Nickel toxicity to cardinal tetra (Paracheirodon axelrodi) differs seasonally and among the black, white and clear river waters of the Amazon basin. (15th October 2017)

• Record Type: Journal Article
• Authors: Holland, Aleicia; Wood, Chris M.; Smith, D. Scott; Correia, Tiago Gabriel; Val, Adalberto L.
• Is Part Of: Water research. Volume 123(2017)
• Page Start: 21
• Page End: 29
• Publication Date: 2017-10-15
• Subjects: Amazon basin -- Tropical -- Dissolved organic carbon -- Fish -- Nickel -- Toxicity; Water -- Pollution -- Research -- Periodicals; 363.7394
• DOI: 10.1016/j.watres.2017.06.044
• Languages: English
• ISSNs: 0043-1354

Abstract

Abstract: This study investigated the acute toxicity of nickel (Ni) to cardinal tetra ( Paracheirodon axelrodi ), within the three main water types of the Amazon basin: black (Rio Negro), white (Rio Solimões) and clear (Rio Tapajós) during the wet and dry season at pH 7 (representative of white and clear rivers) and pH 4 (representative of black waters). The influence of dissolved organic carbon (DOC) quality on Ni toxicity within the three waters was also explored via the use of DOC isolates. Differences in water chemistry, DOC quality and ion concentrations were shown between waters and between seasons. Toxicity of Ni was shown to vary between river waters, seasons, and pHs. Ni was significantly less toxic during the dry season at pH 4 in all three river waters; for example, black water during the wet season had an LC50 of 9.72 mg Ni/L compared to 41.5 mg Ni/L during the dry season. At pH 7, contrasting effects in toxicity between seasons were shown between black and clear waters (black: wet = 28.9 mg/L, dry = 17.3 mg/L; clear: wet = 13.8 mg/L, dry = 24.1 mg/L). There were no significant differences in Ni toxicity for white waters at pH 7 (white: wet = 22.2 mg/L, dry = 21.8). Overall, Ni was shown to be more toxic at pH 7 than at pH 4 except in black water during the wet season. Toxicity of Ni at pH 4 was negatively related to DOC concentration and amount of humic-like and fulvic-like DOC and positively related to fluorescence index. Therefore, at pH 4, Ni is more toxic in waters containing more allochthonous DOC, consisting of higher amounts of humic-like and fulvic-like components. LC50 values for the different DOC concentrates at the same DOC concentration of 4.5 mg/L (black: 26.8 mg/L; white: 73.3 mg/L; clear: 49.2) support the river water findings at pH 4 (Ni more toxic in presence of black DOC) indicating that DOC quality alone can influence Ni toxicity at this pH. Graphical abstract: Image 1 Highlights: Toxicity of Ni varied between river waters, seasons, and pHs. Ni more toxic at pH 7 than at pH 4. Ni more toxic during dry season compared with during the wet season at pH 4. Allochthonous humic-like DOC increases Ni toxicity at pH 4. DOC concentration has contrasting effects on toxicity at pH 4 and pH 7.