Department of Biological Sciences, University of New Brunswick, Saint John, New Brunswick, Canada.
Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada.
Environ Toxicol Chem. 2019 Dec;38(12):2708-2718. doi: 10.1002/etc.4586. Epub 2019 Nov 16.
The aim of the present study was to characterize the effects of particles on metal aquatic toxicity in a tropical system. To this end, we investigated the effects of natural suspended solids on copper (Cu) geochemistry and acute toxicity to the cardinal tetra (Paracheirodon axelrodi), in 2 Amazonian rivers with different total suspended solids (TSS) levels: the Rio Negro (low TSS ~ 8 mg L ) and the Rio Solimões (high TSS ~ 70 mg L ). The effect of particles on Cu aqueous geochemistry was assessed by measuring total, dissolved, and free ionic Cu concentrations in filtered (<0.45 μm) and unfiltered waters. Furthermore, acute Cu toxicity to fish was assessed in both filtered and unfiltered waters, by measuring physiological net fluxes of Na , Cl , K , and total ammonia (in both river waters) and 96-h fish mortality (in Rio Solimões only). The particles in the Rio Negro were not abundant enough to play a significant role in our study. On the other hand, the Rio Solimões particles bound approximately 70% of total aqueous Cu in our tests. In agreement with bioavailability-based models, this decrease in dissolved (and free ionic) Cu concentration decreased Cu lethality in the 96-h toxicity tests. In the physiological measurements, the best evidence of particle protection was the total alleviation of Cu-induced Cl losses. These flux tests also suggested that the particles themselves may negatively affect Na balance in the fish. Overall, the present study supports the use of bioavailability concepts to account for the role of natural suspended solids on metal biological effects in the Amazon River basin. Environ Toxicol Chem 2019;38:2708-2718. © 2019 SETAC.
本研究旨在描述颗粒对热带系统中金属水生毒性的影响。为此，我们研究了天然悬浮固体对铜 (Cu) 地球化学和 cardinal tetra（Paracheirodon axelrodi）急性毒性的影响，这两种鱼分别来自于两条总悬浮固体（TSS）水平不同的亚马逊河流：Rio Negro（低 TSS8mg/L）和 Rio Solimões（高 TSS70mg/L）。通过测量过滤（<0.45μm）和未过滤水中的总、溶解和游离离子 Cu 浓度，评估了颗粒对 Cu 水相地球化学的影响。此外，通过测量生理净 Na 、Cl 、K 和总氨通量（在两条河水中）以及 96 小时鱼类死亡率（仅在 Rio Solimões 中），在过滤和未过滤水中评估了 Cu 对鱼类的急性毒性。Rio Negro 中的颗粒不够丰富，无法在我们的研究中发挥重要作用。另一方面，Rio Solimões 的颗粒在我们的测试中结合了约 70%的总水相 Cu。根据基于生物利用度的模型，溶解（和游离离子）Cu 浓度的降低降低了 96 小时毒性试验中 Cu 的致死率。在生理测量中，颗粒保护的最佳证据是完全缓解了 Cu 诱导的 Cl 损失。这些通量测试还表明，颗粒本身可能会对鱼类的 Na 平衡产生负面影响。总的来说，本研究支持使用生物利用度概念来解释天然悬浮固体对亚马逊河流域金属生物效应的作用。Environ Toxicol Chem 2019;38:2708-2718。 © 2019 SETAC。
