Standard Methods65 were used to evaluate turbidity (Method 2130B;
Hach 2100 N turbidimeter, Loveland, CO), pH (4500-H+B Electrometric
method; Orion 720A pH meter, Thermo Fisher Scientific, Waltham, MA),
alkalinity (Method 2320; titration method with pH end point of 4.5),
DOC concentration (filtration through prerinsed 0.45 μm Nylaflo
membranes, Pall, Port Washington, NY; Method 5310B; Shimadzu TOC-V
CPH analyzer, Kyoto, Japan) with a reporting limit of 0.2 mg/L, and
ultraviolet absorbance at 254 nm (UVA254; Method 5910B;
1 cm quartz cell; Hach DR 5000 Spectrophotometer, Loveland, CO). Specific
ultraviolet absorbance at 254 nm (SUVA) was calculated by dividing
UVA254 absorbance by the DOC concentration.69 (link)Liquid chromatography in combination with
organic carbon detection (LC-OCD) was used to fractionate DOC (as
biopolymers [BPs], humic substances [HS], building blocks [BB], low
molecular-weight [LMW] neutrals, LMW acids) as described in Huber
et al.66 (link) Samples were first filtered through
a prerinsed 0.45 μm polyether sulfone membrane (Millipore Express
PLUS; Merck Millipore, Burlington, MA). Chromatographic separation
was completed using a weak cationic exchange column (Toyopearl, TSK
HW 50S, Tosoh, Japan).
Hach 2100 N turbidimeter, Loveland, CO), pH (4500-H+B Electrometric
method; Orion 720A pH meter, Thermo Fisher Scientific, Waltham, MA),
alkalinity (Method 2320; titration method with pH end point of 4.5),
DOC concentration (filtration through prerinsed 0.45 μm Nylaflo
membranes, Pall, Port Washington, NY; Method 5310B; Shimadzu TOC-V
CPH analyzer, Kyoto, Japan) with a reporting limit of 0.2 mg/L, and
ultraviolet absorbance at 254 nm (UVA254; Method 5910B;
1 cm quartz cell; Hach DR 5000 Spectrophotometer, Loveland, CO). Specific
ultraviolet absorbance at 254 nm (SUVA) was calculated by dividing
UVA254 absorbance by the DOC concentration.69 (link)Liquid chromatography in combination with
organic carbon detection (LC-OCD) was used to fractionate DOC (as
biopolymers [BPs], humic substances [HS], building blocks [BB], low
molecular-weight [LMW] neutrals, LMW acids) as described in Huber
et al.66 (link) Samples were first filtered through
a prerinsed 0.45 μm polyether sulfone membrane (Millipore Express
PLUS; Merck Millipore, Burlington, MA). Chromatographic separation
was completed using a weak cationic exchange column (Toyopearl, TSK
HW 50S, Tosoh, Japan).