Environmental Pollution Series B, Chemical and Physical最新文献

High winter and low summer levels in grass fluoride concentrations have been commonly attributed to growth dilution. A large number of grass fluoride records obtained from routine monitoring around two different major sources of industrial airborne fluoride pollution were considered and there were no real indications of seasonality. Further investigations carried out on grass fluoride, airborne fluorides and meteorological data indicated that grass fluoride levels were positively related to the previous seven days' ambient airborne fluorides levels. It was concluded that meteorological, microclimatic and biological factors were directly or indirectly influencing grass fluoride levels.

The toxicity of trace metals, as free species or in complexed form with humic acids, has been studied by means of a medium-term daphnia test. Four parameters relative to sublethal effects and two lethal criteria were determined over a 30-day period. The toxicity due to metal concentrations—cadmium, 5 μg litre⁻¹; copper, 15 μg litre⁻¹ and zinc, 50 μg litre⁻¹—was significantly established.

Free metal concentrations were determined by differential pulse anodic stripping voltammetry and correlated with toxic effects. Comparison of the equations of the regression lines revealed that the effect of humic acids is not restricted to a pure detoxication by complexation. Their presence modifies the toxic behaviour of free metals, as confirmed by the evaluation of the 30-day LC₅₀.

Ra-226 concentrations were measured in blueberries (Vaccinium angustifolium Ait., late low blueberry) growing around the Stanrock uranium tailings area near Elliot Lake, Ontario, Canada. Elevated levels of total Ra-226 ranging between 20–290 mBq g⁻¹ (dry weight) were observed in samples collected within 500 m from the tailings. Highest levels, ∼285 mBq g⁻¹, were observed in a sample collected on a tailings spill. For sites located more than 500 m away in the upwind direction, and those situated at distances greater than 1 km downwind from the waste pile, the total Ra-226 concentrations approached background levels which were measured as 2–6 mBq g⁻¹. Approximately 17% of the total Ra-226 measured was removable by washing the samples with distilled water. Wind dispersal of the tailings material and its deposition in the form of dust on blueberries was believed to be responsible for the external contamination. Based on the ICRP recommended dose limits for oral intake of Ra-226, it was calculated that approximately 160 kg a⁻¹, 3350 kg a⁻¹ and 47 kg a⁻¹ of washed blueberries (wet weight) from inside (less than 500 m) and outside (greater than 1 km downwind) the influenced zone, and from the tailings spill site (where the highest Ra-226 levels in blueberries were measured), respectively, would need to be consumed before the individual annual limit for the general public was exceeded.

PCBs (Clophen A 50) were added to the sediment of laboratory model systems composed of sediment, water, benthic macroinvertebrates and fish. Part of the PCBs left the sediment and a concentration of 0·2–0·7 μg litre⁻¹ was obtained in the water.

The transport of PCBs from water to air includes at least two processes: volatilization and jet drop transport. Volatilization (as indicated by PCBs trapped on polyurethane foam filters) resulted in a transport of 0·2–1·0 μg PCBs a week to air. Less chlorinated PCBs, i.e. tetrachlorobiphenyls, were transported to the air to a greater extent than more chlorine-substituted PCBs.

Transport of PCBs by jet drops from bursting bubbles (as indicated by the amount of PCBs found on jet drop impactors) was of the same magnitude as volatilization, but the proportion of PCB compounds trapped by the impactor plates was identical with that of sediment and water. The process seems mainly to transfer PCBs containing bulk water and particles to the air.

The results suggest that the contaminated sediment of lakes and watercourses may act as a source of PCBs to the atmosphere.

The CRES model developed by Simpson et al. (1983) is used to estimate worst case scenarios for acid gas and suspended particulate levels in Newcastle, New South Wales, Australia. It is shown that the CRES model allows for the effects of both long-term meteorological fluctuations and changes in emissions. The model is used to identify the extreme meteorological years in an extensive wind speed data set for the period 1951–1981. It is applied to estimate the allowable range of increases in emissions consistent with ambient air quality management policy, demonstrated here as the maintenance of WHO standards. The risk of using restricted data sets is shown by comparing the results for extreme meteorological years. The techniques used here provide a fundamental basis for investigating the effects of control policy and air quality management options in an urban area where the assumptions of the CRES model are applicable.

The environmental consequences of the use of MMT (methylcyclopentadienyl manganese tricarbonyl) on the different components of an experimental freshwater ecosystem have been studied by following the evolution of their manganese concentrations. The results have been compared with those obtained with inorganic manganese in the same experimental conditions.

In the sediments, the quantities of MMT and Mn(i) are accumulated in the same proportion but the accumulation of MMT is located only at the surface. On the other hand, in living organisms (plant, fishes), the accumulation of MMT is, compared with that of Mn(i), nearly ten times higher.

The accumulation of MMT, as well as that of Mn(i), seems to be strongly dependent on whether the medium is stirred or not.

Some results of air quality measurements in enclosed car parks are used to illustrate certain undesirable design or operational features which can allow air quality to deteriorate to unacceptable levels. Data for carbon monoxide in several situations and gathered over several years are given, together with the results of some measurements of other pollutants. The data are compared with ambient concentrations.

Batch studies were carried out to investigate the removal of organic acids by adsorption on fly ash impregnated with hydroxides of Al, Cd, Cu, Fe and Ni. The percentage removals of cinnamic acid, indole-3-acetic acid, β-napthaleneacetic acid, β-naphthoxyacetic acid, oxalic acid and trichloroacetic acid from water were 75%, 63·63%, 100%, 95·25%, 85·71% and 78·26%, respectively. The adsorption data recorded follow the Freundlich adsorption isotherm.