Department of Earth and Environmental Sciences (DISAT), University of Milano-Bicocca, Piazza Della Scienza 1, Milan, 20126, Italy.
Federal University of the Amazon, Institute of Biological Sciences, Av. Rodrigo Otávio Jordao Ramos 3000, Manaus, 69077-000, Brazil.
Chemosphere. 2023 Sep;336:139285. doi: 10.1016/j.chemosphere.2023.139285. Epub 2023 Jun 21.
The Amazon is the largest river by discharge volume and one of the most biodiverse biomes in the world. Lately, there has been a rapid increase of the urban population in the region, which has been translated into a growing emission of organic contaminants such as polycyclic aromatic hydrocarbons (PAHs) into surface water bodies. This study provides the most comprehensive evaluation of the PAH contamination levels in surface waters of the Amazon basin. We investigated the occurrence and potential sources of 16 priority PAHs and characterised their risks for freshwater ecosystems. For this, we took 40 water samples from different sites along the Brazilian part of the Amazon River, including three major tributaries, and smaller rivers crossing the main urban areas. The results of this study show that PAHs are widespread contaminants in rivers of the Brazilian Amazon. The sum of the total concentration of the 16 priority PAHs reached values of 134 ng L in the Amazon River, and 163 ng L near densely populated areas. On the other hand, the total PAH concentration was generally lower in the monitored tributaries. In most samples, the contamination pattern was dominated by high molecular weight PAHs, suggesting a major contribution of pyrogenic sources, although petrogenic contamination was also present in some locations near urban areas. We assessed ecological risks posed by PAH mixtures using a hazard index. The results indicated that PAH contamination is not likely to pose direct toxic effects for Amazonian freshwater organisms, however continued monitoring is recommended near densely populated areas.
亚马逊河是世界上径流量最大、生物多样性最丰富的河流之一。最近，该地区的城市人口迅速增加，这导致有机污染物（如多环芳烃 (PAHs)）排放量不断增加，进入地表水。本研究对亚马逊河流域地表水的 PAH 污染水平进行了最全面的评估。我们调查了 16 种优先 PAHs 的存在情况及其潜在来源，并对其对淡水生态系统的风险进行了特征描述。为此，我们从巴西亚马逊河的不同地点采集了 40 个水样，包括三个主要支流和流经主要城市地区的较小河流。本研究的结果表明，PAHs 是巴西亚马逊河流域河流中广泛存在的污染物。16 种优先 PAHs 的总浓度总和在亚马逊河达到 134ng/L，在人口稠密地区附近达到 163ng/L。另一方面，监测的支流中的总 PAH 浓度通常较低。在大多数样品中，污染模式主要由高分子量 PAHs 主导，表明主要来自于高温源，尽管在靠近城市地区的一些地方也存在石油源污染。我们使用危害指数评估了 PAH 混合物造成的生态风险。结果表明，PAH 污染不太可能对亚马逊淡水生物造成直接毒性影响，但建议在人口稠密地区附近继续监测。
