Tungsten (W) is rarely found in natural waters, yet it can be introduced into the food chain and cause potentially toxic effects. Uptake of W by plants and vegetables, or trace presence of W in drinking water are possible vectors for ingestion of W by humans. The latter is recognized as a possible cause of lymphatic leukemia. Increased uses of W might result in a degradation of water resources, with attendant adverse effects on biota and human health. Therefore, this study was aimed at investigating regional occurrence and speciation of W in aquatic systems in Sardinia, Italy, factors affecting W mobility and possible relations with other oxyanion-forming trace elements such as Sb, As and Mo. Although our results are specifically from Sardinia, the implications are broader and should prompt future studies in other areas with known high W concentrations.

A total of 350 sample sites are reported here, including surface waters, groundwaters, mine drainages, thermal waters and local seawater. The waters were analyzed for major and trace components, including W, Sb, As and Mo. The waters showed a variety of major chemical compositions and W concentrations. High concentrations of W were found in some mine waters and drainages from slag heaps, with W, Sb and As up to 140, 5000 and 800 μg L⁻¹, respectively. The highest concentrations of W occurred under slightly alkaline pH and oxygenated conditions, and were likely due to the dissolution of scheelite [CaWO₄] hosted in materials with which the water came into contact. High W concentrations also were observed in thermal waters, under alkaline pH and reducing conditions, and sometimes coincided with relatively high concentrations either of As or Mo.

Previous studies of W geochemistry have focused on WO₄²⁻ as the major dissolved form of W. For this study, we have augmented the thermodynamic database in PHREEQC to include possible formation of many other W-bearing complexes gleaned from the literature. The results of the speciation calculations with the newly added complexation reactions shows that the neutral species CaWO₄° and MgWO₄° are particularly dominant in most W-bearing waters and lead to undersaturation with respect to scheelite and other W-bearing minerals.

Assessing W contamination in water systems and establishing W limits in drinking water may prevent potential adverse effects of W on human and ecosystem health.

钨 (W) 在天然水域中很少发现，但它可以被引入食物链并导致潜在的毒性影响。植物和蔬菜对 W 的吸收，或饮用水中痕量 W 的存在是人类摄入 W 的可能载体。后者被认为是淋巴白血病的可能原因。增加使用 W 可能会导致水资源退化，从而对生物群和人类健康产生不利影响。因此，本研究旨在调查意大利撒丁岛水生系统中 W 的区域发生和物种形成、影响 W 迁移率的因素以及与其他形成氧阴离子的微量元素（如 Sb、As 和 Mo）的可能关系。尽管我们的结果专门来自撒丁岛，

这里共报告了 350 个采样点，包括地表水、地下水、矿井排水、热水和当地海水。对水的主要和痕量成分进行了分析，包括 W、Sb、As 和 Mo。水显示出多种主要化学成分和 W 浓度。在一些矿井水和渣堆排放物中发现了高浓度的 W，其中 W、Sb 和 As 分别高达 140、5000 和 800 μg L ^-1。W 的最高浓度出现在弱碱性 pH 值和含氧条件下，这可能是由于白钨矿 [CaWO ₄] 寄宿在与水接触的材料中。在碱性 pH 值和还原条件下，在热水中也观察到高 W 浓度，有时与相对高浓度的 As 或 Mo 一致。

以前对 W 地球化学的研究集中在 WO ₄ ^2-作为 W 的主要溶解形式。对于这项研究，我们增加了 PHREEQC 中的热力学数据库，以包括从文献中收集的许多其他含 W 配合物的可能形成。新添加的络合反应的形态计算结果表明，中性物质 CaWO ₄ ° 和 MgWO ₄ ° 在大多数含 W 水中特别占优势，并导致白钨矿和其他含 W 矿物的不饱和。

评估水系统中的 W 污染并确定饮用水中的 W 限制可以防止 W 对人类和生态系统健康的潜在不利影响。