Lipid composition of suspended particulate matter (SPM) in a southeastern blackwater stream
Gary L. Millsa,b, J. Vaun McArthura, Charlotte P. Wolfea
aSavannah
River Ecology Laboratory, University of Georgia, Drawer E, Aiken, SC 29802,
USA
bAdvanced Analytical Center for Environmental Sciences, University
of Georgia, USA
Received 1 March 2001; received in revised form 1 December 2001
Abstract
Suspended particulate matter
(SPM) was collected seasonally for I yr at third- and fifth-order sites
in a blackwater stream on the coastal plain in South Carolina. Fatty acids
with carbon chain lengths from CI2-C32 were the
most abundant component among the lipid classes examined with total concentrations
varying from 8.5 to 60.211µg L -1. Unsaturated fatty
acids predominated while significant concentrations of the even-chained
saturated components C24- C30 derived from cuticular
plant waxes were also found. Concentrations of aliphatic alcohols, with
carbon chain lengths between C16 and C30, ranged
from 0.52 to 2. 7311µg L -1 and was dominated by the
higher molecular weight compounds (C22-C30) derived
primarily from cuticular plant waxes. Total hydrocarbon concentrations
ranged from 0.35 to 5.6611µg L-1 and showed no discernible
trends with time or consistent difference between sites. The hydrocarbon
assemblage observed indicates that these components are entirely of biogenic
origin with no detectable anthropogenic contribution.
The ratios of unsaturated to saturated fatty acids and cuticular to noncuticular
fatty acids and alcohols at both stream locations indicate that the organic
detritus associated with SPM collected during November and January is
of more recent origin and less processed than that collected in the spring
and summer months. Lipid concentrations at the third-order site generally
had higher and more variable concentrations of the lipid classes compared
with the fifth-order site. The ratio of saturated to unsaturated fatty
acids was higher at the third-order site indicating that the organic fraction
of SPM at this site was of more recent origin and less decomposed. The
ratios of cuticular to noncuticular fatty acids and alcohols support this
conclusion. These results indicate an export of particulate lipids of
higher carbon resource quality from upstream to lower stream reaches.
Keywords: Lipids; Suspended
solids; SPM; paM; Particulate organic matter; Fatty acids; Alcohols; Hydrocarbons;
Streams
SREL Reprint #2671
Mills, G. L., J. V. McArthur and C. P. Wolfe. 2003. Lipid composition of suspended particulate matter (SPM) in a southeastern blackwater stream. Water Research 37:1783-1793.
