A simple empirical model for phenanthrene adsorption on soil clay minerals

2021 ◽  
pp. 127849
Author(s):  
Nan Zhao ◽  
Feng Ju ◽  
Quanwei Song ◽  
Hui Pan ◽  
Hao Ling
2007 ◽  
Vol 83 (1) ◽  
pp. 74-85 ◽  
Author(s):  
C. M. Wernerheim ◽  
R. L. Haedrich ◽  
S. Ussif Rashid ◽  
G. R. Munro ◽  
J. G. Sutinen

1996 ◽  
Vol 44 (4) ◽  
pp. 339-356 ◽  
Author(s):  
G.L. Velthof ◽  
J.G. Koops ◽  
J.H. Duyzer ◽  
O. Oenema

Three measurement campaigns were carried out to answer questions related to the factors controlling variations in nitrous oxide (N2O) fluxes from intensively managed grassland on peat soil, comparison of flux measurements with a closed flux chamber method and a flux gradient technique and the development and testing of a simple empirical model for the estimation of N2O fluxes from intensively managed grassland on peat soils. Fluxes of N2O were measured with 42-48 flux chambers and ranged from less than 0.01 to 6.66 mg N/msuperscript 2 per hr. Fluxes were significantly correlated with denitrification activity (Rsuperscript 2=0.34-0.56). Contents of nitrate (NO3-) and ammonium (NH4+) in the top soil and the water-filled pore space (WFPS) explained 37-77% of the variance in N2O flux. Spatial variability of N2O fluxes was large with coefficients of variation ranging from 101 to 320%. Spatial variability was suggested to be related to distribution of mineral N fertilizer and cattle slurry, urine and dung patches and variations in groundwater level within the field. Average field fluxes obtained with the closed flux chamber method were about a factor 10 larger than those with the flux gradient technique on one measurement day but were similar on two other measurement days. The results of the measurement campaigns were used to derive a simple empirical model including total mineral N content and WFPS. This model was tested using an independent data set, i.e. the results of a monitoring study of two years carried out on two other grassland sites on peat soil. The model reasonably predicted magnitude of and temporal variations in N2O fluxes. It is suggested that a simple empirical model which requires only easily obtainable data such as mineral N content and moisture content, in combination with a few days lasting measurement campaigns, may be a valuable tool to predict N2O fluxes from similar sites.


1993 ◽  
Vol 73 (4) ◽  
pp. 421-431 ◽  
Author(s):  
D. W. Bergstrom ◽  
E. G. Beauchamp

We used a simple empirical model to predict denitrification rates from measurements of bulk soil properties. Boundary analysis was used to define relationships between denitrification rate and each of air-filled porosity, respiration rate and mineralizable-C content. The ratio of measured denitrifying enzyme activity to the maximum measured value was used to account for variation in amounts of enzymes and numbers of denitrifiers in soil. Nitrate content had little effect on denitrification rate and was excluded from the model. Because the model did not account for microscale variability, it did not accurately predict rates in individual soil cores. Nevertheless, population means and distributions of predicted and measured values were similar. The seasonal patterns of mean values of predicted and measured denitrification rates were also similar over the second half of the sampling period, which extended from May to November. The model did not account for appreciable denitrification on three dates in May. This discrepancy indicated that environmental regulation of denitrification may not be uniform over the season. The model was not sufficiently sensitive to factors influencing episodic events. Key words: Denitrification rate, model, boundary line


2010 ◽  
Vol 128 (4) ◽  
pp. 2366-2366
Author(s):  
Romina del Rey Tormos ◽  
Jesús Alba Fernández ◽  
Jorge P. Arenas

Geoderma ◽  
2019 ◽  
Vol 347 ◽  
pp. 135-149 ◽  
Author(s):  
Jan Dietel ◽  
Jens Gröger-Trampe ◽  
Marko Bertmer ◽  
Stephan Kaufhold ◽  
Kristian Ufer ◽  
...  

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