was to correlate easily measurable soil properties, such as clay content and water-dispersible colloids, to colloid and phosphorus leaching. Colloid and phosphorus leaching from macropores in undisturbed soil cores sampled across a natural clay gradient at Aarup, Denmark, were studied. Particulate phosphorus (P) was linearly correlated to concentration.The presence of strongly sorbing compounds in groundwater and tile drains can be a result of colloid-facilitated transport. The mass of leached particles was positively correlated to the clay content as well as to water-dispersible colloids. Vendelboe, Anders Lindblad Møldrup, Per Heckrath, Goswin JohannĬorrelated to the accumulated outflow and was described as a diffusion controlled process, using ¾(accumulated outflow).
The arrival of the tracers showed that almost all collected water came from preferential flow paths.Ĭolloid and phosphorus leaching from undisturbed soil cores sampled along a natural clay gradient The deeper lysimeters did not collect any water. The lysimeters directly underneath the filled soil material collected water with a collection efficiency of 45%. Three lysimeters were installed underneath a 1.2 m filling of contaminated silty sand, the others deeper in the undisturbed soil. To validate the results from the numerical study, a dual tracer study with seven lysimeters of 1.25Ã-1.25 m area was conducted in the field.
UNDISTURBED SOIL SAMPLER FREE
Solute breakthrough into zero-tension lysimeter occurs slightly retarded as compared to the free soil, but concentrations in the collected water are similar to the mean flux concentration in the undisturbed soil. Heterogeneities of soil hydraulic properties result into a network of flow channels that enhance the sampling efficiency of the lysimeter plates.
In homogeneous soils with high saturated conductivities the devices perform poorly and even large lysimeters (width 250 cm can be bypassed by the soil water. The collection efficiency was found to be highly dependent on the hydraulic functions, infiltration rate, and lysimeter size, and was furthermore affected by the degree of heterogeneity. To investigate the influence of the lysimeter on the water flow field in the soil, a numerical 2-D simulation study was conducted for homogeneous soils with uni- and bimodal pore-size distributions and stochastic Miller-Miller heterogeneity. We present a modular plate system that allows installation of large zero-tension lysimeter plates under undisturbed soils in the field.
Large sampling devices are required if preferential flow paths are present. Large zero-tension plate lysimeters for soil water and solute collection in undisturbed soilsĭirectory of Open Access Journals (Sweden)įull Text Available Water collection from undisturbed unsaturated soils to estimate in situ water and solute fluxes in the field is a challenge, in particular if soils are heterogeneous.
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