A large amount of nitrogen remains in ion-absorption rare earth tailings with situ leaching technology, and it continually ends up in groundwater sources. However, the distribution and transport of ammonium nitrogen (NH₄⁺-N) and nitrate nitrogen (NO₃⁻-N) across tailings with both depth and hill slopes is still unknown. In this study, the amount of NH₄⁺-N and nitrate nitrogen (NO₃⁻-N) was determined in tailings, and a soil column leaching experiment, served to assess the transport and distribution following mine closure. Firstly, a high concentration of NH₄⁺-N in the leachate at the initial leaching stage was detected, up to 2000 mg L⁻¹, and the concentration of NH₄⁺-N clearly diminished as time passed. Meanwhile the NH₄⁺-N contents remained relatively high in soil. Secondly, both the content of NH₄⁺-N and NO₃⁻-N varied greatly according to vertical distribution after leaching lasting several years. The amounts of NH₄⁺-N and NO₃⁻-N in surface soil were much smaller than those in deep soil, with 3–4 orders of magnitude variation with depth. Thirdly, when disturbed by NH₄⁺-N, the pH not only diminished but also changed irregularly as depth increased. Fourthly, although the amount of NO₃⁻-N was smaller than that of NH₄⁺-N, both their distribution trend was similar with depth. In fact, NH₄⁺-N and NO₃⁻-N were significantly correlated but this declined from the knap to the piedmont. Based on these results, it is suggested that mining activity could cause nitrogen to be dominated by NH₄⁺-N and acidification in a tailing even if leaching occurs over several years. NO₃⁻-N derived from NH₄⁺-N transports easily and it becomes the main nitrogen pollutant with the potential to be a long-lasting threat to the environment around a mine.

采用原位浸出技术的离子吸收型稀土尾矿中残留有大量氮，并不断流入地下水源。然而，铵态氮（NH ₄ ⁺ -N）和硝态氮（NO ₃ ^- -N）在不同深度和坡度的尾矿中的分布和迁移仍然未知。_{在这项研究中，测定了尾矿中NH 4} ⁺ -N 和硝态氮(NO ₃ ⁻ -N)的含量，并进行了土柱淋滤实验，以评估矿山关闭后的迁移和分布。首先，在浸出初期，浸出液中NH ₄ ⁺ -N的浓度很高，高达2000 mg L ^{-1 ，并且随着时间的推移，NH} ₄ ⁺ -N的浓度明显降低。同时土壤中NH ₄ ⁺ -N 含量仍保持较高水平。其次，历经数年淋滤后， NH ₄ ⁺ -N和NO ₃ ⁻ -N的含量在垂直分布上变化较大。_{表层土壤中NH 4} ⁺ -N和NO ₃ ⁻ -N含量远小于深层土壤，随深度变化有3~4个数量级。第三，当受到NH ₄ ⁺ -N干扰时，pH不仅减小，而且随着深度的增加而发生不规则变化。第四，虽然NO ₃ ^- -N的含量小于NH ₄ ⁺ -N的含量，但它们随深度的分布趋势相似。事实上，NH ₄ ⁺ -N 和NO ₃ ⁻ -N 显着相关，但从山丘到山前，这种关系呈下降趋势。基于这些结果，表明采矿活动可能会导致尾矿中的氮以NH ₄ ^{+ -N 为主并发生酸化，即使浸出发生数年。}_{NH 4} ⁺ -N衍生的NO ₃ ⁻ -N 易于迁移，成为主要氮污染物，有可能对矿井周围环境造成长期威胁。