Effective Vertical Solute Transport in Soils by Artificial Macropore System.

Characteristics　of　solute　transport　in　soils　were　important　factors　which　govern　the　soil environmental　processes,　such　as　effective　fertilizer　application　or　dispersion　areas　of　remediation　chemicals　for　contaminated　soils.　However,　soils　were　easy　to　be　clogged　by　long　term　infiltration,　moreover,　infiltration　process　was　disturbed　at　surface　soils　by　formation　of　crust　or,　sometimes,　water　repellency.　Thus　it　is　not　easy　to　maintain　fair　hydraulic　conductivity　for　long　term　experiment.　In　this　study,　artificial　macropores　were　utilized to　achieve　long　term　infiltration　process.　Macropores　are　everywhere　in soils,　and　in　unsaturated　conditions,　they　enhance　air　intrusion　in　soils　and　avoid　clogging　of　the　surface　soils.　However,　their　structure　was　hard　to　maintain　and　collapsed　by　long　term　infiltration　when artificial　macropores　were　made　in　soils.　In　this　experiment,　macropore　fillings　were　introduced　into　the　pores　to　maintain　its　structure.　They were　made　of　glass　fiber　or　paper　towels.　Solute　transport　experiments　were　conducted　for　four　soils　which　have:　no　macropore　inside;　empty　macropores;　macopores　with　paper　towel　fillings;　macropores　with　glass fiber　fillings.　Results　indicated　that　macropore　fillings　successfully　conducted　solution　to　the　deeper　profile,　without　saturation　at　the　surface,　therefore　without　clogging.　When　bioremediation　experiments　were　conducted　for　these　four　soil　columns,　soil　columns　with　macropore　fillings　kept　0.6-0.8　of　saturated　water　content,　thus　it　enhanced biological　activity.　The　resultant　residue　oil　concentration　was　small　for　them,　because　artificial　macropores　with　fabric　fillings　maintained　macropore　structure　and　also　stable　infiltration　for　30 days,　kept unsaturated　condition　by　passing　the　excess　water　to　deeper　profile　and　enhancing　biological　activity.