Soil map of Lower Saxony 1: 50 000 — Local relocation potential — Exchange frequency of soil water (1971-2000)

The map shows the average local relocation potential for non-absorbable substances (also exchange frequency of soil water per year) for the 30-year period 1971-2000. With the help of the exchange frequency (AH) of soil water, the local relocation potential for non- or weakly absorbable substances can be described. The AH indicates how often the soil solution is exchanged in the effective root zone in the course of leachate displacement. The lower the water storage and retention capacity of a soil, the greater its frequency of exchange of soil water. Statements on the concentration and cargo of non-sorbable substances cannot be mapped with the method. For nitrate, deposition, denitrification and mineralisation are not taken into account. Depending on the location, they can have a significant impact on nitrate availability and concentration in leachate.本地图展示了1971-2000年这30年周期内，非吸附性物质（亦为每年土壤水分交换频次）的局地迁移潜力。借助土壤水分交换频次（AH），可表征非吸附或弱吸附性物质的局地迁移潜力。 AH指渗流驱替过程中，有效根区范围内土壤溶液的交换频次。 土壤的储水与持水能力越低，其土壤水分交换频次越高。 该方法无法用于表征非吸附性物质的浓度与载荷情况。 针对硝酸盐而言，沉积、反硝化与矿化过程未被纳入考量范畴。 在不同区位条件下，这些过程会对渗滤液中硝酸盐的可利用性与浓度产生显著影响。