Maghemite (Mh) and magnetic susceptibility have been little studied in relation to phosphorus (P) sorption, despite the fact that tropical soils – particularly those derived from mafic rocks – may contain substantial amounts of this iron oxide. In this work, we investigated the relationship between P adsorption and magnetic susceptibility in tropical soils, and determined the maximum adsorption capacity of P (MACP) and P desorption in seven pedogenic clays from magnetic soils with contrasting parent materials and three synthetic Mh samples. Considering the heterogeneity of the soil dataset in this study, the exclusive adoption of magnetic susceptibility as an indicator of P adsorption potential in soil remains uncertain. The relationship between magnetic susceptibility and adsorbed P was more evident in the B horizon of red soils from basic igneous rocks. In this group, soils with magnetic susceptibility above 20 × 10−6 m3 kg−1 had high adsorbed P. Although the pedogenic clays exhibited lower MACP values (1353–2570 mg kg–1) than the synthetic Mh samples (3786–4321 mg kg–1), P desorption exhibited the opposite trend (~14% vs ~8%). The substantial P adsorption capacity of synthetic Mh confirmed the adsorption data for pedogenic clays, which were strongly influenced by magnetic susceptibility, Mh and gibbsite contents, and specific surface area.

中文翻译：

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将粘土和热带土壤中的磷吸附和磁化率联系起来

尽管热带土壤——尤其是源自镁铁质岩石的土壤——可能含有大量的这种氧化铁，但关于磁赤铁矿 (Mh) 和磁化率与磷 (P) 吸附的关系鲜有研究。在这项工作中，我们研究了热带土壤中 P 吸附与磁化率之间的关系，并确定了来自磁性土壤的 7 种成土粘土中 P 的最大吸附能力（MACP）和 P 解吸能力，具有对比母体材料和三个合成 Mh 样品。考虑到本研究中土壤数据集的异质性，仅采用磁化率作为土壤中 P 吸附潜力的指标仍不确定。基性火成岩红壤B层的磁化率与吸附磷的关系更为明显。在这组中，磁化率高于 20 × 10−6 m3 kg−1 的土壤具有高吸附 P。 尽管土壤中的粘土表现出较低的 MACP 值（1353–2570 mg kg–1）比合成 Mh 样品（3786–4321 mg kg-1)，P 解吸表现出相反的趋势（~14% vs ~8%）。合成 Mh 的显着 P 吸附能力证实了对成土粘土的吸附数据，其受磁化率、Mh 和三水铝石含量以及比表面积的强烈影响。尽管与合成的 Mh 样品（3786-4321 mg kg-1）相比，成土粘土表现出较低的 MACP 值（1353-2570 mg kg-1），但 P 解吸表现出相反的趋势（~14% vs ~8%）。合成 Mh 的显着 P 吸附能力证实了对成土粘土的吸附数据，其受磁化率、Mh 和三水铝石含量以及比表面积的强烈影响。尽管与合成的 Mh 样品（3786-4321 mg kg-1）相比，成土粘土表现出较低的 MACP 值（1353-2570 mg kg-1），但 P 解吸表现出相反的趋势（~14% vs ~8%）。合成 Mh 的显着 P 吸附能力证实了对成土粘土的吸附数据，其受磁化率、Mh 和三水铝石含量以及比表面积的强烈影响。