DOM characteristics along the continuum from river to receiving basin: A comparison of freshwater and saline transects
Journal
Aquatic Sciences
Journal Volume
72
Journal Issue
4
Start Page
403
End Page
417
ISSN
1015-1621
1420-9055
Date Issued
2010-06-10
Author(s)
Minor, Elizabeth C.
Abstract
The chemical characteristics of bulk (sterile-filtered) and high molecular-weight dissolved organic matter (HMW DOM) were analyzed for freshwater (St. Louis River, Minnesota to Lake Superior) and saline (Elizabeth River, Virginia to Chesapeake Bay) river-to-receiving basin transects. Dissolved organic carbon concentrations and UV-Visible spectroscopy of bulk DOM demonstrated a reduction in organic carbon, colored DOM and aromatic compounds downstream in both transects. The proportion of DOM recoverable via ultrafiltration as HMW material also decreased downstream in both transects, although there was an offset in recoveries between the transects that may be explained by the effects of ionic strength and/or differences in ultrafiltration technique. The analysis of HMW DOM by Fourier transform infrared spectroscopy illustrated similar trends between transects, with a general shift from aromatic/carboxylic compounds nearshore to aliphatic/carbohydrate materials offshore. The parallel changes observed along saline and freshwater transects imply that similar processes play significant roles in the down-gradient alteration of DOM and that ionic strength or pH changes cause second-order effects.
Subjects
Chesapeake Bay
DOC
DOM characterization
FTIR
HMW DOM recovery
Lake Superior
Publisher
Springer Science and Business Media LLC
Type
journal article