『Abstract
Organic amendment application to heavy metal contaminated soils
may contribute to leaching of phosphorus (P). The objectives of
this study were to determine the influence of sheep manure and
ethylenediamine tetraacetic acid (EDTA) on the P leaching from
a wide range of calcareous contaminated soils. Glass tubes, 4.9
cm diameter, and 40 cm long, were packed with contaminated soil.
The resulting 20 cm long column of soils had bulk density of 1.3-1.4
g cm3. The columns were leached with distilled water,
0.01 M EDTA, 0.01 M CaCl2 or sheep manure
extract (SME) solutions. The breakthrough curves for P were different
and the amounts of P leached varied considerably between different
soils and leaching solutions. The amounts leached with SME were
less than the amount added through the SME, indicating that some
P was retained by the soil, mainly due to preliminary sorption
of organic ligands on to the soil with the creation of new sorbing
surfaces. The amount leached with EDTA solution varied from 9.9
to 46.3% of the extractable P when 15 pore volumes had passed
through the column. Low amounts of P were leached by 0.01 M CaCl2, which is likely to be due to the high concentration
of soluble Ca used in the solution. Thus, among leaching solutions
the application of EDTA and SME on contaminated calcareous soils
might enhance the mobility of P and large amounts of P will be
leached, leading to contamination of ground and surface waters.
Keywords: Leaching; Calcareous soils; Phosphorus; Contamination;
Sheep manure; EDTA』
Introduction
Materials and methods
The description of study area and soil sampling
Sheep manure extract
Leaching experiments
Results and discussion
Soil
Leaching of P from soils
Conclusion
References