of anisolated building using open-path and point monitoring airpollution detectors to measure concentrations of a tracer gasreleased from a source located either on the building or at thedownwind face of the building. Experiments were conducted underneutral or slightly unstable weather conditions. Either threeor five fast-response point monitors were located along thebeam path of an open-path instrument, in the wake of thebuilding. Experiments were performed with different sourcelocations, detector locations and building orientations to thewind. Visual comparison of data time series showed that datafrom the two types of instruments followed similar trends. Thebest degree of correlation occurred for an averaging timesimilar to the response time of the open-path monitor. Meanconcentrations detected by the open-path instrument weregenerally in very good agreement with the path averaged meanconcentrations from the point monitors. The point monitors werealso capable of providing time-resolved data needed to describedetailed concentration fluctuation statistics.

The concentration of water-soluble organic nitrogen (WSON) in precipitation has been measured at seven sites across the United Kingdom, over a period of 1–2 years, using protocols developed in a pilot study. Samples were collected over 1–2 weeks in continuously open funnels made of stainless steel, draining to a glass bottle, and were preserved during and after collection by the addition of thymol. After chemical analysis, samples were excluded from the long-term average if they showed signs of contamination (significant concentrations of K+ or PO43−). Two methods of measuring total dissolved N were used, persulphate oxidation and high-temperature chemiluminescence. The latter generally gave the larger values, and has been used to asses the organic component of dissolved N. The long-term data set confirms the original results from the pilot study—organic N contributes between 24 and 40% to the total annual wet deposition of dissolved N across the United Kingdom. The fraction of WSON was greatest at western sites, and was strongly correlated with ammonium concentrations. However, the seasonal pattern across all sites showed a late spring maximum for ammonium and nitrate, but a late summer maximum for WSON. The magnitude of the contribution of WSON to wet-deposited N has implications for the setting and assessment of critical loads for N deposition.

The focus of this study was to compare the behavior of different consortiums of aerobic propane-utilizing microorganisms, with respect to both the lag time for growth after exposure to propane, and their ability to transform three chlorinated aliphatic hydrocarbons (CAHs): chloroform (CF), cis-dichloroethylene (c-DCE) and trichloroethylene (TCE). Thirty-three slurry microcosms, representing seven combinations of aquifer solids and groundwater were constructed for this study. The lag time required for establishing propane-utilizing consortiums ranged between 24 and 29 days in 6 of the 7 combinations. Kinetic tests were performed with respect to propane utilization and CAH transformation. After CAH exposure, the ability of the microorganisms to metabolize propane was significantly reduced. CF and TCE were transformed more slowly than c-DCE, the average values of the initial transformation rates being equal to 0.10 ± 0.04, 0.09 ± 0.05 and 0.98 ± 0.18 μmol/(L h),respectively. CF caused the greatest reduction in propane uptake rates, whereas c-DCE exhibited an apparently reversible negative effect on propane uptake rates. The estimates of the Monod half-saturation constants relative to CF, TCE and c-DCE resulted in the 2–3 μmol/L range, but were characterized by a high degree of uncertainty.

Measurements of dry deposition ofparticles 0.1 to 1.0 μm diameter to forest bythroughfall and eddy correlation methods giveresults of 1.0 cm s-1 or more, whilemechanistic models do not explain values greaterthan about 1 mm s-1. Results of othermethods involving radioactive tracers arerecalled. These data indicate values of about 5 mm s-1. The possibility of additionalmechanisms, omitted from the models, is difficultto exclude, but much of the remaining discrepancymay be due to the wide size distribution of theadventitious radioactive tracers in the atmosphere.

A moorland soil site polluted with PCB showed a high diversity ofmetabolically active bacteria. Beside frequent types of 16S rRNAsequences similar to those of the species ofSphingomonasand the Acidobacterium phylum an unusual high number ofsequences from the genus Burkholderia were found. Burkholderia was also the main genus in isolates enriched onbiphenyl or various chlorobenzoates. In microcosm experimentssterilized surfaces exposed to PCB polluted soil always showed thepresence of clay aggregates formed by bacteria attached to thesubstratum. The bacteria use the PCB loaded clay colloids astransport medium for the water insoluble substrate to get accessto the carbon source. This is a novel mechanism of how bacteria dealwith hydrophobic substrates.

Municipal solid waste incineration (MSWI) bottom ash contains economically significant levels of silver and gold. Bottom ashes from incinerators at Amsterdam and Ludwigshafen were sampled, processed, and analyzed to determine the composition, size, and mass distribution of the precious metals. In order to establish accurate statistics of the gold particles, a sample of heavy non-ferrous metals produced from 15 tons of wet processed Amsterdam ash was analyzed by a new technology called magnetic density separation (MDS). Amsterdam’s bottom ash contains approximately 10 ppm of silver and 0.4 ppm of gold, which was found in particulate form in all size fractions below 20 mm. The sample from Ludwigshafen was too small to give accurate values on the gold content, but the silver content was found to be identical to the value measured for the Amsterdam ash. Precious metal value in particles smaller than 2 mm seems to derive mainly from waste of electrical and electronic equipment (WEEE), whereas larger precious metal particles are from jewelry and constitute the major part of the economic value. Economical analysis shows that separation of precious metals from the ash may be viable with the presently high prices of non-ferrous metals. In order to recover the precious metals, bottom ash must first be classified into different size fractions. Then, the heavy non-ferrous (HNF) metals should be concentrated by physical separation (eddy current separation, density separation, etc.). Finally, MDS can separate gold from the other HNF metals (copper, zinc). Gold-enriched concentrates can be sold to the precious metal smelter and the copper-zinc fraction to a brass or copper smelter.

Cameron Highlands has a long history of intensive horticulture especially vegetable and flower cultivation. This industry uses large amounts of nutrients and pesticides. Several simulation models were used to assess the movement of pesticides and nutrients in relation to agronomic practices in farm plots cultivated with cabbage and chrysanthemum. It was shown that most of the pesticides are absorbed by the topsoils which are enriched by organic fertiliser, and are not leached beyond the top 10 cm layer. Methamidophos, dazomet, cyromazine, triforine and NO3N were predicted to cause soil contamination. The application of high amounts of fertilisers can cause nitrate contamination to the groundwater in Cameron Highlands.