MERCURY IN THE SEDIMENT OF PELOTAS RIVER BASIN, BRAZIL

ABSTRACT Many studies have determined the concentration of trace elements in river sediments in Brazil. Notwithstanding, mercury assessments are scarce, especially because of exclusive extraction techniques and expensive analysis techniques. Still, this element is known for its toxicity, persistence, and bioaccumulation, making its presence in the environment an important factor for biota and human health. For this reason, the objective of this study was to determine the mercury concentration in the sediment of the Pelotas River basin, located on the border of the states of Santa Catarina and Rio Grande do Sul. The sediment was collected at eight locations of the Pelotas basin and, after drying, the mercury was quantified by atomic absorption spectrometry based on the Zeeman-background correction, coupled to a pyrolysis reactor. The mercury concentrations in the sediments of the Pelotas River varied from 40.5 ng g-1 to 62.0 ng g-1 and presented a positive correlation with the fraction of silt and clay. The concentrations of mercury found in sediments of the Pelotas River basin have a low probability of negatively affecting the biota. Nonetheless, given the persistence and bioaccumulation potential of this element, the aforementioned region needs further studies to quantify the risks it may cause on the local biota and human health.摘要 已有多项研究测定了巴西河流沉积物中的微量元素浓度。尽管如此，针对汞的相关评估却较为匮乏，这主要缘于其专属的前处理提取技术与高昂的分析检测成本。不过，汞元素以毒性、持久性与生物富集性著称，其在环境中的存在对生物群落与人类健康均为关键影响因素。基于此，本研究旨在对位于圣卡塔琳娜州与南里奥格兰德州交界的佩洛塔斯河（Pelotas River）流域沉积物中的汞浓度进行测定。研究人员在佩洛塔斯流域的8个采样点采集沉积物样品，经干燥处理后，采用搭载热解反应器（pyrolysis reactor）的塞曼背景校正（Zeeman-background correction）原子吸收光谱法（atomic absorption spectrometry）对汞含量进行定量分析。佩洛塔斯河沉积物中的汞浓度范围为40.5 ng·g⁻¹至62.0 ng·g⁻¹，且与粉砂和黏土组分呈正相关关系。佩洛塔斯河流域沉积物中的汞浓度，对当地生物群落产生负面影响的概率较低。尽管如此，鉴于汞元素的持久性与生物富集潜力，上述区域仍需开展进一步研究，以量化其对当地生物群落与人类健康可能造成的风险。