摘要:

Abstract.Radionuclides in the environment come from a wide range of sources, some natural and some artificial. Their biogeochemical behaviour is influenced both by their own physico‐chemical properties and by those of the soil with which they interact. The source of the radionuclides is important, as are any changes in physico‐chemical characteristics that occur during transport and deposition. Once in the soil further reactions can occur as the radionuclides equilibrate. These include immobilization by ion exchange and precipitation and remobilization by complexing and dissolution. Land management and environmental changes that alter conditions in the soil result in changes in the interactions of radionuclides with the soil and thereby to changes in mobility in the s

ISSN:0266-0032    

DOI:10.1111/j.1475-2743.1988.tb00738.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Abstract.The interaction of caesium isotopes with soil has been widely investigated and the influence of important soil properties studied. From the results of such work and a detailed knowledge of the physico‐chemical properties of soils it is possible to classify Cumbrian soil according to its ability to immobilize caesium. The ‘immobilization capacity’ is a reflection principally of the clay mineral content and type, organic content, pH, ammonium content and potassium status. Although it is not quantifiable, the immobilization capacity permits ranking of the soils and indicates which areas may give rise to persistent caesium problems. Combination of the soil sensitivity classification with deposition data for Cumbria indicates that the mountainous region in the south‐west of the county is the most vulnerable. This conclusion is supported by field evidence, since the area identified coincides closely with that where sheep movement and slaughter are restricted and where caesium remains persistently available to the plant‐ani

ISSN:0266-0032    

DOI:10.1111/j.1475-2743.1988.tb00739.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Abstract.The factors influencing uptake of radionuclides from soils into vegetation are discussed with reference to soil type, radionuclide, plant species and organ, and time since initial contamination. Gaps in knowledge are identified, particularly as highlighted by the unexpected behaviour of radiocaesium in many upland areas of Britain, following deposition after the Chernobyl accident. The importance of resuspended soil for contamination of aerial plant parts is also considered in relation to radionuclide type, vegetation height, and meteorological conditions.The development of an international database by the International Union of Radioecologists for soil to crop transfer factors of radionuclides derived from European experiments is briefly described. This database is now being used for statistical analyses aimed at quantifying the importance of environmental and biological factors in influencing uptake of radionuclides from the soil.

ISSN:0266-0032    

DOI:10.1111/j.1475-2743.1988.tb00740.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Abstract.Mathematical models describing radionuclide transport in soil developed for radiological assessment have increased in complexity over the last decade. In particular fairly simple ‘black box’, equilibrium approaches have given way to more complex, time‐dependent, process‐orientated methods. The increase in complexity of these models has outstripped the available data to specify, test and validate them. Current issues in model development include those that are associated with times up to a million years. Further development requires new laboratory and field research to provide adequate data to justify the inclusion or omission of known soil pr

ISSN:0266-0032    

DOI:10.1111/j.1475-2743.1988.tb00741.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Abstract.The Rothamsted Drain Gauges built in 1870 comprise blocks of soil, 0.5, 1.0 and 1.5 m deep, isolated laterally by brickwork and undermined for the collection of drainage water but otherwise undisturbed. The soil has not been cropped, manured or cultivated subsequently. The annual nitrate leakages from these blocks were recorded for the 38 years from 1877/8 to 1914/5. The soil in the 0.5 and 1.5‐m gauges lost on average about 45 kg ha−1of nitrate‐N per year during the first seven years of this period; that in the 1.0‐m gauge lost slightly less. The overall decline in leakage was masked by large annual fluctuations attributable mainly to variation in rainfall. Fitting a simple function that assumed an exponential decline and took account of rainfall fluctuations gave a rate constant for each gauge from which the half‐life could be estimated for the organic nitrogen feeding the leakage. The half‐life for the 1.5‐m gauge was 41 yr. The average nitrate leakage during the first seven years of the record differs little from estimates of the current leakage from soil carrying fully fertilized crops of winter wheat. This and the long half‐life of the leakage show that pollution of drainage water by nitrate will not be controlled by limiting the use of fertilizer in

ISSN:0266-0032    

DOI:10.1111/j.1475-2743.1988.tb00742.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Abstract.Erosion and excessive runoff from a crusting and hard‐setting red‐brown earth may he ameliorated with suitable management. A field trial, near Cowra, New South Wales, to assess the long‐term effect of different tillage systems was used to compare the effect of direct drilling with conventional district cultivation practices under continuous wheat. The soil was sampled in the eighth year for assessment of the soil macropore structure, measurement of bulk density and hydraulic conductivity under tension. Vertical faces were prepared from resin impregnated blocks and the macropore structure described mathematically and visually using digital images and data generated from these images. Infiltration, bulk density and image analysis data all lead to the same conclusions about changes in pore structure. Under direct drilling no crust was evident, and there was greater macroporosity (>0.175 mm diameter in section). The treatment effects appeared to be significant to about 30 to 35 mm depth at the time of sampling. Greater root and faunal activity were observed under direct dri

ISSN:0266-0032    

DOI:10.1111/j.1475-2743.1988.tb00743.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Abstract.Fifteen soil profiles in the Alltcailleach Forest in NE Scotland have been resampled after almost 40 years. The pH, in 0.01 M CaCl2, of the soil has decreased by 0.07 to 1.28 units in 80% of the surface organic horizons and by 0.16 to 0.54 units in 73% of the mineral horizons below 40 cm. The key factors governing increases and decreases in soil pH are changes in ground vegetation and tree canopy, although some effects of acid deposition cannot be ruled out.

ISSN:0266-0032    

DOI:10.1111/j.1475-2743.1988.tb00744.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Abstract.People in rural areas have disposed of their wastes on land for centuries, relying on the soil's ability to degrade and render harmless any toxic elements the wastes may contain. Leather tanneries produce a large amount of sludge and liquid wastes. The liquids contain much sodium and in most circumstances adversely affect both the soil and groundwater. However, in some countries they are used for irrigation. The sludges contain nitrogen, calcium, magnesium, phosphorus, trivalent chromium and some sodium. Given careful management these sludges can be used as soil amendments, either directly or after composting. Application rates of about 200 tonnes ha−1have proved toxic to crops in pot trials, though larger applications than this have not adversely affected crops in the field. Much smaller rates, of less than 20 tonnes ha−1, have been used in the field to minimize nitrate contamination of groundwater. The effects of CrIII depend on complex interactions between the sludge, the soil to which it is added and the plant species grown. Safe limits for the disposal of the sludges and their long term effects are not kn

ISSN:0266-0032    

DOI:10.1111/j.1475-2743.1988.tb00745.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY