The present study focuses on the geochemistry of large phosphogypsum deposits in Huelva (SW Spain). Phosphogypsum slurry waste from fertiliser production was disposed in large ponds containing aqueous waste (i.e. brines) and exposed to weathering. These evaporation ponds were found to be dynamic environments far from attaining steady state conditions where a number of trace pollutants are subjected to temporal variations in response to changing environmental conditions. Chemical, mineralogical and morphological data were used to improve our understanding on the dynamics of a large number of elements in the phosphogypsum-brine-evaporation deposits system. Weekly sampling of brines over the course of 1 yr indicated a substantial enrichment in potentially harmful elements (e.g. As, Cr, Cu, F, Ni, U, V, Zn) present in time-dependent concentrations. The evaporation deposits formed multi-layered precipitates of chlorides, sulphates, phosphates and fluorides containing a large number of pollutants in readily soluble forms. The precipitation sequence revealed a time-dependent composition reflecting alternating precipitation and re-dissolution processes associated with seasonal changes in the local weather conditions. Concatenation of precipitation/re-dissolution stages was found to progressively enrich the brines in pollutants. These findings were supported by the observations from a tank experiment simulating the phosphogypsum-brine-evaporation deposits system under laboratory conditions. Given the substantially high concentrations of pollutants present in mobile forms in the brine-salt system, actions to abate these compounds should be implemented.

中文翻译：

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韦尔瓦（西班牙西南）磷石膏矿床盐水的地球化学演变及其环境影响


本研究的重点是 Huelva（西班牙西南）大型磷石膏矿床的地球化学。肥料生产产生的磷石膏浆料废弃物被丢弃在含有含水废物（即盐水）的大型池塘中，并暴露在风化环境中。这些蒸发池被发现是动态环境，远未达到稳态条件，其中许多微量污染物会随着环境条件的变化而发生时间变化。化学、矿物学和形态学数据用于提高我们对磷石膏-盐水-蒸发沉积系统中大量元素动力学的理解。在 1 年的时间中每周对盐水进行取样表明，以时间依赖性浓度存在的潜在有害元素（例如 As、Cr、Cu、F、Ni、U、V、Zn）大量富集。蒸发沉积物形成氯化物、硫酸盐、磷酸盐和氟化物的多层沉淀物，其中含有大量易溶形式的污染物。降水序列揭示了与时间相关的成分，反映了与当地天气条件的季节性变化相关的交替降水和再溶出过程。发现沉淀/再溶解阶段的串联逐渐富集污染物中的盐水。这些发现得到了在实验室条件下模拟磷石膏-盐水-蒸发沉积系统的储罐实验的观察结果的支持。鉴于盐水-盐系统中以移动形式存在的污染物浓度相当高，应采取行动减少这些化合物。