Environmental Pollution Series B, Chemical and Physical最新文献

Pentachlorophenol (PCP) and tetrachlorophenol (TCP) concentrations in anaerobic Wadden sediments and clams of the Jadebusen were determined two years after the end of a long-lasting discharge of PCP into the region. Concentrations of PCP were of the same order of magnitude as those determined in sediments and organisms of the Weser estuary; concentrations after acid hydrolysis were 2–5 times higher than those of free PCP. 2,3,4,5-TCP contents exceeded those of PCP eight times in sediments and fifteen times in clams. PCP and 2,3,4,5-TCP were accumulated in clams 100- to 1000-fold compared with sediments. It is assumed that, under anaerobic conditions, a reductive dechlorination of PCP occurs, resulting in 2,3,4,5-TCP, which is more persistent than PCP in the environment under study.

The uptake of zinc, copper and nickel by an uncontaminated sewage sludge was studied as a function of added metal concentration and of pH. The quantity of metal taken up at constant pH increased with added metal concentration up to an apparent saturation value in some cases, but the data did not fit Langmuir or Freundlich adsorption isotherms closely.

The proportion of total metal in the solution phase at a given pH in these uptake experiments was generally larger than that in the solution phase in comparable experiments involving the release of the metals into solution from metal-contaminated sludges, to which the metals had been added during sewage treatment.

Differences between the cation exchange capacity of uncontaminated and of metal-loaded sludges were used to calculate the amount of metal held on cation exchange sites by complexation in the metal-loaded sludges. The amount of exchangeable metal was determined by displacement with barium. The proportion of total metal held on the sites in exchangeable and complexed forms in metal-loaded sludges is 52% of zinc, 71% of copper and 92% of nickel.

The distribution of DDT insecticide residues in the environment of western Zimbabwe was surveyed in order to identify the major source(s) of DDT pollution and assess whether residue accumulation in wildlife is sufficient to cause deleterious biological effects. The most important source of DDT contamination in 1982/83 was the tsetse fly control programme, with relatively minor contributions made by mosquito control, commercial agriculture and traditional farming. Although it was shown that DDT residues do not persist in the non-living environment (tree bark, soil, riverine silt), they readily accumulate in insectivorous birds and bats (respective maxima: 32 and 20 μg g⁻¹ wet weight total DDT in viscera) and, to a lesser extent, in detritivorous mussels and piscivorous fish (maxima: 1·0 and 2·2 μg g⁻¹ in whole body and ovary, respectively). These residues are sufficient to cause eggshell thinning in certain avian predators.

The mobility of sediment antimony (Sb) during sediment-water interactions was studied. Emphasis was placed on the fixation of native and added Sb by sediment, long-term (6 months) releases of Sb and sediment properties that affect the mobilization of Sb.

Sequential selective extraction procedures revealed that most native and added sediment Sb was associated with relatively immobile iron (Fe) and aluminum (Al) compounds. In sediments amended with Sb, concentrations of interstitial water and exchangeable phase Sb were also high. Initial and long-term releases of Sb were much higher from Sb-amended sediments than from sediments containing no added Sb, apparently a result of Sb concentrations in more mobile sediment phases. In most sediments, the largest amount of Sb release occurred early in the leaching experiment. These results suggest that Sb release from contaminated sediments is more likely to occur during the first few months of sediment-water interaction. During aerobic leaching, Sb moved into a more unavailable sediment phase, decreasing the potential for further releases. Sediment Fe and CaCO₃ equivalent concentrations were found to affect releases of added Sb. Evolution of volatile Sb compounds was also noted from sediments under anaerobic conditions.

The question of the disposal of sewage to tidal waters is one which is receiving increasing attention. For controlling authorities whose resources are stretched by the pressures of impending legislation and international directives, there is a need for techniques which allow the rapid and effective assessment of the impact of waste discharges on the marine environment. During ecological studies in the vicinity of a number of waste discharges to the North Kent coast the spatial and seasonal variations of sediments redox potential profiles and organic carbon content were examined. In areas where the bottom deposits are reasonably stable, the degree of reproducibility which can be achieved and the simplicity of the techniques permit the rapid generation of results and facilitate contour mapping to delineate the boundary effects of organic waste discharges.

West Yorkshire is one of the few remaining areas in the country where persistent organochlorine insecticides such as dieldrin are used for the mothproofing of textiles. Concentrations of dieldrin in the River Holme catchment were measured during 1980–1981.

A study of both spatial and temporal patterns of dieldrin concentration was undertaken. The spatial pattern revealed that the concentration decreased with the distance downstream of recognised discharges and that dieldrin was absent at detectable concentrations elsewhere in the system.

At selected stations, a detailed temporal survey was carried out and revealed that, close to the pollution source, massive changes in dieldrin concentration occurred over short time periods. As distance from the source increased, these changes were much less marked.

Earlier studies of dieldrin pollution in the catchment did not take into account the massive changes in concentration and attempted to predict mass flows for dieldrin in the system.

The implications of these fluctuations in concentration for future studies are therefore briefly discussed.

A survey was made of the concentration of total cadmium and lead in the topsoil at 125 sites surrounding several emission sources in northern France; one of the most important lead-zinc smelters in Europe was among those sources. A non-linear regression model was evaluated for a single emission source. The concentrations of both metals in soil were almost proportional to the inverse of the distance from the source and to the square root of the wind frequency. As several pollution sources were present in the area, an additive linear model was tested and a satisfactory adequacy between predicted and observed values was obtained. Thus, it was possible to draw a precise mapping of isoconcentration contour plots for both pollutants and to estimate the total burden of lead and cadmium in the topsoil of that area, as well as the relative contribution of each source to the global pollution. It was also possible to give guidelines for a more adequate sampling design.

The effect of simulated rainfall on the fluoride concentration of established pasture grass that had been subjected to ambient gaseous and particulate air fluorides was investigated. Little or no reduction in levels was exhibited, but there was considerable variation within the sward. Further experiments using laboratory-grown grass (Lolium perenne) dusted with artificial cryolite gave little real evidence of reductions in fluoride levels on subjection to simulated rainfall. It was concluded that the variation within the sward was too great to show the effect, if any, of rainfall at the initial fluoride levels, and rates and duration of rainfall used.