Escuela de Agronomía, Facultad de Ciencias, Universidad Mayor, 8580745, Santiago, Chile.
Facultad de Química y Biología, Universidad de Santiago de Chile, 7254758, Santiago, Chile.
Environ Geochem Health. 2018 Dec;40(6):2491-2509. doi: 10.1007/s10653-018-0115-y. Epub 2018 Jun 6.
The frequent use of phosphorus (P) fertilisers accompanied by nitrogen and potassium sources may lead to a serious long-term environmental issue because of the presence of potentially hazardous trace metals (TM) in P fertilisers and unknown effects on the TM chemical fractions in agricultural soils. A 16-month-long column experiment was conducted to investigate the mobility and chemical forms of Cd, Cu, Cr, Ni, and Zn introduced into a Mollisol and an Andisol through surface incorporation (0-2 cm) of triple superphosphate (TSP) fertiliser. The effects of urea and potassium chloride (KCl) applications were investigated as well. After 15 cycles of 300-mm irrigation, TSP addition increased the 4 M HNO extractable TM concentration in the upper (0-5 cm) section of soils. Beyond this depth, metals showed no significant mobility, with minimal leaching losses (< 1.9%, 25-cm depth). The TM chemical forms in the 0-5 cm section were significantly (p < 0.01) affected by the soil type and fertilisers addition. Cadmium, Ni, and Zn were the elements which appeared in a larger proportion (up to 30%) in the most labile fraction (KNO extractable) in fertilised soils. The impact of urea depended on the nitrification-related changes in soil pH, while fertilisation with KCl tended to increase the KNO fraction of most metals probably due to K exchange reactions. Chromium remained minimally affected by the urea and KCl applications since this contaminant is strongly bound to the less labile solid phases. The low mobility of TM was governed mainly by their interaction with the solid phases rather than by their speciation at soil pH. The mass balance showed that the geochemical processes underwent in time by the P fertiliser increased the amount of TM extracted by the chemical fractionation scheme, therefore the reaction period of TSP with soil particles should be taken into account for evaluating TM availability. Long-term soil fertilisation could inadvertently contribute to an increased concentration and availability of these P fertilisers-born contaminants in the cultivated layer of acidic soils.
磷肥（P）的频繁使用伴随着氮源和钾源的使用可能会导致一个严重的长期环境问题，因为在磷肥中存在潜在危险的痕量金属（TM），并且对农业土壤中 TM 化学形态的未知影响。通过表面掺入（0-2 cm）过磷酸钙（TSP）肥料，进行了一项为期 16 个月的柱实验，以研究引入到一种黑钙土和一种灰棕壤中的 Cd、Cu、Cr、Ni 和 Zn 的迁移和化学形态。还研究了尿素和氯化钾（KCl）的应用效果。经过 15 个 300 毫米灌溉周期后，TSP 的添加增加了土壤上层（0-5 cm）4 M HNO3可提取 TM 浓度。在这一深度之外，金属没有表现出明显的迁移性，淋失损失最小（<1.9%，25 cm 深度）。0-5 cm 段的 TM 化学形态受到土壤类型和肥料添加的显著影响（p<0.01）。Cd、Ni 和 Zn 是在施肥土壤中最不稳定（KNO3可提取）部分中以较大比例（高达 30%）出现的元素。尿素的影响取决于与硝化相关的土壤 pH 值变化，而 KCl 的施肥往往会增加大多数金属的 KNO3部分，可能是由于 K 交换反应。由于这种污染物与较不活跃的固相强烈结合，因此 Cr 受尿素和 KCl 应用的影响最小。TM 的低迁移性主要受其与固相的相互作用控制，而不是其在土壤 pH 值下的形态。质量平衡表明，随着时间的推移，P 肥料经历的地球化学过程增加了化学分级提取方案提取的 TM 量，因此，应考虑 TSP 与土壤颗粒的反应时间来评估 TM 的可用性。长期的土壤施肥可能会无意中导致酸性土壤耕层中这些由磷肥产生的污染物的浓度和可用性增加。
