Walther W
Niedersächsischen Landesamt für Wasser und Abfall, Hildesheim.
Dtsch Tierarztl Wochenschr. 1991 Jul;98(7):272-7.
In Germany groundwater represents the main source for the water supply. Up to the present the nitrogen surplus due to agricultural production has increased to about 100 kg N/ha and year. This surplus reaches other, mainly aquatic ecosystems, transported by water and trough the air. The impact of the long-term load through nutrients on groundwater is exemplified here in the case of Lower Saxony. In karst and rock aquifers the transport velocities are usually relatively high. After nutrients have left the root zone of the soil there remains in this kind of aquifer little opportunity for nitrate decomposition. Therefore rising nitrate values can soon be observed in pumpage wells. Intensive cattle production is especially widespread in the northern parts of Lower Saxony. In these areas of sandy aquifers the period of substance transport between the input into the system and reaching pumpage wells may cover years or even decades. Therefore there is a greater chance for nitrate decomposition. Nonetheless many upper aquifers are severely contaminated with nitrates, for instance. In many cases a reductive chemical environment can be observed, which causes an increase in substances such as iron or trace elements like nickel. This leads to considerable problems for water supply and treatment. In order to protect the quality and decomposition capacity of the groundwater for the next generation it is urgently necessary to minimise nutrient surpluses in the field of agricultural production.
在德国，地下水是供水的主要来源。到目前为止，农业生产造成的氮盈余已增至约100千克氮/公顷·年。这种盈余通过水和空气传输到其他生态系统，主要是水生生态系统。在下萨克森州的案例中体现了长期营养负荷对地下水的影响。在岩溶和岩石含水层中，传输速度通常相对较高。营养物质离开土壤根区后，在这类含水层中硝酸盐分解的机会很少。因此，很快就能在抽水井中观测到硝酸盐含量上升。密集型养牛业在下萨克森州北部尤为普遍。在这些砂质含水层地区，从物质进入系统到到达抽水井的传输期可能长达数年甚至数十年。因此，硝酸盐分解的机会更大。尽管如此，例如许多上部含水层仍受到硝酸盐的严重污染。在许多情况下，可以观测到还原化学环境，这会导致铁或镍等微量元素等物质增加。这给供水和水处理带来了相当大的问题。为了为下一代保护地下水的质量和分解能力，迫切需要尽量减少农业生产领域的营养盈余。
