Abstract. In urban and industrialized areas, soil contamination and degradation caused by the deposition of industrial dusts may pose significant health and environmental risks. This problem relates to the vertical mobility and bioavailability of Potentially Toxic Elements (PTE). This study investigates the fate of PTE brought by industrial dusts in urban soils located in the Dunkerque agglomeration, one of the most industrialized areas of France. Four soil short cores were collected in the city of Gravelines (Dunkerque agglomeration) following a gradient from the industrial emitters to the deposition site. The soil cores were cut into discrete 1-cm-sections to study their PTE concentrations (using ICP-AES/MS analyses). Single HCl extraction was performed to evaluate the mobility of PTE in soils and to discuss their specific behavior according to the current soil parameters. For this purpose, the main soil parameters were identified (grain-size distribution, mineralogy, pH, CEC, TOC, calcium carbonates and water contents) in addition to the soil chemical composition (XRF, ICP-AES/MS analyses). The studied soils revealed globally low absorbent capacities for pollutants (CEC averaging 5.3 meq/100g), partially counterbalanced by the buffering effect of calcium carbonates (contents ranging from 8 % to 30 %). We highlighted minor (1<EF<3) to moderately severe (5<EF<10) Enrichment Factors in industrial PTE (Cr, Ni, Mo, Mn, Cd, Zn), in the first 3 centimeters of the soils located near the industrial emitters. The contamination profiles of these soils are concordant with atmospheric inputs of metallurgical dust. Using a relatively strong leaching reagent (HCl 1M), we estimated a low vertical mobility for Cr, Ni and Mo (average leached ratios <25 %) in soils, suggesting that these industrial PTE mainly occur in refractory phases (natural or anthropogenic). Mn, Cd and Zn, related to industrial and/or urban sources, present a higher mobility (average leached ratios > 60 % for Mn and Cd, and averaging 44 % for Zn). Our study points out the stability of industrial PTE in soils under current physicochemical conditions (calcareous soils with a slightly basic pH of 7.8). In this context, the monitoring of industrial PTE in these urban soils is highly recommended, considering (1) the presence of allotment gardens in the vicinity of the emitters and (2) the potential evolution of soil conditions as a result of increased flooding events.

中文翻译：

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敦刻尔克（法国北部）附近暴露于工业粉尘的城市土壤中金属元素行为的定量评估


摘要。在城市和工业化地区，工业粉尘沉积引起的土壤污染和降解可能会带来重大的健康和环境风险。这个问题与潜在毒性元素 （PTE） 的垂直移动性和生物利用度有关。本研究调查了位于法国工业化程度最高的地区之一敦刻尔克城市群的城市土壤中工业粉尘带来的 PTE 的命运。沿着从工业发射器到沉积地点的梯度，在 Gravelines 市（敦刻尔克集聚区）收集了四个土壤短岩芯。将土壤芯切成离散的 1 cm 切片以研究其 PTE 浓度（使用 ICP-AES/MS 分析）。进行单次 HCl 提取以评估 PTE 在土壤中的迁移率，并根据当前土壤参数讨论它们的具体行为。为此，除了土壤化学成分（XRF、ICP-AES/MS 分析）外，还确定了主要土壤参数（粒度分布、矿物学、pH、CEC、TOC、碳酸钙和水分含量）。研究的土壤显示，全球污染物的吸收能力较低（CEC 平均为 5.3 meq/100g），部分被碳酸钙的缓冲作用所抵消（含量从 8 % 到 30 %）。我们强调了位于工业排放源附近土壤的前 3 厘米中工业 PTE （Cr、Ni、Mo、Mn、Cd、Zn） 中的轻微 （1<EF<3） 至中度重度 （5<EF<n） 富集因子。这些土壤的污染概况与冶金粉尘的大气输入一致。 使用相对较强的浸出试剂 （HCl 1M），我们估计土壤中 Cr、Ni 和 Mo 的垂直迁移率较低（平均浸出比 <25 %），表明这些工业 PTE 主要发生在难熔期（自然或人为）。与工业和/或城市来源有关的 Mn、Cd 和 Zn 具有更高的迁移率（Mn 和 Cd 的平均浸出比 > 60%，Zn 的平均浸出率为 44%）。我们的研究指出，在当前物理化学条件下（钙质土壤，pH 值为 7.8 的钙质土壤）中，工业 PTE 在土壤中的稳定性。在这种情况下，考虑到 （1） 排放源附近存在分配花园，以及 （2） 由于洪水事件增加，土壤条件的潜在演变，强烈建议监测这些城市土壤中的工业 PTE。