In Situ Measures of Dissolved Organic Carbon Flux in a Rural Stream

Abstract

Dissolved organic carbon (DOC) dynamics were measured in a second-order stream located in a pasture in southeastern Pennsylvania. In situ measurements made at six stations in early summer showed a diel patern of net DOC release from the streambed communities with predawn minima and afternoon maxima. When an 18-m section of the stream was covered with black plastic for 1 mo to exclude algal growth and measures were repeated in late summer, a net removal of DOC occurred in the covered section, while in an adjacent uncovered section DOC was released. When a bovine manure extract was introduced into the covered section, the DOC removal rate increased by more than an order of magnitude. Jewel-weed (Impatiens capensis L.) extract also elicited an elevated rate of DOC removal. When these extracts were added individually to microcosms, removal rates in the dark were 57 and 65% of the in situ uptake estimates for the manure extract and leachate, respectively. Abiotic controls showed that nearly all of the DOC removal was biotic uptake. DOC flux measurements in a third-order section of White Clay Creek, located on an adjacent watershed, also revealed a net DOC release from the uncovered streambed. Introduction of a bovine manure extract elicited a DOC removal rate an order of magnitude less than in the pasture stream. A companion microcosm experiment yielded an uptake rate that was 178% of the in situ estimate.

Immobilization and metabolism of dissolved organic carbon by natural sediment biofilms in a Mediterranean and temperate stream

“…This translates into considerable mass retention ( Table 2) that is closely bracketed by values reported from field experiments (e.g. Kuserk et al 1984).…”

“…Early field experiments showed that benthic microbial communities can retain considerable amounts of DOC (e.g. Kuserk et al 1984, McDowell 1985 and bacterial uptake and growth efficiency depend on the DOC source (Kaplan & Bott 1983). Kaplan & Bott (1985) and McArthur et al (1985) provided the first evidence that stream bacteria become acclimated to given sources of DOC.…”

Dissolved organic carbon in streams and groundwater

“…Creek, Canagagigue Creek and the Saugeen River were generally greater than those reported for streams of the Hubbard Brook Experimental Forest (1-3 mg/l, Fisher & Likens, 1973;Johnson et al, 1981;McDowell, 1985), for streams of the Pennsylvania Piedmont (means usually < 5 mg/l, Kaplan et al, 1980;Kaplan & Bott, 1982;Bott et al, 1984;Kuserk et al, 1984) or for streams of the Marmot Basin, Alberta (2-2.5 mg/l, Wallis et al, 1981), but were comparable to DOC concentrations reported for other hardwater streams in Michigan (Augusta Ck, annual mean 4.4 (k 45%) mg/l, Wetzel & Manny, 1977) and southern Ontario (2.3 -15.5 mg/l, Lock et al, 1977). Our Waterloo County Streams (Salem and Canagagigue Ck) were probably the most affected by agriculture of all these streams and their high daytime mean DOC concentrations may be attributable in part to enrichment by livestock manure and chemical fertilizers.…”

Does river restoration affect diurnal and seasonal changes to surface water quality? A study along the Thur River, Switzerland

“…(1)) results in an increase in photosynthates like carbohydrates (byproducts of photosynthesis) (Parker et al, 2010;Westhorpe and Mitrovic, 2012) and labile DOC by the phototransformation of recalcitrant DOC into more available forms (Bushaw et al, 1996;Lindell et al, 1996;Westhorpe and Mitrovic, 2012). On the contrary, the consumption by heterotrophs like bacteria, is expected to be higher in the nighttime in the absence of photosynthesis, which causes the DOC to decrease overnight (Bertilsson and Jones, 2003;Kuserk et al, 1984;Nimick et al, 2011). Another hypothesis is that when bacteria are exposed to sunlight, their metabolism can decrease during the day (Lindell et al, 1996;Westhorpe and Mitrovic, 2012).…”