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Articles by P.J. Peterson
Total Records ( 5 ) for P.J. Peterson
  J. Nouri , B. J. Alloway and P.J. Peterson
  A sludge was conducted to attain the chemical extractability and mobility of Ni63 in soil and sludge. The results of this sludge showed a variation in extractable Ni63 activity with different incubation times. The extractions from the spread columns within increase in time showed, the amount of water soluble Ni63 in the soil, sludge and soil mixtures decreased significantly. The percentage removal of organically bound Ni63 by DTPA varied during the eight weeks, while EDTA showed a higher percentage of removal with a correlation with plant uptake. In some cases water decreased the solubility of Ni63 with increasing time in soil, sludge and mixture columns. Organic matter also decreased the Ni63 concentrations in all mixtures. Nitric acid digestion was used as a method of total recovery of Ni63 from all columns and 86-94% of the initial Ni63 was recovered in leachates from the soil and soil/sludge mixtures a greater proportion of cationic species of Ni63 than non cationic special were present, but in the sludge only leachates the reverse was true after 8 weeks. Organic matter content of soil increased by incorporation of sewage sludge may help to reduce the mobility of nickel.
  J. Nouri , B. J. Alloway and P.J. Peterson
  An experiment over a period of 14 months was carried out on duplicate undisturbed cores of 3 soils, with different textures using one sludge in order to obtain more information on the vertical movement of heavy metals through sludge treated soil. Over the first 8 months the pH values were in this order : sandy silt loam > sandy clay> loamy sand of both control and sludge amended soils. The rainwater pH values during the first 8 months were acidic, but during the following six months, they increased loan alkaline value. At the end weathering, it was found that only the amended surface and upper layers contained elevated concentrations of heavy metals. Thus the nature of soil was an extremely important factor in the downward movement of constituents. It appears that a guideline for sludge application to land the pH of soils should be maintained at or above 6.5. Groundwater pollution was likely to be the greatest in highly permeable sandy soils and these should not be used for the application of heavy metals. Soil water influenced the chemistry of surface waters and this affected the survival of fresh water fauna and flora.
  J. Nouri , B. J. Alloway and P.J. Peterson
  Duplicate (250g) samples of air dried sewage sludge / mixtures in different percentages were placed in sintered glass to conduct a study of the mobility of heavy metals in soil amended with sewage sludge. The pH values of saturation extracts showed an increase in all sample mixtures up to 3rd month. The concentrations of nickel in the extracts were higher than those of cadmium and lead. There was a marked depletion in levels of metals with time, thus showing that the greatest release of metals occurred in the early stages after mixing probably due to the flushing out of the initial soluble forms already present in sludge. Another possibility could be that the decrease in metal concentrations with time could be due to the development of anaerobiosis.
  J. Nouri , B. J. Alloway and P.J. Peterson
  A number of extractions were carried out on soils, in order to assess both the relative concentrations of metals available to plants and also the major forms in which these metals existed in soils. The objective of this study was to assess the quantity and forms of metals in different soils, sludge and soils amended with sludge. It seemed that initially each metal will respond differently after incorporation into the soil system. There was a greater fraction of soluble metals in the sludge amended soils than the controls. Micro-organisms might, by using organic and inorganic matter as source of carbon and energy, bring about oxidation and reduction sufficient to change the state of metals.
  J. Nouri , P.J. Peterson and B.J. Alloway
  A study describing the accumulation of Ni63 in leaves of maize grown in various soil / sludge mixtures was conducted to evaluate the gross distribution and chemical forms of Ni63 following absorption and translocation. The study demonstrated the presence of anionic nickel complexes Ni63 in maize leaves indicating that nickel in plant may be species dependant. The electrophoresis results showed, Ni63 associated with chlorophyll. High levels of nickel concentration occurring after sludge application could contribute to the destruction of this pigment. With an increased incubation time Ni-Spiked soil and soil / sludge mixtures decreased. The nickel concentration, thus the amount of sludge present influences the uptake of inorganic nickel by plants. Greater sludge application may cause phytotoxic effects on crops, so that the concentration of nickel and phytotoxic heavy metals in sewage sludge should be monitored. The amount of nickel in the soil plant system was found to change with time as did the soluble nickel complexes in plants, which are of interest and importance to animal and human nutritionists.
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