2013-17 Apex River water chemistry data

Samples of winter snowpack (prior to melt), streams, lakes, and rainfall were collected between May to November in 2013-2017. Each water sample was analysed for electrical conductivity, pH, and temperature in situ (no in situ pH since 2015), and then analysed for dissolved ions, dissolved organic matter (DOM), and stable water isotopes at Queen's University. Samples for ions and stable water isotope analysis were collected in triple sample rinsed 500ml Nalgene bottles, and immediately filtered through a 0.22µm filter in parafilmed and refrigerated. DOM samples were vaccum filtered using a glass filtration apparatus and precombusted 0.7 μm GF/F glass fibre filters. The filtration apparatus was soaked overnight with 30% hydrogen peroxide, and triple rinsed with deionised water and sample for each use. The samples were stored cool in the dark (refrigerated) in amber glass EPA vials, and acidified to a pH of 2 upon return to the laboratory. DOC concentrations were measured as non-purgeable organic carbon via high temperature combustion (720°C) with a Shimadzu TOC-VCPH analyser using a high sensitivity platinum catalyst in line with a total nitrogen module (TNM-1 unit). TDN concentrations were measured as nitrogen monoxide via thermal decomposition. Samples were analysed for cations (Na+, K+, Ca2+, and Mg2+) and anions (Cl-, Br-, NO2-, SO42-, NO3-, PO43-) by liquid ion chromatography with a Dionex ICS-3000. The ion chromatograph was equipped with an ASRS 300 suppressor and AS18 analytical column for anions, and a CSRS 300 suppressor and CS12A analytical column for cations.