Marziali Laura, Roscioli Claudio, Valsecchi Lucia
CNR-IRSA Water Research Institute, National Research Council, Via del Mulino 19, 20861 Brugherio, MB, Italy.
Toxics. 2021 Aug 24;9(9):197. doi: 10.3390/toxics9090197.
Riverine sediments are important sites of mercury methylation and benthic invertebrates may be indicators of Hg exposure to higher organisms. From 2014 to 2018, sediments and invertebrates were collected along a mercury gradient in the Toce River (Northern Italy) and analyzed for THg and MeHg. Concentrations in invertebrates, separated according to taxon and to Functional Feeding Group, ranged from 20 to 253 µg kg dry weight (d.w.) for THg, increasing from grazers (, , ) to predators (). MeHg ranged from 3 to 88 µg kg d.w. in biota, representing 6-53% of THg, while in sediments it was mostly below LOD (0.7 µg kg), accounting for ≤3.8% of THg. The Biota-Sediment Accumulation Factor (BSAF, ranging 0.2-4.6) showed an inverse relation to exposure concentrations (THg in sediments, ranging 0.014-0.403 µg kg d.w.) and to organic carbon. THg in invertebrates (up to 73 µg kg wet weight), i.e., at the basal levels of the aquatic trophic chain, exceeded the European Environmental Quality Standard for biota (20 µg kg w.w.), posing potential risks for top predators. Concentrations in adult insects were close to those in aquatic stages, proving active mercury transfer even to terrestrial food chains.
河流沉积物是汞甲基化的重要场所，底栖无脊椎动物可能是汞暴露于高等生物的指标。2014年至2018年期间，在意大利北部的托切河沿汞梯度采集了沉积物和无脊椎动物，并对总汞（THg）和甲基汞（MeHg）进行了分析。根据分类群和功能摄食组分类的无脊椎动物中，总汞浓度范围为20至253微克/千克干重（d.w.），从食草动物（，，）到捕食者（）逐渐增加。生物群中甲基汞的浓度范围为3至88微克/千克干重，占总汞的6 - 53%，而沉积物中的甲基汞大多低于检测限（0.7微克/千克），占总汞的比例≤3.8%。生物群 - 沉积物积累因子（BSAF，范围为0.2 - 4.6）与暴露浓度（沉积物中的总汞，范围为0.014 - 0.403微克/千克干重）和有机碳呈反比关系。无脊椎动物中的总汞（高达73微克/千克湿重），即在水生营养链的基础水平，超过了欧洲生物群环境质量标准（20微克/千克湿重），对顶级捕食者构成潜在风险。成虫中的浓度与水生阶段的浓度相近，证明汞甚至能有效转移到陆地食物链。
