Dionex integrion

The concentrations
of major ions were measured using two Dionex Integrion high-pressure
ion chromatography (HPIC, Thermo Fischer Scientific, USA) instruments.
Samples and blanks were prepared by filling ion chromatography vials
with 5 mL of the ∼10 mL final eluates from the solid-phase
extractions. The autosampler split the volume of each sample between
the two HPIC instruments, with one column to quantify the cations
(IonPac CS12A, Thermo Fischer Scientific, USA) and the other to quantify
the anions (IonPac AS18, Thermo Fischer Scientific, USA). Here, we
measured the concentrations of cations lithium, sodium, ammonium,
potassium, magnesium, and calcium and anions fluoride, acetate, formate,
chloride, nitrite, carbonate, sulfate, and nitrate in each solution.
The concentrations of the corresponding sample blanks were subtracted
from the samples. Concentrations in solution were calculated from
calibration curves for each ion of interest. Ion concentrations in
particle samples were derived using the total volume of air sampled.

The morphology was analyzed by field emission SEM (TESCAN MAIA3LMH) and TEM (Talos F200X). XRD patterns were recorded on a Shimadzu XRD-6100 with Cu Kα radiation. XPS spectra were collected on a Thermo Fisher ESCALAB Xi+ X-ray photoelectron spectrometer. All the XPS data were calibrated by shifting the C 1s peaks to 284.8 eV. The Raman spectra were measured on a Renishaw inVia Qontor Ramna microscope using laser excitation wavelength of 633 nm for copper and copper oxide detection and 532 nm for Ni(OH)_x species detection. The concentration of nitrate in the electrolyte was quantified on a Thermo Scientific Dionex Integrion. The EPR measurements were performed on a JEOL JES-FA200 spectrometer. The ¹H NMR spectra were measured on a AVANCE III HD 600 MHz NMR spectrometer. The mass spectra were collected on a GCMS-QP2020NX Shimadzu instrument. The contents of Ni and Cu elements in the Ni(OH)_x/Cu samples were measured on a NexION 350D inductively coupled plasma mass spectrometer (ICP-MS).

Different physicochemical parameters of water from the two mines were determined to link the microbial diversity and the geochemistry of the studied water samples. Mine water temperature was measured in situ using a conventional thermometer. pH and redox potential (E_H) were determined in situ using a pH meter 3110 (WTW, Germany) with a BlueLine 16 pH microelectrode (Schott Instruments, Germany) and a micro redox electrode with platinum ring (ORP electrode, Mettler-Toledo InLab, Spain).
For the determination of the geochemical parameters, aliquots of each mine water were centrifuged at 4020 × g for 15 min (Hettich EBA 21, Germany) prior to the analysis. A volume of 50 mL was acidified with nitric acid (HNO₃) and used to measure the total concentration of cations (Na, K, Mg, Ca, Al, Si, P, Mn, Fe, As, Ba, Th, U) by inductively coupled plasma mass spectrometry (ICP-MS, ELAN 9000, PerkinElmer, Germany). Furthermore, an aliquot of 15 mL was taken to measure the total concentration of anions (NO₂⁻, NO₃⁻, PO₄³⁻, SO₄²⁻, Cl⁻) by high-performance ionic chromatography (HPIC, Dionex Integrion, Thermo Fisher Scientific, USA). Total inorganic/organic carbon (TIC/TOC), dissolved organic carbon (DOC), and nitrogen were also quantified (Multi N/C 2100S, Analytik Jena, Germany).